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Cisco IOS Software Releases 12.0 S

Link Bundling on Cisco 12000 Series Internet Routers

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Link Bundling on Cisco 12000 Series Internet Routers

Table Of Contents

Link Bundling on Cisco 12000 Series Internet Routers

Feature Overview

Using EtherChannel Link Bundles

Using POS Channel Link Bundles

Link Bundling in a Cisco 12000 Series Internet Router

Engine 5 Ingress Support

Load-balancing in Cisco 12000 Series Link Bundles

VLAN ID-Based Load-balancing

Software Features Supported on a Link Bundle

Using an EtherChannel for High-Speed Provider Edge Support

Any Transport over MPLS—Ethernet over MPLS

Stacked VLAN Processing—802.1Q-in-Q

Feature Parity on VLAN and Stacked VLAN Member Interfaces

MAC Address Accounting

Multicast and Multicast VPN

Policy-Based Routing

Unicast Reverse Path Forwarding

VLAN Scalability

Quality of Service

Feature Parity on POS Channel Bundles

Route Processor Redundancy Plus

Stateful Switchover

Benefits of Link Bundling

Restrictions for Link Bundling

Related Features and Technologies

Related Documents

Supported Platforms

Supported Standards, MIBs, and RFCs

Configuration Tasks

Configuring a Port-Channel Interface

Configuring a POS-Channel Interface

Adding a Fast Ethernet or Gigabit Ethernet Interface

Adding a Packet-over-SONET Interface

Maximizing VLAN TCAM to Support VLAN Scalability

Removing an Ethernet or Packet-over-SONET Interface from a Link Bundle

Configuring Out-of-Service Support

Configuring Bandwidth Propagation

Verifying an EtherChannel

Verifying a POS Channel

Configuration Examples

Configuring an EtherChannel

Configuring a VLAN EtherChannel

Removing an EtherChannel

Configuring a POS Channel

Removing a POS Channel

Configuring Out-of-Service Support

Configuring Bandwidth Propagation

Command Reference

channel-group

hw-module slot linkbundle-tcam-scalability

interface port-channel

interface pos-channel

show interfaces port-channel

show interfaces pos-channel

Glossary


Link Bundling on Cisco 12000 Series Internet Routers


Part Number OL-8696-01, May 30, 2008

Feature History

Release
Modification

12.0(23)S

This feature was introduced on Engine 0, Engine1, and Engine 2 line cards on the Cisco 12000 series Internet router.

12.0(26)S

This feature was introduced on IP Service Engine (ISE/E3) and Engine 4 Plus (E4+) line cards on the Cisco 12000 series Internet router.

The following new features were introduced:

Out-of-service support

Bandwidth propagation support

12.0(32)S

Support was added for the following features in a link bundle that consists only of ISE/E3 or E4+ Gigabit Ethernet (GE) member interfaces in a
Cisco 12000 series Internet router deployed on the provider edge:

Any Transport over MPLS (AToM: Layer 2 Quality of Service, Ethernet over MPLS—VLAN mode only, and Layer 2 Local Switching)

Stacked VLAN (802.1Q-in-Q) Processing

MAC Address Accounting

Multicast and Multicast VPN (Gigabit Ethernet ISE interfaces only)

Policy-Based Routing

Quality of Service (QoS)

Feature parity on VLAN and Stacked VLAN subinterfaces

Unicast Reverse Path Forwarding (Loose Mode)

VLAN scalability

Engine 5 Ingress support was added.
VLAN ID-based mode of load-balancing was added.
route processor redundancy plus (RPR+) support in link bundles was added.

12.0(33)S

Support was added for the following features in an ISE/E3 link bundle that consists of POS or GE member interfaces:

Multicast Egress QoS

QoS hierarchical policing

QoS hierarchical shaping

Unicast Reverse Path Forwarding (Strict Mode)

Support was added for Engine 5 (E5) Fast Ethernet member interfaces in an EtherChannel link bundle.

Engine 5 Egress support was added so that the following features are now supported in an EtherChannel link bundle that consists of E5 Fast Ethernet or Gigabit Ethernet member interfaces:

Any Transport over MPLS (AToM: Layer 2 Quality of Service, Ethernet over MPLS—VLAN mode only, and Layer 2 Local Switching)

Border Gateway Protocol (BGP) policy accounting

Feature parity on VLAN and Stacked VLAN subinterfaces

Hot Standby Router Protocol (HSRP)

MAC Address Accounting

MPLS VPN

Multicast and Multicast VPN

Policy-Based Routing

Quality of Service (QoS), including:

Multicast Egress QoS

QoS hierarchical policing

QoS hierarchical shaping

Route processor redundancy plus (RPR+)

Sampled and Aggregate NetFlow on input and output interfaces

Stacked VLAN (802.1Q-in-Q) Processing

Unicast Reverse Path Forwarding (Loose and Strict Mode)

VLAN ID-based mode of load-balancing

VLAN scalability

Cisco IOS software feature parity between a POS channel that consists of ISE, E4+, E5, or E6 member interfaces and EtherChannel bundles was added. Table 4 lists supported features.

Stateful Switchover (SSO) support in link bundles was added.


This feature module describes how to configure and use the Link Bundling feature on Cisco 12000 series Internet routers. This document includes the following sections:

Feature Overview

Supported Platforms

Supported Standards, MIBs, and RFCs

Configuration Tasks

Configuration Examples

Glossary

Feature Overview

The Link Bundling feature allows you to group multiple point-to-point links together into one logical link to provide higher bidirectional bandwidth (a bigger pipe), redundancy, and load-balancing between two routers. The following types of link bundling are supported on Cisco 12000 series Internet routers:

Fast EtherChannel—Used to bundle multiple E5 Fast Ethernet (FE) interfaces.

Gigabit EtherChannel—Used to bundle multiple Gigabit Ethernet (GE) interfaces.

POS channel—Used to bundle multiple Packet-over-SONET (POS) interfaces.

Managing Bandwidth

All three link bundling methods on Cisco 12000 series Internet routers provide flexible and incremental bandwidth with link redundancy and greater layer transparency to network applications. You can use link bundles in multiple locations in the same network.

Use link bundling on Cisco 12000 series Internet routers in networks under the following conditions:

Faster links do not exist

The next step available for increasing link capacity is expensive

The operational costs to increase link capacity are high

EtherChannels and POS channels allow you to increase and decrease bandwidth by adding or removing an interface from the link bundle. Also, by incrementally increasing bandwidth, you are no longer dependent on the fixed increases in bandwidth (for example, 1 Gbps, 10 Gbps, and so on) determined by the physical layer technology.

Managing Link Failure

The failure of one link does not necessarily cause a network failure. Traffic is redirected to remaining links within the channel without user intervention. As a result, the availability of a FE, GE, or POS link is increased.

On Cisco 12000 series Internet routers, link bundling is implemented so that a virtual interface is created for each link bundle. You can dynamically add and delete links to the virtual interface. The virtual interface is treated as one interface on which you configure an IP address and other software features used by the link bundle, instead of configuring them on individual GE and POS interfaces.

Packets sent to the link bundle are forwarded on one of the links in the bundle. Load-balancing is supported on all links in a bundle using per-destination load-balancing based on a hash calculated using the source and destination IP addresses in the IP packet. Per-destination load-balancing ensures that packets are delivered in order.

For a description of how to use EtherChannel and POS channel link bundling on Cisco 12000 series Internet routers, see the "Using EtherChannel Link Bundles" section and the "Using POS Channel Link Bundles" section.

Link Bundling Features

Beginning in Cisco IOS Release 12.0(26)S, support for the following features is added to link bundling on Cisco 12000 series Internet routers:

Out-of-service support—If the minimum bandwidth is not available on a link bundle, the EtherChannel or POS channel are brought down. The link bundle is brought up again when the specified minimum number of links are active.

Bandwidth propagation—In releases earlier than Cisco IOS Release 12.0(33)S, when the bandwidth used on a EtherChannel or POS channel changes, each bandwidth change is propagated, by default, to the upper-layer protocols. You can now (optionally) control the propagation of bandwidth changes and specify a bandwidth threshold so that the total bandwidth of a link bundle is propagated at each change until it exceeds the threshold value.

For a description of how to configure out-of-service support and bandwidth propagation, see the "Configuring Out-of-Service Support" section and the "Configuring Bandwidth Propagation" section.

Using EtherChannel Link Bundles

EtherChannel link bundles are at Layer 2 and use one MAC address and one IP address for all FE or GE interfaces in the bundle. A Fast or Gigabit EtherChannel is used mostly in intra-POP applications to interconnect multiple routers. Figure 1 shows how to aggregate Gigabit Ethernet links into one Gigabit EtherChannel interface in an intra-POP application.

Figure 1 Gigabit EtherChannel Used in an Intra-POP Application

You can also use an EtherChannel in metropolitan area networks for Ethernet aggregation at the network edge. For example, you can use a Gigabit EtherChannel to connect multiple sites that are moving from using 1 Gbps to 10 Gbps throughput. Bandwidth demand grows at different rates in metropolitan network sites, depending on business needs and data traffic patterns. You can, therefore, use Gigabit EtherChannel to incrementally increase bandwidth in 1-Gbps segments.

Using POS Channel Link Bundles

POS channel link bundles are at Layer 2 and use one logical IP interface. You can use POS channel link bundling in intra-POP applications (Figure 2), and in backbone (Figure 3) and peering connections.

For example, if the fiber infrastructure required to support greater transmission speeds does not exist, bundling together multiple POS connections is useful. A POS channel link bundle provides an alternative way to support OC-48, OC-192, or OC-768 transmission speeds.

Figure 2 POS Channel Used in an Intra-POP Application

Figure 3 POS Channel Used in a Backbone Application

Link Bundling in a Cisco 12000 Series Internet Router

Link bundling is a capability that must be supported on a system-wide level in a Cisco 12000 series Internet router. The Link Bundling feature requires that each line card in the router recognize an EtherChannel or POS channel bundle as a virtual interface.

The successful flow of data packets into and out of a link bundle consists of the following steps:

1. An EtherChannel or POS channel link bundle is created on a line card or across multiple line cards.

2. An adjacency representing the new bundle is created in the forwarding information base (FIB) table on the route processor (RP) and is forwarded to all the line cards. This adjacency represents a virtual link and has pointers to individual links in the bundle.

3. As incoming data packets are received by the router, line cards route packets to the link bundle as a whole. The ability to route and load balance packets across the bundle depends on whether or not a line card recognizes the new virtual link adjacency. The line card that receives incoming packets and decides how to route them to the link bundle is called the ingress line card. The process of making the decision is called ingress decision support.

If the ingress line card:

Supports the ingress decision capability, the line card recognizes the virtual adjacency, and properly routes and load balances the packets across the subadjacencies represented by the virtual adjacency. Packets are properly routed and load balanced towards the bundle, and then properly transmitted across the bundle.

Does not support the ingress decision capability, the line card routes packets to the virtual adjacency, but does not perform load-balancing across the subadjacencies. Packets are sent across only one link in the bundle. As a result, this link can become saturated and packets can be dropped. For a list of the Cisco 12000 series line cards that support and do not support the ingress decision capability, see the "Restrictions for Link Bundling" section.

4. When incoming packets are received by the link bundle, the packets are properly routed to the destination interface in the router.

Engine 5 Ingress Support

Starting in Cisco IOS Release 12.0(32)S, EtherChannel bundles support load-balancing across member links for the following combinations of IP and MPLS data streams when an Engine 5 line card is the ingress interface and an EtherChannel port-channel interface is the egress interface in a Cisco 12000 series Internet router. An Engine 5 ingress interface:

Receives IP packets; a port-channel interface forwards the IP packets.

Receives IP packets; a port-channel interface encapsulates packets with an MPLS label and forwards the packets.

Encapsulates packets with an MPLS label; a port-channel interface swaps or replaces the MPLS label and forwards the MPLS packets.

Receives MPLS packets; a port-channel interface removes the MPLS labels and forwards IP packets.

Configured for AToM encapsulates incoming packets and transmits them across a pseudowire connection; a port-channel interface decapsulates the packets and transmits the Layer 2 packets.

In these conditions, IP and MPLS packets are load-balanced across the member links in an EtherChannel bundle. For more information about MPLS tag switching, refer to MPLS/Tag Switching.

Load-balancing in Cisco 12000 Series Link Bundles

On Cisco 12000 series Internet routers, EtherChannel, and POS channel link bundling provides load-balancing (equal cost) across all active links in the bundle. Load-balancing (also known as Layer 2 load-balancing) is supported on the links using per-destination load-balancing, based on a hash calculated using the source and destination IP addresses in the IP packet. Per-destination load-balancing ensures that packets are delivered in order.

In an EtherChannel or POS channel link bundle, you can only configure interfaces of the same engine and media type. (For more information, see "Line Card Restrictions in Routers on Each Side of a Link Bundle" section.) Each engine type uses a different hash algorithm to perform load-balancing across member interfaces in a link bundle.

Load-balancing logic is built into the CPU software of lower engine types and into the Layer 3 packet-switching ASIC (PSA) driver modules of higher engine types. Load-balancing logic is stored:

In the CPU software on Engine 0 and Engine 1 line cards

On the packet-switching ASIC (PSA) of Engine 2 line cards

On the ALPHA PSA of IP Service Engine (ISE) line cards

On the Rx Plus PSA of Engine 4 Plus (E4+) line cards

On the WAHOO PSAs of Engine 5 (E5) line cards


Note Layer 2 load-balancing is always performed on the ingress line card when a packet is switched.

Equal load-balancing across all links in a bundle occurs only when the source and destination IP addresses in packets vary across a wide range of IP addresses.


Starting in Cisco IOS Release 12.0(32)S, VLAN ID-based load-balancing, is supported. See "VLAN ID-Based Load-balancing" section for more information.

VLAN ID-Based Load-balancing

VLAN ID-based load-balancing is supported on the port-channel interface of an EtherChannel bundle that consists of the following member interfaces:

E5 Fast Ethernet

ISE (E3) Gigabit Ethernet

E4+ Gigabit Ethernet

E5 Gigabit Ethernet

Outgoing traffic is normally equally balanced across all links in a bundle based on the source and destination IP address of transmitted packets. However, VLAN ID-based load-balancing in a link bundle introduces load-balancing based on the VLAN ID of transmitted packets.

When you configure VLAN ID-based load-balancing, all egress traffic with a specified VLAN ID is internally mapped to outgoing member interfaces through which the traffic is transmitted. To switch between VLAN ID-based and per-destination load-balancing, use the channel-group load-share vlan command in (port-channel) interface configuration mode.

Use VLAN ID-based load sharing in a link bundle in the following configurations:

A customer requires VLAN-specific Quality of Service on egress traffic, which cannot be achieved due to hardware limitations when source- and destination-based load-balancing is enabled.

For Layer 2 traffic or when AToM features are configured on a port-channel interface, Layer 3 parameters, such as source and destination IP address, are not supported. Therefore, we recommend load-balancing based on Layer 2 characteristics.


Note VLAN ID-based load-balancing is effective when there are a large number of (more than 10) VLANs configured on the port-channel interface. When only a few VLANs are configured in an EtherChannel, VLAN ID-based load-balancing is not effective for balancing outgoing traffic across member links.


The VLAN ID-to-interface mapping is performed by assigning the traffic for each VLAN ID according to the load supported on a member interface and the load required by the VLAN. The load required for VLAN traffic is calculated as the bandwidth allocated to the Modified Deficit Round Robin (MDRR) queue. New VLAN traffic is assigned to the member interface transmitting the smallest load. The total load of egress VLAN traffic in a link bundle is balanced among member interfaces. If a change in the number of active member links available for use occurs, the VLAN ID-to-interface mapping is recalculated.

Software Features Supported on a Link Bundle

Sometimes the software features supported on an Fast Ethernet, Gigabit Ethernet, or POS interface are not supported on the entire link bundle because of engineering restrictions. For example, IPv6 is not supported on a link bundle. Configuring an unsupported feature on an EtherChannel or POS channel link-bundle interface may result in unexpected behavior.

On Cisco 12000 series Engine 0 (E0), E1, and E2 line cards, the minimum set of software features supported across an entire link bundle (port-channel or pos-channel and member interfaces) is:

IP unicast

Multiprotocol Label Switching (MPLS)

MPLS virtual private networks (VPNs)

MPLS VPN Inter-Autonomous Systems (Inter-AS)

Weighted Random Early Detection (WRED) and Modified Deficit Round Robin (MDRR) on each member interface


Note Engine 1 and Engine 2 interfaces do not support VLAN configuration in an EtherChannel.


On Cisco 12000 series ISE/E3, E4+, and E5 line cards, the minimum set of software features supported on the port-channel or pos-channel and member interfaces is:

IP unicast

Equal-cost load-balancing of IP traffic is performed across all active links in a link bundle.

VLAN configuration on a link bundle—EtherChannels only

An EtherChannel interface supports the configuration of VLAN subinterfaces. However, the configuration of stacked (802.1Q-in-Q) processing is only supported on certain EtherChannel interfaces. For more detailed information, see "Stacked VLAN Processing—802.1Q-in-Q" section.

For an example of how to configure an EtherChannel that consists of Ethernet VLAN links, see the "Configuring a VLAN EtherChannel" section.

Multiprotocol Label Switching

Equal-cost load-balancing of MPLS traffic is performed across all active links in a link bundle.

MPLS virtual private networks

A Layer 3 MPLS VPN configuration is supported on an EtherChannel or POS channel interface that is used in any of the following Provider Edge (PE) router configurations:

PE-to-CE (customer edge) connection as a VPN routing and forwarding (VRF) instance

PE-to-P (provider core) connection as a core-facing interface

Quality of Service (QoS) features: shaping, policing, MDRR/WRED, and packet marking

Access Control Lists (ACLs)

Named ACLs

Sampled NetFlow on:

Input interfaces only

Output interfaces only

On both input and output interfaces

Border Gateway Protocol (BGP) policy accounting

Hot Standby Router Protocol (HSRP) and Virtual Router Redundancy Protocol (VRRP)—EtherChannels only


Note If the link bundle consists of Engine 5 line cards with different ASIC versions, software features may not be supported in an EtherChannel. For example, stacked VLAN (802.1Q-in-Q) processing is supported in an EtherChannel only if all member interfaces are on SPAs that use the Engine 5 Version 2 FUGU ASIC. The Version 1 GILA ASIC does not support stacked VLAN processing. For information about Engine 5 line card support on specific ASIC versions, refer to Supported Line Cards for the 12000 Series Routers in the Cross-Platform Release Notes for Cisco IOS Release 12.0S.


Using an EtherChannel for High-Speed Provider Edge Support

In addition to the minimum set of software features described in the "Software Features Supported on a Link Bundle" section, the following software features are also supported in an EtherChannel that consists of ISE (E3), Engine 4+ (E4+), or Engine 5 (E5) member interfaces in a Cisco 12000 series Internet router that is deployed as a provider edge (PE) router:

Any Transport over MPLS—Ethernet over MPLS

Ethernet over MPLS—VLAN Mode

Layer 2 Quality of Service

Layer 2 Local Switching

Stacked VLAN Processing—802.1Q-in-Q

Unicast Reverse Path Forwarding

VLAN ID-Based Load-balancing

Multicast and Multicast VPN

Policy-Based Routing

Quality of Service, including: traffic shaping, policing, Modified Deficit Round Robin (MDRR), Weighted Random Early Detection (WRED), packet classification (marking), filtering defined by access control lists (ACLs), and Class of Service (COS) bit mapping

Route Processor Redundancy Plus

Stateful Switchover

Any Transport over MPLS—Ethernet over MPLS

The following Any Transport over Multiprotocol Label Switching (AToM)—Ethernet over MPLS (EoMPLS) features are supported only on the port-channel (logical) interface of an EtherChannel bundle that is configured for EoMPLS:

Ethernet over MPLS—VLAN Mode

Layer 2 Quality of Service

Layer 2 Local Switching

Layer 2 Protocol Tunneling and PDU Filtering

EoMPLS provides the following benefits:

A tunneling mechanism for Ethernet traffic through an MPLS-enabled Layer 3 core. It encapsulates Ethernet protocol data units (PDUs) inside MPLS packets and using label stacking forwards them across the MPLS network.

The ability for service providers to offer customers a virtual Ethernet line service or VLAN service using the service provider's existing MPLS backbone.

For more information about how to configure and use EoMPLS, refer to Any Transport over MPLS.

Ethernet over MPLS—VLAN Mode

In an MPLS network, the Ethernet over MPLS (EoMPLS) feature enables you to connect two VLAN networks located in different locations, without using bridges, routers, or switches at the VLAN locations. You can enable the MPLS backbone network to accept Layer 2 VLAN traffic by configuring the label edge routers (LERs) at both ends of the MPLS backbone.

In the Link Bundling feature on the Cisco 12000 series Internet router, EoMPLS is supported on the port-channel interface of an EtherChannel bundle that consists of the following member interfaces and only in VLAN mode:

ISE/Engine 3 Gigabit Ethernet

Engine 5 Fast Ethernet

Engine 5 Gigabit Ethernet

You can configure an EtherChannel with EoMPLS on the ingress interface of a PE router in a PE-CE (customer edge) connection or on the egress interface in a PE-P provider-core router connection.

VLAN mode transports Ethernet traffic from a source 802.1Q VLAN to a destination 802.1Q VLAN (including stacked VLAN 802.1Q-in-Q traffic) over a core MPLS network. You must configure Ethernet over MPLS (VLAN mode) on the subinterfaces of member interfaces.


Note EoMPLS is not supported in port mode on an EtherChannel port-channel interface. Port mode allows a frame traveling into an interface to be packed into an MPLS packet and transported over the MPLS backbone to an egress interface. The entire Ethernet frame is transported without the preamble or Frame Check Sequence (FCS) as one packet.


When you configure EoMPLS on a port-channel interface, AToM virtual circuits (VCs) are transparently distributed on the interfaces of the member links in PE-to-P router connections by the AToM control plane, which views the link bundle as one virtual interface. A VC label is allocated on a per-VLAN basis. Because all Ethernet packets are forwarded on the same path for a given VLAN, the egress VLAN ID is used to obtain the Layer 2 adjacency.

On the port-channel interface, EoMPLS also supports the VLAN ID Rewrite feature, which enables you to use VLAN interfaces with different VLAN IDs at both ends of the tunnel.

In an EoMPLS configuration on a port-channel interface, only VLAN ID-based load-balancing is supported.

Layer 2 Quality of Service

On the Cisco 12000 series Internet router, Layer 2 QoS features that are normally supported on Fast or Gigabit Ethernet interfaces (see the "Quality of Service" section) are supported on the port-channel (Layer 3) interface of a link bundle that is configured for EoMPLS and consists of the following member interfaces:

ISE/Engine 3 Gigabit Ethernet

Engine 5 Fast Ethernet

Engine 5 Gigabit Ethernet

Supported Layer 2 QoS features include:

Per-class traffic shaping on egress traffic (disposition)

2-rate, 3-color Color-blind policer (supported on Cisco 12000 series ISE and E5 Ethernet line cards, based on RFC 2698)


Note The QoS: Color-Aware Policer feature is not supported on a port-channel interface. You can configure policing for EtherChannel traffic only in color-blind mode. The conform-color command is not supported.


Policing and bit marking on ingress traffic (imposition)

Marking MPLS experimental bits as a policing action, in addition to setting the 802.1p User Priority field (P-bits)

Mapping and copying the Layer 2 class of service (COS) P-bits to MPLS experimental bits at the ingress interface

Mapping and copying MPLS experimental bits to Layer 2 CoS P-bits at the egress interface

Setting Layer 2 CoS P-bits based on the VLAN ID at the egress interface

Policing and shaping Layer 2 VPN traffic at the MPLS imposition and disposition interfaces allows a service provider to offer service level agreements (SLAs) to customers in terms that include bandwidth, delay, jitter, and packet-loss guarantees in an EtherChannel connection. At imposition, Ethernet QoS markers are mapped to MPLS experimental bits. The traffic can be classified by the MPLS experimental bit then policed and shaped on provider interfaces.

For traffic traversing an EtherChannel, Modified Deficit Round Robin (MDRR) Congestion management and Weighted Random Early Detection (WRED) congestion avoidance are supported for MPLS packets with Layer 2 VPN payloads. Because packet queuing characteristics vary among Cisco 12000 series line cards, MDRR and WRED configurations can vary with the line card combinations used for MPLS imposition and disposition interfaces.

The following restrictions apply to Layer 2 QoS features configured on a port-channel interface:

Per-class traffic shaping is not supported in a QoS policy attached to an ingress port-channel interface that performs EoMPLS label imposition and disposition.

MDRR and WRED on ToFab queues are not supported on a port-channel interface that performs EoMPLS label imposition.

For a complete description and configuration information of the Layer 2 QoS features supported on Cisco 12000 series ISE and E5 interfaces, refer to Any Transport over MPLS (AToM): Layer 2 QoS (Quality of Service).

Layer 2 Local Switching

The Layer 2 Local Switching feature allows you to switch Layer 2 data between two interfaces of the same type (for example, Ethernet to Ethernet VLAN) or between interfaces of different types (for example, ATM to Ethernet) on the same router.

In the Link Bundling feature on the Cisco 12000 series Internet router, Layer 2 Local Switching is supported on the port-channel interface of an EtherChannel bundle that is configured for EoMPLS and consists of the following member interfaces:

ISE/Engine 3 Gigabit Ethernet

Engine 5 Fast Ethernet

Engine 5 Gigabit Ethernet

In addition, Layer 2 local switching is only supported for "like-to-like" switching between two member interfaces or subinterfaces of the same type as follows:

Gigabit Ethernet to Gigabit Ethernet interface

802.1Q VLAN to 802.1Q VLAN subinterface

Stacked VLAN (802.1Q-in-Q) to 802.1Q-in-Q subinterface

Apart from "like-to-like" switching, ATM-Ethernet interworking mode (bridged mode) for link bundling is also supported.


Note Only bridged mode is supported for link bundling. Routed mode is not supported.


The interfaces can reside on the same line card or on two different cards. During these kinds of like-to-like switching, the Layer 2 address is used, not any Layer 3 address. Additionally, same-port local switching allows you to switch Layer 2 data between two circuits on the same interface. For more information, refer to Layer 2 Local Switching.

In an EtherChannel, local switching involves switching Ethernet packets between customer edge (CE) routers that are on the same side of the connection as the Cisco 12000 series Internet (PE) router. Because the packet switching is performed using fake VC labels in a way similar to AToM label imposition, the VC label cannot be used for load-balancing. For load-balancing, the hash index is calculated using the VLAN ID in EoMPLS VLAN mode. (EoMPLS port mode is not supported for Layer 2 local switching.) The hash index is used to select the adjacency and is programmed into the hardware.

Layer 2 Protocol Tunneling and PDU Filtering

In the Link Bundling feature on the Cisco 12000 series Internet router, EoMPLS supports Layer 2 protocol tunneling (L2PT) and Layer 2 PDU filtering on the port-channel interface of an EtherChannel bundle that consists of the following member interfaces:

ISE/Engine 3 Gigabit Ethernet

Engine 5 Fast Ethernet

Engine 5 Gigabit Ethernet

Layer 2 protocol tunneling allows service providers to carry traffic from multiple customers across a core network, and maintain the VLAN and Layer 2 protocol configurations of each customer without impacting the traffic of other customers. The Transparent Layer 2 Protocol Tunneling feature allows Layer 2 protocol data units (PDUs) to be tunneled across the core network without being interpreted and processed by intermediary network devices. Layer 2 PDU filtering allows a service provider to specify which Layer 2 PDUs are to be dropped at an ingress interface on a provider edge (PE) router. Transparent Layer 2 Protocol Tunneling and PDU filtering provide an enhanced feature set for service providers that transmit customer VLAN traffic from metro Ethernet VPNs across an MPLS core network.

Transparent Layer 2 protocol tunneling and PDU filtering are intended for use on provider edge (PE) routers in an MPLS-enabled service-provider core network.

For more information, refer to Transparent Layer 2 Protocol Tunneling and PDU Filtering.

Stacked VLAN Processing—802.1Q-in-Q

Stacked VLAN processing is supported only on the port-channel interface of an EtherChannel bundle that consists of the following member interfaces:

ISE (E3) 4-port Gigabit Ethernet

E5 (FUGU ASIC-based) Fast Ethernet

E5 (FUGU ASIC-based) Gigabit Ethernet

The Stacked VLAN Processing feature supports the encapsulation of IEEE 802.1Q VLAN tags within a second layer of 802.1Q tag on provider edge (PE) routers to allow service providers to use a single VLAN to support customers who have multiple VLANs. The core service-provider network carries traffic with double-tagged, stacked VLAN (802.1Q-in-Q) headers of multiple customers while maintaining the VLAN and Layer 2 protocol configurations of each customer and without impacting the traffic of other customers. The Stacked VLAN Processing feature preserves VLAN IDs and keeps traffic in different customer VLANs segregated.

To allow a subinterface in an EtherChannel bundle on a PE-POP Cisco 12000 series Internet router to connect to a third-party PE-CLE switch that supports an EtherType value that is different from the default Cisco EtherType value (0x8100), enter the dot1q tunneling ethertype command on the port-channel interface. (The EtherType value supported on Cisco routers and switches is 0x8100. The networking devices of some other vendors support EtherType 0x9100.)

After you enter this command, only stacked VLAN packets with the specified EtherType value in the SP-VLAN tag of the packet header are received on subinterfaces in the link bundle. The new EtherType value is used in the SP-VLAN tag of all stacked VLAN packets sent from subinterfaces in the EtherChannel bundle to the PE-CLE switch, except if EoMPLS is configured on the port-channel interface. If EoMPLS is configured, all traffic received on an EoMPLS member interface (or subinterface) is sent to the PE-CLE switch as it was received from the peer PE router, without the new EtherType value.

For more information about how to configure and use stacked VLAN processing, refer to Stacked VLAN Processing.

Feature Parity on VLAN and Stacked VLAN Member Interfaces

VLAN and Stacked VLAN subinterfaces on member interfaces support all software features that are supported on a port-channel interface of an EtherChannel bundle that consists of the following member interfaces:

E5 Fast Ethernet

ISE (E3) Gigabit Ethernet

E4+ Gigabit Ethernet

E5 Gigabit Ethernet

Some of the software features supported both on the EtherChannel interface and member VLAN and stacked VLAN subinterfaces include:

Access control lists (ACLs)

BGP policy-map accounting (only on ingress port-channel and subinterfaces)

Hot Standby Router Protocol (HSRP) and Virtual Router Redundancy Protocol (VRRP)

MPLS VPN Interautonomous Systems

Multiprotocol Label Switching (MPLS) Virtual Private Network (VPN)

MAC Address Accounting

MAC address accounting is supported only on the port-channel interface of an EtherChannel bundle that consists of the following member interfaces:

E5 Fast Ethernet

ISE (E3) Gigabit Ethernet

E4+, Gigabit Ethernet

E5 Gigabit Ethernet

The MAC address accounting feature provides accounting information for IP traffic based on the source and destination MAC addresses on LAN interfaces. This feature calculates the total packet and byte counts for the EtherChannel that receives or sends IP packets to or from a unique MAC address. It also records a timestamp for the last packet received or sent.

To configure a port-channel interface for IP accounting based on the MAC address, enter the ip accounting mac-address {input | output} command in interface configuration mode, where:

input performs accounting based on the source MAC address on received packets.

output performs accounting based on the destination MAC address on received packets.

To display the MAC accounting information for an EtherChannel, use the show interfaces mac command in privileged EXEC mode.


Note An EtherChannel that consists of Modular Gigabit Ethernet (E4+) member interfaces supports either byte or packet accounting, but not both.


Multicast and Multicast VPN

Multicast routing protocols and multicast VPN are supported on the 802.1Q VLAN and stacked VLAN 802.1Q-in-Q subinterfaces and on the port-channel interface of an EtherChannel bundle that consists of the following member interfaces:

E5 Fast Ethernet

ISE 4-port Gigabit Ethernet

E5 Gigabit Ethernet

Multicast Routing Protocols

You can enable multicast routing protocols on the port-channel interface and 802.1Q VLAN and 802.1Q-in-Q subinterfaces of an EtherChannel bundle, including Internet Group Management Protocol (IGMP), Protocol-Independent Multicast (PIM), Protocol Independent Multicast dense mode (PIM-DM), PIM sparse mode (PIM-SM), source specific multicast (SSM), Multicast Distributed Switching (MDS), Distance Vector Multicast Routing Protocol (DVMRP), and Cisco Group Management Protocol (CGMP).

For information about how to use and configure multicast routing protocols, refer to:

P1C: Cisco IOS IP and IP Routing Configuration Guide

FC: Cisco IOS Release 12.0 Configuration Fundamentals Configuration Guide

FR: Cisco IOS Release 12.0 Configuration Fundamentals Command Reference

Multicast Distributed Switching

Multicast Source Discovery Protocol

Multicast Fast-path Forwarding

Multicast fast-path forwarding allows hardware-based fast forwarding of IPv4 multicast traffic, resulting in high throughputs and performance. Packet forwarding is performed in the hardware switching engine instead of on the line card CPU. For more information, refer to Fast-Path Multicast Forwarding on Cisco 12000 Series Engine 2 and ISE Line Cards.

Multicast VPN

Multicast VPN provides the ability to support the multicast feature over a Layer 3 VPN. A multicast VPN allows an enterprise to transparently interconnect its private network across the network backbone of a service provider. Because MPLS VPNs support only unicast traffic connectivity, deploying the Multicast VPN feature in conjunction with MPLS VPN allows service providers to offer both unicast and multicast connectivity to MPLS VPN customers.

The Multicast VPN—IP Multicast Support for MPLS VPNs feature allows a service provider to configure and support multicast traffic in an MPLS Virtual Private Network (VPN) environment. This feature supports routing and forwarding of multicast packets for each individual VPN routing and forwarding (VRF) instance, and it also provides a mechanism to transport VPN multicast packets across the service provider backbone. For more information about this feature, refer to Multicast VPN—IP Multicast Support for MPLS VPNs.

Multicast QoS

Quality-of-service (QoS) features, which are supported on Fast Ethernet or Gigabit member interfaces and VLAN subinterfaces, are also supported in the egress direction on an EtherChannel interface configured for multicast traffic. For more information about this feature, refer to Multicast Egress QoS Support on Cisco 12000 Series Router, Integrated Services Engine (ISE) Line Cards. For more information on specific QoS features and the EtherChannels on which they are supported, see the "Quality of Service" section.

Multicast Configuration Commands

You must configure all multicast and multicast VPN commands on the port-channel interface associated with an EtherChannel after you enter the interface port-channel command. The configuration of multicast commands is not supported on:

Member interfaces

Port-channel interfaces of bundles that have one or more non-ISE or non-E5 member interfaces

The multicast and multicast VPN control plane and protocols that you configure on a port-channel interface are not aware of the member interfaces. All packets transmitted through member interfaces appear to the multicast control plane as packets sent through the logical EtherChannel interface. All multicast show commands that you enter on the control-plane level display multicast information for the port-channel (logical) interface.

Load-balancing for multicast traffic is performed using a hash algorithm that takes group information in (*,G) entries and (S,G) entries. The outgoing member link is selected using the source and destination IP addresses. If you enable VLAN ID-based load-balancing, multicast traffic is forwarded based on the VLAN ID of transmitted packets.

Policy-Based Routing

Policy-based routing (PBR) is supported on the port-channel interface of an EtherChannel bundle that consists of the following member interfaces:

E5 Fast Ethernet

ISE Gigabit Ethernet

E4+ Gigabit Ethernet

E5 Gigabit Ethernet

You can also configure a routing policy for individual Fast Ethernet and Gigabit Ethernet member subinterfaces.

Policy-based routing provides a flexible means of routing packets by allowing you to configure a defined policy for traffic flows, lessening reliance on routes derived from routing protocols. You can set up PBR as a way to route packets based on configured policies. For example, you can implement routing policies to allow or deny paths based on the identity of a particular end system or an application protocol.

You can configure a unique routing policy for any of the following:

Port-channel interface of an EtherChannel bundle

An individual subinterface configured on the port-channel interface

Multiple subinterfaces configured on an EtherChannel port-channel interface

A policy contains one or more route maps. Each route map has one or more statements that specify the required matching criteria and actions. For example, a matching statement can be an access control list (ACL). If the matching criteria are met, the action statements are executed. An action statement can contain a routing action or a quality of service (QoS) action. The routing action determines the output interfaces for a packet or the next hop. The QoS action may be to set the type of service (ToS) or IP precedence parameter to a specific value.

For information about configuring policy-based routing, refer to Configuring Policy-Based Routing.

Unicast Reverse Path Forwarding

The Unicast Reverse Path Forwarding (Unicast RPF) feature is supported in an EtherChannel bundle as follows:

In an EtherChannel bundle that consists only of E5 Fast Ethernet, ISE Gigabit Ethernet, or E5 Gigabit Ethernet member interfaces, Unicast RPF is supported in loose and strict modes on the main port-channel interface, VLAN subinterfaces, and stacked VLAN subinterfaces.

In an EtherChannel bundle that consists only of E4+ Modular Gigabit Ethernet member interfaces, Unicast RPF is supported only in loose mode on the main port-channel interface.

The Unicast Reverse Path Forwarding Loose Mode feature provides a scalable anti-spoofing mechanism for use in multihome network configuration. This mechanism is effective in service-provider networks on routers that have multiple links to multiple Internet service providers (ISPs), on an ISP-to-ISP network edge.

Unicast RPF (loose or strict mode) provides a quick reaction mechanism for dropping network traffic on the basis of either the source or destination IP address. Network administrators can use this configuration as a tool for mitigating denial of service (DoS) and distributed denial of service (DDoS) attacks.

Verifying Source IPv4 Addresses

The difference between loose and strict checking modes is as follows:

Loose (exist-only) checking mode only verifies that a source IPv4 address exists in the routing table and that a valid return path through any interface exists in the Forwarding Information Base (FIB).

Strict checking mode verifies that the source IPv4 address of an IPv4 packet exists in the routing table and that the source IPv4 address is reachable by a path through the input interface (the interface on which the packet enters the router), such as a link-bundle member interface.

To provide ISPs with a DDoS resistance tool on the ISP-to-ISP edge of a network, Unicast RPF is enhanced from its original strict mode implementation to check the source addresses of each ingress packet without regard for the specific interface on which it was received.

You can enable Unicast RPF in strict or loose mode on an EtherChannel interface or subinterface. For information about enabling Unicast RPF, refer to Unicast Reverse Path Forwarding Loose Mode or Unicast Reverse Path Forwarding in Strict Mode on the Cisco 12000 Series Internet Router.

VLAN Scalability

Enhanced VLAN scalability is only supported on the port-channel interface of an EtherChannel bundle that consists of the following member interfaces:

E5 Fast Ethernet

ISE 4-port Gigabit Ethernet

E5 Gigabit Ethernet

In Cisco IOS Release 12.0(31)S and earlier releases, when you create a subinterface on a member interface of an EtherChannel bundle, a subinterface is also created on all other member interfaces in the bundle. The following equation shows the total number of software data structures (known as IDBs) used for tracking Cisco IOS interfaces and interface status when you configure N number of subinterfaces in a link bundle:

Number of IDBs created = (1 + M) x N

Where:

M is the total number of member interfaces in the bundle

1 is added for the IDB used for the subinterface created for the port-channel (logical) interface

N is the number of subinterfaces created

For example, if a link bundle consists of 4 member interfaces and you configure 2 subinterfaces on member interfaces, the total number of IDBs created is 10.


Note In the forwarding information base (FIB) table, the total number of IDBs created is included in the total number of IDBs created.


The equation shows how the number of subinterfaces supported on an EtherChannel bundle, and therefore the number of supported VLANs, is limited due to the increased amount of route processor memory used by the IDBs.

For this reason, in Cisco IOS Release 12.0(31)S and earlier releases, the number of VLANs supported in an EtherChannel bundle that consists of 4-port Gigabit Ethernet ISE member interfaces is 300. However, starting in Cisco IOS Release 12.0(32)S and later releases, a software enhancement allows you to configure up to 1000 VLANs on the supported Gigabit Ethernet member interfaces in a link bundle. Engine 5 Fast Ethernet member interfaces are supported starting in Cisco IOS Release 12.0(33)S.

In addition, when you increase the number of VLANs on the member interfaces of an EtherChannel, the performance of VLAN load-balancing and data transmission depends on the percentage of ternary content addressable memory (TCAM) allocated for VLANs on each line card, whose interfaces belong to the link bundle. You can maximize the VLAN TCAM size allocated to each ISE/E3 Gigabit Ethernet subinterface by using the hw-module slot linkbundle-tcam-scalability command (see the "Maximizing VLAN TCAM to Support VLAN Scalability" section). When you enter this command, the Layer 2 TCAM regions on an ISE (E3) line card are recarved to support 1K of VLAN traffic on each subinterface in a link bundle.


Note The hw-module slot linkbundle-tcam-scalability command is a required command for an ISE line card.


Quality of Service

The Quality-of-Service (QoS) features described in this section are supported only on the port-channel interface of an EtherChannel bundle that consists of the following member interfaces:

E5 Fast Ethernet

ISE 4-port Gigabit Ethernet

E4+ Modular Gigabit Ethernet

E5 Gigabit Ethernet

Certain QoS features supported on Ethernet interfaces are also supported when you assign these interfaces to an EtherChannel bundle. See Table 1, Table 2, and Table 3 for a list of supported QoS features.

The following restrictions apply when you use QoS features in an EtherChannel bundle:

On ISE 4-port Gigabit Ethernet member links, QoS features are configured on the port-channel interface and supported on main Gigabit Ethernet interfaces and on subinterfaces when VLAN ID-based load-balancing is enabled. Main interfaces support only QoS packet classification and marking. QoS packet classification and marking are supported only in the ingress direction on main and subinterfaces. QoS features are supported on a port-channel interface only in the ingress and egress direction for multicast traffic.

On E4+ Modular Gigabit Ethernet member links, QoS features are configured on the port-channel interface and supported only on main Gigabit Ethernet interfaces. QoS features are not supported on subinterfaces.

On E5 Fast Ethernet and Gigabit Ethernet member links, QoS features are configured on the port-channel interface and supported on main Gigabit Ethernet interfaces and on subterfaces when VLAN ID-based load-balancing is enabled. Main interfaces support only QoS packet classification and marking. QoS packet classification and marking are supported only in the ingress direction on main and subinterfaces.

The match VLAN statement in class-map configuration mode is not supported.

In an EtherChannel bundle, traffic policing configured on ingress interfaces works properly only if incoming traffic is transmitted from another network device that uses VLAN ID-based load-balancing.

To configure QoS features, you must use the modular Quality-of-Service command-line (MQC) interface. For information, refer to:

Cisco IOS Quality of Service Solutions Configuration Guide, Release 12.3

Modular Quality of Service Command-Line Interface

For E3 link bundling interfaces, QoS policies are not attached on secondary RP in SSO redundancy mode after one of the following:

Router reload or bootup

Secondary RP reload

Link bundle member link flaps

After the switchover, remove and reattach QoS policies to enable them again. Also, switch to RPR or RPR+ redundancy mode toavoid secondary RP crash.

Table 1 QoS Features Supported on 4-port Gigabit Ethernet ISE Interfaces in an EtherChannel

QoS Command or Feature in Ingress and Egress Directions
4-port Gigabit Ethernet ISE Interface
4-port Gigabit Ethernet ISE VLAN 802.1Q Subinterface
Stacked VLAN
(802.1Q-in-Q)
Subinterface

Committed access rate (CAR) using rate-limit

Not supported

Supported

Supported

Modified Deficit Round Robin (MDRR)

Not supported

Not supported: ingress Supported: egress

Not supported: ingress Supported: egress

Weighted Random Early Detection (WRED)

Not supported: ingress Not supported: egress

Not supported: ingress Supported: egress

Not supported: ingress Supported: egress

set cos (egress only)

Not supported

Supported

Supported

set discard-class (ingress only)

Supported

Supported

Supported

set dscp

Supported

Supported

Supported

set ip precedence

Supported

Supported

Supported

set mpls experimental

Supported

Supported

Supported

set qos-group (ingress only)

Supported

Supported

Supported

Shaping

Not supported: ingress Not supported: egress

Not supported: ingress Supported: egress

Not supported: ingress Supported: egress

Hierarchical shaping

Not supported: ingress Not supported: egress

Supported: egress only

Supported: egress only

Hierarchical policing

Not supported: ingress Not supported: egress

Supported: ingress Supported: egress

Supported: ingress Supported: egress


Table 2 QoS Features Supported on Modular Gigabit Ethernet Interfaces in an EtherChannel

QoS Command or Feature in Ingress and Egress Directions
Modular Gigabit Ethernet Interface
Modular Gigabit Ethernet VLAN Subinterface 1

Committed access rate (CAR) using rate-limit

Not supported

Not supported

Modified Deficit Round Robin (MDRR)

Not supported

Not supported

Weighted Random Early Detection (WRED)

Not supported

Not supported

set cos (egress only)

Not supported

Not supported

set discard-class (ingress only)

Supported

Not supported

set dscp

Supported

Not supported

set ip precedence

Supported

Not supported

set mpls experimental

Supported

Not supported

set qos-group (ingress only)

Supported

Not supported

Shaping

Not supported

Not supported

Hierarchical shaping

Not supported

Not supported

Hierarchical policing

Not supported

Not supported

1 In an EtherChannel bundle, modular Gigabit Ethernet (E4+) member subinterfaces do not support any of the QoS features normally supported on a modular Gigabit Ethernet (E4+) subinterface.


Table 3 QoS Features Supported on Engine 5 Fast and Gigabit Ethernet Interfaces in an EtherChannel

QoS Command or Feature in Ingress and Egress Directions
E5 Fast Ethernet or Gigabit Ethernet Interface
E5 Fast Ethernet or Gigabit Ethernet VLAN 802.1Q Subinterface
E5 Stacked VLAN (802.1Q-in-Q) Subinterface

Committed access rate (CAR) using rate-limit

Not supported

Supported

Supported

Modified Deficit Round Robin (MDRR)

Not supported

Not supported: ingress Supported: egress

Not supported: ingress Supported: egress

Weighted Random Early Detection (WRED)

Not supported: ingress Not supported: egress

Not supported: ingress Supported: egress

Not supported: ingress Supported: egress

set cos (egress only)

Not supported

Supported

Supported

set discard-class (ingress only)

Supported: ingress

Supported

Supported

set dscp

Supported

Supported

Supported

set ip precedence

Supported

Supported

Supported

set mpls experimental

Supported

Supported

Supported

set qos-group (ingress only)

Supported

Supported

Supported

Shaping

Not supported: ingress Not supported: egress

Not supported: ingress Supported: egress

Not supported: ingress Supported: egress

Hierarchical shaping

Not supported: ingress Not supported: egress

Supported: egress only

Supported: egress only

Hierarchical policing

Not supported: ingress Not supported: egress

Supported: ingress Supported: egress

Supported: ingress Supported: egress


Feature Parity on POS Channel Bundles

Starting in Cisco IOS Release 12.0(33)S, the same level of support for IOS software features exists on a POS channel bundle that consists of ISE, E4+, E5, and E6 member interfaces as on an EtherChannel link bundle. For a description of the supported software features, see the "Software Features Supported on a Link Bundle" section and the "Using an EtherChannel for High-Speed Provider Edge Support" section.

Table 4 summarizes the support for each Cisco IOS software feature in a POS channel link-bundle interface according to the engine type of member interfaces.

Table 4 IOS Software Features Supported on a POS Channel Interface by Engine Type

IOS Software Feature or QoS Command
ISE/E3 POS Channel Main Interface
E4+ POS Channel Main Interface
E5 POS Channel Main Interface
E6 POS Channel Main Interface

IPv4 forwarding

Supported

Supported

Supported

Supported

MPLS forwarding

Supported

Supported

Supported

Supported

MPLS VPNs

Supported

Supported

Supported

Supported

MPLS VPN Inter-Autonomous Systems (Inter-AS)

Supported

Supported

Supported

Supported

Multicast forwarding

Supported

Not supported

Supported

Not supported

Multicast QoS

Supported

Not supported

Supported

Not supported

Multicast VPN

Supported

Not supported

Supported

Not supported

Policy-based routing

Supported

Supported

Supported

Supported

set cos (egress only)

Supported

Supported

Supported

Supported

set discard-class (ingress only)

Supported

Supported

Supported

Supported

set dscp

Supported

Supported

Supported

Supported

set ip precedence

Supported

Supported

Supported

Supported

set mpls experimental

Supported

Supported

Supported

Supported

set qos-group (ingress only)

Supported

Supported

Supported

Supported

MDRR/WRED

Not supported

Not supported

Not supported

Not supported

Policing

Not supported

Not supported

Not supported

Not supported

Shaping (egress interface)

Not supported

Not supported

Not supported

Not supported

Access Control Lists (ACLs): input and output interfaces

Supported

Supported

Supported

Supported

Border Gateway Protocol (BGP) policy accounting

Supported

Supported

Supported

Supported

Sampled NetFlow

Supported

Supported

Supported

Supported

Stateful Switchover (SSO)

Supported

Supported

Supported

Supported

Unicast RPF in loose mode

Supported

Supported

Supported

Supported

Unicast RPF in strict mode

Supported

Not supported

Supported

Not supported


Route Processor Redundancy Plus

Both EtherChannel and POS channel bundles support the Route Processor Redundancy Plus (RPR+) feature. The standby route processor (RP) maintains an updated configuration of the link bundle for use during the switchover.

When two RPs are installed in a Cisco 12000 series Internet router chassis, one RP acts as the active RP, and the other acts as a backup (or standby) RP. If the active RP fails or is removed from the system, the standby RP detects the failure and initiates a switchover. During a switchover, the standby RP assumes control of the router, connects with the network interfaces, and activates the local network management interface and system console.

Using the RPR+ feature, the standby RP is fully initialized and configured, which allows RPR+ to dramatically shorten the switchover time if the active RP fails or if a manual switchover is performed. Because both the startup configuration and the running configuration are continually synchronized from the active to the standby RP, line cards are not reset during a switchover. The state of the interfaces does not change during switchover, so that neighboring routers do not detect a link flap (that is, the link does not go down and back up). For more information, refer to Route Processor Redundancy Plus for the Cisco 12000 Series Internet Router.

Stateful Switchover

Both EtherChannel and POS channel bundles also support the Stateful Switchover (SSO) feature. Like the RPR+ feature, SSO is one link in a chain of Cisco IOS redundancy features designed to provide progressively higher system and network availability.

In a Cisco 12000 series Internet router that support dual RPs, SSO takes advantage of RP redundancy to synchronize critical state information between the active and standby RP. Following an initial synchronization between the two processors, SSO dynamically maintains RP state information between them.

SSO mode provides all the functionality of RPR+ in that Cisco IOS software is fully initialized on the standby RP. In addition, SSO supports synchronization of line card, protocol, and application state information between RPs for supported features and protocols (a "hot standby").

A switchover from the active to the standby processor occurs when the active RP fails, is removed from the networking device, or is manually taken down for maintenance. Because SSO is used with the Cisco Nonstop Forwarding (NSF) feature, Cisco NSF allows for the forwarding of data packets to continue along known routes while the routing protocol information is being restored following a switchover. With Cisco NSF, peer networking devices do not experience routing flaps, thereby reducing loss of service outages for customers.

Unlike the RPR+ feature, the last known FIB information is used by the backup RP when it takes over the active RP function. All link bundle activity (for example, active-to-passive member transition, VLAN load-balancing, bandwidth changes) is synchronized in the standby RP. During the switchover, packet forwarding in link bundles remains uninterruptred.

For information about the differences between the RPR+ and SSO redundancy modes and how to configure SSO, refer to Stateful Switchover.

Benefits of Link Bundling

EtherChannel and POS channel link bundling on Cisco 12000 series Internet routers provide the following benefits:

Flexible, incremental bandwidth

Transparency to network applications

Support for IP unicast and MPLS traffic

Load-balancing (equal cost) across all active links in the bundle

Redundancy: if there is a failure of an individual GE or POS link, the traffic flow through the channel is evenly distributed across the available links.

Interoperability with link bundling implementations in other Cisco and OEM routers and switches.

Out-of-service support: an EtherChannel or POS channel is brought down if the minimum number of GE or POS links are not up.

Bandwidth propagation support: bandwidth changes in an EtherChannel or POS channel can be (optionally) propagated to the upper-layer protocols until the amount of bandwidth required in the link bundle exceeds a specified threshold.

Restrictions for Link Bundling

Line Cards Supported on the Cisco 12000 Router

EtherChannel and POS channel link bundling are supported on the following line cards in Cisco 12000 series Internet routers:

Engine 0:

4-port OC-3c/STM-1c POS/SDH line card

1-port OC-12c/STM-4c POS/SDH line card

Engine 1:

1-port Gigabit Ethernet line card

Engine 2:

3-port Gigabit Ethernet line card

4-port OC-3c/STM-1c POS/SDH line card

8-port OC-3c/STM-1c POS/SDH line card

16-port OC-3c/STM-1c POS/SDH line card

4-port OC-12c/STM-4c POS/SDH line card

1-port OC-48c/STM-16c POS/SDH line card

IP Service Engine (ISE):

4-port Gigabit Ethernet ISE line card

4-port OC-3c/STM-1c POS/SDH ISE line card

8-port OC-3c/STM-1c POS/SDH ISE line card

16-port OC-3c/STM-1c POS/SDH ISE line card

4-port OC-12c/STM-4c POS/SDH ISE line card

1-port OC-48c/STM-16c POS/SDH ISE line card

Engine 4 Plus (E4+):

Modular Gigabit Ethernet line card

1-port 10-Gigabit Ethernet line card

4-port OC-48c/STM-16c POS/SDH line card

1-port OC-192c/STM-64c POS/SDH line card

Engine 5 shared port adapters (SPAs):

1-port 10-Gigabit Ethernet

2-port Gigabit Ethernet

5-port Gigabit Ethernet

10-port Gigabit Ethernet

8-port Fast Ethernet

8-port 10/100 Ethernet

4-port OC-3/STM4 POS

8-port OC-3/STM4 POS

2-port OC-12/STM4 POS

4-port OC-12/STM4 POS

8-port OC-12/STM4 POS

2-port OC-48/STM16 POS/RPR

1-port OC-192/STM64 POS/RPR

Engine 5 SPA Interface Processors (SIPs):

10G Engine 5 SPA Interface Processor (12000-SIP-600)

2.5G multiservice engine SPA Interface Processor (12000-SIP-401)

5G multiservice engine SPA Interface Processor (12000-SIP-501)

10G multiservice engine SPA Interface Processor (12000-SIP-601)

Engine 6:

8-port OC-48/STM16-c POS line card

2-port OC-192 POS line card

Line Card Restrictions in Routers on Each Side of a Link Bundle

In an EtherChannel or POS channel link bundle, the following restrictions apply:

You can only configure interfaces of the same media type, engine type, and port speed on the router at each end of a connection. For example, you can only add an Engine 2 OC-12 POS interface to a POS channel that consists of Engine 2 OC-12 POS interfaces. You cannot add an Engine 2 OC-12 POS interface to a POS channel that consists of Engine 3 (ISE) OC-12 POS or Engine 2 OC-3 POS interfaces, or to an EtherChannel that consists of Engine 5 GE interfaces.

You can configure interfaces of the same media type and engine type that are on different line cards, different shared port adapters (SPAs), and different SPA interface processors (SIPs). For example:

You can configure a POS channel that consists of Engine 2 POS interfaces on line cards in slots 2, 3, and 4 in a router.

You can configure an EtherChannel that consists of Engine 5 GE interfaces on SPAs in different jackets cards on different SIPs, such as 12000-SIP-600 and 12000-SIP-601.

You can configure an EtherChannel or POS channel with a certain media type and engine type (for example, Engine 3/ISE Gigabit Ethernet) on one router, and configure the link bundle on the remote router with the same media but a different engine type (for example, Engine 5 Gigabit Ethernet).

Although you can create an EtherChannel that consists of Engine 5 member interfaces on SPAs with different ASIC versions (Version 1 GILA and Version 2 FUGU), software features are supported across the link bundle (on port-channel and member interfaces) only if they are supported on both ASIC versions.

For example, stacked VLAN (802.1Q-in-Q) processing is supported in a Engine 5 Gigabit EtherChannel only if all member interfaces are on SPAs that use the Engine 5 Version 2 FUGU ASIC. The Version 1 GILA ASIC does not support stacked VLAN processing.

For information about which Engine 5 line cards support the different ASIC versions, refer to Supported Line Cards for the 12000 Series Routers in the Cross-Platform Release Notes for Cisco IOS Release 12.0S.

Symmetric Configuration on Both Sides of a Link Bundle

In both EtherChannel and POS channel link bundles, the Link Aggregation Control Protocol (LACP) for signalling and the 802.3ad protocol for automatic negotiation of the channel are not supported. This means that in order for the channel between two routers to be active, you must disable signaling on switches (such as the Cisco 6500/7600 Series) in the channel, and configure the switches in ON mode.

In addition, an EtherChannel or POS channel between two adjacent routers must be configured with the same number of members (interfaces) on the router at each end of the channel. This is required for an EtherChannel or POS channel interface to function correctly and for the link status to come up.

Ingress Decision Support

For an EtherChannel or POS channel to operate correctly with equal cost load-balancing, the Link Bundling feature requires that all line cards in a Cisco 12000 series Internet router support the ingress decision capability (described in the "Link Bundling in a Cisco 12000 Series Internet Router" section).

Only the following Cisco 12000 series line cards support ingress decision capability:

Engine 0 Asynchronous Transfer Mode (ATM) line cards

Engine 0 Channelized DS3/E3 line cards

Engine 0 Dynamic Packet Transport (DPT) line cards

Engine 0 Packet-over-SONET line cards

Engine 1 Fast Ethernet line cards

Engine 1 Gigabit Ethernet line cards

Engine 2 8-port OC-3/STM-1 ATM line cards

Engine 2 Dynamic Packet Transport (DPT) line cards

Engine 2 Gigabit Ethernet line cards

Engine 2 Packet-over-SONET line cards

IP Service Engine (ISE) line cards:

4-port Gigabit Ethernet ISE line card

4-port OC-3c/STM-1c POS/SDH ISE line card

8-port OC-3c/STM-1c POS/SDH ISE line card

16-port OC-3c/STM-1c POS/SDH ISE line card

4-port OC-12c/STM-4c POS/SDH ISE line card

1-port OC-48c/STM-16c POS/SDH ISE line card

Engine 6/4+ line cards

Engine 5 line cards

The following Cisco 12000 series line cards do not support ingress decision capability:

Engine 0 Channelized DS1/E1, OC-3, and T3 line cards

Engine 2 Asynchronous Transfer Mode (ATM) line cards, except for the 8-port OC-3/STM-1 ATM line card

Engine 4 line cards

Engine 5 Ingress and Egress Support

Starting in Cisco IOS Release 12.0(32)S, Engine 5 line cards are supported as the ingress interface when an EtherChannel port-channel interface is the egress interface in a Cisco 12000 series Internet router. In this case, an EtherChannel bundle supports load-balancing for IP and MPLS packets across member links for the following combinations of IP and MPLS data streams. An Engine 5 ingress interface:

Receives IP packets; a port-channel interface forwards the IP packets.

Receives IP packets; a port-channel interface encapsulates packets with an MPLS label and forwards the packets.

Encapsulates packets with an MPLS label; a port-channel interface swaps or replaces the MPLS label and forwards the MPLS packets.

Receives MPLS packets; a port-channel interface removes the MPLS labels and forwards IP packets.

Configured for AToM encapsulates incoming packets and transmits them across a pseudowire connection; a port-channel interface decapsulates the packets and transmits the Layer 2 packets.

For more information about MPLS tag switching, refer to MPLS/Tag Switching.

Starting in Cisco IOS Release 12.0(33)S, Engine 5 line cards are also supported as the egress interface on which you can configure a virtual interface (EtherChannel or POS channel) for a link bundle. For a list of supported Engine 5 interfaces, see Line Cards Supported on the Cisco 12000 Router.

Cisco IOS Command Restrictions

Layer 1/Layer 2 commands are physical interface-specific and are supported on an EtherChannel or POS channel interface, for example, crc 32, keepalive, clock, and negotiation commands.

Layer 3 commands are channel-specific and are not supported on a member interface; for example, ip address, mpls, acl, and mtu commands.

EtherChannel Restrictions

Up to 8 FE or GE links are supported per EtherChannel bundle. Up to 16 EtherChannel bundles are supported per Cisco 12000 series Internet router.

The Fast or Gigabit Ethernet ports that you bundle together must be of the same engine type. For example, you can bundle together supported Engine 1 line cards to form a Gigabit EtherChannel, or you can bundle Gigabit Ethernet ports on supported Engine 2 line cards to form a Gigabit EtherChannel. However, you cannot combine Engine 1 Gigabit Ethernet ports with Engine 2 Gigabit Ethernet ports in a Gigabit EtherChannel.

Link bundles that consist of Fast Ethernet interfaces are supported only on Engine 5 line cards, starting in Cisco IOS Release 12.0(33)S. You cannot combine ISE (Engine 3) ports with Engine 5 Fast Ethernet ports in a Fast EtherChannel.

MAC Address—An EtherChannel is configured with the MAC address of the first active member (FE or GE link). All other members are configured with the MAC address of the port-channel interface. The static MAC address on the port-channel interface is propagated to all member interfaces. If the first active member:

Is removed from the link bundle, the MAC address of the second active member is assigned to the EtherChannel interface.

Interface goes down, Cisco IOS software automatically changes the interface from active member to passive member status. The EtherChannel remains configured with the MAC address of the first active member although it is now passive. The interface is not removed from the channel. When the interface comes back up, the software automatically changes the interface back to active member status.

We do not recommend using static ARP and static routes, such as IP route 1.1.1.1 255.255.255.0 gig/1/1/0.

Engine 5 ASICs—Software features may not be supported in an EtherChannel if the link bundle consists of Engine 5 line cards with different ASIC versions. For example, stacked VLAN (802.1Q-in-Q) processing is supported in a Gigabit EtherChannel only if all member interfaces are on SPAs that use the Engine 5 Version 2 FUGU ASIC. The Version 1 GILA ASIC does not support stacked VLAN processing.

For information about Engine 5 line card support for specific ASIC versions, refer to Supported Line Cards for the 12000 Series Routers in the Cross-Platform Release Notes for Cisco IOS Release 12.0S.

Fast EtherChannel bundles—In an EtherChannel bundle that consists of Fast Ethernet links, only Engine 5 (E5) Fast Ethernet member interfaces are supported.

POS Channel Restrictions

Up to 8 POS links are supported per POS channel bundle. Up to 16 POS channel bundles are supported per Cisco 12000 series Internet router.

The POS ports that you bundle together must be of the same engine type. For example, you can bundle together POS ports on supported Engine 0 line cards to form a POS channel, or you can bundle POS ports on supported Engine 2 line cards to form a POS channel. However, you cannot combine Engine 0 POS ports with Engine 2 POS ports in a POS channel.

In a POS channel, only HDLC encapsulation is supported.

Load-Balancing Restrictions

The hash algorithm used for load-balancing by each Cisco 12000 series engine type may not result in complete load-balancing for all IP address patterns.

EoMPLS Restrictions

AToM EoMPLS features (see the "Any Transport over MPLS—Ethernet over MPLS" section) are supported only in VLAN mode (802.1Q VLAN or stacked VLAN 802.1Q-in-802.1Q) on the port-channel interface of an EtherChannel bundle. Port mode is not supported.

AToM EoMPLS features are not supported in a POS channel link bundle.

In an EtherChannel bundle that consists of E5 member interfaces, Layer 2 PDU filtering (L2PDU) and Layer 2 protocol tunneling (L2PT) are only supported on FUGU ASIC-based SPA interfaces; these features are not supported on GILA ASIC-based SPAs.

VLAN Scalability Restrictions

On the port-channel interface of an EtherChannel bundle that consists of E5 Fast Ethernet, ISE 4-port Gigabit Ethernet, or E5 Gigabit Ethernet member interfaces, VLAN load-balancing and data transmission may be limited by the percentage of TCAM allocated for VLANs on ISE line cards. To increase the VLAN TCAM size, use the hw-module slot linkbundle-tcam-scalability command, as described in the "Maximizing VLAN TCAM to Support VLAN Scalability" section.

MPLS Carrier Supporting Carrier Restrictions

The MPLS Carrier Supporting Carrier (CsC) feature is not supported on an EtherChannel or POS channel interface.

Related Features and Technologies

Metropolitan area network (MAN)

Multiprotocol Label Switching (MPLS)

Virtual Private Networks (VPNs)

Related Documents

Cisco IOS Switching Services Configuration Guide, Release 12.3

Cisco IOS Switching Services Command Reference, Release 12.3

Network Protocols Command Reference, Part 1, Release 11.3

Fast EtherChannel Feature Module

Supported Platforms

Cisco 12000 series Internet routers

Determining Platform Support Through Cisco Feature Navigator

Cisco IOS software is packaged in feature sets that are supported on specific platforms. To obtain updated information on platform support for this feature, access Cisco Feature Navigator. Cisco Feature Navigator dynamically updates as new platform support is added for a feature.

Cisco Feature Navigator is a web-based tool that enables you to determine which Cisco IOS software images support a specific set of features. You can search by feature or release. Under the release section, you can compare releases to display both the features unique to each software release and the features in common.

To access Cisco Feature Navigator, you must have an account on Cisco.com. If you forgot or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check verifies that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password are e-mailed to you. Qualified users can establish an account on Cisco.com at:

http://www.cisco.com/register

For the most current information, go to the Cisco Feature Navigator home page at:

http://www.cisco.com/go/fn

Availability of Cisco IOS Software Images

Platform support for particular Cisco IOS software releases is dependent on the availability of the software images for those platforms. Software images for some platforms may be deferred, delayed, or changed without notice.

Supported Standards, MIBs, and RFCs

Standards

No new or modified standards are supported by this feature.

MIBs

BGP4-MIB

CISCO-BGP-POLICY-ACCOUNTING-MIB

CISCO-BGP4-MIB

CISCO-C12000-IF-HC-COUNTERS-MIB

CISCO-CAR-MIB

CISCO-CLASS-BASED-QOS-MIB

CISCO-ENHANCED-WRED-MIB

CISCO-HSRP-MIB

CISCO-IETF-IP-FORWARD-MIB

CISCO-IETF-IP-MIB

CISCO-IF-EXTENSION-MIB

CISCO-IP-STAT-MIB

CISCO-IPMROUTE-MIB

CISCO-LAG-MIB

CISCO-OSPF-MIB

CISCO-PSA-MICROCODE-MIB

CISCO-QUEUE-MIB

CISCO-VLAN-IFTABLE-RELATIONSHIP-MIB

ETHERLIKE-MIB

IEEE8023-LAG-MIB

IF-MIB

MPL-VPN-MIB

MPLS-LDP-MIB

OSPF-MIB

RMON-MIB

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator at:

http://tools.cisco.com/ITDIT/MIBS/servility/index

If Cisco MIB Locator does not support the MIB information that you need, you can view supported MIBs and download MIBs from the Cisco MIBs page at:

http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

To access Cisco MIB Locator, you must have an account on Cisco.com. If you forgot or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check verifies that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password are e-mailed to you. Qualified users can establish an account on Cisco.com at:

http://www.cisco.com/register

RFCs

No new or modified RFCs are supported by this feature.

Configuration Tasks

Configuring the Link Bundling (EtherChannel and POS channel) feature on Cisco 12000 series Internet routers consists of the following steps:

1. For an EtherChannel, create a port-channel interface; for a POS channel, create a pos-channel interface. Then assign an IP address.

2. Assign a Fast Ethernet (FE) or Gigabit Ethernet (GE) interface to the port-channel interface or a Packet-over-SONET (POS) interface to the pos-channel interface.

3. Repeat Step 2 to add an additional GE or POS interface to the link bundle.

4. Repeat Steps 1 to 3 to configure the EtherChannel or POS channel on the router at the other end of the channel.

After you configure an EtherChannel or POS channel, you can configure the out-of-service support and bandwidth propagation features on the link bundle interface.

See the following sections for configuration tasks for the Link Bundling feature. Each task in the list is identified as either optional or required.

Configuring a Port-Channel Interface (required)

Configuring a POS-Channel Interface (required)

Adding a Fast Ethernet or Gigabit Ethernet Interface (required)

Adding a Packet-over-SONET Interface (required)

Removing an Ethernet or Packet-over-SONET Interface from a Link Bundle (optional)

Configuring Out-of-Service Support (optional)

Configuring Bandwidth Propagation (optional)

Verifying an EtherChannel (optional)

Verifying a POS Channel (optional)

For information on other configuration tasks for EtherChannel and POS channel link bundling, refer to the Gigabit Ethernet and Packet-over-SONET sections in the "Configuring Interfaces" chapter of the Configuration Fundamentals Configuration Guide.

Configuring a Port-Channel Interface

You must configure a port-channel (logical) interface for each EtherChannel link bundle on the routers at each end of the channel (see the "Configuring an EtherChannel" section).

To configure a port-channel interface for an EtherChannel, perform the following steps beginning in global configuration mode:

 
Command
Purpose

Step 1 

Router(config)# interface port-channel channel-number

Creates the port-channel (logical) interface to be used for the EtherChannel and enters interface configuration mode. The valid values for channel-number are 1 to 16.

Step 2 

Router(config-if)# ip address ip-address mask

Assigns an IP address and subnet mask to the EtherChannel.

Step 3 

Router(config-if)# mac address ieee-address

(Optional) Assigns a static MAC address to the EtherChannel.

Step 4 

Router(config-if)# channel-group bandwidth control-propagation

(Optional) Enables the automatic propagation of bandwidth changes to upper-layer protocols for the bandwidth threshold specified by the threshold threshold-number parameter.

Step 5 

Router(config-if)# channel-group bandwidth threshold threshold-number

(Optional) Specifies the maximum number of active member interfaces allowed in order for the total bandwidth used in the active members of an EtherChannel to be propagated to upper-layer protocols each time there is a change in bandwidth.

When a member interface is brought up and the number of active links exceeds the threshold number, the aggregate bandwidth of the active members is not propagated.

When the number of active members becomes one more than the threshold value, the aggregate bandwidth of all member interfaces (both active and passive) in the EtherChannel is propagated to upper-layer protocols.

Note that the channel-group bandwidth threshold threshold-number command is valid only after you enter the channel-group bandwidth control-propagation command.

Also, this value is not valid and a bandwidth change is not propagated if the EtherChannel is down because the minimum number of active member interfaces configured with the channel-group minimum active command are not operational.

Step 6 

Router(config-if)# channel-group minimum active link-number

(Optional) Configures the minimum number of active members (GE links) that must be active in order for the EtherChannel to be operational. The valid values for link-number are from 1 to 8.

Step 7 

Router(config-if)# channel-group load-share vlan

(Optional) Configures load-balancing across member interfaces based on the VLAN ID of transmitted packets.

Step 8 

Router(config-if)# ios-command

(Optional) Enables other supported interface commands for the software features supported across the entire bundle (see the "Restrictions for Link Bundling" section).

Step 9 

Router(config-if)# end

Exits from interface configuration mode.

Configuring a POS-Channel Interface

You must configure a pos-channel (logical) interface for each POS channel link bundle on the routers at each end of the POS channel (see the "Configuring a POS Channel" section).

To configure a pos-channel interface for a POS channel, perform the following steps beginning in global configuration mode:

 
Command
Purpose

Step 1 

Router(config)# interface pos-channel channel-number

Creates the port-channel (logical) interface to be used for the POS channel and enters interface configuration mode. The valid values for channel-number are 1 to 16.

Step 2 

Router(config-if)# ip address ip-address mask

Assigns an IP address and subnet mask to the POS channel.

Step 3 

Router(config-if)# channel-group bandwidth control-propagation

(Optional) Enables the automatic propagation of bandwidth changes to upper-layer protocols for the bandwidth threshold specified by the threshold threshold-number parameter.

Step 4 

Router(config-if)# channel-group bandwidth threshold threshold-number

(Optional) Specifies the maximum number of active member interfaces allowed in order for the total bandwidth used in the active members of a POS channel to be propagated to upper-layer protocols each time there is a change in bandwidth.

When a member interface goes up and the number of active links exceeds the threshold number, the aggregate bandwidth of the active members is not propagated.

When the number of active members becomes one more than the threshold value, the aggregate bandwidth of all member interfaces (both active and passive) in the POS channel is propagated to upper-layer protocols.

Note that the channel-group bandwidth threshold threshold-number command is valid only after you enter the channel-group bandwidth control-propagation command.

Also, this value is not valid and a bandwidth change is not propagated if the POS channel is down because the minimum number of active member interfaces configured with the channel-group minimum active command are not up.

Step 5 

Router(config-if)# channel-group minimum active link-number

(Optional) Configures the minimum number of active members (POS links) that must be active in order for the POS channel to be up. The valid values for link-number are from 1 to 8.

Step 6 

Router(config-if)# ios-command

(Optional) Enables other supported interface commands for the software features supported across the entire bundle (see the "Restrictions for Link Bundling" section).

Step 7 

Router(config-if)# end

Exits from interface configuration mode.

Adding a Fast Ethernet or Gigabit Ethernet Interface

After you configure a port-channel interface on the router at one end of an EtherChannel, you can add up to 8 Fast Ethernet or Gigabit Ethernet interfaces to the EtherChannel group. The interfaces you add to the port-channel must be of the same engine number and media type. For example, a Gigabit EtherChannel can consist only of all Engine 1 GE interfaces or all Engine 2 GE interfaces. The interfaces you add to the port-channel can, however, belong to line cards in different slots.

You must add the same number of members (FE or GE interfaces) to the port-channel logical interface on the router at each end of an EtherChannel (see Configuring an EtherChannel).

To add a Fast Ethernet or Gigabit Ethernet interface to an EtherChannel bundle, perform the following steps beginning in global configuration mode:

 
Command
Purpose

Step 1 

Router(config)# interface gigabitethernet slot/port


Router(config)# interface fastethernet slot/port

Creates or modifies an existing Fast Ethernet or Gigabit Ethernet interface by specifying the Ethernet line card, subslot (if available), and port number and then enters interface configuration mode.

Step 2 

Router(config-if)# channel-group channel-number


Command will clear some config: IP address(es), loopback

Manually remove other configs

Assigns the Ethernet interface to the EtherChannel associated with the specified channel number. The valid values for channel-number are 1 to 16.

Step 3 

Continue? [yes]: yes

(Optional) Enter yes at the command prompt to configure the Ethernet interface as a member of the port-channel group. The interface's IP address and loopback configuration are deleted.

Step 4 

Router(config-if)# exit

Exits interface configuration mode. Repeat Step 1 through Step 4 to add up to eight FE or GE interfaces to the EtherChannel bundle.

Step 5 

Router(config-if)# end

Exits interface configuration mode when you finish configuring the EtherChannel.

Adding a Packet-over-SONET Interface

After you configure a pos-channel interface on the router at one end of a POS channel, you can add up to 8 Packet-over-SONET interfaces to the POS channel group. The interfaces you add to the POS channel must be of the same engine number and media type. For example, a POS channel can consist only of all Engine 0 POS interfaces or all Engine 2 POS interfaces. The interfaces you add can belong to POS line cards in different slots.

You must add the same number of members (POS interfaces) to the pos-channel logical interface on the router at each end of a POS channel (see the "Configuring a POS Channel" section).

To add a Packet-over-SONET (POS) interface to a POS channel bundle, perform the following steps beginning in global configuration mode:

 
Command
Purpose

Step 1 

Router(config)# interface pos slot/port

Creates or modifies an existing Packet-over-SONET interface by specifying the line-card slot, subslot (if available), and port number and then enters interface configuration mode.

Step 2 

Router(config-if)# channel-group channel-number


Command will clear some config: IP address(es), loopback

Manually remove other configs

Assigns the POS interface to the POS channel associated with the specified channel number. The valid values for channel-number are 1 to 16.

Step 3 

Continue? [yes]: yes

(Optional) Enter yes at the command prompt to configure the Packet-over-SONET interface as a member of the pos-channel group. The interface's IP address and loopback configuration are deleted.

Step 4 

Router(config-if)# exit

Exits interface configuration mode. Repeat Step 1 through Step 4 to add up to 8 POS interfaces to the POS channel bundle.

Step 5 

Router(config-if)# end

Exits interface configuration mode when you finish configuring the POS channel.

Maximizing VLAN TCAM to Support VLAN Scalability

As you increase the number of VLANs configured on a port-channel interface (see VLAN Scalability), the performance of VLAN load-balancing and data transmission in an EtherChannel depends on the percentage of TCAM allocated for VLANs on each Fast Ethernet o r Gigabit Ethernet line card whose interfaces belong to the link bundle.

To display the amount of TCAM allocated for Cisco IOS features on an Ethernet line card, enter the show controllers frfab alpha tcam carve command.

To increase the VLAN TCAM size so that a maximum of 1K of TCAM is allocated to process VLAN traffic on each member subinterface, perform the following steps starting in global configuration mode:

 
Command
Purpose

Step 1 

Router(config)# hw-module slot number linkbundle-tcam-scalability

Increases VLAN TCAM size on the line card so that 1K of TCAM is allocated to each VLAN subinterface used in an EtherChannel link bundle. Other TCAM regions are recarved accordingly.

Step 2 

Router(config)# microcode reload slot-number

Reloads the software and microcode on the line card so that the newly configured TCAM region sizes take effect.

Note You must enter the microcode reload command only one time on an ISE line card, and only if you reconfigure TCAM regions on the line card. For example, if you add a new member interface to the EtherChannel after you reconfigure VLAN TCAM and reload the microcode, you do not have to reload the microcode a second time.

After you enter the microcode reload command, the line card is reset. As a result, traffic forwarding is interrupted. The control protocols and interfaces are down until the line card reset is complete.

Removing an Ethernet or Packet-over-SONET Interface from a Link Bundle

To remove a Fast Ethernet or Gigabit Ethernet interface from an EtherChannel bundle or a Packet-over-SONET interface from a POS channel bundle, perform the following steps beginning in global configuration mode:

 
Command
Purpose

Step 1 

Router(config)# interface fastethernet slot/port

or

Router(config)# interface gigabitethernet slot/port

or

Router(config)# interface pos slot/port

Specifies a Fast Ethernet, Gigabit Ethernet or Packet-over-SONET interface and enters interface configuration mode.

Step 2 

Router(config-if)# no channel-group channel-number

Removes the FE, GE, or POS interface from an EtherChannel or POS channel.

Step 3 

Router(config-if)# end

Exits interface configuration mode.


Note If an interface goes down in an EtherChannel or POS channel, the Cisco IOS software automatically changes the FE, GE, or POS interface from active member to passive member status. The interface is not removed from the channel. When the interface comes back up, the software automatically changes the interface back to active member status.


To monitor the status of an EtherChannel, use the show interfaces port-channel EXEC command. To monitor the status of a POS channel interface, use the show interfaces pos-channel command.

Configuring Out-of-Service Support

After you configure an EtherChannel (see the "Configuring a Port-Channel Interface" section) or a POS channel (see the "Configuring a POS-Channel Interface" section), you can specify the minimum number of active member interfaces required to be up and active for the link bundle to stay up or to come up if it is down. This is called out-of-service support and is an optional task.

Configure out-of-service support when you use link bundles that consist of two or more member interfaces and want to avoid overdriving the link bundle interface if a specified amount of bandwidth is not needed in the link bundle. The amount of bandwidth used by a link bundle is the combined amount of default bandwidth on each of its member interfaces.

You can specify a new value for the amount of bandwidth required for a link bundle by specifying the minimum number of active member links that must be up for the link bundle to be up. When a minimum number of member interfaces is not up, the link bundle interface goes down. The link bundle comes up from being out-of-service as soon as the required minimum number of member links become active.

To configure out-of-service support for an EtherChannel or POS channel bundle, perform the following steps beginning in global configuration mode:

 
Command
Purpose

Step 1 

Router(config)# interface port-channel channel-number

or

Router(config)# interface pos-channel channel-number

Specifies an EtherChannel or POS channel interface and enters interface configuration mode.

Step 2 

Router(config-if)# channel-group minimum active link-number

Specifies the minimum number of active member links that must be up in order for the link bundle to stay up. The default is that one member interface must be up for the link bundle to stay up.

Step 3 

Router(config-if)# exit

Exits interface configuration mode.

Configuring Bandwidth Propagation

After you configure an EtherChannel (see the "Configuring a Port-Channel Interface" section) or a POS channel (see the "Configuring a POS-Channel Interface" section), you can also specify the upper bandwidth threshold to use for propagating bandwidth changes to upper-layer protocols. By default, at each change in bandwidth in a link bundle, the combined amount of bandwidth used on all active member links is propagated.

A bandwidth change in a link bundle occurs when any of the following events occur:

A new, active member interface is added or a member interface is removed.

An active member interface goes down or a member interface that is down comes up.

The bandwidth threshold is specified according to the number of active member interfaces in the link bundle. When the required number of active member interfaces is less than or equal to the specified threshold number, the total amount of bandwidth used in the link bundle is propagated to upper-layer protocols at each bandwidth change. As soon as the number of active member links becomes greater than the specified threshold number, bandwidth changes are no longer propagated.

In addition, bandwidth changes are not propagated if the link bundle goes down because the number of active member interfaces is less than the configured minimum number of active member links required (see Configuring Out-of-Service Support).


Note The bandwidth command is supported on an EtherChannel or POS channel interface, but is not supported on a member interface in a link bundle.


To configure an upper bandwidth threshold to use for propagating bandwidth changes in an EtherChannel or POS channel bundle to upper-layer protocols, perform the following steps beginning in global configuration mode:

 
Command
Purpose

Step 1 

Router(config)# interface port-channel channel-number

or

Router(config)# interface pos-channel channel-number

Specifies an EtherChannel or POS channel interface and enters interface configuration mode.

Step 2 

Router(config-if)# channel-group bandwidth control-propagation

Enables the automatic propagation of bandwidth changes to upper-layer protocols for the bandwidth threshold specified in Step 3.

Step 3 

Router(config-if)# channel-group bandwidth threshold threshold-number

Specifies the maximum number of active member interfaces allowed in order for the total bandwidth used in the active members of a link bundle to be propagated to upper-layer protocols each time there is a change in bandwidth.

When a member interface goes up and the number of active links exceeds the threshold number, the aggregate bandwidth of the active members is not propagated.

When the number of active members becomes one more than the threshold value, the aggregate bandwidth of all member interfaces (both active and passive) in the bundle is propagated to upper-layer protocols.

Note that the channel-group bandwidth threshold threshold-number command is valid only after you enter the channel-group bandwidth control-propagation command.

Also, this value is not valid and a bandwidth change is not propagated if the link bundle is down because the minimum number of active member interfaces configured with the channel-group minimum active command are not up.

Step 4 

Router(config-if)# exit

Exits interface configuration mode.

Verifying an EtherChannel

To monitor the status of an EtherChannel, use the show interfaces port-channel command in privileged EXEC mode. The following output is for a Gigabit EtherChannel with three GE interfaces. All interfaces are up and therefore appear as active members of the channel. If one of the active interfaces goes down, it would be listed as a passive member. The status of a Gigabit EtherChannel is up if it has at least one active member interface.

Router# show interfaces port-channel 1
Port-channel1 is up, line protocol is up 
  Hardware is GEChannel, address is 0050.2ac6.9581 (bia 0000.0000.0000)
  Internet address is 22.1.0.2/16
  MTU 1500 bytes, BW 3000000 Kbit, DLY 10 usec, rely 255/255, load 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  ARP type: ARPA, ARP Timeout 04:00:00
    No. of active members in this channel: 3 
        Member 0 : GigabitEthernet3/1 , Full-duplex, 1000Mb/s
        Member 1 : GigabitEthernet3/2 , Full-duplex, 1000Mb/s
        Member 2 : GigabitEthernet1/2 , Full-duplex, 1000Mb/s
    No. of passive members in this channel: 0 
  Last input 00:00:01, output 00:00:01, output hang never
  Last clearing of "show interface" counters 3d15h
  Queueing strategy: fifo
  Output queue 0/120, 0 drops; input queue 0/225, 0 drops
  30 second input rate 1425032000 bits/sec, 1038111 packets/sec
  30 second output rate 0 bits/sec, 0 packets/sec
     328903597021 packets input, 56454340092292 bytes, 0 no buffer
     Received 50815 broadcasts, 0 runts, 0 giants, 0 throttles
     528238 input errors, 0 CRC, 0 frame, 528238 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     128365 packets output, 9409520 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 pause output
     0 output buffer failures, 0 output buffers swapped out

Verifying a POS Channel

To monitor the status of a POS channel, use the show interfaces pos-channel command in privileged EXEC mode. The following output is for a POS channel with three POS interfaces.

Two of the interfaces are up, and appear as active members of the channel.

One POS interface is down, and is listed as a passive member.

If an active member interface goes down, it is shown in the list of passive members. L

ewise, when a passive member comes up, it appears in the active member list. If the POS channel has at least one active member interface, the status of the POS channel is up.

Router# show interfaces pos-channel 1
Pos-channel1 is up, line protocol is up 
  Hardware is POSChannel
  Internet address is 41.1.0.1/16
  MTU 4470 bytes, BW 1244000 Kbit, DLY 100 usec, rely 255/255, load 236/255
  Encapsulation HDLC, loopback not set
  Keepalive set (10 sec)
    No. of active members in this channel: 2 
        Member 0 : POS5/0 
        Member 1 : POS2/3 
    No. of passive members in this channel: 1 
        Member 0 : POS5/1 
  Last input 00:00:01, output 00:00:03, output hang never
  Last clearing of "show interface" counters 3d15h
  Queueing strategy: fifo
  Output queue 0/80, 3665649311 drops; input queue 0/150, 0 drops
  30 second input rate 0 bits/sec, 0 packets/sec
  30 second output rate 1168138000 bits/sec, 627497 packets/sec
     192649 packets input, 12073574 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     197631584356 packets output, 46098596464843 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions

Configuration Examples

This section provides the following configuration examples:

Configuring an EtherChannel

Configuring a VLAN EtherChannel

Removing an EtherChannel

Configuring a POS Channel

Removing a POS Channel

Configuring Out-of-Service Support

Configuring Bandwidth Propagation

Configuring an EtherChannel

The following is a sample configuration of an EtherChannel between two adjacent routers, in which three Gigabit Ethernet interfaces on each router are configured in the link bundle.

Router1# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)# interface port-channel 1
Router1(config-if)# ip address 22.1.0.1 255.255.0.0
Router1(config-if)# exit 
Router1(config)# interface gigabitethernet4/1
Urbana(config-if)# channel-group 1
Command will clear some config: IP address(es), loopback
  Manually remove other configs

Continue? [yes]: yes
GigabitEthernet4/1 added as member-1 to port-channel1
GigabitEthernet4/1, cleared IP address and loopback mode

Router1(config)# interface gigabitethernet4/2
Urbana(config-if)# channel-group 1
Command will clear some config: IP address(es), loopback
  Manually remove other configs

Continue? [yes]: yes
GigabitEthernet4/2 added as member-2 to port-channel1
GigabitEthernet4/2, cleared IP address and loopback mode

Router1(config)# interface gigabitethernet5/2
Urbana(config-if)# channel-group 1
Command will clear some config: IP address(es), loopback
  Manually remove other configs.

Continue? [yes]: yes
GigabitEthernet5/2 added as member-3 to port-channel1
GigabitEthernet4/1, cleared IP address and loopback mode

Router1(config-if)# exit 

Router2# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router2(config)# interface port-channel 1
Router2(config-if)# ip address 22.1.0.2 255.255.0.0
Router2(config-if)# exit 
Router2(config)# interface gigabitethernet3/1
Urbana(config-if)# channel-group 1
Command will clear some config: IP address(es), loopback
  Manually remove other configs.

Continue? [yes]: yes
GigabitEthernet3/1 added as member-1 to port-channel1
GigabitEthernet3/1, cleared IP address and loopback mode

Router2(config)# interface gigabitethernet3/2
Urbana(config-if)# channel-group 1
Command will clear some config: IP address(es), loopback
  Manually remove other configs.

Continue? [yes]: yes
GigabitEthernet3/2 added as member-2 to port-channel1
GigabitEthernet3/2, cleared IP address and loopback mode

Router2(config)# interface gigabitethernet1/2
Urbana(config-if)# channel-group 1
Command will clear some config: IP address(es), loopback
  Manually remove other configs.

Continue? [yes]: yes
GigabitEthernet1/2 added as member-3 to port-channel1
GigabitEthernet1/2, cleared IP address and loopback mode

Router2(config-if)# exit 

The following example shows how to verify EtherChannel connectivity by pinging each router.

Router1# ping 22.1.0.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 22.1.0.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms

Router2# ping 22.1.0.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 22.1.0.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms

Configuring a VLAN EtherChannel

The following shows a sample configuration of an EtherChannel that consists of two Ethernet 802.1q VLAN links. Bandwidth changes in Gigabit EtherChannel 6 are propagated to upper-layer protocols only when two or more member interfaces are up and active.

Router1# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)# interface port-channel 6
Router1(config-if)# channel-group minimum active 2
Router1(config-if)# no channel-group bandwidth control-propagation
Router1(config-if)# exit 
Router1(config)# interface port-channel 6.1
Router1(config-if)# encapsulation dot1Q 1
Router1(config-if)# ip address 21.1.6.7 255.255.255.0
Router1(config-if)# exit 
Router1(config)# interface port-channel 6.3
Router1(config-if)# encapsulation dot1Q 2
Router1(config-if)# ip address 21.1.6.7 255.255.255.0
Router1(config-if)# exit 

Removing an EtherChannel

The following example shows how to remove all GE interfaces and delete a Gigabit EtherChannel between two routers:

Router1(config)# no interface port-channel 1
GigabitEthernet4/1 taken out of port-channel1
GigabitEthernet5/2 taken out of port-channel1
GigabitEthernet4/2 taken out of port-channel1

Router2(config)# no interface port-channel 1
GigabitEthernet3/1 taken out of port-channel1
GigabitEthernet1/2 taken out of port-channel1
GigabitEthernet3/2 taken out of port-channel1

Configuring a POS Channel

The following is a sample configuration of a POS channel between two adjacent routers in which three Packet-over-SONET interfaces on each router are configured in the link bundle.

Router1# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)# interface pos-channel 1
Router1(config-if)# ip address 41.1.0.1 255.255.0.0
Router1(config-if)# exit 
Router1(config)# interface pos5/0
Urbana(config-if)# channel-group 1
Command will clear some config: IP address(es), loopback
  Manually remove other configs.

Continue? [yes]: yes
POS5/0 added as member-1 to POS-channel1
POS5/0, cleared IP address and loopback mode

Router1(config)# interface pos5/1
Urbana(config-if)# channel-group 1
Command will clear some config: IP address(es), loopback
  Manually remove other configs.

Continue? [yes]: yes
POS5/1 added as member-2 to port-channel1
POS5/1, cleared IP address and loopback mode

Router1(config)# interface pos2/3
Urbana(config-if)# channel-group 1
Command will clear some config: IP address(es), loopback
  Manually remove other configs.

Continue? [yes]: yes
POS2/3 added as member-3 to port-channel1
POS2/3, cleared IP address and loopback mode

Router1(config-if)# exit 


Router2# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router2(config)# interface pos-channel 1
Router2(config-if)# ip address 41.1.0.2 255.255.0.0
Router2(config-if)# exit 
Router2(config)# interface pos5/0
Urbana(config-if)# channel-group 1
Command will clear some config: IP address(es), loopback
  Manually remove other configs.

Continue? [yes]: yes
POS5/0 added as member-1 to POS-channel1
POS5/0, cleared IP address and loopback mode

Router2(config)# interface pos5/1
Urbana(config-if)# channel-group 1
Command will clear some config: IP address(es), loopback
  Manually remove other configs.

Continue? [yes]: yes
POS5/1 added as member-2 to port-channel1
POS5/1, cleared IP address and loopback mode

Router2(config)# interface pos5/3
Urbana(config-if)# channel-group 1
Command will clear some config: IP address(es), loopback
  Manually remove other configs.

Continue? [yes]: yes
POS5/3 added as member-3 to port-channel1
POS5/3, cleared IP address and loopback mode

The following example shows how to verify POS channel connectivity by pinging each router.

Router1# ping 41.1.0.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 41.1.0.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms

Router2# ping 41.1.0.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 41.1.0.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms

Removing a POS Channel

The following example shows how to remove all POS interfaces and delete a POS channel between 2 routers:

Router1(config)# no interface pos-channel 1
POS5/0 taken out of Poschannel1
POS2/3 taken out of Poschannel1

Router2(config)# no interface pos-channel 1
POS5/0 taken out of Poschannel1
POS5/3 taken out of Poschannel1

Configuring Out-of-Service Support

The following example shows how to configure out-of-service support for an EtherChannel so that the following events occur:

The link bundle is brought down if a minimum number of 4 member interfaces are not up and active.

The link bundle comes up as soon as 2 member interfaces are up.

Router1# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)# interface port-channel 1
Router1(config-if)# channel-group minimum active 2
Router1(config-if)# exit 

Configuring Bandwidth Propagation

The following example shows how to control the propagation of bandwidth changes and configure a bandwidth threshold on an EtherChannel so that as long as up to 4 member interfaces are up and active, the total amount of bandwidth used by the active members in the link bundle is propagated to upper-layer protocols at each bandwidth changes.

Note that this example assumes that there are seven member interfaces and that 2 or more active member interfaces are required for the EtherChannel to be up, as shown in the example for Configuring Out-of-Service Support.

Router1# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)# interface port-channel 1
Router1(config-if)# channel-group bandwidth control-propagation
Router1(config-if)# channel-group bandwidth threshold 4
Router1(config-if)# exit 

For the EtherChannel in the preceding example, bandwidth changes are propagated to upper-layer protocols as long as two, three, four, or five member interfaces are active:

If 2 member interfaces are up, a total bandwidth amount of 2 Gigabits is propagated.

If 3 member interfaces are up, a total bandwidth amount of 3 Gigabits is propagated.

If 4 member interfaces are up, a total bandwidth amount of 4 Gigabits is propagated.

If 5 member interfaces are up, the total bandwidth amount, or 7 Gigabits, of all member interfaces in the EtherChannel is propagated.

As soon as one member interface more than the configured threshold value becomes active (in this example, 5 interfaces), the total bandwidth propagated to upper-layer protocols is the combined total of all member interfaces in the link bundle (in this example, 7 interfaces or 7 Gigabits).

If 6 member interfaces are up, bandwidth changes are not propagated.

If 7 member interfaces are up, bandwidth changes are not propagated.

Command Reference

This section documents new commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command reference publications.

channel-group

hw-module slot linkbundle-tcam-scalability

interface port-channel

interface pos-channel

show interfaces port-channel

show interfaces pos-channel

channel-group

To assign a Fast Ethernet or Gigabit Ethernet interface to an EtherChannel or a Packet-over-SONET interface to a POS channel link bundle, use the channel-group command in interface configuration mode. To remove an interface from an EtherChannel or POS channel, use the no form of this command.

channel-group channel-number

no channel-group channel-number

Use the channel-group command in interface configuration mode for an EtherChannel or Packet-over-SONET channel interface to perform the following tasks:

Control the propagation of bandwidth changes and configure a bandwidth threshold to use for propagating bandwidth changes.

Configure the minimum number of active members required for the link bundle to stay up.

Configure VLAN ID-based load-balancing on the Cisco 12000 series ISE, E4+, or E5 member interfaces of an EtherChannel.

To restore the default (minimum number of active links required or bandwidth propagation) settings for an EtherChannel or POS channel, use the no form of the following commands. These channel-group commands cannot be used for a Fast Ethernet, Gigabit Ethernet, or Packet-over-SONET member interface.

channel-group minimum active link-number

no channel-group minimum active link-number

channel-group bandwidth control-propagation

no channel-group bandwidth control-propagation

channel-group bandwidth threshold threshold-number

no channel-group bandwidth threshold threshold-number

channel-group load-share vlan

no channel-group load-share vlan

Syntax Description

channel-number

Port-channel number of the EtherChannel or pos-channel number of the POS channel to which you add (or from which you remove) the GE or POS interface. Assign the port-channel number using the interface port-channel command; assign the pos-channel number using the interface pos-channel command. The valid values of channel-number are from 1 to 16.

minimum active link-number

(Optional) Specifies the minimum number of active member links that must be up in order for the link bundle to stay up. The valid values for link-number are from 1 to 8.

bandwidth control-propagation

(Optional) Enables the automatic propagation of bandwidth changes to upper-layer protocols for the bandwidth threshold specified by the bandwidth threshold threshold-number parameter.

bandwidth threshold threshold-number

(Optional) Specifies the maximum number of active member links allowed for the total amount of bandwidth used in the active members of a link bundle to be propagated to upper-layer protocols each time there is a change in bandwidth. The valid values for threshold-number are from 1 to 8.

When a member interface goes up and the number of active links exceeds the threshold number, the aggregate bandwidth of the active members is not propagated.

When the number of active members becomes one more than the threshold value, the aggregate bandwidth of all member interfaces (both active and passive) in the bundle is propagated to upper-layer protocols.

Note that the channel-group bandwidth threshold threshold-number command is valid only after you enter the channel-group bandwidth control-propagation command.

Also, this value is not valid and a bandwidth change is not propagated if the link bundle is down because the minimum number of active member interfaces configured with the channel-group minimum active command are not up.

load-share vlan

(Optional- for port-channel interfaces only) Configures load-balancing in an EtherChannel bundle based on the VLAN ID of transmitted packets, instead o f the source and destination IP address of the packets.


Defaults

No channel group is assigned.

The default number of minimum active links required in an EtherChannel or POS channel is 1.

Bandwidth changes are propagated, by default, to upper-layer protocols.

The default load-balancing in an EtherChannel is to balance outgoing traffic across all member links according to the source and destination IP address of transmitted packets.

Command Modes

Interface configuration mode

Command History

Release
Modification

12.0(23)S

This command was introduced on Cisco 12000 series Internet routers.

12.0(26)S

This command was enhanced to include the minimum active link-number and bandwidth control-propagation parameters.

12.0(32)S

This command was enhanced to include the load-share vlan parameter.


Usage Guidelines

Configuring an EtherChannel

Before you assign a FE or GE interface to an EtherChannel, you must first create a port-channel logical interface using the interface port-channel command in global configuration mode. After you configure a port-channel interface on the router at one end of an EtherChannel, you use the channel-group command to add up to eight Fast Ethernet or Gigabit Ethernet interfaces to the EtherChannel group.

The interfaces you add to the port-channel must be of the same Engine number and media type. For example, a Gigabit EtherChannel can consist only of all Engine 1 GE interfaces or all Engine 2 GE interfaces. The interfaces you add to the port-channel can, however, belong to line cards in different slots.

You must add the same number of FE or GE member interfaces to the port-channel logical interface on the router at each end of an EtherChannel (see the "Configuring an EtherChannel" section).

If the FE or GE interface already has an IP address assigned, you must disable it before adding the interface to an EtherChannel or POS channel. You are prompted to disable the IP address and other configuration settings after you enter the channel-group command. To disable the IP address, type yes at the prompt.


Note If you do not enter yes at the prompt to disable the IP address assigned to a FE or GE interface, the channel-group command is aborted. The MAC address assigned by default to an EtherChannel by Cisco IOS software is the MAC address of the first FE or GE member of the port-channel interface.


To display information about an EtherChannel, use the show interfaces port-channel command in privileged EXEC mode.

Configuring a POS Channel

Before you assign a POS interface to a POS channel, you must first create a pos-channel logical interface using the interface pos-channel command in global configuration mode. After you configure a pos-channel interface on the router at one end of a POS channel, you use the channel-group command to add up to eight POS interfaces to the POS channel group.

The interfaces you add to the pos-channel must be of the same Engine number and media type. For example, a POS channel can consist only of all Engine 0 POS interfaces or all Engine 2 POS interfaces. The interfaces you add to the pos-channel can, however, belong to line cards in different slots.

You must add the same number of POS member interfaces to the pos-channel logical interface on the router at each end of a POS channel (see the "Configuring a POS Channel" section). If the POS interface already has an IP address assigned, you must disable it before adding the interface to a POS channel. You are prompted to disable the IP address and other configuration settings after you enter the channel-group command. To disable the IP address, type yes at the prompt.


Note If you do not enter yes at the prompt to disable the IP address assigned to a POS interface, the channel-group command is aborted.


To view information about a POS channel, use the show interfaces pos-channel command in privileged EXEC mode.

Out-of-Service Support

Use the channel-group minimum active link-number command in interface configuration mode for an EtherChannel or POS channel interface to configure the minimum number of active member links that must be up and active in order for the link bundle to stay up.

For example, you can have an EtherChannel that consists of eight Gigabit Ethernet links. By default (that is, if you do not use the bandwidth command to configure the amount of available bandwidth), the EtherChannel uses eight gigabits of bandwidth; one gigabit is reserved for each Gigabit Ethernet member interface. However, to avoid overdriving the channel if the amount of required bandwidth falls below three gigabits, you can use the channel-group minimum active 3 command to specify that the EtherChannel is brought down if fewer than three member links are active.

Bandwidth Propagation

Use the channel-group bandwidth control-propagation command in interface configuration mode for an EtherChannel or POS channel interface (see the "interface port-channel" section and the "interface pos-channel" section) to enable and disable the default propagation of the amount of bandwidth used in a link bundle to upper-layer protocols each time there is a bandwidth change. This command allows you to manually control (turn on and off) the propagation of bandwidth changes for the bandwidth threshold specified by the channel-group bandwidth threshold threshold-number command.


Note The channel-group bandwidth threshold threshold-number command is only valid if you have already entered the channel-group bandwidth control-propagation command in interface configuration mode for an EtherChannel or POS channel interface.


A bandwidth change in a link bundle occurs when any of the following events occur:

A new, active member interface is added or a member interface is removed.

An active member interface goes down or a member interface that is down comes up.

The bandwidth threshold is specified according to the number of active member interfaces in the link bundle. When the required number of active member interfaces is less than or equal to the specified threshold number, the total amount of bandwidth used on active members in the link bundle is propagated to upper-layer protocols at each bandwidth change.

When a member interface goes up and the number of active links exceeds the threshold number, the aggregate bandwidth of the active members is not propagated.

When the number of active members becomes one more than the threshold value, the aggregate bandwidth of all member interfaces (both active and passive) in the bundle is propagated to upper-layer protocols.

In addition, bandwidth changes are not propagated if the link bundle goes down because the number of active member interfaces is less than the configured minimum number of active member links required, as described in the "Out-of-Service Support" section.


Note The bandwidth command is supported on an EtherChannel or POS channel interface, but is not supported on a member interface in a link bundle. The bandwidth on each member interface is the default bandwidth value of the interface. The bandwidth on the link bundle is the combined default bandwidth of all active member links.

The bandwidth command is supported on a member interface only after you remove it from the link bundle. The bandwidth of the link bundle is then reduced by the default bandwidth of the interface that you removed.


EtherChannel Load-balancing

To configure load-balancing in the link bundle based on the VLAN ID of transmitted packets, use the channel-group load-share vlan command in interface configuration mode for an EtherChannel (port-channel) interface. Outgoing traffic is normally balanced across all links in a bundle based on the source and destination IP address of packets. To switch back to per-destination load-balancing, use the no channel-group load-share vlan command.

VLAN ID-based load sharing is recommended in an EtherChannel bundle in the following configurations:

A customer requires VLAN-specific quality-of-service policies on egress traffic, which cannot be achieved due to hardware limitations.

For Layer 2 traffic or when AToM features are configured on member interfaces, Layer 3 parameters, such as source and destination IP address, are not supported. Load-balancing based on Layer 2 characteristics is, therefore, recommended.

LAN ID-based load sharing is supported in link bundles on other platforms or third-party devices deployed at the provider edge.

Examples

The following example adds a Gigabit Ethernet interface to the EtherChannel bundle specified by port-channel 1:

Router(config)# interface port-channel 1
Router(config-if)# ip address 22.1.0.1 255.255.255.0
Router(config-if)# end
Router(config)# interface gigabitethernet 1/0
Router(config-if)# channel-group 1

The next example shows how to configure the automatic propagation of bandwidth changes in the EtherChannel only when two, three or four Gigabit Ethernet member interfaces are up and active:

Router(config)# interface port-channel 1
Router(config-if)# channel-group minimum active 2
Router(config-if)# channel-group bandwidth control-propagation
Router(config-if)# channel-group bandwidth threshold 4

This example shows how to configure load-balancing across member links of an EtherChannel based on the VLAN ID of transmitted packets:

Router(config)# interface port-channel 2
Router(config-if)# channel-group load-share vlan 

Related Commands

Command
Description

interface port-channel

Specifies an EtherChannel and enters interface configuration mode.

interface pos-channel

Specifies a POS channel and enters interface configuration mode.

show interfaces port-channel

Displays information about an EtherChannel.

show interfaces pos-channel

Displays information about a POS channel.


hw-module slot linkbundle-tcam-scalability

To maximize the amount of VLAN TCAM allocated to process VLAN traffic on a Fast Ethernet or Gigabit Ethernet line card whose interfaces belong to an EtherChannel link bundle, use the hw-module slot linkbundle-tcam-scalability command in global configuration mode. To restore the default VLAN TCAM size, use the no form of this command.

hw-module slot number linkbundle-tcam-scalability

Syntax Description

number

Slot number of a line card.


Defaults

No default behavior or values.

Command Modes

Global configuration

Command History

Release
Modification

12.0(32)S

This command was introduced on Cisco 12000 series ISE line cards.


Usage Guidelines

When you increase the number of VLANs on the member interfaces of an EtherChannel, the performance of VLAN load-balancing and data transmission depends on the percentage of ternary content addressable memory (TCAM) allocated for VLANs on each Fast Ethernet or Gigabit Ethernet line card, whose interfaces belong to the link bundle.The hw-module slot linkbundle-tcam-scalability command allows you to recarve Layer 2 TCAM regions so that 1K of TCAM is allocated to process VLAN traffic on each subinterface used in a link bundle.

To display the amount of TCAM allocated for Cisco IOS features on a line card, enter the show controllers frfab alpha tcam carve command.

After you enter the hw-module slot linkbundle-tcam-scalability command, you must enter the microcode reload command to reload the software and microcode on the line card so that the newly configured VLAN TCAM size take effect.

Examples

The following example shows how to maximize the VLAN TCAM allocated to member subinterfaces on the Gigabit Ethernet line card in slot 3:

Router(config)# hw-module slot 3 linkbundle-tcam-scalability

Router(config)# microcode reload 3

Related Commands

Command
Description

show controllers frfab alpha tcam carve

Displays the amount of TCAM allocated to Cisco IOS features on a line card.


interface port-channel

To specify a port-channel interface to associate with an EtherChannel and enter interface configuration mode, use the interface port-channel command in global configuration mode. To delete all interfaces from an EtherChannel, use the no form of this command.

interface port-channel channel-number

no interface port-channel channel-number

Syntax Description

channel-number

Specifies the channel number assigned to an EtherChannel.


Defaults

No default behavior or values.

Command Modes

Global configuration mode

Command History

Release
Modification

12.0(23)S

This command was introduced on Cisco 12000 series Internet routers.


Usage Guidelines

The Cisco 12000 series Link Bundling feature allows you to bundle multiple Fast Ethernet or Gigabit Ethernet point-to-point links into one logical link to provide higher bidirectional bandwidth. You can configure an EtherChannel between the following routers:

Cisco 12000 series Internet routers

Cisco 12000 series Internet routers and Cisco 7500 series routers or Cisco 7000 series routers with the 7000 Series Route Switch Processor (RSP7000) and 7000 Series Chassis Interface (RSP7000CI) and a Catalyst 5000 switch.

Using the interface port-channel command, you configure the port-channel (logical) interface associated with an EtherChannel link bundle. Using the channel-group command, you then add up to eight Fast Ethernet or Gigabit Ethernet interfaces to an EtherChannel group.

You must configure the port-channel (logical) interface on the router at each end of the EtherChannel (see the "Configuring an EtherChannel" section). You can configure a different port-channel number on each router.

To display information about an EtherChannel, use the show interfaces port-channel command in privileged EXEC mode.

To delete the counters for one or all Cisco 12000 series FE or GE interfaces in an EtherChannel link bundle, use the clear counters command in privileged EXEC mode.


Note If you do not assign a static MAC address on the port-channel interface, Cisco IOS software automatically assigns a MAC address. If you assign a static MAC address and then later remove it, Cisco IOS software automatically assigns a MAC address.


Examples

The following example creates a port-channel interface for an EtherChannel bundle with a channel group number of 1:

router# configure terminal
router(config)# interface port-channel 1
router(config-if)# ip address 22.1.0.1 255.255.0.0
router(config-if)# end 

Related Commands

Command
Description

channel-group

Assigns a Fast Ethernet or Gigabit Ethernet interface to an EtherChannel or a Packet-over-SONET interface to a POS channel.

show interfaces port-channel

Displays information about an EtherChannel.


interface pos-channel

To specify a pos-channel interface to associate with a POS channel link bundle and enter interface configuration mode, use the interface pos-channel command in global configuration mode. To delete all interfaces from a POS channel, use the no form of this command.

interface pos-channel channel-number

no interface pos-channel channel-number

Syntax Description

channel-number

Specifies the channel number assigned to a POS channel.


Defaults

No default behavior or values.

Command Modes

Global configuration mode

Command History

Release
Modification

12.0(23)S

This command was introduced on Cisco 12000 series Internet routers.


Usage Guidelines

The Link Bundling feature allows you to bundle multiple Packet-over-SONET point-to-point links into one logical link to provide higher bidirectional bandwidth. You can configure a POS channel between the following routers:

Cisco 12000 series Internet routers

Cisco 12000 series Internet routers and Cisco 7500 series routers or Cisco 7000 series routers with the 7000 Series Route Switch Processor (RSP7000) and 7000 Series Chassis Interface (RSP7000CI) and a Catalyst 5000 switch

Using the interface pos-channel command, you configure the pos-channel (logical) interface associated with a POS channel link bundle. Using the channel-group command, you then add up to 8 packet over SONET interfaces to a POS channel group.

You must configure the pos-channel (logical) interface on the router at each end of the POS channel (see the "Configuring a POS Channel" section). You can configure a different pos-channel number on each router.

To display information about a POS channel, use the show interfaces pos-channel command in privileged EXEC mode.

To delete the counters for one or all POS interfaces in a POS channel link bundle, use the clear counters command in privileged EXEC mode.

Examples

The following example creates a pos-channel interface for a POS channel bundle with a channel group number of 3:

router# configure terminal
router(config)# interface pos-channel 3
router(config-if)# ip address 23.1.0.1 255.255.0.0
router(config-if)# end 

Related Commands

Command
Description

channel-group

Assigns a Fast Ethernet or Gigabit Ethernet interface to an EtherChannel or a Packet-over-SONET interface to a POS channel.

show interfaces pos-channel

Displays information about a POS channel.


show interfaces port-channel

To display information about an EtherChannel, use the show interfaces port-channel command in privileged EXEC configuration mode.

show interfaces port-channel channel-number

Syntax Description

channel-number

Port channel number associated with an EtherChannel. The valid values are from 1 to 16.


Defaults

No default behavior or values.

Command Modes

Privileged EXEC

Command History

Release
Modification

12.0(23)S

This command was introduced on Cisco 12000 series Internet routers.


Usage Guidelines

Use the show interfaces port-channel command to display information about the bundled FE or GE links in an EtherChannel.

Examples

The following example shows sample output for a Cisco 12000 series EtherChannel.

Router# show interfaces port-channel 1
Port-channel1 is up, line protocol is up 
  Hardware is GEChannel, address is 0050.2ac6.9581 (bia 0000.0000.0000)
  Internet address is 22.1.0.2/16
  MTU 1500 bytes, BW 3000000 Kbit, DLY 10 usec, rely 255/255, load 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  ARP type: ARPA, ARP Timeout 04:00:00
    No. of active members in this channel: 3 
        Member 0 : GigabitEthernet3/1 , Full-duplex, 1000Mb/s
        Member 1 : GigabitEthernet3/2 , Full-duplex, 1000Mb/s
        Member 2 : GigabitEthernet1/2 , Full-duplex, 1000Mb/s
    No. of passive members in this channel: 0 
  Last input 00:00:01, output 00:00:01, output hang never
  Last clearing of "show interface" counters 3d15h
  Queueing strategy: fifo
  Output queue 0/120, 0 drops; input queue 0/225, 0 drops
  30 second input rate 1425032000 bits/sec, 1038111 packets/sec
  30 second output rate 0 bits/sec, 0 packets/sec
     328903597021 packets input, 56454340092292 bytes, 0 no buffer
     Received 50815 broadcasts, 0 runts, 0 giants, 0 throttles
     528238 input errors, 0 CRC, 0 frame, 528238 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     128365 packets output, 9409520 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 pause output
     0 output buffer failures, 0 output buffers swapped out

Table 5 lists field descriptions for the show interfaces port-channel command.

Table 5 show interfaces port-channel Field Descriptions

Field 
Description

Port-channel1 is up, line protocol is up

Indicates if the interface hardware is currently active and can transmit and receive, or if it has been taken down by an administrator.

Hardware is

Hardware type (Fast EtherChannel or Gigabit EtherChannel).

address is

MAC address being used by the interface.

MTU

Maximum transmission unit of the interface.

BW

Bandwidth of the interface in kilobits per second.

DLY

Delay of the interface in microseconds.

rely

Reliability of the interface as a fraction of 255 (255/255 is 100% reliability), calculated as an exponential average over 5 minutes.

load

Load on the interface as a fraction of 255 (255/255 is completely saturated), calculated as an exponential average over 5 minutes. The calculation uses the value from the bandwidth interface configuration command.

Encapsulation

Encapsulation method assigned to the interface.

loopback

Indicates if loopbacks are set.

Keepalive

Indicates if keepalives are set.

No. of active members in this channel

Indicates the number of FE or GE interfaces in the bundle that are up (active).

No. of passive members in this channel

Indicates the number of FE or GE interfaces in the bundle that are down (passive).

Last input

Number of hours, minutes, and seconds since the last packet was successfully received by an interface. Useful for knowing when a dead interface failed.

output

Number of hours, minutes, and seconds since the last packet was successfully transmitted by an interface.

output hang

Number of hours, minutes, and seconds (or never) since the interface was last reset because of a transmission that took too long. When the number of hours in any of the "last" fields exceeds 24 hours, the number of days and hours is printed. If that field overflows, asterisks are printed.

Last clearing

Time at which the counters that measure cumulative statistics (such as number of bytes transmitted and received) shown in this report were last reset to zero. Variables that might affect routing (for example, load and reliability) are not cleared when the counters are cleared.

*** indicates the elapsed time is too large to be displayed.

0:00:00 indicates the counters were cleared more than 231ms (and less then 232ms) ago.

Queueing strategy

First-in, first-out queuing strategy (other queueing strategies you might see are priority-list, custom-list, and weighted fair).

Output queue, drops
input queue, drops

Number of packets dropped in output and input queues. Each number is followed by a slash, the maximum size of the queue, and the number of packets dropped because a queue was full.

n second/minute input rate
n second/minute output rate

Average number of bits and packets received or transmitted per second in the last n seconds or minutes.

packets input

Total number of error-free packets received by the system.

bytes (input)

Total number of bytes, including data and MAC encapsulation, in the error-free packets received by the system.

no buffer

Number of received packets discarded because there was no buffer space in the main system. Compare with ignored count. Broadcast storms on Ethernets and bursts of noise on serial lines are often responsible for no input buffer events.

broadcasts

Total number of broadcast or multicast packets received by the interface.

runts

Number of packets that are discarded because they are smaller than the medium's minimum packet size.

giants

Number of packets that are discarded because they exceed the medium's maximum packet size.

throttles

Number of times the receiver on the port was disabled, possibly due to buffer or processor overload.

input errors

Total number of no buffer, runts, giants, CRCs, frame, overrun, ignored, and abort counts. Other input-related errors can also increment the count, so that this sum might not balance with the other counts.

CRC

Cyclic redundancy checksum generated by the originating LAN station or far-end device does not match the checksum calculated from the data received. On a LAN, this usually indicates noise or transmission problems on the LAN interface or the LAN bus itself. A high number of CRCs is usually the result of collisions or a station transmitting bad data.

frame

Number of packets received incorrectly having a CRC error and a noninteger number of octets. On a serial line, this is usually the result of noise or other transmission problems.

overrun

Number of times the serial receiver hardware was unable to hand received data to a hardware buffer because the input rate exceeded the receiver's ability to manage the data.

ignored

Number of received packets ignored by the interface because the interface hardware ran low on internal buffers. These buffers are different than the system buffers mentioned previously in the buffer description. Broadcast storms and bursts of noise can cause the ignored count to be incremented.

watchdog

Number of times watchdog receive timer expired. It happens when receiving a packet with length greater than 2048.

multicast

Number of multicast packets received.

packets output

Total number of messages transmitted by the system.

bytes (output)

Total number of bytes, including data and MAC encapsulation, transmitted by the system.

underruns

Number of times that the far-end transmitter has been running faster than the near-end router's receiver can manage.

output errors

Sum of all errors that prevented the final transmission of datagrams out of the interface being examined. Note that this might not balance with the sum of the enumerated output errors, as some datagrams can have more than one error, and others can have errors that do not fall into any of the specifically tabulated categories.

collisions

Number of messages retransmitted due to an Ethernet collision. This is usually the result of an overextended LAN (Ethernet or transceiver cable too long, more than two repeaters between stations, or too many cascaded multiport transceivers). A packet that collides is counted only once in output packets.

interface resets

Number of times an interface has been completely reset. This can happen if packets queued for transmission were not sent within a certain interval. If the system notices that the carrier detect line of an interface is up, but the line protocol is down, it periodically resets the interface in an effort to restart it. Interface resets can also occur when an unrecoverable interface processor error occurred, or when an interface is looped back or shut down.

babbles

The transmit jabber timer expired.

late collision

Number of late collisions. Late collision happens when a collision occurs after transmitting the preamble.

deferred

Indicates that the chip had to defer while ready to transmit a frame because the carrier was asserted.

lost carrier

Number of times the carrier was lost during transmission.

no carrier

Number of times the carrier was not present during the transmission.

output buffer failures

Number of times that a packet was not output from the output hold queue.

output buffers swapped out

Number of packets stored in main memory when the output queue is full; swapping buffers to main memory prevents packets from being dropped when output is congested. The number is high when traffic is bursty.


Related Commands

Command
Description

interface port-channel

Specifies an EtherChannel and enters interface configuration mode.


show interfaces pos-channel

To display information about a POS channel, use the show interfaces pos-channel command in privileged EXEC configuration mode.

show interfaces pos-channel channel-number

Syntax Description

channel-number

Port channel number associated with a POS channel. The valid values are from 1 to 16.


Defaults

No default behavior or values.

Command Modes

Privileged EXEC

Command History

Release
Modification

12.0(23)S

This command was introduced on Cisco 12000 series Internet routers.


Usage Guidelines

Use the show interfaces pos-channel command to display information about the bundled POS links in a POS channel.

Examples

The following example shows sample output for a Cisco 12000 series POS channel.

Router# show interfaces pos-channel 1
Pos-channel1 is up, line protocol is up 
  Hardware is POSChannel
  Internet address is 41.1.0.1/16
  MTU 4470 bytes, BW 1244000 Kbit, DLY 100 usec, rely 255/255, load 236/255
  Encapsulation HDLC, loopback not set
  Keepalive set (10 sec)
    No. of active members in this channel: 2 
        Member 0 : POS5/0 
        Member 1 : POS2/3 
    No. of passive members in this channel: 1 
        Member 0 : POS5/1 
  Last input 00:00:01, output 00:00:03, output hang never
  Last clearing of "show interface" counters 3d15h
  Queueing strategy: fifo
  Output queue 0/80, 3665649311 drops; input queue 0/150, 0 drops
  30 second input rate 0 bits/sec, 0 packets/sec
  30 second output rate 1168138000 bits/sec, 627497 packets/sec
     192649 packets input, 12073574 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     197631584356 packets output, 46098596464843 bytes, 0 underruns
     0 output errors, 0 appliques, 0 interface resets
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions

Table 6 lists field descriptions for the show interfaces pos-channel command.

Table 6 show interfaces pos-channel Field Descriptions

Field 
Description

Port-channel1 is up, line protocol is up

Indicates if the interface hardware is currently active and can transmit and receive, or if it has been taken down by an administrator.

Hardware is

Hardware type (POS channel).

MTU

Maximum transmission unit of the interface.

BW

Bandwidth of the interface in kilobits per second.

DLY

Delay of the interface in microseconds.

rely

Reliability of the interface as a fraction of 255 (255/255 is 100% reliability), calculated as an exponential average over 5 minutes.

load

Load on the interface as a fraction of 255 (255/255 is completely saturated), calculated as an exponential average over 5 minutes. The calculation uses the value from the bandwidth interface configuration command.

Encapsulation

Encapsulation method assigned to the interface.

loopback

Indicates if loopbacks are set.

Keepalive

Indicates if keepalives are set.

No. of active members in this channel

Indicates the number of Packet-over-SONET interfaces in the bundle that are up (active).

No. of passive members in this channel

Indicates the number of Packet-over-SONET interfaces in the bundle that are down (passive).

Last input

Number of hours, minutes, and seconds since the last packet was successfully received by an interface. Useful for knowing when a dead interface failed.

output

Number of hours, minutes, and seconds since the last packet was successfully transmitted by an interface.

output hang

Number of hours, minutes, and seconds (or never) since the interface was last reset because of a transmission that took too long. When the number of hours in any of the "last" fields exceeds 24 hours, the number of days and hours is printed. If that field overflows, asterisks are printed.

Last clearing

Time at which the counters that measure cumulative statistics (such as number of bytes transmitted and received) shown in this report were last reset to zero. Variables that might affect routing (for example, load and reliability) are not cleared when the counters are cleared.

*** indicates the elapsed time is too large to be displayed.

0:00:00 indicates the counters were cleared more than 231ms (and less then 232ms) ago.

Queueing strategy

First-in, first-out queuing strategy (other queueing strategies you might see are priority-list, custom-list, and weighted fair).

Output queue, drops
input queue, drops

Number of packets dropped in output and input queues. Each number is followed by a slash, the maximum size of the queue, and the number of packets dropped because a queue was full.

n second/minute input rate
n second/minute output rate

Average number of bits and packets received or transmitted per second in the last n seconds or minutes.

packets input

Total number of error-free packets received by the system.

bytes (input)

Total number of bytes, including data and MAC encapsulation, in the error-free packets received by the system.

no buffer

Number of received packets discarded because there was no buffer space in the main system. Compare with ignored count. Bursts of noise on serial lines are often responsible for no input buffer events.

broadcasts

Total number of broadcast or multicast packets received by the interface.

runts

Number of packets that are discarded because they are smaller than the medium's minimum packet size.

giants

Number of packets that are discarded because they exceed the medium's maximum packet size.

throttles

Number of times the receiver on the port was disabled, possibly due to buffer or processor overload.

input errors

Total number of no buffer, runts, giants, CRCs, frame, overrun, ignored, and abort counts. Other input-related errors can also increment the count, so that this sum might not balance with the other counts.

CRC

Cyclic redundancy checksum generated by the originating LAN station or far-end device does not match the checksum calculated from the data received. On a LAN, this usually indicates noise or transmission problems on the LAN interface or the LAN bus itself. On a serial link, CRCs usually indicate noise, gain hits, or other transmission problems on the data link.

frame

Number of packets received incorrectly having a CRC error and a noninteger number of octets. On a serial line, this is usually the result of noise or other transmission problems.

overrun

Number of times the serial receiver hardware was unable to hand received data to a hardware buffer because the input rate exceeded the receiver's ability to manage the data.

ignored

Number of received packets ignored by the interface because the interface hardware ran low on internal buffers. These buffers are different than the system buffers mentioned previously in the buffer description. Broadcast storms and bursts of noise can cause the ignored count to be incremented.

abort

Illegal sequence of ones bit on the interface.

packets output

Total number of messages transmitted by the system.

bytes (output)

Total number of bytes, including data and MAC encapsulation, transmitted by the system.

underruns

Number of times that the far-end transmitter has been running faster than the near-end router's receiver can manage.

output errors

Sum of all errors that prevented the final transmission of datagrams out of the interface being examined. Note that this might not balance with the sum of the enumerated output errors, as some datagrams can have more than one error, and others can have errors that do not fall into any of the specifically tabulated categories.

applique

Indicates an unrecoverable error has occurred on the POS IP applique. The system then invokes an interface reset.

interface resets

Number of times an interface has been completely reset. This can happen if packets queued for transmission were not sent within a certain interval. If the system notices that the carrier detect line of an interface is up, but the line protocol is down, it periodically resets the interface in an effort to restart it. Interface resets can also occur when an unrecoverable interface processor error occurred, or when an interface is looped back or shut down.

output buffer failures

Number of times that a packet was not output from the output hold queue.

output buffers swapped out

Number of packets stored in main memory when the output queue is full; swapping buffers to main memory prevents packets from being dropped when output is congested. The number is high when traffic is bursty.

carrier transitions

Number of times the carrier detect signal of the interface changed state.


Related Commands

Command
Description

interface pos-channel

Specifies a POS channel and enters interface configuration mode.


Glossary

active member—Member interface of an EtherChannel or POS channel whose link status is up and can pass traffic.

ALPHA—Packet-switching ASIC on Cisco 12000 series IP Service Engine (ISE) line cards.

ASIC—application specific integrated circuit. Circuit designs used by manufacturers to consolidate many chips into a single package, reducing board size and power consumption.

EtherChannel—Developed and copyrighted by Cisco Systems. Logical aggregation of multiple Ethernet interfaces used to form a single higher bandwidth routing or bridging endpoint.

Fast EtherChannel members—Fast Ethernet interfaces (both active and passive) added to an EtherChannel.

Gbps—Gigabits per second.

Gigabit EtherChannel members—Gigabit Ethernet interfaces (both active and passive) added to an EtherChannel.

IOS—Cisco IOS software is an innovative and feature-rich network systems software that gives networks intelligence and agility. It allows the effective deployment of new applications and services that enable our customers's business to generate revenue, reduce costs and improve customer service.

link—In the context of a transmission network, a link is a point-to-point connection between adjacent nodes. There can be more than one link between adjacent nodes.

link bundle—Synonym for EtherChannel or POS channel.

passive member—Member interface of an EtherChannel or POS channel whose link status is down and cannot pass traffic.

point-to-point connection—One of two fundamental connection types. Communication between one receiver and one location.

POP—Point of presence. In an Operations Support System (OSS), a physical location where an interexchange carrier installed equipment to interconnect with a local exchange carrier (LEC).

port-channel—Type of interface in Cisco IOS software used to group Fast Ethernet and Gigabit Ethernet interfaces.

POS—Packet-over-SONET. A technology in which IP packets are mapped into SONET frames with intervening use of an ATM layer.

pos-channel—Type of interface in Cisco IOS software used to group Packet-over-SONET interfaces.

POS channel members—POS interfaces (both active and passive) added to a POS channel.

PSA—Packet-switching ASIC on Cisco 12000 series line cards.