Catalyst 4000 Family Software Configuration Guide, 7.1 - Configuring Fast EtherChannel and Gigabit EtherChannel [Cisco Catalyst 4000 Series Switches]

Table Of Contents

Configuring Fast EtherChannel and Gigabit EtherChannel

Understanding How EtherChannel Works

EtherChannel Overview

Understanding Frame Distribution

Hardware Support for EtherChannel

Port Aggregation Control Protocol and Link Aggregation Control Protocol

EtherChannel Configuration Guidelines and Restrictions

Guidelines for Port Configuration

Guidelines for VLAN and Trunk Configuration

EtherChannel Interaction with Other Features

Understanding the Port Aggregation Protocol

PAgP Modes

Understanding Administrative Groups and EtherChannel IDs

Configuring EtherChannel Using PAgP

Creating an EtherChannel

Defining an EtherChannel Administrative Group

Setting the EtherChannel Spanning Tree Port Cost

Setting the EtherChannel Spanning Tree Port VLAN Cost

Removing an EtherChannel Bundle

Displaying EtherChannel Configuration Information

Displaying EtherChannel Traffic Statistics

Displaying EtherChannel PAgP Statistics

EtherChannel Configuration Examples

Four-Port Fast EtherChannel Configuration Example

Two-Port Gigabit EtherChannel Configuration Example

Understanding the Link Aggregation Control Protocol

LACP Modes

LACP Parameters

Configuring EtherChannel Using LACP

Specifying the EtherChannel Protocol

Specifying the System Priority

Specifying the Port Priority

Specifying an Administrative Key Value

Changing the Channel Mode

Specifying the Channel Path Cost

Specifying the Channel VLAN Cost

Clearing LACP Statistics

Displaying EtherChannel Traffic Utilization

Disabling an EtherChannel

Display Spanning Tree-Related Information for EtherChannels

Configuring Fast EtherChannel and Gigabit EtherChannel

This chapter describes how to configure Fast EtherChannel and Gigabit EtherChannel port bundles on the Catalyst enterprise LAN switches. The configuration tasks in this chapter apply to Fast Ethernet and Gigabit Ethernet switch ports on switching modules and fixed-configuration switches, as well as to supervisor engine Fast Ethernet and Gigabit Ethernet uplink ports.

Note For complete information on installing Catalyst 4000 family Fast Ethernet and Gigabit Ethernet modules, refer to the Catalyst 4000 Family Installation Guide.

Note For complete syntax and usage information for the commands used in this chapter, refer to the Command Reference—Catalyst 4000 Family, Catalyst 2948G, and Catalyst 2980G Switches.

This chapter consists of these sections:

•Understanding How EtherChannel Works

•Port Aggregation Control Protocol and Link Aggregation Control Protocol

•EtherChannel Configuration Guidelines and Restrictions

•Understanding the Port Aggregation Protocol

•Configuring EtherChannel Using PAgP

•Understanding the Link Aggregation Control Protocol

•Configuring EtherChannel Using LACP

Understanding How EtherChannel Works

These sections describe how EtherChannel works:

•EtherChannel Overview

•Understanding Frame Distribution

•Hardware Support for EtherChannel

EtherChannel Overview

Fast EtherChannel and Gigabit EtherChannel port bundles let you group multiple Fast or Gigabit Ethernet ports into a single logical transmission path between switch and router, host, or other switch.

Depending on your hardware, you can form an EtherChannel with up to eight compatibly configured Fast or Gigabit Ethernet ports on the switch. In addition, on the Catalyst 4000 family switches, you can configure an EtherChannel using ports from multiple modules. All ports in an EtherChannel must be the same speed.

The switch distributes frames across the ports in an EtherChannel according to the source and destination Media Access Control (MAC) addresses. If a port within an EtherChannel fails, traffic previously carried over the failed port switches to the remaining ports within the EtherChannel. A trap is sent upon a failure identifying the switch, the EtherChannel, and the failed link.

Both Fast and Gigabit EtherChannel bundles can be configured as trunk links. After a channel has been formed, configuring any port in the channel as a trunk applies the configuration to all ports in the channel. Identically configured trunk ports can be configured as an EtherChannel. For more information, see the "EtherChannel Configuration Guidelines and Restrictions" section and "Configuring VLAN Trunks on Fast Ethernet and Gigabit Ethernet Ports."

Understanding Frame Distribution

EtherChannel distributes frames across the links in a channel based on the low-order bits of the source and destination Media Access Control (MAC) addresses of each frame. The frame distribution method is not configurable.

Hardware Support for EtherChannel

EtherChannel support is hardware-dependent. In general, you can use the show port capabilities command to determine whether your hardware supports EtherChannel, and to confirm which ports you can bundle into a single EtherChannel.

An EtherChannel bundle can consist of any two to eight ports. Ports in an EtherChannel bundle do not have to be continuous, and they do not have to be on the same module.

Due to the port ID handling by the spanning tree feature, the maximum supported number of channels is 126 for a 6-slot chassis.

Port Aggregation Control Protocol and Link Aggregation Control Protocol

Port Aggregation Control Protocol (PAgP) and Link Aggregation Control Protocol (LACP) are two different protocols that allow ports with similar characteristics to form a channel through dynamic negotiation with adjoining switches. PAgP is a Cisco-proprietary protocol that can be run only on Cisco switches and those switches released by licensed vendors. LACP, which is defined in IEEE 802.3ad, allows Cisco switches to manage Ethernet channeling with devices that conform to the 802.3ad specification.

To use PAgP, see the "Understanding the Port Aggregation Protocol" section. To use LACP, see the "Understanding the Link Aggregation Control Protocol" section.

EtherChannel Configuration Guidelines and Restrictions

If improperly configured, some EtherChannel ports are disabled automatically to avoid network loops and other problems. Follow these guidelines to avoid configuration problems.

Note Except where specifically differentiated, these guidelines apply to both PAgP and LACP.

These sections provide EtherChannel configuration guidelines:

•Guidelines for Port Configuration

•Guidelines for VLAN and Trunk Configuration

•EtherChannel Interaction with Other Features

Guidelines for Port Configuration

Follow these port configuration guidelines:

•You can have a maximum of eight compatibly configured ports per EtherChannel; the ports do not have to be contiguous or on the same module.

•All ports in an EtherChannel must use the same protocol; you cannot run two protocols on one module.

•PAgP and LACP are not compatible; both ends of a channel must use the same protocol.

Note Switches can be configured manually, with PAgP on one side and LACP on the other side in the on mode.

•You can change the protocol at any time, but this change causes all existing EtherChannels to reset to the default channel mode for the new protocol.

•Configure all ports in an EtherChannel to operate at the same speed and duplex mode (full duplex only for LACP mode).

•Enable all ports in an EtherChannel. If you disable a port in an EtherChannel, it is treated as a link failure and its traffic is transferred to one of the remaining ports in the EtherChannel.

•A port cannot belong to more than one channel group at the same time.

•Ports with different port path costs, set by the set spantree portcost command, can form an EtherChannel as long as they are otherwise compatibly configured. Setting different port path costs does not, by itself, make ports incompatible for the formation of an EtherChannel.

•PAgP and LACP manage channels differently. When all the ports in a channel get disabled, PAgP removes them from its internal channels list; show commands do not display the channel. With LACP, when all the ports in a channel get disabled, LACP does not remove the channel; show commands continue to display the channel even though all its ports are down. To determine if a channel is actively sending and receiving traffic with LACP, use the show port command to see if the link is up or down.

•LACP does not support half-duplex links. If a port is in active/passive mode and becomes half duplex, the port is suspended (and a syslog message is generated). The port is shown as "connected" using the show port command and as "not connected" using the show spantree command. This discrepancy is because the port is physically connected but never joined spanning tree. To get the port to join spanning tree, either set the duplex to full or set the channel mode to off for that port.

Guidelines for VLAN and Trunk Configuration

Follow these VLAN and trunk-related guidelines:

•Assign all ports in an EtherChannel to the same VLAN, or configure them as trunk ports.

•If you configure the EtherChannel as a trunk, configure the same trunk mode on all the ports in the EtherChannel. Configuring ports in an EtherChannel in different trunk modes can have unexpected results.

•An EtherChannel supports the same allowed range of VLANs on all the ports in a trunking EtherChannel. If the allowed range of VLANs is not the same for a port list, the ports do not form an EtherChannel even when set to the auto or desirable mode with the set port channel command.

•Do not configure the ports in an EtherChannel as dynamic VLAN ports. Doing so can adversely affect switch performance.

•Ports with different VLAN costs or VLAN configurations cannot form a channel.

EtherChannel Interaction with Other Features

Follow these guidelines associated with EtherChannel's interaction with other features:

•An EtherChannel will not form with ports that have different GARP VLAN Registration Protocol (GVRP), GARP Multicast Registration Protocol (GMRP), and quality of service (QoS) configurations.

•An EtherChannel will not form with ports where the port security feature is enabled. You cannot enable the port security feature for ports in an EtherChannel.

•An EtherChannel will not form if one of the ports is a SPAN destination port.

•An EtherChannel will not form if protocol filtering is set differently on the ports.

•Cisco Discovery Protocol (CDP) runs on the physical port even after the port is added to a channel.

•VLAN Trunking Protocol (VTP) and Dual Ring Protocol (DRiP) run on the channel.

•During fast switchover to the standby supervisor engine, all channeling ports are cleared on its channeling configuration and state, and the links are pulled down temporarily to cause partner ports to reset. All ports are reset to the nonchanneling state.

•Ports with different dot1q port types cannot form a channel.

•Ports with different jumbo frame configurations cannot form a channel.

•Ports with different dynamic configurations cannot form a channel.

•During high-availability switchover to the standby supervisor engine, all channeling ports remain operational. Ports are reset only if there are events missing during the switchover.

•If one port in an EtherChannel is used by IGMP multicast filtering, you must set the EtherChannel mode for both PAgP and LACP to off. No other mode may be used.

Note With software releases 6.3(1) and later, a PAgP-configured EtherChannel is preserved even if it contains only one port (this does not apply to LACP-configured EtherChannels). In software releases prior to 6.3(1), traffic was disrupted when you removed a 1-port channel from spanning tree and then added it to spanning tree as an individual port.

Note With software releases 6.3(1) and later, due to the port ID handling by the spanning tree feature, the maximum supported number of EtherChannels is 126 for a 6- or 9-slot chassis and 63 for a 13-slot chassis.

Understanding the Port Aggregation Protocol

Note Use the information in these sections if you are configuring EtherChannel using PAgP. If you are using LACP, see the "Understanding the Link Aggregation Control Protocol" section.

These sections describe PAgP:

•PAgP Modes

•Understanding Administrative Groups and EtherChannel IDs

PAgP Modes

The Port Aggregation Protocol (PAgP) facilitates the automatic creation of Fast EtherChannel and Gigabit EtherChannel links by exchanging packets between channel-capable ports. The protocol learns the capabilities of port groups dynamically and informs the neighboring ports.

After PAgP identifies correctly paired channel-capable links, it groups the ports into a channel. The channel is then added to the spanning tree as a single bridge port. A given outbound broadcast or multicast packet is transmitted out one port in the channel only, not out every port in the channel. In addition, outbound broadcast and multicast packets transmitted on one port in a channel are blocked from returning on any other port of the channel.

There are four user-configurable channel modes: on, off, auto, and desirable. PAgP packets are exchanged only between ports in auto and desirable mode. Ports configured in on or off mode do not exchange PAgP packets. The auto and desirable modes can be modified with the silent and non-silent keywords. Table 6-1 describes each mode.

Table 6-1 Channel Modes

Mode

Description

on

Forces the port to channel without negotiation. PAgP packets are not exchanged. The port is channeling regardless of how the peer port is configured. If the peer port is in on mode, a channel is formed. In any other mode, the peer port is placed in the errdisable state due to a channel misconfiguration.

off

Prevents the port from channeling. PAgP packets are not exchanged. The port is not channeling regardless of how the peer port is configured. No channel is formed.

auto

Places a port into a passive negotiating state, in which the port responds to PAgP packets it receives but does not initiate PAgP packet negotiation. A channel is formed only with another port group in desirable mode. (Default)

desirable

Places a port into an active negotiating state, in which the port initiates negotiations with other ports by sending PAgP packets. A channel is formed with another port group in either desirable or auto mode.

Use the silent keyword when you are connecting to a "silent partner" (a device that is not generating BPDUs or other traffic). An example of a silent partner is a traffic generator that is not transmitting packets. Use this keyword with the auto or desirable mode. If you do not specify silent or non-silent, silent is assumed.

Use the non-silent keyword when you are connecting to a device that will transmit BPDUs or other traffic. Use this keyword with the auto or desirable mode.

Both the auto and desirable modes allow ports to negotiate with connected ports to determine if they can form a channel, based on criteria such as port speed, trunking state, native VLAN, and so on.

Ports can form an EtherChannel when they are in different channel modes as long as the modes are compatible. For example:

•A port in desirable mode can form an EtherChannel successfully with another port that is in desirable or auto mode.

•A port in auto mode can form an EtherChannel with another port in desirable mode.

•A port in auto mode cannot form an EtherChannel with another port that is also in auto mode, since neither port will initiate negotiation.

•A port in on mode can form a channel only with a port in on mode, because ports in on mode do not exchange PAgP packets.

•A port in off mode will not form a channel with any port.

Understanding Administrative Groups and EtherChannel IDs

Configuring an EtherChannel creates an administrative group, designated by an integer between 1 and 1024 inclusive, to which the EtherChannel belongs. You can assign an administrative group number manually or let the system software assign the next available administrative group number automatically.

Forming an EtherChannel without specifying an administrative group number creates a new automatically numbered administrative group consisting of the ports you configure as an EtherChannel. An administrative group can contain a maximum of eight ports.

You can define an EtherChannel administrative group without forming an EtherChannel. Only ports belonging to the same administrative group can form a single EtherChannel together.

In addition to the administrative group number, each EtherChannel is automatically assigned a unique EtherChannel ID. Use the show channel group admin_group command to display the EtherChannel ID.

EtherChannel administrative group numbers are stored in NVRAM and remain the same after the switch is reset or power cycled. EtherChannel IDs are not saved in NVRAM. The ID can change if the EtherChannel is torn down and renegotiated, or if the switch is reset or power cycled.

Configuring EtherChannel Using PAgP

These sections describe how to configure an EtherChannel bundle using PAgP:

•Creating an EtherChannel

•Defining an EtherChannel Administrative Group

•Setting the EtherChannel Spanning Tree Port Cost

•Setting the EtherChannel Spanning Tree Port VLAN Cost

•Removing an EtherChannel Bundle

•Displaying EtherChannel Configuration Information

•Displaying EtherChannel Traffic Statistics

•Displaying EtherChannel PAgP Statistics

Note Before you configure the EtherChannel, see the "EtherChannel Configuration Guidelines and Restrictions" section.

Creating an EtherChannel

You create an EtherChannel port bundle by specifying the ports in the channel and the channeling mode. When you create an EtherChannel, an administrative group number is assigned automatically if one is not already assigned to the specified ports. In addition, a channel ID is assigned.

The silent and non-silent keywords function only with the auto and desirable modes.

To create an EtherChannel port bundle, perform this task in privileged mode:

Task

Command

Step 1

If you are unsure which ports you can configure as an EtherChannel, verify the EtherChannel capabilities for the module or switch you are configuring.

show port capabilities [mod_num[/port_num]]

Step 2

Create an EtherChannel with the desired ports.

set port channel port_list [admin_group] mode {on | off | desirable | auto} [silent | non-silent]

Step 3

Verify the EtherChannel configuration.

show port channel [port_list]

This example shows how to create an EtherChannel bundle and verify the configuration:
Console> (enable) set port channel 3/5-6 on
Port(s) 3/5-6 are assigned to admin group 57.
Port(s) 3/5-6 channel mode set to on.
Console> (enable) show port channel
Port  Status     Channel              Admin Ch
                 Mode                 Group Id
----- ---------- -------------------- ----- -----
 3/5  connected  on                      57   835
 3/6  connected  on                      57   835
----- ---------- -------------------- ----- -----
Port  Device-ID                       Port-ID                   Platform
----- ------------------------------- ------------------------- ----------------
 3/5  069003103(5500)                 3/5                       WS-C4000
 3/6  069003103(5500)                 3/6                       WS-C4000
----- ------------------------------- ------------------------- ----------------
Console> (enable)
Defining an EtherChannel Administrative Group

You can define EtherChannel administrative groups manually to identify groups of ports that are allowed to form an EtherChannel bundle. When you create an EtherChannel port bundle, an administrative group is defined automatically. Administrative group membership is limited by hardware restrictions.

The admin_group can be any value between 1 and 1024 inclusive.

Caution Modifying the EtherChannel administrative group on connected ports causes the specified ports to be removed from and then added to spanning tree (that is, a spanning tree topology change occurs and the ports must enter listening and learning mode before returning to forwarding mode).

To define an EtherChannel administrative group, perform this task in privileged mode:

Task

Command

Step 1

Define the administrative group by specifying the ports in the group.

set port channel port_list admin_group

Step 2

Verify the administrative group configuration.

show channel group [admin_group]

This example shows how to assign ports to an administrative group and verify the configuration:
Console> (enable) set port channel 3/5-6 50
Port(s) 3/5-6 are assigned to admin group 50.
Console> (enable) show channel group 50
Admin Port  Status     Channel              Channel
group                  Mode                 id
----- ----- ---------- -------------------- --------
   50  3/5  connected  auto silent                 0
   50  3/6  connected  auto silent                 0
Admin Port  Device-ID                       Port-ID                   Platform
group
----- ----- ------------------------------- ------------------------- ----------
   50  3/5  
   50  3/6  
Console> (enable)
Setting the EtherChannel Spanning Tree Port Cost

To set the spanning tree port cost for an EtherChannel, perform this task in privileged mode:

Task

Command

Step 1

Determine the EtherChannel ID of the EtherChannel for which you want to set the port cost.

show channel group admin_group

Step 2

Set the spanning tree port cost for an EtherChannel using the EtherChannel ID obtained in Step 1.

set channel cost {channel_id | all} cost

This example shows how to set the EtherChannel port path cost for channel ID 768:
Console> (enable) show channel group 20
Admin Port  Status     Channel   Channel
group                  Mode      id
----- ----- ---------- --------- --------
  20    1/1 notconnect on             768
  20    1/2 connected  on             768
Admin Port  Device-ID                       Port-ID                   Platform
group
----- ----- ------------------------------- ------------------------- ----------
  20    1/1  
  20    1/2  066510644(cat26-lnf(NET25))     2/1                       WS-C6009
Console> (enable)
Console> (enable) set channel cost 768 12
Port(s) 1/1,1/2 port path cost are updated to 31.
Channel 768 cost is set to 12.
Warning:channel cost may not be applicable if channel is broken.
Console> (enable)
Setting the EtherChannel Spanning Tree Port VLAN Cost

The spanning tree port VLAN cost provides an alternate cost for some of the VLANs in a trunk channel. This provides load balancing of VLAN traffic accross multiple channels configured with trunking, as some VLANs in the channel can have port VLAN cost, and the remaining VLANS in the channel have port cost.

To set the spanning tree port VLAN cost for an EtherChannel, perform this task in privileged mode:

Task

Command

Step 1

Determine the EtherChannel ID of the EtherChannel for which you want to set the port VLAN cost.

show channel group admin_group

Step 2

Set the spanning tree port VLAN cost for an EtherChannel using the EtherChannel ID obtained in Step 1.

set channel vlancost {channel_id | all} cost

This example shows how to set the EtherChannel VLAN cost for channel ID 768:
Console> (enable) show channel group 20
Admin Port  Status     Channel   Channel
group                  Mode      id
----- ----- ---------- --------- --------
  20    1/1 notconnect on             768
  20    1/2 connected  on             768
Admin Port  Device-ID                       Port-ID                   Platform
group
----- ----- ------------------------------- ------------------------- ----------
  20    1/1  
  20    1/2  066510644(cat26-lnf(NET25))     2/1                       WS-C6009
Console> (enable)
Console> (enable) set channel vlancost 768 12
Channel 768 vlancost set to 12.
Console> (enable)
Removing an EtherChannel Bundle

To return a Fast EtherChannel or Gigabit EtherChannel bundle to its default configuration, perform this task in privileged mode:

Task

Command

Step 1

Return a channel to its default configuration (you must perform this task on both sides of the channel).

set port channel port_list mode auto

Step 2

Verify the configuration.

show port channel [mod_num[/port_num]]

This example shows how to return a channel to its default configuration and how to verify the configuration:
Console> (enable) set port channel 3/5-6 mode auto
Port(s) 3/5-6 channel mode set to auto.
Console> (enable) show port channel
No ports channelling
Console> (enable)
Displaying EtherChannel Configuration Information

To display EtherChannel configuration information, perform one of these tasks in privileged mode:

Task

Command

•Display EtherChannel configuration information by port.

show port channel [mod_num[/port_num]] info [spantree | trunk | protocol | gmrp | gvrp | qos]

•Display EtherChannel configuration information by EtherChannel administrative group.

show channel group [admin_group] info [spantree | trunk | protocol | gmrp | gvrp | qos]

•Display EtherChannel configuration information by EtherChannel ID.

show channel [channel_id] info [spantree | trunk | protocol | gmrp | gvrp | qos]

This example shows how to display EtherChannel configuration information by port:
Console> (enable) show port channel info
Switch Frame Distribution Method: mac both
Port  Status     Channel              Admin Channel Speed Duplex Vlan
                 mode                 group id
----- ---------- -------------------- ----- ------- ----- ------ ----
 3/5  connected  on                      56     835 a-100 a-full    1
 3/6  connected  on                      56     835 a-100 a-full    1
----- ---------- -------------------- ----- ------- ----- ------ ----
Port  ifIndex Oper-group Neighbor   Oper-Distribution PortSecurity/
                         Oper-group Method            Dynamic port
----- ------- ---------- ---------- ----------------- -------------
 3/5  377              1            mac both                       
 3/6  377              1            mac both                       
----- ------- ---------- ---------- ----------------- -------------
Port  Device-ID                       Port-ID                   Platform
----- ------------------------------- ------------------------- ----------------
 3/5  069003103(5500)                 3/5                       WS-C4000
 3/6  069003103(5500)                 3/6                       WS-C4000
----- ------------------------------- ------------------------- ----------------
Port  Trunk-status Trunk-type    Trunk-vlans
----- ------------ ------------- -----------------------------------------------
 3/5  not-trunking negotiate     1-1005
 3/6  not-trunking negotiate     1-1005
----- ------------ ------------- -----------------------------------------------
Port  Portvlancost-vlans
----- --------------------------------------------------------------------------
 3/5  
 3/6  
----- --------------------------------------------------------------------------
Port  Port     Portfast Port    Port
      priority          vlanpri vlanpri-vlans
----- -------- -------- ------- ------------------------------------------------
 3/5        32 disabled       0 
 3/6        32 disabled       0 
----- -------- -------- ------- ------------------------------------------------
Port  IP       IPX      Group
----- -------- -------- --------
 3/5  on       auto-on  auto-on 
 3/6  on       auto-on  auto-on 
----- -------- -------- --------
Port  GMRP     GMRP         GMRP
      status   registration forwardAll
----- -------- ------------ ----------
 3/5  enabled  normal       disabled  
 3/6  enabled  normal       disabled  
----- -------- ------------ ----------
Port  GVRP     GVRP          GVRP
      status   registeration applicant
----- -------- ------------- ---------
 3/5  disabled normal        normal   
 3/6  disabled normal        normal   
----- -------- ------------- ---------
Port  Qos-Tx Qos-Rx Qos-Trust    Qos-DefCos
----- ------ ------ ------------ ----------
 3/5  -      -      untrusted             0
 3/6  -      -      untrusted             0
----- ------ ------ ------------ ----------
Console> (enable)
Displaying EtherChannel Traffic Statistics

To display EtherChannel traffic statistics, perform this task in privileged mode:

Task

Command

Display EtherChannel traffic statistics.

show channel [channel_id] mac

This example shows how to display EtherChannel traffic statistics information for EtherChannel ID 835:
Console> show channel 835 mac
Channel  Rcv-Unicast          Rcv-Multicast        Rcv-Broadcast
-------- -------------------- -------------------- --------------------
835                         0               119200                    0
Channel  Xmit-Unicast         Xmit-Multicast       Xmit-Broadcast
-------- -------------------- -------------------- --------------------
835                         0               184171                    0
Channel  Rcv-Octet            Xmit-Octet
-------- -------------------- --------------------
835                  11283708             14942104
Channel  Dely-Exced MTU-Exced  In-Discard Lrn-Discrd In-Lost    Out-Lost
-------- ---------- ---------- ---------- ---------- ---------- ----------
835               0          0          0          0          0          0
Console> (enable)
Displaying EtherChannel PAgP Statistics

To display EtherChannel PAgP statistics, perform one of these tasks in privileged mode:

Task

Command

•Display EtherChannel PAgP statistics by port.

show port channel [mod_num[/port_num]] statistics

•Display EtherChannel PAgP statistics by EtherChannel administrative group.

show channel group [admin_group] statistics

•Display EtherChannel PAgP statistics by EtherChannel ID.

show channel [admin_group] statistics

This example shows how to display EtherChannel PAgP statistics information by EtherChannel administrative group:
Console> show channel group 58 statistics
Port  Admin   PAgP Pkts   PAgP Pkts PAgP Pkts PAgP Pkts PAgP Pkts PAgP Pkts
      Group   Transmitted Received  InFlush   RetnFlush OutFlush  InError
----- ------- ----------- --------- --------- --------- --------- ---------
 3/5       58         194        81         0         0         0         0
 3/6       58         204        85         0         0         0         0
Console> (enable)
EtherChannel Configuration Examples

These sections contain Fast and Gigabit EtherChannel configuration examples:

•Four-Port Fast EtherChannel Configuration Example

•Two-Port Gigabit EtherChannel Configuration Example

Note For examples of configuring VLAN trunks on EtherChannel port bundles, see the "Example VLAN Trunk Configurations" section.

Four-Port Fast EtherChannel Configuration Example

This example configuration shows how to configure a four-port Fast EtherChannel link between two switches. Figure 6-1 shows two switches connected through four 100BASE-TX Fast Ethernet ports.

Figure 6-1 Fast EtherChannel Port Bundle Example

Step 1 Make sure that all ports on Switch A and Switch B have the same port configuration, including VLAN membership, speed, and duplex.
Switch_A> (enable) set vlan 50 1/1-4
VLAN 50 modified.
VLAN 1 modified.
VLAN  Mod/Ports
---- -----------------------
50    1/1-4
      2/1-2
      3/1-3
Switch_A> (enable) set port speed 1/1-4 100
Ports 1/1-4 transmission speed set to 100Mbps.
Switch_A> (enable) set port duplex 1/1-4 full
Ports 1/1-4 set to full-duplex.
Switch_A> (enable) 
Switch_B> (enable) set vlan 50 3/1-4
VLAN 50 modified.
VLAN 1 modified.
VLAN  Mod/Ports
---- -----------------------
50    3/1-4
Switch_B> (enable) set port speed 3/1-4 100
Ports 3/1-4 transmission speed set to 100Mbps.
Switch_B> (enable) set port duplex 3/1-4 full
Ports 3/1-4 set to full-duplex.
Switch_B> (enable)
Step 2 Confirm the channeling status of the switches using the show port channel command.
Switch_A> (enable) show port channel
No ports channelling
Switch_A> (enable)
Switch_B> (enable) show port channel
No ports channelling
Switch_B> (enable)
Step 3 Configure the ports on Switch A to negotiate a Fast EtherChannel bundle with the neighboring switch. This example assumes that the neighboring ports on Switch B are in EtherChannel auto mode. The system logging messages provide information about the formation of the EtherChannel bundle.
Switch_A> (enable) set port channel 1/1-4 desirable
Port(s) 1/1-4 channel mode set to desirable.
Switch_A> (enable) %PAGP-5-PORTFROMSTP:Port 1/1 left bridge port 1/1
%PAGP-5-PORTFROMSTP:Port 1/2 left bridge port 1/2
%PAGP-5-PORTFROMSTP:Port 1/3 left bridge port 1/3
%PAGP-5-PORTFROMSTP:Port 1/4 left bridge port 1/4
%PAGP-5-PORTFROMSTP:Port 1/2 left bridge port 1/2
%PAGP-5-PORTFROMSTP:Port 1/3 left bridge port 1/3
%PAGP-5-PORTFROMSTP:Port 1/4 left bridge port 1/4
%PAGP-5-PORTTOSTP:Port 1/1 joined bridge port 1/1-4
%PAGP-5-PORTTOSTP:Port 1/2 joined bridge port 1/1-4
%PAGP-5-PORTTOSTP:Port 1/3 joined bridge port 1/1-4
%PAGP-5-PORTTOSTP:Port 1/4 joined bridge port 1/1-4
Switch_B> (enable) %PAGP-5-PORTFROMSTP:Port 3/1 left bridge port 3/1
%PAGP-5-PORTFROMSTP:Port 3/2 left bridge port 3/2
%PAGP-5-PORTFROMSTP:Port 3/3 left bridge port 3/3
%PAGP-5-PORTFROMSTP:Port 3/4 left bridge port 3/4
%PAGP-5-PORTFROMSTP:Port 3/2 left bridge port 3/1-4
%PAGP-5-PORTFROMSTP:Port 3/3 left bridge port 3/1-4
%PAGP-5-PORTFROMSTP:Port 3/4 left bridge port 3/1-4
%PAGP-5-PORTTOSTP:Port 3/1 joined bridge port 3/1-4
%PAGP-5-PORTTOSTP:Port 3/2 joined bridge port 3/1-4
%PAGP-5-PORTTOSTP:Port 3/3 joined bridge port 3/1-4
%PAGP-5-PORTTOSTP:Port 3/4 joined bridge port 3/1-4
Step 4 After the EtherChannel bundle is negotiated, enter the show port channel command to verify the configuration.
Switch_A> (enable) show port channel
Port  Status     Channel   Channel     Neighbor                  Neighbor
                 mode      status      device                    port
----- ---------- --------- ----------- ------------------------- ---------- 
 1/1  connected  desirable channel     WS-C4003    JAB023806(Sw  3/1       
 1/2  connected  desirable channel     WS-C4003    JAB023806(Sw  3/2       
 1/3  connected  desirable channel     WS-C4003    JAB023806(Sw  3/3       
 1/4  connected  desirable channel     WS-C4003    JAB023806(Sw  3/4       
----- ---------- --------- ----------- ------------------------- ---------- 
Switch_A> (enable) 
Switch_B> (enable) show port channel
Port  Status     Channel   Channel     Neighbor                  Neighbor
                 mode      status      device                    port
----- ---------- --------- ----------- ------------------------- ---------- 
 3/1  connected  auto      channel     WS-C4012    009979082(Sw  1/1       
 3/2  connected  auto      channel     WS-C4012    009979082(Sw  1/2       
 3/3  connected  auto      channel     WS-C4012    009979082(Sw  1/3       
 3/4  connected  auto      channel     WS-C4012    009979082(Sw  1/4       
----- ---------- --------- ----------- ------------------------- ---------- 
Switch_B> (enable) 
Two-Port Gigabit EtherChannel Configuration Example

This example configuration shows how to configure a two-port Gigabit EtherChannel link between two switches. Figure 6-2 shows two switches connected through four 1000BASE-SX Gigabit Ethernet ports.

Figure 6-2 Gigabit EtherChannel Port Bundle Example

Step 1 Make sure that all ports on Switch A and Switch B have the same port configuration, such as VLAN membership.
Switch_A> (enable) set vlan 100 2/1-2
VLAN 100 modified.
VLAN 1 modified.
VLAN  Mod/Ports
---- -----------------------
100   2/1-2
Switch_A> (enable) 
Switch_B> (enable) set vlan 100 3/1-2
VLAN 100 modified.
VLAN 1 modified.
VLAN  Mod/Ports
---- -----------------------
100   3/1-2
Switch_B> (enable)
Step 2 Confirm the channeling status of the switches using the show port channel command.
Switch_A> (enable) show port channel
No ports channelling
Switch_A> (enable)
Switch_B> (enable) show port channel
No ports channelling
Switch_B> (enable)
Step 3 Note that in this example, EtherChannel is configured on for all ports. If you configure ports on, you must configure the ports on both ends of the EtherChannel bundle on. The switches will not negotiate an EtherChannel port bundle automatically in on mode. The system logging messages provide information about the formation of the EtherChannel bundle.
Switch_A> (enable) set port channel 2/1-2 on
Port(s) 2/1-2 channel mode set to on.
Switch_A> (enable) %PAGP-5-PORTFROMSTP:Port 2/1 left bridge port 2/1
%PAGP-5-PORTFROMSTP:Port 2/2 left bridge port 2/2
%PAGP-5-PORTTOSTP:Port 2/1 joined bridge port 2/1-2
%PAGP-5-PORTTOSTP:Port 2/2 joined bridge port 2/1-2
Switch_B> (enable) set port channel 3/1-2 on
Port(s) 3/1-2 channel mode set to on.
Switch_B> (enable) %PAGP-5-PORTFROMSTP:Port 3/1 left bridge port 3/1
%PAGP-5-PORTFROMSTP:Port 3/2 left bridge port 3/2
%PAGP-5-PORTTOSTP:Port 3/1 joined bridge port 3/1-2
%PAGP-5-PORTTOSTP:Port 3/2 joined bridge port 3/1-2
Step 4 After the EtherChannel bundle is negotiated, enter the show port channel command to verify the configuration. If you configure only the ports on one side of the link on, the show port channel command will show that the ports are channeling, but no traffic will pass over the EtherChannel. Spanning tree loops can occur, and eventually the switch will disable the incorrectly configured EtherChannel.
Switch_A> (enable) show port channel
Port  Status     Channel   Channel     Neighbor                  Neighbor
                 mode      status      device                    port
----- ---------- --------- ----------- ------------------------- ---------- 
 2/1  connected  on        channel     WS-C4003    JAB023806LN(  3/1       
 2/2  connected  on        channel     WS-C4003    JAB023806LN(  3/2       
----- ---------- --------- ----------- ------------------------- ---------- 
Switch_A> (enable) 
Switch_B> (enable) show port channel
Port  Status     Channel   Channel     Neighbor                  Neighbor
                 mode      status      device                    port
----- ---------- --------- ----------- ------------------------- ---------- 
 3/1  connected  on        channel     WS-C4003    JAB023806JR(  2/1       
 3/2  connected  on        channel     WS-C4003    JAB023806JR(  2/2       
----- ---------- --------- ----------- ------------------------- ---------- 
Switch_B> (enable)
Understanding the Link Aggregation Control Protocol

Note Use the information in these sections if you are configuring EtherChannel using LACP. If you are using PAgP, see the "Understanding the Port Aggregation Protocol" section.

This section contains the following descriptions:

•LACP Modes

•LACP Parameters

LACP Modes

You may manually turn on channeling by setting the port channel mode to on, and you may turn channeling off by setting the port channel mode to off.

If you want LACP to handle channeling, use the active and passive channel modes. To start automatic EtherChannel configuration with LACP, you need to configure at least one end of the link to active mode to initiate channeling, because ports in passive mode passively respond to initiation and never initiate the sending of LACP packets.

Table 6-2 describes the EtherChannel modes that use LACP.

Table 6-2 EtherChannel Modes That Use LACP

Mode

Description

on

Mode that forces the port to channel without LACP. With the on mode, a usable EtherChannel exists only when a port group in on mode is connected to another port group in on mode.

off

Mode that prevents the port from channeling.

passive

LACP mode that places a port into a passive negotiating state, in which the port responds to LACP packets it receives but does not initiate LACP packet negotiation. (Default)

active

LACP mode that places a port into an active negotiating state, in which the port initiates negotiations with other ports by sending LACP packets.

LACP Parameters

The following parameters are used in configuring LACP:

•System priority

Each switch running LACP must have a system priority. The system priority can be specified automatically or through the CLI (see the "Specifying the System Priority" section). The switch uses the MAC address and the system priority to form the system ID and is also used during negotiation with other systems.

•Port priority

Each port in the switch must have a port priority. The port priority can be specified automatically or through the CLI (see the "Specifying the Port Priority" section). The port priority and the port number form the port identifier. The switch uses the port priority to decide which ports to put in standby mode when a hardware limitation prevents all compatible ports from aggregating.

•Administrative key

Each port in the switch must have an administrative key value. The administrative key valuethat can be specified automatically or through the CLI (see the "Specifying an Administrative Key Value" section). The adminstrative key defines the ability of a port to aggregate with other ports. The following factors determine a port's ability to aggregate with other ports:

–Port physical characteristics, such as data rate, duplex capability, and point-to-point or shared medium

–Configuration constraints that you establish

When enabled, LACP always tries to configure the maximum number of compatible ports in a channel, up to the maximum allowed by the hardware (eight ports). If LACP is not able to aggregate all the ports that are compatible (for example, the remote system might have more restrictive hardware limitations), then all the ports that cannot be actively included in the channel are put in hot standby state and are used only if one of the channeled ports fails.

You can configure different channels with ports that have been assigned the same administrative key. For example, if eight ports are assigned the same administrative key, you may configure four ports in a channel using LACP active mode and the remaining four ports in a manually configured channel using the on mode. An administrative key is meaningful only in the context of the switch that allocates it; there is no global significance to administrative key values.

Configuring EtherChannel Using LACP

These sections describe how to configure EtherChannel using LACP:

•Specifying the EtherChannel Protocol

•Specifying the System Priority

•Specifying the Port Priority

•Specifying an Administrative Key Value

•Changing the Channel Mode

•Specifying the Channel Path Cost

•Specifying the Channel VLAN Cost

•Clearing LACP Statistics

•Displaying EtherChannel Traffic Utilization

•Disabling an EtherChannel

•Display Spanning Tree-Related Information for EtherChannels

Note Before you configure the EtherChannel, see the "EtherChannel Configuration Guidelines and Restrictions" section.

Specifying the EtherChannel Protocol

Note The default protocol is PAgP.

Note You can specify only one protocol, PAgP or LACP, per module.

To specify the EtherChannel protocol, perform this task in privileged mode:

Task

Command

Specify the EtherChannel protocol.

set channelprotocol [pagp | lacp] mod

This example shows how to specify the LACP protocol for modules 2 and 3:
Console> (enable) set channelprotocol lacp 2,3
Mod 2 is set to LACP protocol.
Mod 3 is set to LACP protocol.
Console> (enable)
Use the show channelprotocol command to display the protocols for all modules.