Configuring POS Interfaces

This module describes the configuration of Packet-over-SONET/SDH (POS) interfaces.

POS interfaces provide secure and reliable data transmission over SONET and Synchronous Digital Hierarchy (SDH) frames using Cisco High-Level Data Link Control (HDLC) protocol or Point-to-Point Protocol (PPP) encapsulation. In addition to Cisco HDLC and PPP encapsulation, the Cisco ASR 9000 Series Router supports Frame Relay encapsulation.

The commands for configuring Layer 1 POS interfaces are provided in the Cisco IOS XR Interface and Hardware Component Command Reference.

Feature History for Configuring POS Interfaces


Release	Modification
Release 4.0.0	This feature was introduced on the Cisco ASR 9000 Series Router on the following SPAs: Cisco 1-Port Channelized OC-48/STM-16 SPA Cisco 2-Port Channelized OC-12c/DS0 SPA Cisco 1-Port OC-192c/STM-64 POS/RPR XFP SPA Cisco 2-Port OC-48c/STM-16 POS/RPR SPA Cisco 8-Port OC-12c/STM-4 POS SPA
Release 4.0.1	Support for the following SPAs was added on the Cisco ASR 9000 Series Router: Cisco 4-Port OC-3c/STM-1 POS SPA Cisco 8-Port OC-3c/STM-1 POS SPA

Prerequisites for Configuring POS Interfaces

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

Before configuring POS interfaces, be sure that the following conditions are met:

You know the IP address of the interface you will assign to the new POS interface configuration.
You have configured a clear channel or channelized SONET controller, as described in the Configuring Clear Channel SONET Controllers or Configuring Channelized SONET/SDH modules.

Information About Configuring POS Interfaces

To configure POS interfaces, you must understand the following concepts:

On the Cisco ASR 9000 Series Router, a single POS interface carries data using PPP, Cisco HDLC, or Frame Relay encapsulation.

The router identifies the POS interface address by the physical layer interface module (PLIM) card rack number, slot number, bay number, and port number that are associated with that interface. If a subinterface and permanent virtual circuits (PVCs) are configured under the POS interface, then the router includes the subinterface number in the POS interface path ID.

Default Settings for POS Interfaces

When a POS interface is brought up and no additional configuration commands are applied, the default interface settings shown in this table are present. These default settings can be changed by configuration.

Table 1. POS Modular Services Card and PLIM Default Interface Settings

Parameter

Configuration File Entry

Default Settings

Keepalive

Note

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

keepalive {interval[retry] |disable }  no keepalive

Interval of 10 seconds

Retry of:

5 (with PPP encapsulation)
3 (with HDLC encapsulation)

Encapsulation

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

hdlc

Maximum transmission unit (MTU)

mtu bytes

4474 bytes

Cyclic redundancy check (CRC)

crc [16 | 32]

Note

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

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 on page 553.

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 three ECHOREQ packets are sent without receiving an ECHOREP response.

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

IP Control Protocol (IPCP)—negotiates IP properties
Multiprotocol Label Switching control processor (MPLSCP)—negotiates MPLS properties
Cisco Discovery Protocol control processor (CDPCP)—negotiates CDP properties
IPv6CP—negotiates IP Version 6 (IPv6) properties
Open Systems Interconnection control processor (OSICP)—negotiates OSI properties

PPP uses keepalives to monitor the link state, as described in the “Keepalive Timer” section on page 587.

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 remote device’s name 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 Authentication module later in this manual.

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

Note

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

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.

If three keepalives are sent to the peer and no response is received from peer, then the link makes the transition to the down state. ECHOREQ packets are sent out only when LCP negotiation is complete (for example, when LCP is open).

Note

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

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 .

To remove the keepalive command from the configuration entirely, use the no keepalive command. You must remove the keepalive command from an interface configuration before you can configure Frame Relay encapsulation on that interface. Frame Relay interfaces do not support keepalives.

Note

During MDR, the keepalive interval must be 10 seconds or more.

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 while the other end has 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

On the Cisco ASR 9000 Series Router, Frame Relay encapsulated POS interface configuration is hierarchical and comprises the following elements:

The POS main interface is comprised of the physical interface and port. If you are not using the POS interface to support Cisco HDLC and PPP encapsulated connections, then you must configure subinterfaces with PVCs under the POS main interface. Frame Relay connections are supported on PVCs only.
POS subinterfaces are configured under the POS main interface. A POS subinterface does not actively carry traffic until you configure a PVC under the POS subinterface.
Point-to-point and Layer 2 attachment circut (AC) PVCs are configured under a POS subinterface. You cannot configure a PVC directly under a main interface. A single point-to-point or L2 AC 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. Connections on the POS PVC support Frame Relay encapsulation only.
Layer 3 configuration typically takes place on the subinterface.

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.

On the Cisco ASR 9000 Series Router, the following SPAs support Frame Relay encapsulation:

Cisco 4-Port OC-3c/STM-1 POS SPA
Cisco 8-Port OC-3c/STM-1 POS SPA
Cisco 1-Port OC-192c/STM-64 POS/RPR XFP SPA
Cisco 2-Port OC-48c/STM-16 POS/RPR SPA
Cisco 8-Port OC-12c/STM-4 POS SPA

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

Frame Relay interfaces support two types of encapsulated frames:

Cisco (this is the 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 POS interface

Note

Cisco encapsulation is required on POS 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 module later 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 POS interface is 4474 bytes. Therefore, the default numbers of PVCs supported on a POS interface configured with cisco LMI is 557.

You must configure the LMI interface type on Frame Relay interfaces; otherwise, the POS interface does not come up. For connections between Provider Edge (PE) and Customer Edge (CE) routers, the PE end must be DCE and the CE end must be DTE for LMI to come up. For more information about configuring the LMI interface type on a Frame Relay interface, see the Configuring Frame Relay module.

How to Configure a POS Interface

This section contains the following procedures:

Bringing Up a POS Interface

This task describes the commands you can use to bring up a POS interface.

Before you begin

You must have a POS line card or SPA installed in a router that is running Cisco IOS XR software.

Restrictions

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

SUMMARY STEPS

show interfaces
configure
interface pos interface-path-id
ipv4 address ipv4_address/prefix
no shutdown
end or commit
exit
exit
Repeat Step 1 through Step 8 to bring up the interface at the other end of the connection.
show ipv4 interface brief
show interfaces pos interface-path-id

DETAILED STEPS

Command or Action Purpose

Step 1

show interfaces

Example:


RP/0/RSP0/CPU0:router# show interfaces

(Optional) Displays configured interfaces.

Use this command to also confirm that the router recognizes the PLIM card.

Step 2

configure

Example:


RP/0/RSP0/CPU0:router# configure

Enters global configuration mode.

Step 3

interface pos interface-path-id

Example:


RP/0/RSP0/CPU0:router(config)# interface POS 0/3/0/0

Specifies the POS interface name and notation rack/slot/module/port, and enters interface configuration mode.

Step 4

ipv4 address ipv4_address/prefix

Example:


RP/0/RSP0/CPU0:router (config)#ipv4 address 10.46.8.6/24

Assigns an IP address and subnet mask to the interface.

Note

Skip this step if you are configuring Frame Relay encapsulation on this interface. For Frame Relay, the IP address and subnet mask are configured under the subinterface.

Step 5

no shutdown

Example:


RP/0/RSP0/CPU0:router (config-if)# no shutdown

Removes the shutdown configuration.

Note

Removal of the shutdown configuration eliminates the forced administrative down on the interface, enabling it to move to an up or down state (assuming the parent SONET layer is not configured administratively down).

Step 6

end or commit

Example:


RP/0/RSP0/CPU0:router (config-if)# end


RP/0/RSP0/CPU0:router(config-if)# commit

Saves configuration changes.

When you issue the end command, the system prompts you to commit changes:
```
Uncommitted changes found, commit them before exiting(yes/no/cancel)?
[cancel]:
```
- Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

- Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

- Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.
Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

Step 7

exit

Example:


RP/0/RSP0/CPU0:router (config-if)# exit

Exits interface configuration mode and enters global configuration mode.

Step 8

exit

Example:


RP/0/RSP0/CPU0:router (config)# exit

Exits global configuration mode and enters EXEC mode.

Step 9

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

Example:


RP/0/RSP0/CPU0:router# show interfaces


RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router (config)# interface pos 0/3/0/0
RP/0/RSP0/CPU0:router (config-if)# no shutdown
RP/0/RSP0/CPU0:router (config-if)# commit
RP/0/RSP0/CPU0:router (config-if)# exit
RP/0/RSP0/CPU0:router (config)# exit

Note

The configuration on both ends of the POS connection must match.

Step 10

show ipv4 interface brief

Example:


RP/0/RSP0/CPU0:router # show ipv4 interface brief

Verifies that the interface is active and properly configured.

If you have brought up a POS interface properly, the “Status” field for that interface in the show ipv4 interface brief command output shows “Up.”

Step 11

show interfaces pos interface-path-id

Example:


RP/0/RSP0/CPU0:router# show interfaces pos 0/3/0/0

(Optional) Displays the interface configuration.

What to do next

To modify the default configuration of the POS interface you just brought up, see the “Configuring Optional POS Interface Parameters” section on page 594.

Configuring Optional POS Interface Parameters

This task describes the commands you can use to modify the default configuration on a POS interface.

Before you begin

Before you modify the default POS interface configuration, you must bring up the POS interface and remove the shutdown configuration, as described in the “Bringing Up a POS Interface” section on page 590.

Restrictions

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

SUMMARY STEPS

configure
interface pos interface-path-id
encapsulation [hdlc | ppp | frame-relay [IETF ]]
pos crc {16 | 32 }
mtu value
end or commit
exit
exit
show interfaces pos [interface-path-id]

DETAILED STEPS

Command or Action Purpose

Step 1

configure

Example:


RP/0/RSP0/CPU0:router# configure

Enters global configuration mode.

Step 2

interface pos interface-path-id

Example:


RP/0/RSP0/CPU0:router(config)# interface POS 0/3/0/0

Specifies the POS interface name and notation rack/slot/module/port, and enters interface configuration mode.

Step 3

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

Example:


RP/0/RSP0/CPU0:router(config-if)# encapsulation hdlc

(Optional) Configures the interface encapsulation parameters and details such as HDLC or PPP.

Note

The default encapsulation is hdlc.

Step 4

pos crc {16 | 32 }

Example:


RP/0/RSP0/CPU0:router(config-if)# pos crc 32

(Optional) Configures the CRC value for the interface. Enter the 16 keyword to specify 16-bit CRC mode, or enter the 32 keyword to specify 32-bit CRC mode.

Note

The default CRC is 32.

Step 5

mtu value

Example:


RP/0/RSP0/CPU0:router(config-if)# mtu 4474

(Optional) Configures the MTU value.

The default value is 4474.
The POS MTU range is 64–9216.

Step 6

end or commit

Example:


RP/0/RSP0/CPU0:router (config-if)# end


RP/0/RSP0/CPU0:router(config-if)# commit

Saves configuration changes.

When you issue the end command, the system prompts you to commit changes:
```
Uncommitted changes found, commit them before exiting(yes/no/cancel)?
[cancel]:
```
- Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

- Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

- Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.
Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

Step 7

exit

Example:


RP/0/RSP0/CPU0:router (config-if)# exit

Exits interface configuration mode and enters global configuration mode.

Step 8

exit

Example:


RP/0/RSP0/CPU0:router (config)# exit

Exits global configuration mode and enters EXEC mode.

Step 9

show interfaces pos [interface-path-id]

Example:


RP/0/RSP0/CPU0:router# show interface pos 0/3/0/0

(Optional) Displays general information for the specified POS interface.

What to do next

To create a point-to-point Frame Relay subinterface with a PVC on the POS interface you just brought up, see the “Creating a Point-to-Point POS Subinterface with a PVC” section on page 596.
To configure PPP authentication on POS interfaces where PPP encapsulation is enabled, see the Configuring PPP on the Cisco ASR 9000 Series Router module later in this manual.
To modify the keepalive interval on POS interfaces that have Cisco HDLC or PPP encapsulation enabled, see the “Modifying the Keepalive Interval on POS Interfaces” section on page 601.
To modify the default Frame Relay configuration on POS interfaces that have Frame Relay encapsulation enabled, see the “Modifying the Default Frame Relay Configuration on an Interface” of the Configuring Frame Relay on the Cisco ASR 9000 Series Router module in this manual.

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

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

Note

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

Before you begin

Before you can create a subinterface on a POS interface, you must bring up the main POS interface with Frame Relay encapsulation, as described in the “Bringing Up a POS Interface” section on page 590.

Restrictions

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

SUMMARY STEPS

configure
interface pos interface-path-id .subinterfacepoint-to-point
ipv4 address ipv4_address/prefix
pvc dlci
end or commit
Repeat Step 1 through Step 5 to bring up the POS subinterface and any associated PVC at the other end of the connection.

DETAILED STEPS

Command or Action Purpose

Step 1

configure

Example:


RP/0/RSP0/CPU0:router# configure

Enters global configuration mode.

Step 2

interface pos interface-path-id .subinterfacepoint-to-point

Example:


RP/0/RSP0/CPU0:router (config)# interface pos 0/3/0/0.1 point-to-point

Enters POS subinterface configuration mode.

Replace subinterface with a subinterface ID, in the range from 1 through 4294967295.

Step 3

ipv4 address ipv4_address/prefix

Example:


RP/0/RSP0/CPU0:router (config-subif)#ipv4 address 10.46.8.6/24

Assigns an IP address and subnet mask to the subinterface.

Step 4

pvc dlci

Example:


RP/0/RSP0/CPU0:router (config-subif)# pvc 20

Creates a POS permanent virtual circuit (PVC) and enters Frame Relay PVC configuration submode.

Replace dlci with a PVC identifier, in the range from 16 to 1007.

Note

Only one PVC is allowed per subinterface.

Step 5

end or commit

Example:


RP/0/RSP0/CPU0:router (config-fr-vc)# end


RP/0/RSP0/CPU0:router(config-fr-vc)# commit

Saves configuration changes.

When you issue the end command, the system prompts you to commit changes:
```
Uncommitted changes found, commit them before exiting(yes/no/cancel)?
[cancel]:
```
- Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

- Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

- Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.
Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

Step 6

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

Example:

RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router (config)# interface pos 0/3/0/1.1


RP/0/RSP0/CPU0:router (config-subif)#ipv4 address 10.46.8.5/24


RP/0/RSP0/CPU0:router (config-subif)# pvc 20
RP/0/RSP0/CPU0:router (config-fr-vc)# commit

Note

When assigning an IP address and subnet mask to the subinterface at the other end of the connection, keep in mind that the addresses at both ends of the connection must be in the same subnet.

The DLCI (or PVC identifier) must match on both ends of the subinterface connection.

What to do next

To configure optional PVC parameters, see the “Configuring Optional PVC Parameters” section on page 598.
To modify the default Frame Relay configuration on POS interfaces that have Frame Relay encapsulation enabled, see the “Modifying the Default Frame Relay Configuration on an Interface” of the “Configuring Frame Relay on the Cisco ASR 9000 Series Router” 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 POS PVC.

Before you begin

Before you can modify the default PVC configuration, you must create the PVC on a POS subinterface, as described in the “Creating a Point-to-Point POS Subinterface with a PVC” section on page 595.

Restrictions

The DLCI (or PVC 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

configure
interface pos interface-path-id .subinterface
pvc dlci
encap [cisco | ietf ]
service-policy {input | output } policy-map
end or commit
Repeat Step 1 through Step 6 to bring up the POS subinterface and any associated PVC at the other end of the connection.
show frame-relay pvc dlci-number
show policy-map interface pos interface-path-id .subinterface{input | output } or show policy-map type qos interface pos interface-path-id .subinterface{input | output }

DETAILED STEPS

Command or Action Purpose

Step 1

configure

Example:


RP/0/RSP0/CPU0:router# configure

Enters global configuration mode.

Step 2

interface pos interface-path-id .subinterface

Example:


RP/0/RSP0/CPU0:router (config)# interface pos 0/3/0/0.1

Enters POS subinterface configuration mode.

Step 3

pvc dlci

Example:


RP/0/RSP0/CPU0:router (config-subif)# pvc 20

Enters subinterface configuration mode for the PVC.

Replace dlci with the DLCI number used to identify the PVC. Range is from 16 to 1007.

Step 4

encap [cisco | ietf ]

Example:


RP/0/RSP0/CPU0:router (config-fr-vc)# encap ietf

(Optional) Configures the encapsulation for a Frame Relay PVC.

Note

If the encapsulation type is not configured explicitly for a PVC, then that PVC inherits the encapsulation type from the main POS interface.

Step 5

service-policy {input | output } policy-map

Example:


RP/0/RSP0/CPU0:router (config-fr-vc)# service-policy output policy1

Attaches a policy map to an input subinterface or output subinterface. Once attached, the policy map is used as the service policy for the subinterface.

Note

For information on creating and configuring policy maps, refer to the Cisco IOS XR Modular Quality of Service Configuration Guide,

Step 6

end or commit

Example:


RP/0/RSP0/CPU0:router (config-fr-vc)# end


RP/0/RSP0/CPU0:router(config-fr-vc)# commit

Saves configuration changes.

When you issue the end command, the system prompts you to commit changes:
```
Uncommitted changes found, commit them before exiting(yes/no/cancel)?
[cancel]:
```
- Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

- Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

- Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.
Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

Step 7

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

Example:


RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router (config)# interface pos 0/3/0/1.1


RP/0/RSP0/CPU0:router (config-subif)# pvc 20


RP/0/RSP0/CPU0:router (config-fr-vc)# encap cisco
RP/0/RSP0/CPU0:router (config-fr-vc)# commit

Note

The configuration on both ends of the subinterface connection must match.

Step 8

show frame-relay pvc dlci-number

Example:


RP/0/RSP0/CPU0:router# show frame-relay pvc 20

(Optional) Verifies the configuration of specified POS interface.

Step 9

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

Example:


RP/0/RSP0/CPU0:router# show policy-map interface pos 0/3/0/0.1 output


RP/0/RSP0/CPU0:router# show policy-map type qos interface pos 0/3/0/0.1 output

(Optional) Displays the statistics and the configurations of the input and output policies that are attached to a subinterface.

What to do next

To modify the default Frame Relay configuration on POS interfaces that have Frame Relay encapsulation enabled, see the “Modifying the Default Frame Relay Configuration on an Interface” of the “Configuring Frame Relay on the Cisco ASR 9000 Series Router” module.

Modifying the Keepalive Interval on POS Interfaces

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

Note

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

Cisco HDLC is enabled by default on POS interfaces.

Before you begin

Before you can modify the keepalive timer configuration, you must 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 POS Interface Parameters” section on page 592.

Restrictions

During MDR, the keepalive interval must be 10 seconds or more.

SUMMARY STEPS

configure
interface pos interface-path-id
keepalive {seconds [retry-count] | disable } or no keepalive
end or commit
show interfaces pos interface-path-id

DETAILED STEPS

	Command or Action	Purpose
Step 1	configure Example: `RP/0/RSP0/CPU0:router# configure`	Enters global configuration mode.
Step 2	interface pos `interface-path-id` Example: `RP/0/RSP0/CPU0:router(config)# interface POS 0/3/0/0`	Specifies the POS interface name and notation `rack/slot/module/port` and enters interface configuration mode.
Step 3	keepalive {`seconds` [`retry-count`] \| disable } or no keepalive Example: `RP/0/RSP0/CPU0:router(config-if)# keepalive 3` or `RP/0/RSP0/CPU0:router(config-if)# no keepalive`	Specifies the number of seconds between keepalive messages, and optionally the number of keepalive messages that can be sent to a peer without a response before transitioning the link to the down state. Use the keepalive disable command, the no keepalive , or the keepalive command with an argument of 0 to disable the keepalive feature entirely. If keepalives are configured on an interface, use the no keepalive command to disable the keepalive feature before you configure Frame Relay encapsulation on that interface.
Step 4	end or commit Example: `RP/0/RSP0/CPU0:router(config-if)# end` or `RP/0/RSP0/CPU0:router(config-if)# commit`	Saves configuration changes. When you issue the end command, the system prompts you to commit changes: `Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]:` - Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode. - Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. - Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 5	show interfaces pos `interface-path-id` Example: `RP/0/RSP0/CPU0:router# show interfaces POS 0/3/0/0`	(Optional) Verifies the interface configuration.

How to Configure a Layer 2 Attachment Circuit

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

Note

After you configure an interface for Layer 2 switching, no routing commands such as ipv4 address are permissible.

Layer 2 ACs are not supported on interfaces configured with HDLC or PPP encapsulation.

Creating a Layer 2 Frame Relay Subinterface with a PVC

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

Before you begin

Before you can create a subinterface on a POS interface, you must bring up a POS interface, as described in the “Bringing Up a POS Interface” section on page 590.

Note

You must skip Step 4 of the “Bringing Up a POS Interface” configuration steps when configuring an interface for Layer 2 switching. The ipv4 address command is not permissible on Frame Relay encapsulated interface.

Restrictions

Only one PVC can be configured for each subinterface.
The configuration on both ends of the PVC must match for the connection to operate properly.
The ipv4 address command is not permissible on Frame Relay encapsulated interface. Any previous configuration of an IP address must be removed before you can configure an interface for Layer 2 transport mode.
Layer 2 configuration is supported on Frame Relay PVCs only. Layer 2 Port mode, where Layer 2 configuration is applied directly under the main POS interface, is not supported.

SUMMARY STEPS

configure
interface pos interface-path-id .subinterface l2transport
pvc dlci
end or commit
Repeat Step 1 through Step 4 to bring up the subinterface and any associated PVC at the other end of the AC.

DETAILED STEPS

Command or Action Purpose

Step 1

configure

Example:


RP/0/RSP0/CPU0:router# configure

Enters global configuration mode.

Step 2

interface pos interface-path-id .subinterface l2transport

Example:


RP/0/RSP0/CPU0:router(config)# interface pos 0/3/0/0.1 l2transport

Creates a subinterface and enters POS subinterface configuration mode for that subinterface.

Note

The subinterface must be unique to any other subinterfaces configured under a single main interface.

Step 3

pvc dlci

Example:


RP/0/RSP0/CPU0:router(config-if)# pvc 100

Creates a Frame Relay permanent virtual circuit (PVC) and enters Layer 2 transport PVC configuration mode.

Replace dlci with the DLCI number used to identify the PVC. Range is from 16 to 1007.

Note

Only one PVC is allowed per subinterface.

Step 4

end or commit

Example:


RP/0/RSP0/CPU0:router(config-fr-vc)# end


RP/0/RSP0/CPU0:router(config-fr-vc)# commit

Saves configuration changes.

When you issue the end command, the system prompts you to commit changes:
```
Uncommitted changes found, commit them before exiting(yes/no/cancel)?
[cancel]:
```
- Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

- Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

- Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.
Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

Step 5

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

Brings up the AC.

Note

The configuration on both ends of the AC must match.

What to do next

To configure optional subinterface parameters, see the “Configuring Optional Layer 2 Subinterface Parameters” section on page 608.
To configure optional PVC parameters, see the “Configuring Optional Layer 2 PVC Parameters” section on page 606.
For more information about configuring Layer 2 services on the Cisco ASR 9000 Series Router, see the “Implementing Point to Point Layer 2 Services” module of the Cisco ASR 9000 Series Aggregation Services Router L2VPN and Ethernet Services Configuration Guide.

Configuring Optional Layer 2 PVC Parameters

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

Before you begin

You must create the PVC on a Layer 2 subinterface, as described in the “Creating a Layer 2 Frame Relay Subinterface with a PVC” section on page 601.

SUMMARY STEPS

configure
interface pos interface-path-id .subinterfacel2transport
pvc dlci
encap {cisco | ietf }
service-policy {input | output } policy-map
end or commit
Repeat Step 1 through Step 5 to configure the PVC at the other end of the AC.
show policy-map interface pos interface-path-id .subinterface{input | output } or show policy-map type qos interface pos interface-path-id .subinterface{input | output }

DETAILED STEPS

Command or Action Purpose

Step 1

configure

Example:


RP/0/RSP0/CPU0:router# configure

Enters global configuration mode.

Step 2

interface pos interface-path-id .subinterfacel2transport

Example:


RP/0/RSP0/CPU0:router(config)# interface pos 0/6/0/1.10 l2transport

Enters POS subinterface configuration mode for a Layer 2 Frame Relay subinterface.

Step 3

pvc dlci

Example:


RP/0/RSP0/CPU0:router(config-if)# pvc 100

Enters Frame Relay PVC configuration mode for the specified PVC.

Replace dlci with the DLCI number used to identify the PVC. Range is from 16 to 1007.

Step 4

encap {cisco | ietf }

Example:


RP/0/RSP0/CPU0:router(config-fr-vc)# encap ietf

Configures the encapsulation for a Frame Relay PVC.

The encapsulation type must match on both ends of the PVC.

Step 5

service-policy {input | output } policy-map

Example:


RP/0/RSP0/CPU0:router (config-fr-vc)# service-policy output policy1

Attaches a policy map to an input subinterface or output subinterface. Once attached, the policy map is used as the service policy for the subinterface.

Note

For information on creating and configuring policy maps, refer to the Cisco IOS XR Modular Quality of Service Configuration Guide,

Step 6

end or commit

Example:


RP/0/RSP0/CPU0:router(config-pos-l2transport-pvc)# end


RP/0/RSP0/CPU0:router(config-pos-l2transport-pvc)# commit

Saves configuration changes.

When you issue the end command, the system prompts you to commit changes:
```
Uncommitted changes found, commit them before exiting(yes/no/cancel)?
[cancel]:
```
- Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

- Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

- Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.
Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

Step 7

Repeat Step 1 through Step 5 to configure the PVC at the other end of the AC.

Brings up the AC.

Note

The configuration on both ends of the connection must match.

Step 8

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

Example:


RP/0/RSP0/CPU0:router# show policy-map interface pos 0/6/0/1.10 output


RP/0/RSP0/CPU0:router# show policy-map type qos interface pos 0/6/0/1.10 output

(Optional) Displays the statistics and the configurations of the input and output policies that are attached to a subinterface.

Configuring Optional Layer 2 Subinterface Parameters

This task describes the commands you can use to modify the default configuration on a Frame Relay Layer 2 subinterface.

Before you begin

Before you can modify the default PVC configuration, you must create the PVC on a Layer 2 subinterface, as described in the “Creating a Layer 2 Frame Relay Subinterface with a PVC” section on page 601.

Restrictions

In most cases, the MTU that is configured under the subinterface has priority over the MTU that is configured under the main interface. The exception to this rule is when the subinterface MTU is higher than main interface MTU. In such cases, the subinterface MTU displays the configured value in the CLI output, but the actual operational MTU is the value that is configured under the main interface value. To avoid confusion when troubleshooting and optimizing your Layer 2 connections, we recommend always configuring a higher MTU on main interface.

SUMMARY STEPS

configure
interface pos interface-path-id .subinterface
mtu value
end or commit
Repeat Step 1 through Step 4 to configure the PVC at the other end of the AC.

DETAILED STEPS

Command or Action Purpose

Step 1

configure

Example:


RP/0/RSP0/CPU0:router# configure

Enters global configuration mode.

Step 2

interface pos interface-path-id .subinterface

Example:


RP/0/RSP0/CPU0:router(config)# interface pos 0/3/0/1.1

Enters POS subinterface configuration mode for a Layer 2 Frame Relay subinterface.

Step 3

mtu value

Example:


RP/0/RSP0/CPU0:router(config-if)# mtu 5000

(Optional) Configures the MTU value. Range is from 64 through 65535.

Step 4

end or commit

Example:


RP/0/RSP0/CPU0:router(config-pos-l2transport-pvc)# end


RP/0/RSP0/CPU0:router(config-pos-l2transport-pvc)# commit

Saves configuration changes.

When you issue the end command, the system prompts you to commit changes:
```
Uncommitted changes found, commit them before exiting(yes/no/cancel)?
[cancel]:
```
- Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

- Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

- Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.
Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

Step 5

Repeat Step 1 through Step 4 to configure the PVC at the other end of the AC.

Brings up the AC.

Note

The configuration on both ends of the connection must match.

Configuration Examples for POS Interfaces

This section provides the following configuration examples:

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

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


RP/0/RSP0/CPU0:router# configure  
RP/0/RSP0/CPU0:router(config)# interface POS 0/3/0/0  
RP/0/RSP0/CPU0:router(config-if)# ipv4 address 172.18.189.38 255.255.255.224  
RP/0/RSP0/CPU0:router(config-if)# no shutdown  
RP/0/RSP0/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/RSP0/CPU0:router# configure  
RP/0/RSP0/CPU0:router(config)# interface POS 0/3/0/0  
RP/0/RSP0/CPU0:router(config-if)# keepalive 10  
RP/0/RSP0/CPU0:router(config-if)# commit

Configuring a POS Interface with Frame Relay Encapsulation: Example

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


RP/0/RSP0/CPU0:router# configure  
RP/0/RSP0/CPU0:router(config)# interface POS 0/3/0/0  
RP/0/RSP0/CPU0:router(config-if)# encapsulation frame-relay  
RP/0/RSP0/CPU0:router(config-if)# no shutdown  
RP/0/RSP0/CPU0:router(config-if)# end  
Uncommitted changes found, commit them? [yes]: yes  

RP/0/RSP0/CPU0:router# configure


RP/0/RSP0/CPU0:router (config)# interface pos 0/3/0/0.1 point-to-point


RP/0/RSP0/CPU0:router (config-subif)#ipv4 address 10.20.3.1/24


RP/0/RSP0/CPU0:router (config-subif)# pvc 100


RP/0/RSP0/CPU0:router(config-if)# end  
Uncommitted changes found, commit them? [yes]: yes  
RP/0/RSP0/CPU0:router# show interface POS 0/3/0/0

Wed Oct  8 04:20:30.248 PST DST
POS0/3/0/0 is up, line protocol is up
  Interface state transitions: 1
  Hardware is Packet over SONET/SDH
  Internet address is 10.20.3.1/24
  MTU 4474 bytes, BW 155520 Kbit
     reliability 255/255, txload 0/255, rxload 0/255
  Encapsulation FRAME-RELAY, crc 32, controller loopback not set,
  LMI enq sent  116, LMI stat recvd 76, 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 00:00:06
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     1 packets input, 13 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
     1 packets output, 13 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 POS interface with Frame Relay encapsulation and a point-to-point POS subinterface with a PVC on router 2, which is connected to router 1:


RP/0/RSP0/CPU0:router# configure  
RP/0/RSP0/CPU0:router(config)# interface POS 0/3/0/1  
RP/0/RSP0/CPU0:router(config-if)# encapsulation frame-relay  
RP/0/RSP0/CPU0:router(config-if)# frame-relay intf-type dce
RP/0/RSP0/CPU0:router(config-if)# no shutdown  
RP/0/RSP0/CPU0:router(config-if)# end  
Uncommitted changes found, commit them? [yes]: yes  

RP/0/RSP0/CPU0:router# configure


RP/0/RSP0/CPU0:router (config)# interface pos 0/3/0/1.1 point-to-point


RP/0/RSP0/CPU0:router (config-subif)#ipv4 address 10.20.3.2/24


RP/0/RSP0/CPU0:router (config-subif)# pvc 100


RP/0/RSP0/CPU0:router(config-if)# end  
Uncommitted changes found, commit them? [yes]: yes  
RP/0/RSP0/CPU0:router# show interface POS 0/3/0/1

Wed Oct  8 04:20:38.037 PST DST
POS0/3/0/1 is up, line protocol is up
  Interface state transitions: 1
  Hardware is Packet over SONET/SDH
  Internet address is 10.20.3.2/24
  MTU 4474 bytes, BW 155520 Kbit
     reliability 255/255, txload 0/255, rxload 0/255
  Encapsulation FRAME-RELAY, crc 32, controller loopback not set,
  LMI enq sent  0, LMI stat recvd 0, LMI upd recvd 0
  LMI enq recvd 77, LMI stat sent  77, LMI upd sent  0 , DCE LMI up
  LMI DLCI 1023  LMI type is CISCO  frame relay DCE
  Last clearing of "show interface" counters 00:00:14
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     2 packets input, 26 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
     2 packets output, 26 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 create a Layer 2 POS subinterface with a PVC on the main POS interface:


RP/0/RSP0/CPU0:router# configure


RP/0/RSP0/CPU0:router (config)# interface pos 0/3/0/0.1 l2transport


RP/0/RSP0/CPU0:router (config-subif)# pvc 100


RP/0/RSP0/CPU0:router(config-subif)# commit

Configuring a POS Interface with PPP Encapsulation: Example

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


RP/0/RSP0/CPU0:router# configure  
RP/0/RSP0/CPU0:router(config)# interface POS 0/3/0/0  
RP/0/RSP0/CPU0:router(config-if)# ipv4 address 172.18.189.38 255.255.255.224  
RP/0/RSP0/CPU0:router(config-if)# encapsulation ppp  
RP/0/RSP0/CPU0:router(config-if)# no shutdown  
RP/0/RSP0/CPU0:router(config-if)# end  
Uncommitted changes found, commit them? [yes]: yes  

RP/0/RSP0/CPU0:router# show interfaces POS 0/3/0/0  

POS0/3/0/0 is down, line protocol is down
  Hardware is Packet over SONET
  Internet address is 172.18.189.38/27
  MTU 4474 bytes, BW 2488320 Kbit
     reliability 0/255, txload Unknown, rxload Unknown
  Encapsulation PPP, crc 32, controller loopback not set, keepalive set (
10 sec)
  LCP Closed
  Closed: IPCP
  Last clearing of "show interface" counters never
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 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
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     0 packets output, 0 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

Cisco ASR 9000 Series Aggregation Services Router Interface and Hardware Component Configuration Guide, Release 5.3.x

Bias-Free Language

Results

Chapter: Configuring POS Interfaces

Configuring POS Interfaces

Feature History for Configuring POS Interfaces

Prerequisites for Configuring POS Interfaces

Information About Configuring POS Interfaces

Default Settings for POS Interfaces

Cisco HDLC Encapsulation

PPP Encapsulation

Keepalive Timer

Frame Relay Encapsulation

LMI on Frame Relay Interfaces

How to Configure a POS Interface

Bringing Up a POS Interface

Before you begin

SUMMARY STEPS

DETAILED STEPS

Example:

Example:

Example:

Example:

Example:

Example:

Example:

Example:

Example:

Example:

Example:

What to do next

Configuring Optional POS Interface Parameters

Before you begin

SUMMARY STEPS

DETAILED STEPS

Example:

Example:

Example:

Example:

Example:

Example:

Example:

Example:

Example:

What to do next

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

Before you begin

SUMMARY STEPS

DETAILED STEPS

Example:

Example:

Example:

Example:

Example:

Example:

What to do next

Configuring Optional PVC Parameters

Before you begin

SUMMARY STEPS

DETAILED STEPS

Example:

Example:

Example:

Example:

Example:

Example:

Example:

Example:

Example:

What to do next

Modifying the Keepalive Interval on POS Interfaces

Before you begin

SUMMARY STEPS

DETAILED STEPS

Example:

Example:

Example:

Example:

Example:

How to Configure a Layer 2 Attachment Circuit