Configuring Packet over SONET SPAs

Configuring POS SPAs on Cisco IOS XR Software

This chapter provides information about configuring POS SPAs on the Cisco XR 12000 Series Router running Cisco IOS XR software. It includes the following sections:

• Configuration Tasks

• Verifying the Interface Configuration

• Configuration Examples

For information about managing your system images and configuration files, refer to the Cisco IOS XR Getting Started Guide and the Cisco IOS XR Commands Master List publications.

For more information about the commands used in this chapter, see first Chapter 10, "Command Reference," which documents new and modified commands and the Cisco IOS XR Interface and Hardware Component Command Reference. For more information about accessing these publications, see the "Related Documentation" section in the "Preface".

Configuration Tasks

On Cisco IOS XR software, all physical POS ports are configured using a SONET controller. Therefore, the first step in a POS interface configuration is to configure the SONET controller.

All SONET-related configurations of a SONET-based physical port are grouped under the command-line interface (CLI) SONET controller configuration command mode prompt (config-sonet). All SONET path-related configuration commands are grouped under the CLI SONET path command mode (config-sonet-path).

When the SONET controller configuration is complete, the POS interfaces can be configured in interface configuration mode.

The following tasks are available for configuring POS interfaces:

• Specifying the Interface Address

• Configuring a SONET Controller (Required)

• Configuring SONET APS (Optional)

• Configuring Fast Reroute and SONET APS (Optional)

• Configuring a POS Interface (Required)

• Configuring Cisco HDLC on a POS Interface (Optional)

• Configuring PPP on a POS Interface (Optional)

Specifying the Interface Address

SPAs on Cisco XR 12000 Series Routers running Cisco IOS XR software use an addressing format that specifies the physical location of the SPA interface processor (SIP), SPA, and interface. The interface address format is rack/slot/subslot/port:

•rack—Specifies the rack number, 0 for the Cisco XR 12000 Series Router.

•slot—Specifies the slot number in the Cisco XR 12000 Series Router in which the MSC that contains the SPA is installed.

•subslot—Specifies the secondary slot on the MSC where the SPA that you want to select is installed.

•port—Specifies the interface number that you want to select on the SPA:

–For the 1-Port OC-192c/STM-64 POS/RPR XFP SPA—0 is the only option.

Figure 6-1 shows the slot, subslot, and interface port locations of the 1-Port OC-192c/STM-64 POS/RPR XFP SPA.

Figure 6-1 Slot, Subslot, and Port Locations for the 1-Port OC-192c/STM-64 POS/RPR XFP SPA


1	Router slot number 1	2	SPA subslot 0 with port 0/1/0/0

For more information about the installation of cards on the Cisco XR 12000 Series Router, refer to the Cisco 12000 Series Router SIP and SPA Hardware Installation Guide.

Configuring a SONET Controller

This task explains how to configure SONET controllers, as a prerequisite to configuring POS interfaces.

Summary Steps

1. configure

2. controller sonet number

3. clock source {internal | line}

4. delay trigger line value

5. framing {sdh | sonet}

6. loopback {internal | line}

7. overhead {j0 | s1s0e} byte-value

8. ais-shut

9. threshold {b1-tca | b2-tca | sd-ber | sf-ber} bit-error-rate

10. path keyword values

11. end
or
commit

12. show controllers sonet number

Detailed Steps


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	controller sonet number Example: RP/0/0/CPU0:router(config)# controller sonet 0/4/1/0	Enters SONET controller configuration submode, where: •number—Specifies the SONET controller number, which is the same as the associated POS interface, in the notation rack/slot/module/port.
Step 3	clock source {internal \| line} Example: RP/0/0/CPU0:router(config-sonet)# clock source internal	(Optional) Configures the SONET port TX clock source, where: •internal—Sets the internal clock. Use this option when two routers are connected back-to-back or over fiber for which no clocking is available. •line—Sets the clock to be recovered from the line (default). Use this option whenever clocking is derived from the network.
Step 4	delay trigger line value Example: RP/0/0/CPU0:router(config-sonet)# delay trigger line 0	(Optional) Configures the SONET port delay trigger line value, where the trigger value can be 0-511 milliseconds and the default is 0.
Step 5	framing {sdh \| sonet} Example: RP/0/0/CPU0:router(config-sonet)# framing sonet	(Optional) Configures the controller framing, where: •sdh—Specifies Synchronous Digital Hierarchy (SDH) framing. •sonet—Specifies SONET framing (default).
Step 6	loopback {internal \| line} Example: RP/0/0/CPU0:router(config-sonet)# loopback internal	(Optional) Configures the SONET controller for loopback where •internal—Selects internal (terminal) loopback. •line—Selects line (facility) loopback.
Step 7	overhead {j0 \| s1s0} byte-value Example: RP/0/0/CPU0:router(config-sonet)# overhead s1s0	(Optional) Configures the controller's overhead where •j0—Specifies the synchronous transfer signal (STS) identifier (J0/C1) byte (default is 0xcc). •s1s0—Specifies bits s1 and s0 of H1 byte (default is 0).
Step 8	ais-shut Example: RP/0/0/CPU0:router(config-sonet)# ais-shut	(Optional) Configures the automatic insertion of a line alarm indication signal (LAIS) in the sent SONET signal whenever the SONET port enters the administrative shutdown state.
Step 9	threshold {b1-tca \| b2-tca \| sd-ber \| sf-ber} bit-error-rate Example: RP/0/0/CPU0:router(config-sonet)# threshold b1-tca 4	(Optional) Configures the bit-error rate (BER) threshold values of the specified alarms for a SONET controller.
Step 10	path keyword [values] Example: RP/0/0/CPU0:router(config-sonet)# path delay trigger 25	(Optional) Configures SONET controller path values. Keyword definitions are as follows: •ais-shut—Sets sending path alarm indication signal (PAIS) when shut down. •delay trigger—Sets SONET path delay trigger value, which can be 0-511 milliseconds (default 0). •overhead—Sets SONET POH byte or bit values where c2 specifies STS synchronous payload envelope (SPE) content (C2) byte, and j1 configures the SONET path trace (J1) buffer. •report—Sets SONET path alarm reporting. Specifies which alarms are reported and which bit error rate (BER) thresholds will signal an alarm. The following keywords can be used: –b3-tca sets B3 BER threshold crossing alert (TCA) reporting status –pais sets PAIS reporting status –plop sets path loss of pointer reporting status –prdi sets path remote defect indication reporting status –puneq sets path unequipped defect indication reporting status •scrambling—Disables SPE scrambling with keyword disable. •threshold—Sets SONET path BER threshold value to 3-9; bit error rate (10 to the minus x) (where the default is 6). •uneq-shut—Sets sending unequipped (UNEQ) when shut down.
Step 11	end or commit Example: RP/0/0/CPU0:router(config-sonet)# end or RP/0/0/CPU0:router(config-sonet)# 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 12	show controllers sonet number Example: RP/0/0/CPU0:router# show controllers sonet 0/1/0/0	Verifies the SONET controller configuration.

Configuring SONET APS

This task explains how to configure basic automatic protection switching (APS) on the router and how to configure more than one protect or working interface on a router by using the aps group command.

The SONET APS is a feature offering recovery from fiber (external) or equipment (interface and internal) failures at the SONET line layer.

Note The loopback interface in the example is used as the interconnect. The aps group command is used even when a single protect group is configured.

To verify the configuration or to determine if a switchover has occurred, use the show aps command.

Summary Steps

1. configure

2. aps group number

3. channel {0 | 1} local {sonet | preconfigure} number

4. Repeat Step 3 for each channel in the group.

5. exit

6. interface loopback number

7. ipv4 address ip-address mask

8. exit

9. interface type number

10. ipv4 address ip-address mask

11. pos crc {16 | 32}

12. keepalive [seconds | disable]

13. no shutdown

14. exit

15. Repeat Step 9 through Step 14 for each channel in the group.

16. controller {sonet | preconfigure} number

17. ais-shut

18. no path scrambling disable

19. clock source {internal | line}

20. Repeat Step 16 through Step 19 for each channel of the group.

21. end
or
commit

22. show aps

23. show aps group [number]

Detailed Steps


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	aps group number Example: RP/0/0/CPU0:router(config)# aps group 1	Adds an APS group with a specified number and enters APS group configuration mode. •Use the aps group command in global configuration mode. •To remove a group, use the no form of this command, as in: no aps group number, where the value range is from 1-255. Note To use the aps group command, you must be a member of a user group associated with the proper task IDs for APS commands.
Step 3	channel {0 \| 1} local {sonet \| preconfigure} number Example: RP/0/0/CPU0:router(config-aps)# channel 0 local SONET 0/0/0/1	Creates a channel for the APS group, where: •0 designates a protect channel •1 designates a working channel Note If the protect channel is local, it must be assigned using a channel command before any of the working channels are assigned.
Step 4	Repeat Step 3 for each channel in the group.	—
Step 5	exit Example: RP/0/0/CPU0:router(config-aps)# exit	Exits APS group configuration mode.
Step 6	interface loopback number Example: RP/0/0/CPU0:router(config)# interface loopback 1	(Optional) Configures a loopback interface if a two-router APS is desired and enters interface configuration mode.
Step 7	ipv4 address ip-address mask Example: RP/0/0/CPU0:router(config-if)# ipv4 address 172.18.0.1 255.255.255.224	Assigns an IPv4 address and subnet mask to the interface.
Step 8	exit Example: RP/0/0/CPU0:router(config-aps)# exit	Exits loopback interface configuration mode.
Step 9	`interface pos number` Example: RP/0/0/CPU0:router(config-if)# interface pos 0/2/0/0	Connects the interface for the each channel selected in Step 3, where: •number—Specifies the POS interface, in the notation rack/slot/module/port. The example indicates POS interface 0, on a SPA in subslot 0, in line card slot 2.
Step 10	ipv4 address ip-address mask Example: RP/0/0/CPU0:router(config-if)# ipv4 address 172.18.0.1 255.255.255.224	Assigns an IPv4 address and subnet mask to the interface.
Step 11	pos crc (16 \| 32) Example: RP/0/0/CPU0:router(config-if)# pos crc 32	Selects a CRC value for the channel. The default CRC value is 32.
Step 12	keepalive [seconds \| disable] Example: RP/0/0/CPU0:router(config-if)# keepalive disable	Sets the keepalive timer for the channel.
Step 13	no shutdown Example: RP/0/0/CPU0:router(config-if)# no shutdown	Removes the shutdown configuration. The removal of the shutdown configuration removes 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 14	exit Example: RP/0/0/CPU0:router(config-if)# exit	Exits interface configuration mode.
Step 15	Repeat Step 9 through Step 14 for each channel in the group.	—
Step 16	controller sonet number Example: RP/0/0/CPU0:router(config)# controller sonet 0/1/0/0	Enters SONET controller configuration submode, where: number—Specifies the SONET controller number, which is the same as the associated POS interface, in the notation rack/slot/module/port.
Step 17	ais-shut Example: RP/0/0/CPU0:router(config-sonet)# ais-shut	Configures line alarm indication signal (LAIS) at shutdown.
Step 18	no path scrambling disable Example: RP/0/0/CPU0:router(config-sonet)# no path scrambling disable	(Optional) Enables synchronous payload envelope (SPE) scrambling. Scrambling is enabled by default; you only need to enable it if you have previously disabled it.
Step 19	clock source {internal \| line} Example: RP/0/0/CPU0:router(config-sonet)# clock source internal	(Optional) Configures the SONET port TX clock source, where: •internal—Sets the internal clock. Use this option when two routers are connected back-to-back or over fiber for which no clocking is available. •line—Sets the clock to be recovered from the line (default). Use this option whenever clocking is derived from the network.
Step 20	Repeat Step 16 to Step 19 for each channel in the group.	—
Step 21	end or commit Example: RP/0/0/CPU0:router(config-sonet)# end or RP/0/0/CPU0:router(config-sonet)# 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 22	show aps Example: RP/0/0/CPU0:router# show aps	(Optional) Displays operational status for all configured SONET APS groups.
Step 23	show aps group [number] Example: RP/0/0/CPU0:router# show aps group 3	(Optional) Displays operational status for configured SONET APS groups. •The show aps group command is more useful than the show aps command when there are multiple groups defined.

Configuring Fast Reroute and SONET APS

When APS is configured on a router, it does not offer protection for tunnels; because of this limitation, fast reroute (FRR) still remains the protection mechanism for Multiprotocol Label Switching (MPLS) traffic-engineering.

When APS is configured in a SONET core network, an alarm might be generated toward a router downstream. If this router is configured with FRR, you may want to configure a hold-off timer at the SONET level in order to prevent FRR from being triggered while the core network is doing a restoration. Perform this task to configure the delay.

Summary Steps

1. configure

2. controller sonet number

3. delay trigger line value
or
path delay trigger value

4. end
or
commit

Detailed Steps


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	controller sonet number Example: RP/0/0/CPU0:router(config)# controller sonet 0/6/0/0	Enters SONET controller configuration submode, where: •number—Specifies the SONET controller number, which is the same as the associated POS interface, in the notation rack/slot/module/port.
Step 3	delay trigger line value or path delay trigger value Example: RP/0/0/CPU0:router(config-sonet)# delay trigger line 250 or RP/0/0/CPU0:router(config-sonet)# path delay trigger 300	Configures SONET port delay trigger values in milliseconds. Tip The commands in Step 1 and Step 2 can be combined in one command string and entered from global configuration mode like this: controller sonet rack/slot/subslot/port delay trigger line or controller sonet rack/slot/subslot/port path delay trigger.
Step 4	end or commit Example: RP/0/0/CPU0:router(config-sonet)# end or RP/0/0/CPU0:router(config-sonet)# 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.

Configuring a POS Interface

This task explains how to create a basic POS configuration. There are many other possible parameters that can be set. Only the most basic are illustrated. Not all configuration steps are required.

Default Settings for POS Interface Configurations

When an interface is enabled on a POS SPA and its associated SIP with no additional configuration commands applied, the default interface settings shown in Table 6-1 are present. These default settings can be changed by configuration. Default settings do not appear in the output of the show running-config command.

Table 6-1 POS SPA and SIP Default Interface Settings
Parameter	Configuration File Entry	Default Settings
Keepalive	keepalive [disable] no keepalive [disable]	keepalive 10 seconds
Encapsulation	encapsulation [hdlc \| ppp]	hdlc
Maximum Transmission Unit (MTU)	mtu bytes	4474 bytes
Cyclic Redundancy Check (CRC)	crc [16 \| 32]	32

Keepalive Timer

The high-level data-link control (HDLC) usage of the keepalive timer also applies to PPP encapsulation to control how often echo request (ECHOREQ) packets are sent out.

Use the keepalive command in interface configuration mode to set how frequently Link Control Protocol (LCP) should send out 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 no keepalive or keepalive disable commands. For both PPP and HDLC, a keepalive of 0 disables keepalives and is reported in the show running-config command as keepalive disable.

When LCP is running on the peer and receives an ECHOREQ packet, it should respond 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 will still respond with ECHOREP packets to the ECHOREQ packets it receives. Similarly, it will also work if the period of keepalives at each end is different.

When the interface has PPP encapsulation, if LCP sends three ECHOREQ packets without an ECHOREP being received then it declares the link down and initiates full LCP negotiation again. If the interface has HDLC encapsulation, the number of resends is only three before the link is taken down. Only when LCP negotiation is complete (for example, when LCP is open) are ECHOREQ packets sent out.

Summary Steps

1. show interfaces

2. configure

3. interface type number

4. ipv4 address ip-address

5. encapsulation [hdlc | ppp]

6. pos crc {16 | 32}

7. keepalive [seconds | disable]

8. mtu value

9. no shutdown

10. end
or
commit

11. show interfaces type number

12. show running-config

Detailed Steps


	Command or Action	Purpose
Step 1	show interfaces Example: RP/0/0/CPU0:router# show interfaces	(Optional) Displays configured interfaces.
Step 2	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 3	interface type number Example: RP/0/0/CPU0:router(config)# interface POS 0/4/1/0	Enters interface configuration mode, where: •type—Specifies pos for the 1-Port OC-192c/STM-64 POS/RPR XFP SPA. •number—Specifies the POS interface in the notation rack/slot/module/port. The example indicates POS interface 0, on a SPA in subslot 1, in line card slot 4.
Step 4	ipv4 address ip-address Example: RP/0/0/CPU0:router(config-if)# ipv4 address 172.18.189.38 255.255.255.224	Assigns an IP address and subnet mask to the interface.
Step 5	encapsulation [hdlc \| ppp] Example: RP/0/0/CPU0:router(config-if)# encapsulation hdlc	(Optional) Configures the interface encapsulation parameters and details such as HDLC or PPP.
Step 6	pos crc {16 \| 32} Example: RP/0/0/CPU0:router(config-if)# pos crc 32	(Optional) Configures the value of cyclic redundancy check (crc). The default CRC value is 32.
Step 7	keepalive [seconds \| disable] Example: RP/0/0/CPU0:router(config-if)# keepalive 10	(Optional) Configures the value of keepalive.
Step 8	mtu value Example: RP/0/0/CPU0:router(config-if)# mtu 4474	(Optional) Configures the value of MTU. •Default is 4474; range is 64-65535 on the Cisco XR 12000 Series Router.
Step 9	no shutdown Example: RP/0/0/CPU0:router(config-if)# no shutdown	Removes the shutdown configuration. •The removal of the shutdown configuration removes 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 10	end or commit Example: RP/0/0/CPU0:router(config-if)# end or RP/0/0/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 11	show interfaces type number Example: RP/0/0/CPU0:router# show interfaces pos 0/1/0/0	(Optional) Displays the interface configuration.
Step 12	show running-config Example: RP/0/0/CPU0:router# show running-config	(Optional) Displays the configuration information currently running on the router.

Configuring Cisco HDLC on a POS Interface

Cisco High-Level Data Link Controller (HDLC) is Cisco's 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 for POS interfaces under Cisco IOS XR software.

Perform this task to configure the Cisco HDLC encapsulation type on a POS interface.

Prerequisites

To use the keepalive command, you must be in a user group associated with a task group that includes the proper task IDs for HDLC commands. To use the encapsulation hdlc command, you must be in a user group associated with a task group that includes the proper task IDs for interface and HDLC commands.

Task IDs for commands are listed in the Cisco IOS XR Task ID Reference Guide.

Note Cisco HDLC is enabled by default for POS configurations on the Cisco XR 12000 Series Router.

Cisco HDLC keepalives are useful for monitoring the link state. Periodic keepalives are sent to and received from the peer at a frequency determined by the keepalive value. 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 keepalive is 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.

The Serial Line Address Resolution Protocol (SLARP) packets sent to the peer after keepalive has been configured can be displayed using the debug chdlc slarp packet and other Cisco HDLC debug commands.

Summary Steps

1. configure

2. interface type number

3. ipv4 address ip-address

4. encapsulation [hdlc | ppp]

5. keepalive [seconds | disable]
or
no keepalive

6. no shutdown

7. end
or
commit

8. show interfaces pos number

9. show running-config

Detailed Steps


	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enters global configuration mode.
Step 2	interface type number Example: RP/0/0/CPU0:router(config)# interface pos 0/4/1/0	Enters interface configuration mode, where: •type—Specifies pos for POS SPAs. •number—Specifies the POS interface in the notation rack/slot/module/port. The example indicates POS interface 0, on a SPA in subslot 1, in line card slot 4.
Step 3	ipv4 address ip-address Example: RP/0/0/CPU0:router(config-if)# ipv4 address 172.18.189.38 255.255.255.224	Assigns an IP address and subnet mask to the interface.
Step 4	encapsulation [hdlc \| ppp] Example: RP/0/0/CPU0:router(config-if)# encapsulation hdlc	Configures the interface encapsulation parameter for HDLC or PPP.
Step 5	keepalive [seconds \| disable] or no keepalive Example: `RP/0/0/CPU0:router(config-if)# keepalive 3` or `RP/0/0/CPU0:router(config-if)# no keepalive`	Specifies the number of seconds between keepalive messages. •Use the keepalive disable command, the no keepalive command, or the keepalive command with an argument of 0 to disable the keepalive feature.
Step 6	no shutdown Example: RP/0/0/CPU0:router(config-if)# no shutdown	Removes the shutdown configuration. •The removal of the shutdown configuration removes 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 7	end or commit Example: RP/0/0/CPU0:router(config-if)# end or RP/0/0/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 8	show interfaces pos number Example: RP/0/0/CPU0:router# show interfaces POS 0/4/1/0	(Optional) Displays the interface configuration for the POS interface, where: •number—Specifies the POS interface in the notation rack/slot/module/port. The example indicates POS interface 0, on a SPA in subslot 1, in line card slot 4.
Step 9	show running-config Example: RP/0/0/CPU0:router# show running-config	(Optional) Displays the configuration information currently running on the router.

Configuring PPP on a POS Interface

Note The default encapsulation type for the POS SPA configurations is Cisco HDLC.

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.

PPP provides 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, and Open Systems Interconnection control processor (OSICP) to negotiate OSI properties.

Perform this task to configure PPP on POS interfaces.

Prerequisites

To use the encapsulation ppp command, you must be in a user group associated with a task group that includes the proper task IDs for interface and PPP commands. To use the ppp authentication command, you must be in a user group associated with a task group that includes the proper task IDs for AAA and PPP commands.

Task IDs for commands are listed in the Cisco IOS XR Task ID Reference Guide.

PPP Encapsulation

Use the encapsulation ppp command to enable PPP encapsulation on an interface.

To enable Challenge Handshake Authentication Protocol (CHAP) or Password Authentication Protocol (PAP) or both, and to specify the order in which CHAP, MS-CHAP, and PAP authentication is selected on the interface, use the ppp authentication command in interface configuration mode.

When you enable CHAP or PAP authentication (or both), the local router requires the remote device to prove its identity before allowing data traffic to flow. 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. 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.

You can enable CHAP, MS-CHAP, or PAP in any order. If you enable all three methods, the first method specified is requested during link negotiation. If the peer suggests using the second method, or refuses the first method, the second method is tried. Some remote devices support only one method. Base the order in which you specify methods on the remote device's ability to correctly negotiate the appropriate method, and on the level of data line security you require. PAP usernames and passwords are sent as clear text strings, which can be intercepted and reused.

Enabling or disabling PPP authentication does not affect the local router's ability to authenticate itself to the remote device.

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.

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

Caution

If you use a list-name value that was not configured with the aaa authentication ppp command, you will disable PPP on the interface. For details on implementing the aaa authentication command with the ppp keyword, see the Authentication, Authorization, and Accounting Commands on Cisco IOS XR Software module of the Cisco IOS XR System Security Command Reference and the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.

Summary Steps

1. configure

2. interface type number

3. encapsulation ppp

4. ppp authentication protocol list-name

5. end
or
commit

Detailed Steps


	Command or Action	Purpose
Step 1	configure Example: `RP/0/0/CPU0:router# configure`	Enters global configuration mode.
Step 2	interface type number Example: `RP/0/0/CPU0:router(config)# interface pos 0/4/1/0`	Enters interface configuration mode, where: •type—Specifies pos for POS SPAs. •number—Specifies the POS interface in the notation rack/slot/module/port. The example indicates POS interface 0, on a SPA in subslot 1, in line card slot 4.
Step 3	encapsulation ppp Example: `RP/0/0/CPU0:router(config-if)# encapsulation ppp`	Configures the interface encapsulation parameter for PPP.
Step 4	ppp authentication protocol list-name Example: `RP/0/0/CPU0:router(config-if)# ppp authentication chap MIS-access`	Enables CHAP, MS-CHAP, or PAP and specifies the order of selection on the interface. •The allowed values for protocol are: –chap—Enables CHAP on a serial interface –ms-chap—Enables Microsoft's CHAP on a serial interface –pap—Enables PAP on a serial interface
Step 5	end or commit Example: RP/0/0/CPU0:router(config-if)# end or RP/0/0/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.

Verifying the Interface Configuration

Besides using the show running-configuration command to display your Cisco XR 12000 Series Router configuration settings, you can use the show interfaces pos and the show controllers pos commands to get detailed information on a per-port basis for your SPA. The use of these commands is indicated at the end of each configuration task.

Configuration Examples

This section contains the following examples:

• SONET Controller Configuration Example

• SONET APS Group Configuration Example

• Configuring Basic POS Example

• Configuring PPP Example

SONET Controller Configuration Example

The following example shows the commands and output generated when you are performing the configuration of a SONET controller interface following the steps outlined in the "Configuring a SONET Controller" section. This example shows the usage of every optional command, along with listings of options within commands where relevant. An actual configuration may or may not include all of these commands.

RP/0/0/CPU0:router# configure

RP/0/0/CPU0:router(config)# controller sonet 0/1/0/0

RP/0/0/CPU0:router(config-sonet)# ais-shut

RP/0/0/CPU0:router(config-sonet)# clock source internal

RP/0/0/CPU0:router(config-sonet)# framing sonet

RP/0/0/CPU0:router(config-sonet)# loopback internal

RP/0/0/CPU0:router(config-sonet)# overhead s1s0 2

RP/0/0/CPU0:router(config-sonet)# path ais-shut

RP/0/0/CPU0:router(config-sonet)# path delay trigger 0

RP/0/0/CPU0:router(config-sonet)# path overhead j1 transmit-message

RP/0/0/CPU0:router(config-sonet)# path report b3-tca

RP/0/0/CPU0:router(config-sonet)# path threshold b3-tca 6

RP/0/0/CPU0:router(config-sonet)# path uneq-shut

RP/0/0/CPU0:router(config-sonet)# report lais

RP/0/0/CPU0:router(config-sonet)# threshold b2-tca 4

SONET APS Group Configuration Example

The following example shows how to configure a two-router SONET APS group:

RP/0/0/CPU0:router# configure

RP/0/0/CPU0:router(config)# aps group 1

RP/0/0/CPU0:router(config-aps)# channel 0 local sonet 0/0/0/1

RP/0/0/CPU0:router(config-aps)# channel 1 local sonet 0/0/0/2

RP/0/0/CPU0:router(config-aps)# interface loopback0

RP/0/0/CPU0:router(config-if)# ipv4 address 172.18.23.169 255.255.255.0

RP/0/0/CPU0:router(config-if)# interface pos 0/0/0/2

RP/0/0/CPU0:router(config-if)# ipv4 address 172.18.69.123 255.255.255.0

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

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

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

RP/0/0/CPU0:router(config-if)# interface pos 0/0/0/1

RP/0/0/CPU0:router(config-if)# ipv4 address 172.18.69.123 255.255.255.0

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

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

RP/0/0/CPU0:router(config-if)# controller sonet 0/0/0/2

RP/0/0/CPU0:router(config-sonet)# ais-shut

RP/0/0/CPU0:router(config-sonet)# path

RP/0/0/CPU0:router(config-sonet-path)# scrambling disable

RP/0/0/CPU0:router(config-sonet-path)# clock source internal

RP/0/0/CPU0:router(config-sonet)# controller sonet 0/0/0/1

RP/0/0/CPU0:router(config-sonet)# ais-shut

RP/0/0/CPU0:router(config-sonet)# path

RP/0/0/CPU0:router(config-sonet-path)# scrambling disable

RP/0/0/CPU0:router(config-sonet-path)# clock source internal

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

Uncommitted changes found. Commit them before exiting (yes/no/cancel)? [cancel]: yes

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

APS Group 1

  Protect ch 0 (SONET0_0_0_1): Disabled

    SONET framing, SONET signalling, bidirectional, non-revertive

    Rx K1: 0x00 (No Request - Null)

       K2: 0x05 (bridging Null, 1+1, bidirectional)

    Tx K1: 0x00 (No Request - Null)

       K2: 0x05 (bridging Null, 1+1, bidirectional)

  Working ch 1 (SONET0_0_0_2): Enabled

    Rx K1: 0x00 (No Request - Null)

       K2: 0x00 (bridging Null, 1+1, non-aps)

    Tx K1: 0x00 (No Request - Null)

       K2: 0x00 (bridging Null, 1+1, non-aps)

RP/0/0/CPU0:router# show aps group 1

APS Group 1

  Protect ch 0 (SONET0_0_0_1): Disabled

    SONET framing, SONET signalling, bidirectional, non-revertive

    Rx K1: 0x00 (No Request - Null)

       K2: 0x05 (bridging Null, 1+1, bidirectional)

    Tx K1: 0x00 (No Request - Null)

       K2: 0x05 (bridging Null, 1+1, bidirectional)

  Working ch 1 (SONET0_0_0_2): Enabled

    Rx K1: 0x00 (No Request - Null)

       K2: 0x00 (bridging Null, 1+1, non-aps)

    Tx K1: 0x00 (No Request - Null)

       K2: 0x00 (bridging Null, 1+1, non-aps)

Configuring Basic POS Example

The following example indicates how to configure a basic POS interface with Cisco HDLC:

RP/0/0/CPU0:router# configure

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

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 hdlc

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

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

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

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

Uncommitted changes found. Commit them before exiting (yes/no/cancel)? [cancel]: yes

RP/0/0/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 HDLC, crc 32, controller loopback not set, keepalive set

(10 sec)

  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

Configuring PPP Example

The following example illustrates PPP encapsulation on a POS interface:

RP/0/0/CPU0:router# configure

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

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

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 before exiting (yes/no/cancel)? [cancel]: yes

RP/0/0/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

Table Of Contents

Configuring POS SPAs on Cisco IOS XR Software

Configuration Tasks

Specifying the Interface Address

Configuring a SONET Controller

Summary Steps

Detailed Steps

Configuring SONET APS

Summary Steps

Detailed Steps

Configuring Fast Reroute and SONET APS

Summary Steps

Detailed Steps

Configuring a POS Interface

Default Settings for POS Interface Configurations

Keepalive Timer

Summary Steps

Detailed Steps

Configuring Cisco HDLC on a POS Interface

Prerequisites

Summary Steps

Detailed Steps

Configuring PPP on a POS Interface

Prerequisites

PPP Encapsulation

Summary Steps

Detailed Steps

Verifying the Interface Configuration

Configuration Examples

SONET Controller Configuration Example

SONET APS Group Configuration Example

Configuring Basic POS Example

Configuring PPP Example