Cisco IOS XR Interface and Hardware Component Configuration Guide for the Cisco XR 12000 Series Router, Release 4.3.x

Configuring Serial Interfaces on Cisco IOS XR Sotware

This module describes the configuration of serial interfaces on the Cisco XR 12000 Series Router.

Before you configure a serial interface, you must configure the clear channel T3/E3 controller or channelized T1/E1controller (DS0 channel) that is associated with that interface.

Feature History for Configuring Serial Controller Interfaces

Contents

•Prerequisites for Configuring Serial Interfaces

•Information About Configuring Serial Interfaces

•How to Configure Serial Interfaces

•Configuration Examples for Serial Interfaces

•Additional References

Prerequisites for Configuring Serial Interfaces

Before configuring serial interfaces, ensure that the following tasks and conditions are met:

•You must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

•Your hardware must support T3/E3 or T1/E1 controllers and serial interfaces.

The following hardware supports T3/E3 controllers and serial interfaces:

–Cisco 2-Port and 4-Port Clear Channel T3/E3 SPAs

–Cisco 2-Port and 4-Port Channelized T3 SPAs

–Cisco 4-Port Channelized OC-12/DS3 line cards

–Cisco 1-Port Channelized OC-48/STM-16 SPA and line cards

The following hardware supports T1/E1 controllers and DS0 channels:

–Cisco 2-Port and 4-Port Channelized T3 SPAs

–Cisco 4-Port Channelized OC-12/DS3 line cards

–Cisco 1-Port Channelized OC-12/DS0 SPAs and line cards

–Cisco 1-Port Channelized OC-48/DS3 SPAs and line cards

–Cisco 1-Port Channelized OC3/STM-1 SPA

–Cisco 8-Port Channelized T1/E1 SPA

The following hardware supports serial interfaces:

–Cisco 2-Port and 4-Port Clear Channel T3/E3 SPAs

–Cisco 2-Port and 4-Port Channelized T3 SPAs

–Cisco 4-Port Channelized OC-12/DS3 line cards

–Cisco 1-Port Channelized OC-12/DS0 SPAs and line cards

–Cisco 1-Port Channelized OC-48/DS3 SPAs and line cards

–Cisco 1-Port Channelized OC3/STM-1 SPA

–Cisco 8-Port Channelized T1/E1 SPA

Note The Cisco 2-Port and 4-Port Channelized T3 SPAs can run in clear channel mode, or they can be channelized into 28 T1 or 21 E1 controllers.

•You should have configured the clear channel T3/E3 controller or channelized T3 to T1/E1 controller that is associated with the serial interface you want to configure, as described in the "Configuring Clear Channel T3/E3 and Channelized T3 and T1/E1 Controllers on Cisco IOS XR Software" module in this manual.

Note On channelized T3 to T1/E1 controllers, serial interfaces are automatically created when users configure individual DS0 channel groups on the T1/E1 controllers.

Information About Configuring Serial Interfaces

To configure serial interfaces, study the following concepts:

•High-Level Overview: Serial Interface Configuration on Clear-Channel SPAs

•High-Level Overview: Serial Interface Configuration on Channelized SPAs

•Cisco HDLC Encapsulation

•PPP Encapsulation

•Keepalive Timer

•Frame Relay Encapsulation

•Layer 2 Tunnel Protocol Version 3-Based Layer 2 VPN on Frame Relay

•Default Settings for Serial Interface Configurations

•Serial Interface Naming Notation

•IPHC Overview

On the , a single serial interface carries data over a single interface using PPP, Cisco HDLC, or Frame Relay encapsulation.

High-Level Overview: Serial Interface Configuration on Clear-Channel SPAs

Table 17 provides a high-level overview of the tasks required to configure a T3 serial interface on the Cisco 2-Port and 4-Port Clear Channel T3/E3 SPA.

Table 18 provides a high-level overview of the tasks required to configure an E3 serial interface on a 2-Port and 4-Port Clear Channel T3/E3 SPA.

High-Level Overview: Serial Interface Configuration on Channelized SPAs

Table 19 provides a high-level overview of the tasks required to configure a T1 serial interface on the following SPAs and line cards.

•Cisco 2-Port and 4-Port Channelized T3 SPA

•Cisco 4-Port Channelized OC-12/DS3 line cards

•Cisco 1-Port Channelized OC-12/DS0 SPAs and line cards

•Cisco 1-Port Channelized OC-48/STM-16 SPA and line cards

Table 20 provides a high-level overview of the tasks required to configure an E1 serial interface on the following SPAs and line cards.

•2-Port and 4-Port Channelized T3 SPA

•4-Port Channelized OC-12/DS3 line cards

•1-Port Channelized OC-12/DS0 SPAs and line cards

•1-Port Channelized OC-48/DS3 SPAs and line cards

Cisco HDLC Encapsulation

Cisco High-Level Data Link Controller (HDLC) is the Cisco proprietary protocol for sending data over synchronous serial links using HDLC. Cisco HDLC also provides a simple control protocol called Serial Line Address Resolution Protocol (SLARP) to maintain serial link keepalives. HDLC is the default encapsulation type for serial interfaces under Cisco IOS XR software. Cisco HDLC is the default for data encapsulation at Layer 2 (data link) of the Open System Interconnection (OSI) stack for efficient packet delineation and error control.

Note Cisco HDLC is the default encapsulation type for the serial interfaces.

Cisco HDLC uses keepalives to monitor the link state, as described in the "Keepalive Timer" section.

Note Use the debug chdlc slarp packet command to display information about the Serial Line Address Resolution Protocol (SLARP) packets that are sent to the peer after the keepalive timer has been configured.

PPP Encapsulation

PPP is a standard protocol used to send data over synchronous serial links. PPP also provides a Link Control Protocol (LCP) for negotiating properties of the link. LCP uses echo requests and responses to monitor the continuing availability of the link.

Note When an interface is configured with PPP encapsulation, a link is declared down, and full LCP negotiation is re-initiated after five ECHOREQ packets are sent without receiving an ECHOREP response.

PPP provides the following Network Control Protocols (NCPs) for negotiating properties of data protocols that will run on the link:

•IP Control Protocol (IPCP) to negotiate IP properties

•Multiprotocol Label Switching control processor (MPLSCP) to negotiate MPLS properties

•Cisco Discovery Protocol control processor (CDPCP) to negotiate CDP properties

•IPv6CP to negotiate IP Version 6 (IPv6) properties

•Open Systems Interconnection control processor (OSICP) to negotiate OSI properties

PPP uses keepalives to monitor the link state, as described in the "Keepalive Timer" section.

PPP supports the following authentication protocols, which require a remote device to prove its identity before allowing data traffic to flow over a connection:

•Challenge Handshake Authentication Protocol (CHAP)—CHAP authentication sends a challenge message to the remote device. The remote device encrypts the challenge value with a shared secret and returns the encrypted value and its name to the local router in a response message. The local router attempts to match the name of the remote device with an associated secret stored in the local username or remote security server database; it uses the stored secret to encrypt the original challenge and verify that the encrypted values match.

•Microsoft Challenge Handshake Authentication Protocol (MS-CHAP)—MS-CHAP is the Microsoft version of CHAP. Like the standard version of CHAP, MS-CHAP is used for PPP authentication; in this case, authentication occurs between a personal computer using Microsoft Windows NT or Microsoft Windows 95 and a Cisco router or access server acting as a network access server.

•Password Authentication Protocol (PAP)—PAP authentication requires the remote device to send a name and a password, which are checked against a matching entry in the local username database or in the remote security server database.

Note For more information on enabling and configuring PPP authentication protocols, see the "Configuring PPP on Cisco IOS XR Software" module in this manual.

Use the ppp authentication command in interface configuration mode to enable CHAP, MS-CHAP, and PAP on a serial interface.

Note Enabling or disabling PPP authentication does not effect the local router's willingness to authenticate itself to the remote device.

Multilink PPP

Multilink Point-to-Point Protocol (MLPPP) is supported on the following SPAs:

•1-Port Channelized OC-12/DS0 SPAs and line cards

•2-Port and 4-Port Channelized T3 SPAs

•8-Port Channelized T1/E1 SPA

MLPPP provides a method for combining multiple physical links into one logical link. The implementation of MLPPP combines multiple PPP serial interfaces into one multilink interface. MLPPP performs the fragmenting, reassembling, and sequencing of datagrams across multiple PPP links.

MLPPP provides the same features that are supported on PPP Serial interfaces with the exception of QoS. It also provides the following additional features:

•Fragment sizes of 128, 256, and 512 bytes

•Long sequence numbers (24-bit)

•Lost fragment detection timeout period of 80 ms

•Minimum-active-links configuration option

•LCP echo request/reply support over multilink interface

•Full T1 and E1 framed and unframed links

For more information about configuring MLPPP on a serial interface, see the "Configuring PPP on Cisco IOS XR Software" module in this document.

Keepalive Timer

Cisco keepalives are useful for monitoring the link state. Periodic keepalives are sent to and received from the peer at a frequency determined by the value of the keepalive timer. If an acceptable keepalive response is not received from the peer, the link makes the transition to the down state. As soon as an acceptable keepalive response is obtained from the peer or if keepalives are disabled, the link makes the transition to the up state.

Note The keepalive command applies to serial interfaces using HDLC or PPP encapsulation. It does not apply to serial interfaces using Frame Relay encapsulation.

For each encapsulation type, a certain number of keepalives ignored by a peer triggers the serial interface to transition to the down state. For HDLC encapsulation, three ignored keepalives causes the interface to be brought down. For PPP encapsulation, five ignored keepalives causes the interface to be brought down. ECHOREQ packets are sent out only when LCP negotiation is complete (for example, when LCP is open).

Note Use the keepalive command in interface configuration mode to set the frequency at which LCP sends ECHOREQ packets to its peer. To restore the system to the default keepalive interval of 10 seconds, use the keepalive command with no argument. To disable keepalives, use the keepalive disable command. For both PPP and Cisco HDLC, a keepalive of 0 disables keepalives and is reported in the show running-config command output as keepalive disable.Before performing a Minimal Disruptive Restart (MDR) upgrade, we recommend disabling keepalives on a Cisco XR 12000 Series Router.

When LCP is running on the peer and receives an ECHOREQ packet, it responds with an echo reply (ECHOREP) packet, regardless of whether keepalives are enabled on the peer.

Keepalives are independent between the two peers. One peer end can have keepalives enabled; the other end can have them disabled. Even if keepalives are disabled locally, LCP still responds with ECHOREP packets to the ECHOREQ packets it receives. Similarly, LCP also works if the period of keepalives at each end is different.

Note Use the debug chdlc slarp packet command and other Cisco HDLC debug commands to display information about the Serial Line Address Resolution Protocol (SLARP) packets that are sent to the peer after the keepalive timer has been configured.

Frame Relay Encapsulation

When Frame Relay encapsulation is enabled on a serial interface, the interface configuration is hierarchical and comprises the following elements:

1. The serial main interface comprises the physical interface and port. If you are not using the serial interface to support Cisco HDLC and PPP encapsulated connections, then you must configure subinterfaces with permanent virtual circuits (PVCs) under the serial main interface. Frame Relay connections are supported on PVCs only.

2. Serial subinterfaces are configured under the serial main interface. A serial subinterface does not actively carry traffic until you configure a PVC under the serial subinterface. Layer 3 configuration typically takes place on the subinterface.

3. Point-to-point PVCs are configured under a serial subinterface. You cannot configure a PVC directly under a main interface. A single point-to-point PVC is allowed per subinterface. PVCs use a predefined circuit path and fail if the path is interrupted. PVCs remain active until the circuit is removed from either configuration. Connections on the serial PVC support Frame Relay encapsulation only.

Note The administrative state of a parent interface drives the state of the subinterface and its PVC. When the administrative state of a parent interface or subinterface changes, so does the administrative state of any child PVC configured under that parent interface or subinterface.

To configure Frame Relay encapsulation on serial interfaces, use the encapsulation frame-relay command.

Frame Relay interfaces support two types of encapsulated frames:

•Cisco (default)

•IETF

Use the encap command in PVC configuration mode to configure Cisco or IETF encapsulation on a PVC. If the encapsulation type is not configured explicitly for a PVC, then that PVC inherits the encapsulation type from the main serial interface.

Note Cisco encapsulation is required on serial main interfaces that are configured for MPLS. IETF encapsulation is not supported for MPLS.

Before you configure Frame Relay encapsulation on an interface, you must verify that all prior Layer 3 configuration is removed from that interface. For example, you must ensure that there is no IP address configured directly under the main interface; otherwise, any Frame Relay configuration done under the main interface will not be viable.

LMI on Frame Relay Interfaces

The Local Management Interface (LMI) protocol monitors the addition, deletion, and status of PVCs. LMI also verifies the integrity of the link that forms a Frame Relay UNI interface. By default, cisco LMI is enabled on all PVCs. However, you can modify the default LMI type to be ANSI or Q.933, as described in the "Modifying the Default Frame Relay Configuration on an Interface" section of the "Configuring Frame Relay Cisco IOS XR Software" module in this manual.

If the LMI type is cisco (the default LMI type), the maximum number of PVCs that can be supported under a single interface is related to the MTU size of the main interface. Use the following formula to calculate the maximum number of PVCs supported on a card or SPA:

(MTU - 13)/8 = maximum number of PVCs

Note The default setting of the mtu command for a serial interface is 1504 bytes. Therefore, the default numbers of PVCs supported on a serial interface configured with cisco LMI is 186.

Layer 2 Tunnel Protocol Version 3-Based Layer 2 VPN on Frame Relay

The Layer 2 Tunnel Protocol Version 3 (L2TPv3) feature defines the L2TP protocol for tunneling Layer 2 payloads over an IP core network using Layer 2 virtual private networks (VPNs).

L2TPv3 is a tunneling protocol used for transporting Layer 2 protocols. It can operate in a number of different configurations and tunnel a number of different Layer 2 protocols and connections over a packet-switched network.

Before you can configure L2TPv3, you need to configure a connection between the two attachment circuits (ACs) that will host the L2TPv3 psuedowire. Cisco IOS XR software supports a point-to-point, end-to-end service, where two ACs are connected together.

This module describes how to configure a Layer 2 AC on a Frame Relay encapsulated serial interface.

Note Serial interfaces support DLCI mode layer 2 ACs only; layer 2 port mode ACs are not supported on serial interfaces.

For detailed information about configuring L2TPv3 in your network, see the "Implementing Layer 2 Tunnel Protocol Version 3 on Cisco IOS XR Software" module of the Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco XR 12000 Series Router. For detailed information about configuring L2VPNs, see the "Implementing MPLS Layer 2 VPNs on Cisco IOS XR Software" module of the Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco XR 12000 Series Router.

Default Settings for Serial Interface Configurations

When an interface is enabled on a T3/E3 SPA, and no additional configuration commands are applied, the default interface settings shown in Table 21 are present. These default settings can be changed by configuration.

Note Default settings do not appear in the output of the show running-config command.

Serial Interface Naming Notation

The naming notation for serial interfaces on a clear channel SPA is rack/slot/module/port, as shown in the following example:

interface serial 0/0/1/2 

The naming notation for T1, E1, and DS0 interfaces on a channelized SPA is rack/slot/module/port/channel-num:channel-group-number, as shown in the following example:

interface serial 0/0/1/2/4:3

If a subinterface and PVC are configured under the serial interface, then the router includes the subinterface number at the end of the serial interface address. In this case, the naming notation is rack/slot/module/port[/channel-num:channel-group-number].subinterface, as shown in the following examples:

interface serial 0/0/1/2.1

interface serial 0/0/1/2/4:3.1

Note A slash between values is required as part of the notation.

The naming notation syntax for serial interfaces is as follows:

•rack: Chassis number of the rack.

•slot: Physical slot number of the modular services card or line card.

•module: Module number. Shared port adapters (SPAs) are referenced by their subslot number.

•port: Physical port number of the controller.

•channel-num: T1 or E1 channel number. T1 channels range from 0 to 23; E1 channels range from 0 to 31.

•channel-group-number: Time slot number. T1 time slots range from 1 to 24; E1 time slots range from 1 to 31. The channel-group-number is preceded by a colon and not a slash.

•subinterface: Subinterface number.

Use the question mark (?) online help function following the serial keyword to view a list of all valid interface choices.

IPHC Overview

IP header compression (IPHC) is based on the premise that most of the headers in the packets of a particular transmission remain constant throughout the flow. Only a few fields in the headers of related packets change during a flow.

IPHC compresses these headers so that the compressed header contains only the fields that change from packet to packet. All fields that remain the same from packet to packet are eliminated in the compressed headers. Full headers are sent between compressed headers.

Full headers are uncompressed headers that contain all the original header fields along with additional information (context ID) to identify the flow. The interval at which full headers are sent between compressed packets is configurable using the refresh max-period and command.

IPHC contexts are used by the compressor (sender) and decompressor (receiver) of compressed packets to encode and decode the packets in a flow. A context is stored on the compressor and decompressor and is used in the delta calculation at both ends. The number of contexts allowed on a particular interface is configurable. The maximum size of the header that can be compressed is also configurable.

IPHC supports the compression and decompression of RTP and UDP traffic and the decompression of CN on TCP and CTCP traffic.

Users may choose one of the following types of compression formats:

•Internet Engineering Task Force (IETF) standard format.
Uses RFC2507 and RFC2508 compression schemes.

•IPHC format.
Provides options similar to IETF.

Table 22 shows the IPHC features, the values of the features, and their defaults:

Currently, only IPv4 unicast packets with UDP in the protocol field of the IP header are compressed.

IPHC is configured on an interface as follows:

•Configure the IPHC slot level command

•Create an IPHC profile

•Configure IPHC attributes in the profile

•Attach the profile to an interface

IPHC profiles must contain the rtp command to enable Real Time Protocol (RTP) on the interface, or the profile is not enabled. The refresh rtp command must be used to enable the configured refresh settings for RTP packets. By default, refresh RTP is disabled and only the first packet in the flow is sent as a `full-header' packet.

If some attributes, such as feedback messages, maximum refresh period size and maximum header size, are not configured in the profile, the default values for those attributes apply when the profile is enabled on the interface.

Currently, IPHC is supported only on serial interfaces with PPP encapsulation and on multilink with PPP encapsulation interfaces.

IPHC is typically configured between the Customer Edge (CE) and Provide Edge (PE) ends of an interface and must be configured at both ends of the interface to work. The PPP protocol negotiates the IPHC specific parameters between the two ends of the interface and settles on the lowest value configured between the two ends.

QoS and IPHC

An IPHC profile can be enabled on an interface so that the IPHC profile applies only to packets that match a Quality of Service (QoS) service policy. In this case, the QoS service-policy class attributes determine which packets are compressed. This allows users to fine tune IPHC with greater granularity.

Policy maps are attached to an interface using the service-policy command. IPHC action applies only to output service policies. IPHC is not supported on input service policies.

The user can configure IPHC using QoS as follows:

•Create a QoS policy-map with the compress header ip action.

•Attach the IPHC profile to the interface using the ipv4 iphc profile profile_name mode service-policy command.

•Attach the QoS policy-map with compress header ip action using the service-policy output command.

See "IPHC on a Serial Interface with MLPPP/LFI and QoS Configuration: Example" section for an example of how to configure IPHC using QoS.

For complete information on configuring QoS, refer to the Cisco XR 12000 Series Router Modular Quality of Service Configuration Guide and the Cisco XR 12000 Series Router Modular Quality of Service Command Reference.

How to Configure Serial Interfaces

After you have configured a channelized or clear channel T3/E3 controller, as described in the "Configuring Clear Channel T3/E3 and Channelized T3 and T1/E1 Controllers on Cisco IOS XR Software" module in this document, you can configure the serial interfaces associated with that controller.

The following tasks describe how to configure a serial interface:

•Bringing Up a Serial Interface

•Configuring Optional Serial Interface Parameters

•Creating a Point-to-Point Serial Subinterface with a PVC

•Configuring Optional PVC Parameters

•Modifying the Keepalive Interval on Serial Interfaces

•How to Configure a Layer 2 Attachment Circuit

–Creating a Serial Layer 2 Subinterface with a PVC

–Configuring Optional Serial Layer 2 PVC Parameters

•Configuring IPHC

–Configuring the IPHC Slot Level Command

–Configuring an IPHC Profile

–Enabling an IPHC Profile on an Interface

Bringing Up a Serial Interface

This task describes the commands used to bring up a serial interface.

Prerequisites

The Cisco XR 12000 Series Router must have at least one of the SIPs and one of the SPAs or line cards installed and be running Cisco IOS XR software:

•Cisco XR 12000 SIP-401

•Cisco XR 12000 SIP-501

•Cisco XR 12000 SIP-601

•2-Port and 4-Port T3/E3 Serial SPA

•2-Port and 4-Port Channelized T3/DS0 Serial SPA

•4-Port Channelized OC-12/DS3 line cards

•1-Port Channelized OC-12/DS0 SPAs and line cards

•1-Port Channelized OC-48/DS3 SPAs and line cards

•1-Port Channelized OC3/STM-1 SPA

•8-Port Channelized T1/E1 SPA

Restrictions

The configuration on both ends of the serial connection must match for the interface to be active.

SUMMARY STEPS

1. show interfaces

2. configure

3. interface serial interface-path-id

4. ipv4 address ip-address

5. no shutdown

6. end
or
commit

7. exit

8. exit

9. Repeat Step 1 through Step 8 to bring up the interface at the other end of the connection.

10. show ipv4 interface brief

11. show interfaces serial interface-path-id

DETAILED STEPS

Uncommitted changes found, commit them before 

exiting(yes/no/cancel)? 

[cancel]:

RP/0/0/CPU0:router# show interfaces

What to Do Next

To modify the default configuration of the serial interface you just brought up, see the "Configuring Optional Serial Interface Parameters" section.

Configuring Optional Serial Interface Parameters

This task describes the commands used to modify the default configuration on a serial interface.

Prerequisites

Before you modify the default serial interface configuration, you must bring up the serial interface and remove the shutdown configuration, as described in the "Bringing Up a Serial Interface" section.

Restrictions

The configuration on both ends of the serial connection must match for the interface to be active.

SUMMARY STEPS

1. configure

2. interface serial interface-path-id

3. encapsulation [hdlc | ppp | frame-relay [IETF]

4. serial

5. crc length

6. invert

7. scramble

8. transmit-delay hdlc-flags

9. end
or
commit

10. exit

11. exit

12. exit

13. show interfaces serial [interface-path-id]

Uncommitted changes found, commit them before 

exiting(yes/no/cancel)? 

[cancel]:

What to Do Next

•To create a point-to-point Frame Relay subinterface with a PVC on the serial interface you just brought up, see the "Creating a Point-to-Point Serial Subinterface with a PVC" section.

•To configure PPP authentication on serial interfaces with PPP encapsulation, see the "Configuring PPP on Cisco IOS XR Software" module later in this manual.

•To modify the default keepalive configuration, see the "Modifying the Keepalive Interval on Serial Interfaces" section.

•To modify the default Frame Relay configuration on serial interfaces that have Frame Relay encapsulation enabled, see the "Modifying the Default Frame Relay Configuration on an Interface" section of the "Configuring Frame Relay Cisco IOS XR Software" module.

Creating a Point-to-Point Serial Subinterface with a PVC

The procedure in this section creates a point-to-point serial subinterface and configures a permanent virtual circuit (PVC) on that serial subinterface.

Note Subinterface and PVC creation is supported on interfaces with Frame Relay encapsulation only.

Prerequisites

Before you can create a subinterface on a serial interface, you must bring up the main serial interface with Frame Relay encapsulation, as described in the "Bringing Up a Serial Interface" section.

Restrictions

Only one PVC can be configured for each point-to-point serial subinterface.

SUMMARY STEPS

1. configure

2. interface serial interface-path-id.subinterface point-to-point

3. ipv4 address ipv4_address/prefix

4. pvc dlci

5. end
or
commit

6. Repeat Step 1 through Step 5 to bring up the serial subinterface and any associated PVC at the other end of the connection.

DETAILED STEPS

RP/0/0/CPU0:router (config-subif)#ipv4 address 
10.46.8.6/24

Uncommitted changes found, commit them before 

exiting(yes/no/cancel)? 

[cancel]:

RP/0/0/CPU0:router (config-subif)#ipv4 address 
10.46.8.5/24

What to Do Next

•To configure optional PVC parameters, see the "Configuring Optional Serial Interface Parameters" section.

•To modify the default Frame Relay configuration on serial interfaces that have Frame Relay encapsulation enabled, see the"Modifying the Default Frame Relay Configuration on an Interface" section of the "Configuring Frame Relay Cisco IOS XR Software" module.

•To attach a Layer 3 QOS service policy to the PVC under the PVC submode, refer to the appropriate Cisco IOS XR software configuration guide.

Configuring Optional PVC Parameters

This task describes the commands you can use to modify the default configuration on a serial PVC.

For additional information about Frame Relay options, see the "Configuring Frame Relay on Cisco IOS XR Software" module in the Cisco IOS XR Interface and Hardware Component Configuration Guide for the Cisco XR 12000 Series Router.

Prerequisites

Before you can modify the default PVC configuration, you must create the PVC on a serial subinterface, as described in the "Creating a Point-to-Point Serial Subinterface with a PVC" section.

Restrictions

•The DLCI (or PVI identifier) must match on both ends of the PVC for the connection to be active.

•To change the PVC DLCI, you must delete the PVC and then add it back with the new DLCI.

SUMMARY STEPS

1. configure

2. interface serial interface-path-id.subinterface

3. pvc dlci

4. encap [cisco | ietf]

5. service-policy {input | output} policy-map

6. end
or
commit

7. Repeat Step 1 through Step 6 to configure the PVC at the other end of the connection.

8. show frame-relay pvc dlci-number

9. show policy-map interface serial interface-path-id.subinterface {input | output}
or
show policy-map type qos interface serial interface-path-id.subinterface {input | output}

Uncommitted changes found, commit them before 

exiting(yes/no/cancel)? 

[cancel]:

RP/0/0/CPU0:router (config-subif)# pvc 20

What to Do Next

•To modify the default Frame Relay configuration on serial interfaces that have Frame Relay encapsulation enabled, see the "Modifying the Default Frame Relay Configuration on an Interface" section of the "Configuring Frame Relay Cisco IOS XR Software" module in this manual.

Modifying the Keepalive Interval on Serial Interfaces

Perform this task to modify the keepalive interval on serial interfaces that have Cisco HDLC or PPP encapsulation enabled.

Note When you enable Cisco HDLC or PPP encapsulation on a serial interface, the default keepalive interval is 10 seconds. Use this procedure to modify that default keepalive interval.

Note Cisco HDLC is enabled by default on serial interfaces.

Prerequisites

Before modifying the keepalive timer configuration, ensure that Cisco HDLC or PPP encapsulation is enabled on the interface. Use the encapsulation command to enable Cisco HDLC or PPP encapsulation on the interface, as described in the "Configuring Optional Serial Interface Parameters" section.

Restrictions

•Before performing a Minimal Disruptive Restart (MDR) upgrade, we recommend disabling keepalives on a Cisco XR 12000 Series Router.

SUMMARY STEPS

1. configure

2. interface serial interface-path-id

3. keepalive {seconds | disable}
or
no keepalive

4. end
or
commit

5. show interfaces type interface-path-id

DETAILED STEPS

RP/0/0/CPU0:router(config-if)# keepalive 3

RP/0/0/CPU0:router(config-if)# no keepalive

Uncommitted changes found, commit them before 

exiting(yes/no/cancel)? 

[cancel]:

How to Configure a Layer 2 Attachment Circuit

The Layer 2 AC configuration tasks are described in the following procedures:

•Creating a Serial Layer 2 Subinterface with a PVC

•Configuring Optional Serial Layer 2 PVC Parameters

Note After you configure an interface for Layer 2 switching, no routing commands such as ipv4 address are permissible. If any routing commands are configured on the interface, then the l2transport command is rejected.

Creating a Serial Layer 2 Subinterface with a PVC

The procedure in this section creates a Layer 2 subinterface with a PVC.

Prerequisites

Before you can create a subinterface on a serial interface, you must bring up a serial interface, as described in the "Bringing Up a Serial Interface" section.

Restrictions

Only one PVC can be configured for each serial subinterface.

SUMMARY STEPS

1. configure

2. interface serial interface-path-id.subinterface l2transport

3. pvc vpi/vci

4. end
or
commit

5. Repeat Step 1 through Step 4 to bring up the serial subinterface and any associated PVC at the other end of the AC.

DETAILED STEPS

Uncommitted changes found, commit them before 

exiting(yes/no/cancel)? 

[cancel]:

What to Do Next

•To configure optional PVC parameters, see the "Configuring Optional Serial Layer 2 PVC Parameters" section.

•For detailed information about configuring L2TPv3 in your network, see the "Implementing Layer 2 Tunnel Protocol Version 3 on Cisco IOS XR Software" module of the Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco XR 12000 Series Router. For detailed information about configuring L2VPNs, see the "Implementing MPLS Layer 2 VPNs on Cisco IOS XR Software" module of the Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco XR 12000 Series Router.

Configuring Optional Serial Layer 2 PVC Parameters

This task describes the commands you can use to modify the default configuration on a serial Layer 2 PVC.

Prerequisites

Before you can modify the default PVC configuration, you must create the PVC on a Layer 2 subinterface, as described in the "Creating a Serial Layer 2 Subinterface with a PVC" section.

Restrictions

The configuration on both ends of the PVC must match for the connection to be active.

SUMMARY STEPS

1. configure

2. interface serial interface-path-id.subinterface l2transport

3. pvc dlci

4. encap [cisco | ietf]

5. service-policy {input | output} policy-map

6. fragment end-to-end fragment-size

7. fragment-counter

8. end
or
commit

9. Repeat Step 1 through Step 7 to configure the PVC at the other end of the AC.

10. show policy-map interface serial interface-path-id.subinterface {input | output}
or
show policy-map type qos interface serial interface-path-id.subinterface {input | output}

DETAILED STEPS

Uncommitted changes found, commit them before 

exiting(yes/no/cancel)? 

[cancel]:

What to Do Next

•To configure a point-to-point pseudowire XConnect on the AC you just created, see the "Implementing Layer 2 Tunnel Protocol Version 3 on Cisco IOS XR Software" module of the Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco XR 12000 Series Router.

•To configure an L2VPN, see the "Implementing MPLS Layer 2 VPNs on Cisco IOS XR Software" module of the Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco XR 12000 Series Router.

Configuring IPHC

This section contains the following step procedures:

•Prerequisites for Configuring IPHC

•Configuring the IPHC Slot Level Command

•Configuring an IPHC Profile

•Enabling an IPHC Profile on an Interface

Prerequisites for Configuring IPHC

IP header compression (IPHC) is supported on the following cards:

•Cisco 1-Port Channelized OC-12/STM-4

•Cisco 1-Port Channelized OC-48/STM-16

•Cisco 1-Port Channelized STM-1/OC-3

•Cisco 8-Port Channelized T1/E1 SPA

•Cisco 2-Port and 4-Port Clear Channel T3/E3 SPA

•Cisco 2-Port and 4-Port Channelized T3 SPA

•Cisco Multirate 10G IP Services Engines SIPs

–Cisco 12000-SIP-600

–Cisco 12000-SIP-401

–Cisco 12000-SIP-501

–Cisco 12000-SIP-601

Configuring the IPHC Slot Level Command

This section describes how to configure the IP header compression (IPHC) slot level command, which reserves the IPHC resources, enables IPHC on the line card, and defines the maximum number of TCP and non-TCP connections for the nodes. This configuration must be done before an IPHC profile can be created.

Note IPHC slot level configuration is required on both the peer routers.

SUMMARY STEPS

To configure the IP header compression (IPHC) slot level, perform the following steps.

1. config

2. iphc tcp connections max-number location node-id

3. iphc non-tcp connections max-number location node-id

4. commit

DETAILED STEPS

Uncommitted changes found, commit them 
before exiting (yes/no/cancel)? 

[cancel]:

Configuring an IPHC Profile

This section describes how to create and configure an IP header compression (IPHC) profile. This procedure is for TCP and non-TCP compression.

SUMMARY STEPS

To configure an IP header compression (IPHC) profile, perform the following steps.

1. configure

2. iphc profile profile-name type {ietf | iphc}

3. tcp compression

4. tcp context absolute number-of-contexts

5. non-tcp compression

6. non-tcp context absolute number-of-contexts

7. rtp

8. refresh max-period {max-number | infinite}

9. refresh rtp

10. feedback disable

11. max-header number-of-bytes

12. end
or
commit

DETAILED STEPS

Uncommitted changes found, commit them 
before exiting (yes/no/cancel)? 

[cancel]:

Enabling an IPHC Profile on an Interface

This section describes how to enable an IP header compression (IPHC) profile on an interface by attaching the profile directly to the interface.

SUMMARY STEPS

To configure to enable an IPHC profile on an interface, perform the following steps.

1. config

2. interface type interface-path-id

3. encapsulation ppp

4. ipv4 iphc profile profile-name [mode service-policy]

5. service policy input | output | type service-policy-name

6. commit

DETAILED STEPS

Uncommitted changes found, commit them 
before exiting (yes/no/cancel)? 

[cancel]:

Configuration Examples for Serial Interfaces

This section provides the following configuration examples:

•Bringing Up and Configuring a Serial Interface with Cisco HDLC Encapsulation: Example

•Configuring a Serial Interface with Frame Relay Encapsulation: Example

•Configuring a Serial Interface with PPP Encapsulation: Example

•IPHC Configuration: Examples

Bringing Up and Configuring a Serial Interface with Cisco HDLC Encapsulation: Example

The following example shows how to bring up a basic serial interface with Cisco HDLC encapsulation:

RP/0/0/CPU0:Router#config

RP/0/0/CPU0:Router(config)# interface serial 0/3/0/0/0:0

RP/0/0/CPU0:Router(config-if)# ipv4 address 192.0.2.2 255.255.255.252

RP/0/0/CPU0:Router(config-if)# no shutdown

RP/0/0/CPU0:router(config-if)# end

Uncommitted changes found, commit them? [yes]: yes

The following example shows how to configure the interval between keepalive messages to be 10 seconds:

RP/0/0/CPU0:router# configure

RP/0/0/CPU0:router(config)# interface serial 0/3/0/0/0:0

RP/0/0/CPU0:router(config-if)# keepalive 10

RP/0/0/CPU0:router(config-if)# commit

The following example shows how to modify the optional serial interface parameters:

RP/0/0/CPU0:router# configure

RP/0/0/CPU0:router(config)# interface serial 0/3/0/0/0:0

RP/0/0/CPU0:Router(config-if)# serial

RP/0/0/CPU0:Router(config-if-serial)# crc 16

RP/0/0/CPU0:Router(config-if-serial)# invert

RP/0/0/CPU0:Router(config-if-serial)# scramble

RP/0/0/CPU0:Router(config-if-serial)# transmit-delay 3

RP/0/0/CPU0:Router(config-if-serial)# commit

The following is sample output from the show interfaces serial command:

RP/0/0/CPU0:Router# show interfaces serial 0/0/3/0/5:23

Serial0/0/3/0/5:23 is down, line protocol is down

  Hardware is Serial network interface(s)

  Internet address is Unknown

  MTU 1504 bytes, BW 64 Kbit

     reliability 143/255, txload 1/255, rxload 1/255

  Encapsulation HDLC, crc 16,  loopback not set, keepalive set (10 sec)

  Last clearing of "show interface" counters 18:11:15

  5 minute input rate 0 bits/sec, 0 packets/sec

  5 minute output rate 0 bits/sec, 0 packets/sec

     2764 packets input, 2816 bytes, 3046 total input drops

     0 drops for unrecognized upper-level protocol

     Received 0 broadcast packets, 0 multicast packets

              0 runts, 0 giants, 0 throttles, 0 parity

     3046 input errors, 1 CRC, 0 frame, 0 overrun, 2764 ignored, 281 abort

     2764 packets output, 60804 bytes, 0 total output drops

     Output 0 broadcast packets, 0 multicast packets

     0 output errors, 0 underruns, 0 applique, 0 resets

     0 output buffer failures, 0 output buffers swapped out

     0 carrier transitions

Configuring a Serial Interface with Frame Relay Encapsulation: Example

The following example shows how to create a serial interface on a SPA with Frame Relay encapsulation and a serial subinterface with a PVC on router 1:

RP/0/0/CPU0:router# configure

RP/0/0/CPU0:router(config)# interface serial 0/1/0/0

RP/0/0/CPU0:router(config-if)# encapsulation frame-relay

RP/0/0/CPU0:router(config-if)#frame-relay intf-type dce

RP/0/0/CPU0:router(config-if)# no shutdown

RP/0/0/CPU0:router(config-if)# end

Uncommitted changes found, commit them? [yes]: yes

RP/0/0/CPU0:router# configure

RP/0/0/CPU0:router(config)# interface serial 0/1/0/0.1 point-to-point

RP/0/0/CPU0:router (config-subif)#ipv4 address 10.20.3.1/24

RP/0/0/CPU0:router (config-subif)# pvc 16

RP/0/0/CPU0:router (config-fr-vc)# encapsulation ietf

RP/0/0/CPU0:router (config-fr-vc)# commit

RP/0/0/CPU0:router(config-fr-vc)# exit

RP/0/0/CPU0:router(config-subif)# exit

RP/0/0/CPU0:router(config)# exit

RP/0/0/CPU0:router# show interface serial 0/1/0/0

Wed Oct 8 04:14:39.946 PST DST

Serial0/1/0/0 is up, line protocol is up

Interface state transitions: 5

Hardware is Serial network interface(s)

Internet address is 10.20.3.1/24

MTU 4474 bytes, BW 44210 Kbit

reliability 255/255, txload 0/255, rxload 0/255

Encapsulation FRAME-RELAY, crc 16,

Scrambling is disabled, Invert data is disabled

LMI enq sent 0, LMI stat recvd 0, LMI upd recvd 0

LMI enq recvd 880, LMI stat sent 880, LMI upd sent 0 , DCE LMI up

LMI DLCI 1023 LMI type is CISCO frame relay DCE

Last clearing of "show interface" counters 02:23:04

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

858 packets input, 11154 bytes, 0 total input drops

0 drops for unrecognized upper-level protocol

Received 0 runts, 0 giants, 0 throttles, 0 parity

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

858 packets output, 12226 bytes, 0 total output drops

0 output errors, 0 underruns, 0 applique, 0 resets

0 output buffer failures, 0 output buffers swapped out

The following example shows how to create a serial interface on a SPA with Frame Relay encapsulation and a serial subinterface with a PVC on router 2, which is connected to router 1:

RP/0/0/CPU0:router# configure

RP/0/0/CPU0:router(config)# interface serial 0/1/0/1

RP/0/0/CPU0:router(config-if)# encapsulation frame-relay

RP/0/0/CPU0:router(config-if)# no shutdown

RP/0/0/CPU0:router(config-if)# end

Uncommitted changes found, commit them? [yes]: yes

RP/0/0/CPU0:router# configure

RP/0/0/CPU0:router(config)# interface serial 0/1/0/1.1 point-to-point

RP/0/0/CPU0:router (config-subif)#ipv4 address 10.20.3.2/24

RP/0/0/CPU0:router (config-subif)# pvc 16

RP/0/0/CPU0:router (config-fr-vc)# encapsulation ietf

RP/0/0/CPU0:router (config-fr-vc)# commit

RP/0/0/CPU0:router(config-fr-vc)# exit

RP/0/0/CPU0:router(config-subif)# exit

RP/0/0/CPU0:router(config)# exit

RP/0/0/CPU0:router# show interface serial 0/1/0/1

Wed Oct 8 04:13:45.046 PST DST

Serial0/1/0/1 is up, line protocol is up

Interface state transitions: 7

Hardware is Serial network interface(s)

Internet address is Unknown

MTU 4474 bytes, BW 44210 Kbit

reliability 255/255, txload 0/255, rxload 0/255

Encapsulation FRAME-RELAY, crc 16,

Scrambling is disabled, Invert data is disabled

LMI enq sent 1110, LMI stat recvd 875, LMI upd recvd 0, DTE LMI up

LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0

LMI DLCI 1023 LMI type is CISCO frame relay DTE

Last clearing of "show interface" counters 02:22:09

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

853 packets input, 12153 bytes, 0 total input drops

0 drops for unrecognized upper-level protocol

Received 0 runts, 0 giants, 0 throttles, 0 parity

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

853 packets output, 11089 bytes, 0 total output drops

0 output errors, 0 underruns, 0 applique, 0 resets

0 output buffer failures, 0 output buffers swapped out

Configuring a Serial Interface with PPP Encapsulation: Example

The following example shows how to create and configure a serial interface with PPP encapsulation:

RP/0/0/CPU0:router# configure

RP/0/0/CPU0:router(config)# interface serial 0/3/0/0/0:0

RP/0/0/CPU0:router(config-if)# ipv4 address 172.18.189.38 255.255.255.224

RP/0/0/CPU0:router(config-if)# encapsulation ppp

RP/0/0/CPU0:router(config-if)# no shutdown

RP/0/0/CPU0:router(config-if)# ppp authentication chap MIS-access

RP/0/0/CPU0:router(config-if)# end

Uncommitted changes found, commit them? [yes]: yes

The following example shows how to configure serial interface 0/3/0/0/0:0 to allow two additional retries after an initial authentication failure (for a total of three failed authentication attempts):

RP/0/0/CPU0:router# configuration

RP/0/0/CPU0:router(config)# interface serial 0/3/0/0/0:0

RP/0/0/CPU0:router(config-if)# encapsulation ppp

RP/0/0/CPU0:router(config-if)# ppp authentication chap

RP/0/0/CPU0:router(config-if)# ppp max-bad-auth 3

RP/0/0/CPU0:router(config-if)# end

Uncommitted changes found, commit them? [yes]: yes

IPHC Configuration: Examples

This section provides the following examples:

•IPHC Profile Configuration: Example

•IPHC on a Serial Interface Configuration: Examples

•IPHC on Multilink Configuration: Example

•IPHC on a Serial Interface with MLPPP/LFI and QoS Configuration: Example

IPHC Profile Configuration: Example

The following example shows how to configure an IPHC Profile:

config 

  iphc tcp connections 6000 location 0/2/1  

  iphc non-tcp connections 6000 location 0/2/1 

  iphc profile Profile_1 type iphc  

    tcp compression 

    tcp context absolute 255 

    non-tcp compression

    non-tcp context absolute 255 

    rtp

    refresh max-period 50 

	refresh rtp 

	feedback disable 

    max-header 20 

commit 

IPHC on a Serial Interface Configuration: Examples

Example 1

The following example shows how to enable an IP header compression (IPHC) profile on a serial interface by attaching the profile directly to the interface:

config 

  interface serial 0/1/0/1 

    encapsulation ppp

    ipv4 iphc profile Profile_1 

commit 

Example 2

The following example shows how to enable an IP header compression (IPHC) profile on an interface by specifying a QoS service policy that contains an IPHC profile:

config 

  interface serial 0/1/0/1:1 

    encapsulation ppp

    ipv4 iphc profile Profile_2 mode service-policy 

    service-policy output ip_header_compression_policy_map 

commit 

IPHC on Multilink Configuration: Example

The following example shows how to configure an IP header compression (IPHC) on a multilink interface:

config 

  interface multilink 0/4/3/0/4 

    ipv4 address 10.10.10.10 

    encapsulation ppp

    ipv4 iphc profile Profile_1 

    commit 

  interface serial 0/1/0/1:1 

    encapsulation ppp

    multilink group 4

    commit

IPHC on a Serial Interface with MLPPP/LFI and QoS Configuration: Example

The following example shows how to configure IP header compression (IPHC) on a serial interface with LFI and by specifying a QoS service policy that contains an IPHC profile:

config 

  interface multilink 0/4/3/0/4 

    ipv4 address 10.10.10.10 

      multilink 

        fragment-size 128

        interleave

    ipv4 iphc profile Profile_2 mode service-policy 

    service-policy output SP_2 

    commit

  interface serial 0/1/0/1:2 

    encapsulation ppp

    multilink group 4

    commit

Additional References

These sections provide references related to T3/E3 and T1/E1 controllers and serial interfaces.

Related Documents

Standards

MIBs

RFCs

Technical Assistance