Cisco ASR 903 Router Chassis Software Configuration Guide, IOS XE Release 3.10S
Configuring Optical Interface Modules
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Table of Contents

Configuring Optical Interface Modules

Limitations and Restrictions

Configuring the Controller

Configuring SDH

Configuring SDH Mode

Configuring SDH in POS Mode

Configuring SONET Mode

Configuring SONET Mode

Configuring SONET POS Mode

Configuring a CEM group

Configuring CEM Group in SONET Mode

Configuring CEM Group in SDH Mode

Configuring DS3 Clear Channel on OC-3 and OC-12 Interface Module

Configuring DS3 Clear Channel in SONET Mode

Configuring DS3 Clear Channel in SDH Mode

Optional Configurations

Configuring the Encapsulation Method

Configuring the CRC Size for T1

Optional Packet over SONET Configurations

Encapsulation

MTU Value

CRC Value

Keepalive Value

Bandwidth

Scrambling

C2 Flag

J1 Flag

Managing Interface Naming

Identifying Slots and Subslot

Configuring Multilink Point-to-Point Protocol

MLPPP Configuration Guidelines

Creating a Multilink Bundle

Assigning an Interface to a Multilink Bundle

Configuring Fragmentation Size and Delay on an MLPPP Bundle

Changing the Default Endpoint Discriminator

Disabling Fragmentation on an MLPPP Bundle

Configuring BERT

Configuring Automatic Protection Switching

Verifying Interface Configuration

Verifying Per-Port Interface Status

Troubleshooting

Configuration Examples

Example of Cyclic Redundancy Check Configuration

Example of Facility Data Link Configuration

Example of Invert Data on T1/E1 Interface

Additional Resources

Limitations and Restrictions

The following limitations and restrictions apply when configuring optical interface modules on the Cisco ASR 900 Series Router:

  • SDH framing mode is supported; SONET framing is supported beginning in Release 3.8.
  • HDLC, PPP, and MLPPP encapsulation are supported. In POS mode, HDLC and PPP are supported.
  • Frame Relay and SMDS encapsulation are not supported.
  • ATM Layer 2 AAL0 and AAL5 encapsulation types are supported.
  • E1 unframed encapsulation is not supported except using SAToP pseudowire interfaces.
  • MPLS-TP is not supported over Packet Over Sonet (POS) interfaces.
  • Multicast is not supported on OC-12 interfaces.
  • QoS is supported using MLPPP interfaces and egress POS interfaces.
  • MPLS is supported only on PoS interfaces; MPLS on T1/E1 links is not supported.
  • Channelization is not supported for serial interfaces. However, Channelization is supported for CEM at the DS0 level.
  • DS3 clear channel is supported only on CEM.

Configuring the Controller

Use the following command to configure the controller for SONET or SDH framing:


NoteWhen the mode is changed, the interface module reloads. When the mode is changed, the interface module reloads.


 

Command
Purpose

Router(config)# controller sonet slot / subslot / port

Selects the controller to configure and enters controller configuration mode, where:

  • slot / subslot / port —Specifies the location of the interface.

Note The slot number is always zero on the Cisco ASR 900 Series Router.

Configuring SDH

The following sections describe how to configure SDH on the optical interface module:

Configuring SDH Mode

To configure SDH mode, complete the following steps:

 

 
Command
Purpose

Step 1

Router(config-controller)# framing s dh

Specifies SDH as the frame type.

Step 2

Router(config-controller)# aug mapping { au-3 | au-4 }

Configures AUG mapping for SDH framing.

If the AUG mapping is configured to be AU-4, then the following muxing, alignment, and mapping will be used:

TUG-3 <--> VC-4 <--> AU-4 <--> AUG

If the mapping is configured to be AU-3, then the following muxing, alignment, and mapping will be used:

VC-3 <--> AU-3 <--> AUG

The default setting is au-3.

Step 3

Router(config-controller)# clock source {internal | line}

Sets the clock source, where:

  • internal—Specifies that the internal clock source is used.
  • line—Specifies that the network clock source is used. This is the default for T1 and E1.

Step 4

Router(config-controller)# au-4 au-4# tug-3 tug-3#

or

Router(config-controller)# au-3 au-3#

Configures AU-3, AU-4, and tributary unit groups, type 3 (TUG-3) for AU-4 and enters specific configuration mode.

Depending on the framing mode of SONET or SDH, each STS-1, AU-3, TUG-3, and AU-4 can be configured with one of these commands.

Depending on currently configured AUG mapping setting, this command further specifies TUG-3, AU-3, AU-4 or STS-1 muxing. The CLI command parser enters into config-ctrlr-tug3 (SDH mode), config-ctrlr-au3 (SDH mode), or config-ctrlr-sts1 parser mode (SONET mode), which makes only relevant commands visible.

  • au-4# —Range is from 1 to 4 for OC-12 mode and 1 for OC-3 mode
  • tug-3# —Range is from 1 to 3.
  • au-3# —Range is from 1 to 12 for OC-12 mode. For OC-3 mode, the value is 1–3.

Step 5

In SDH framing in AU-4 mode:

Router(config-ctrlr-tug3)# mode { c-11 | c-12 | t3 | e3 }

In SDH framing AU-3 mode:

Router(config-ctrlr-au3)# mode { c-11 | c-12 | t3 | e3 }

Configures mode of operation for AU-3 or AU-4 mode, where:

C-11 and C-12 are container level-n (SDH) channelized T3s. They are types of T3 channels that are subdivided into 28 T1 channels.

  • c-11 —Specifies an AU-3/AU-4 TUG-3 divided into seven TUG-2s. Each TUG-2 is then divided into four TU11s, each carrying a C-11 T1.
  • c-12 —Specifies an AU-3/AU-4 TUG-3 divided into seven TUG-2. Each TUG-2 is then divided into three TU12s, each carrying a C-12 E1.
  • t3 —Specifies an AU-3/AU-4 TUG-3 carrying an unchannelized (clear channel) T3.
  • e3 —Specifies an AU-3/AU-4 TUG-3 carrying an unchannelized (clear channel) E3.

Note Only c-11 and c-12 are currently supported.

Step 6

SAToP CEM Group

Router(config-ctrlr-tug3)# tug-2 1 e1 1 cem-group 1 unframed
 

CESoPSN CEM Group

Router(config-ctrlr-tug3)# tug-2 1 e1 1 cem-group 1 timeslots 1-31
 

Clear-Channel ATM

Router(config-ctrlr-tug3)# tug-2 1 e1 1 atm
 

IMA Group

Router(config-ctrlr-tug3)# tug-2 1 e1 1 ima-group 1
 

Channel Group

Router(config-ctrlr-tug3)# tug-2 1 e1 1 [[ channel-group channel-group-number] [ timeslots list-of-timeslots]]
 

Creates a CEM group, IMA group, or channel-group for the AU-3 or AU-4. Valid values are:

  • e1— 1–3
  • t1 —Range is from 1 to 12 for OC-12 mode. For OC-3 mode, the value is 1–3.
  • tug-2 —1–7
  • unframed —Specifies that a single CEM channel is being created including all time slots and the framing structure of the line.

Example

Router# configure terminal
Router(config)# controller sonet 0/1/0
Router(config-controller)# framing sdh
Router(config-controller)# aug mapping au-4
Router(config-controller)# clock source internal
Router(config-controller)# au-4 1 tug-3 2
Router(config-ctrlr-tug3)# mode e3
Router(config-ctrlr-tug3)# tug-2 1 e1 1 cem-group 1 unframed
 

For information about configuring optional features, see Optional Configurations.

Configuring SDH in POS Mode

Follow these steps to configure SDH in POS mode on the optical interface module.

SUMMARY STEPS

1. controller sonet slot/subslot/interface-id

2. framing sdh

3. aug mapping au-4

4. au-4 au4-number pos

5. end

DETAILED STEPS

 
Command
Purpose

Step 1

Router(config)# controller sonet 0/1/0

Selects the controller to be configured.

Step 2

framing {sonet | sdh}

 

Router(config)# framing sdh

Specifies SDH as the framing mode.

Note The interface module reloads if the framing is changed.

Step 3

aug mapping { au-3 | au-4 }

 

Router(config-controller)# aug mapping au-4

Specifies AUG mapping.

Note POS mode is only supported with AU-4 mode.

Step 4

au-4 au-4-number pos

 

Router(config-controller)# au-4 1 pos

Selects the AU-4 to be configured in POS mode with SDH framing. The command creates a POS interface, such as POS0/0/1:1. In OC-3 mode, the value is 1; in OC-12 mode, valid values are 1-4.

Step 5

end

 

Router(config-controller)# end

Exits configuration mode.

Example

Router# configure terminal
Router(config)# controller sonet 0/1/0
Router(config-controller)# framing sdh
Router(config-controller)# aug mapping au-4
Router(config-controller)# au-4 1 pos
Router(config-controller)# end
 

For information about configuring optional features, see Optional Packet over SONET Configurations

Configuring SONET Mode

The following sections describe how to configure SONET mode on the optical interface module:

Configuring SONET Mode

To configure an interface module to use SONET mode:

SUMMARY STEPS

1. framing sonet

2. clock source { line | internal }

3. sts-1 starting-number - ending-number

4. mode

5. vtg vtg_number t1 t1_line_number cem-group channel-number timeslots list-of-timesolts

6. end

DETAILED STEPS

 
Command or Action
Purpose

Step 1

controller sonet slot / subslot / port

 

Router(config)# controller sonet 0/1/0

Selects the controller to be configured.

Step 1

framing {sonet | sdh}

 

Router(config-controller)# framing sonet

Specifies SONET as the framing mode.

Step 2

clock source { line | internal }

 

Router(config-if)# clock source line

Specifies the clock source for the POS link, where:

  • line —The link uses the recovered clock from the line. This is the default setting.
  • internal —The link uses the internal clock source.

Step 3

sts-1 {1 - 12 | 1 - 3 | 4 - 6 | 7 - 9 | 10 - 12}

 

Router(config-controller)# sts-1 1 - 3

Specifies the SONET Synchronous Transport Signal (STS) level and enters STS-1 configuration mode. The starting-number and ending-number arguments indicate the starting and ending STS value of the interface.

For OC-3 interfaces, this value is 1.

Note The 1-12 value is supported only in OC-12 mode.

Step 4

mode {t3 | vt-15}

 

Router(config-ctrlr-sts1)# mode t3

Specifies the mode of operation of an STS-1 path, where:

Note VT-15 is the only supported mode.

  • t3—STS-1 carries an unchannelized (clear channel) T3.
  • vt-15—A STS-1 is divided into seven Virtual Tributary Groups (VTG). Each VTG is then divided into four VT1.5's, each carrying a T1.

Step 5

vtg vtg_number t1 t1_line_number cem-group channel-number timeslots list-of-timesolts

 

Router(config-ctrlr-sts1)# vtg 1 t1 1 cem-group 1 timeslots 1-10

Configures the T1 on the VTG, where:

  • vtg# —Specifies the VTG number. For SONET framing, values are 1 to 7.

Step 6

end

 

Router(config-if)# end

Exits configuration mode.

Example

Router# configure terminal
Router(config)# controller sonet 0/1/0
Router(config-controller)# framing sdh
Router(config-controller)# clock source line
Router(config-controller)# sts-1 1 - 3
Router(config-ctrlr-sts1)# mode t3
Router(config-ctrlr-sts1)# vtg 1 t1 1 cem-group 1 timeslots 1-10
Router(config-controller)# end

For information on optional SONET configurations, see “$paratext>” section. For information on optional ATM, IMA, POS and Serial interface configuration, see “$paratext>” section.

Configuring SONET POS Mode

To configure an interface module to use SONET in POS mode, perform the following procedure.

SUMMARY STEPS

1. controller sonet slot / subslot / port

2. framing sonet

3. clock source { line | internal }

4. sts-1 starting-number - ending-number pos

5. exit

6. interface pos slot / subslot / port : sts-1#

7. encapsulation encapsulation-type

8. end

DETAILED STEPS

 
Command or Action
Purpose

Step 1

controller sonet slot / subslot / port

 

Router(config)# controller sonet 0/1/0

Selects the controller to be configured.

Step 2

framing {sonet | sdh}

 

Router(config-controller)# framing sonet

Specifies SONET as the framing mode.

Step 3

clock source { line | internal }

 
Router(config-controller)# clock source line

Specifies the clock source for the POS link, where:

  • line —The link uses the recovered clock from the line. This is the default setting.
  • internal —The link uses the internal clock source.

Step 4

sts-1 {1- 12 | 1 - 3 | 4 - 6 | 7 - 9 | 10 - 12} pos

 

Router(config-controller)# sts-1 1 - 3 pos

Specifies POS mode; starting-number and ending-number arguments indicate the starting and ending STS value of the POS interface. For OC-3 interfaces, this value is 1.

Note The 1-12 value is supported only in OC-12 mode.

Step 5

exit

 

Router(config-controller# exit

Exits controller configuration mode.

Step 6

interface POS slot / subslot / port

or

interface POS slot / subslot / port.POS-interface

or

interface POS slot / subslot / port:POS-interface

 

interface POS0/0/1

interface POS0/0/1.1

interface POS0/0/1:1

Use any of the following commands to access the POS interface.

Step 7

encapsulation encapsulation-type { hdlc | ppp }

 

Router(config-if)# encapsulation hdlc

Configures encapsulation; you can configure the following options:

  • hdlc —Serial HDLC. This is the default for synchronous serial interfaces
  • ppp —Point-to-Point Protocol (for serial interface).

Step 8

end

 

Router(config-if)# end

Exits configuration mode.

Example

Router# configure terminal
Router(config)# controller sonet 0/1/0
Router(config-controller)# framing sdh
Router(config-controller)# clock source line
Router(config-controller)# sts-1 1 - 3 pos
Router(config-controller)# exit
Router(config)# interface POS0/0/1
Router(config-if)# encapsulation hdlc
Router(config-if)# end
 

For information on optional SONET configurations, see “$paratext>” section.

Configuring a CEM group

Configuring CEM Group in SONET Mode

To configure a T1 CEM group in SONET mode:

DETAILED STEPS

 
Command or Action
Purpose

Step 1

enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted

Step 2

configure terminal

Enters global configuration mode.

Step 3

controller sonet slot/bay/port

Example:

Router(config)# controller sonet 0/4/1

Selects the controller to configure and enters controller configuration mode, where:

  • slot/bay/port —Specifies the location of the interface.

Note The slot number is always 1 and the bay number is always 0.

Step 4

framing {sonet | sdh}

Example:

Router(config)# framing sonet

Specifies SONET as the framing mode.

Step 5

sts-1 {1 - 12 | 1 - 3 | 4 - 6 | 7 - 9 | 10 - 12}

 

Router(config-controller)# sts-1 1 - 3

Specifies the SONET Synchronous Transport Signal (STS) level and enters STS-1 configuration mode. The starting-number and ending-number arguments indicate the starting and ending STS value of the interface.

For OC-3 interfaces, this value is 1.

Note The 1-12 value is supported only in OC-12 mode.

Step 6

mode { t3 | vt-15}

Example:

Router(config-ctrlr-sts1-3)# mode t3

Specifies the mode of operation of an STS-1 path, where:

Note Note VT-15 is the only supported mode.

  • t3 —DS3 clear channel mode. STS-1carries an unchannelized (clear channel) T3.
  • vt-15 —A STS-1 is divided into seven Virtual Tributary Groups (VTG). Each VTG is then divided into four VT1.5's, each carrying a T1.

Step 7

vtg vtg_number t1 t1_line_number cem-group channel-number timeslots list-of-timesolts

 

Router(config-ctrlr-sts1-3)# vtg 1 t1 1 cem-group 1 timeslots 1-10

Configures the T1 on the VTG, where:

  • vtg_number —Specifies the VTG number. For SONET framing, values are 1 to 7.
  • t1_line_number —Specifes the T1 line number. Valid range is 1 to 4.
  • channel-number —Specifies the channel number. Valid range is 0 to 2015.
  • list-of-timeslots —Specifies the list of timeslots. Valid range is from 1 to 24.

Step 8

end

Exits controller configuration mode and returns to privileged EXEC mode.

 

Example

Router# configure terminal
Router(config)# controller sonet 0/1/0
Router(config-controller)# framing sdh
Router(config-controller)# sts-1 1 - 3
Router(config-ctrlr-sts1-3)# mode t3
Router(config-ctrlr-sts1-3)# vtg 1 t1 1 cem-group 1 timeslots 1-10
Router(config-ctrlr-sts1-3)# exit

Configuring CEM Group in SDH Mode

To configure CEM group in SDH mode:

DETAILED STEPS

 
Command or Action
Purpose

Step 1

enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Enters global configuration mode.

Step 3

controller sonet slot/bay/port

Example:

Router(config)# controller sonet 0/1/0

Selects the controller to configure and enters controller configuration mode, where:

  • slot/bay/port —Specifies the location of the interface.

Note The slot number is always 1 and the bay number is always 0.

Step 4

framing {sonet | sdh}

Example:

Router(config-controller)# framing sdh

Specifies SDH as the framing mode.

Step 5

au-4 au-4# tug-3 tug-3#

Example:

Router(config-controller)# au-4 3

Configures AU-4, and tributary unit groups, type 3 (TUG-3) for AU-4 and enters specific configuration mode.

In SDH framing mode, each TUG-3, and AU-4 can be configured with one of these commands.

Depending on currently configured AUG mapping setting, this command further specifies TUG-3, or AU-4 muxing. The CLI command parser enters into config-ctrlr-tug3 (SDH mode) or config-ctrlr-au3 (SDH mode), which makes only relevant commands visible.

  • au-4#—Range is from 1 to 4. For OC-3 mode, the value is 1.

Note DS3 configuration is supported only on AuU-4.

  • tug-3#—Range is from 1 to 3.

Note T1 can only be configured in au-3 mode, E1 can only be configured in the au-4 mode.

Step 6

mode {t3 | e3}

Example:

Router(config-ctrlr-au3)# mode e3

Specifies the mode of operation.

  • t3 —Specifies an unchannelized (clear channel) T3.
  • e3 —Specifies a AU-3 or C3 that carries a unchannelized (DS3 clear channel) E3.

Note Only e3 mode is supported for SDH framing.

Step 7

cem-group group-number {unframed}

Example:

Router(config-ctrlr-au3)# cem-group 4 unframed

Creates a CEM group.

  • unframed —Specifies that a single CEM channel is being created including all time slots and the framing structure of the line.

Step 8

end

Exits controller configuration mode and returns to privileged EXEC mode.

Example

Router# configure terminal
Router(config)# controller sonet 0/1/0
Router(config-controller)# framing sdh
Router(config-controller)# au-4 3
Router(config-ctrlr-au3)# mode e3
Router(config-ctrlr-au3)# cem-group 4 unframed
Router(config-ctrlr-au3)# end

Configuring DS3 Clear Channel on OC-3 and OC-12 Interface Module


NoteDS3 clear channel is supported only on CEM. DS3 clear channel is supported only on CEM.


Configuring DS3 Clear Channel in SONET Mode

To configure DS3 clear channel in SONET mode:

DETAILED STEPS

 
Command or Action
Purpose

Step 1

enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted

Step 2

configure terminal

Enters global configuration mode.

Step 3

controller sonet slot/bay/port

Example:

Router(config)# controller sonet 0/4/1

Selects the controller to configure and enters controller configuration mode, where:

  • slot/bay/port —Specifies the location of the interface.

Note The slot number is always 1 and the bay number is always 0.

Step 4

framing {sonet | sdh}

Example:

Router(config)# framing sonet

Specifies SONET as the framing mode.

Step 5

clock source { line | internal }

 

Router(config-if)# clock source internal

Specifies the clock source for the POS link, where:

  • line —The link uses the recovered clock from the line. This is the default setting.
  • internal —The link uses the internal clock source.

Step 6

sts-1 {1 - 12 | 1 - 3 | 4 - 6 | 7 - 9 | 10 - 12}

Example:

Router(config-controller)# sts-1 1

Specifies the SONET Synchronous Transport Signal (STS) level and enters STS-1 configuration mode. The starting-number and ending-number arguments indicate the starting and ending STS value of the interface.

For OC-3 interfaces, this value is 1.

The 1-12 value is supported only in OC-12 mode.

Step 7

mode {t3 | vt-15}

Example:

Router(config-ctrlr-sts1)# mode t3

Specifies the mode of operation of an STS-1 path, where:

  • t3 —DS3 clear channel mode. STS-1 carries an unchannelized (clear channel) T3.
  • vt-15 —A STS-1 is divided into seven Virtual Tributary Groups (VTG). Each VTG is then divided into four VT1.5's, each carrying a T1.

Step 8

end

Exits controller configuration mode and returns to privileged EXEC mode.

Configuring DS3 Clear Channel in SDH Mode

To configure DS3 clear channel in SDH mode:

DETAILED STEPS

 
Command or Action
Purpose

Step 1

enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Enters global configuration mode.

Step 3

controller sonet slot/bay/port

Example:

Router(config)# controller sonet 0/1/0

Selects the controller to configure and enters controller configuration mode, where:

  • slot/bay/port —Specifies the location of the interface.

Note The slot number is always 1 and the bay number is always 0.

Step 4

framing {sonet | sdh}

Example:

Router(config-controller)# framing sdh

Specifies SDH as the framing mode.

Step 5

clock source { line | internal }

 

Router(config-controller)# clock source line

Specifies the clock source for the POS link, where:

  • line —The link uses the recovered clock from the line. This is the default setting.
  • internal —The link uses the internal clock source.

Step 6

aug mapping au-4

Example:

Router(config-controller)# aug mapping au-4

Configures AUG mapping for SDH framing.

If the AUG mapping is configured to be AU-4, then the following muxing, alignment, and mapping will be used:

TUG-3 <--> VC-4 <--> AU-4 <--> AUG.

Step 7

au-4 au-4# tug-3 tug-3#

Example:

Router(config-controller)# au-4 1 tug-3 1

Configures AU-4, and tributary unit groups, type 3 (TUG-3) for AU-4 and enters specific configuration mode.

In SDH framing mode TUG-3, and AU-4 can be configured with one of these commands.

Depending on currently configured AUG mapping setting, this command further specifies TUG-3, or AU-4 muxing. The CLI command parser enters into config-ctrlr-tug3 (SDH mode) or config-ctrlr-au3 (SDH mode), which makes only relevant commands visible.

  • au-4#—Range is from 1 to 4. For OC-3 mode, the value is 1.
  • tug-3#—Range is from 1 to 3.

Note E1 can only be configured in the AU-4 mode.

Step 8

mode e3

Example:

Router(config-ctrlr-au4)# mode e3

Specifies the mode of operation.

  • e3 —Specifies a C3 that carries a unchannelized (DS3 clear channel) E3.

Step 9

end

Exits controller configuration mode and returns to privileged EXEC mode.

Example

Router# configure terminal
Router(config)# controller sonet 0/1/0
Router(config-controller)# framing sdh
Router(config-controller)# clock source line
Router(config-controller)# aug mapping au-4
Router(config-controller)# au-4 1 tug-3 1
Router(config-ctrlr-au4)# mode e3
Router(config-ctrlr-au4)# end

Optional Configurations

There are several standard, but optional, configurations that might be necessary to complete the configuration of your interface module.

Configuring the Encapsulation Method

When traffic crosses a WAN link, the connection needs a Layer 2 protocol to encapsulate traffic. To set the encapsulation method, use the following commands:

 

 
Command
Purpose

Step 10

Router(config)# interface serial slot / subslot / port : channel-group

Selects the interface to configure and enters interface configuration mode.

  • slot / subslot / port : channel-group —Specifies the location of the interface.

Step 11

Router(config-if)# encapsulation encapsulation-type {hdlc | ppp}

Sets the encapsulation method on the interface, where:

  • hdlc—Sets the High-Level Data Link Control (HDLC) protocol for serial interface. This encapsulation method provides the synchronous framing and error detection functions of HDLC without windowing or retransmission. This is the default for synchronous serial interfaces.
  • ppp—Sets point-to-point protocol (PPP) for serial interface.

Note Frame relay encapsulation is not supported.

Configuring the CRC Size for T1

CRC is an error-checking technique that uses a calculated numeric value to detect errors in transmitted data. The 1-Port Channelized OC-3/STM-1 SPA and 1-Port Channelized OC-12/STM-4 SPA uses a 16-bit cyclic redundancy check (CRC) by default, but also supports a 32-bit CRC. The designators 16 and 32 indicate the length (in bits) of the frame check sequence (FCS). A CRC of 32 bits provides more powerful error detection, but adds overhead. Both the sender and receiver must use the same setting.

To set the length of the cyclic redundancy check (CRC) on a T1 interface, use these commands:

 

 
Command
Purpose

Step 12

Router(config)# interface serial slot / subslot / port : channel-group

Selects the interface to configure and enters interface configuration mode.

  • slot / subslot / port : channel-group —Specifies the location of the interface.

Step 13

Router(config-if)# crc {16 | 32}

Selects the CRC size in bits, where:

  • 16—16-bit CRC. This is the default.
  • 32—32-bit CRC.

Optional Packet over SONET Configurations

The following sections describe how to configure optional settings on a packet over SONET (POS) interface.

Encapsulation

 

encapsulation encapsulation-type

 

Router(config-if)# encapsulation hdlc

Configures encapsulation; you can configure the following options:

  • HDLC
  • PPP

MTU Value

 

mtu bytes

 
Router(config-if)# mtu 4000

Configures the maximum packet size for an interface in bytes. The default packet size is 4470 bytes.

 

CRC Value

 

crc size-in-bits

 
Router(config-if)# crc 32

CRC size in bits. Valid values are 16 and 32. The default is 16.

Keepalive Value

 

keepalive [ period [ retries ]]

 
Router(config-if)# keepalive 9 4

Specifies the frequency at which the Cisco IOS software sends messages to the other end of the line to ensure that a network interface is alive, where:

  • period Specifies the time interval in seconds for sending keepalive packets. The default is 10 seconds.
  • retries Specifies the number of times that the device continues to send keepalive packets without response before bringing the interface down. The default is 3 retries.

Bandwidth

Use the following command to configure the bandwidth of a POS interface.

 

bandwidth { kbps | inherit [ kbps ]}

To set and communicate the current bandwidth value for an interface to higher-level protocols, use the bandwidth command in interface configuration mode.Valid values are from 1 to 10000000. You can apply the following keywords:

  • inherit —Specifies how a subinterface inherits the bandwidth of its main interface.
  • receive —Specifies the receive-side bandwidth.

Scrambling

Use the following command to enable scrambling on a POS interface.

 

pos scramble-atm

Enables scrambling on the interface.

C2 Flag

Use the following command to configure the C2 flag on a POS interface.

 

pos flag c2 value

Specifies the C2 byte field for the interface as defined in RFC 2615. Valid values are 0-255.

J1 Flag

Use the following command to configure the J1 flag on a POS interface.

 

pos flag j1 message word

Specifies the value of the J1 byte in the SONET Path OverHead (POH) column.

You can use the following commands to verify your configuration:

  • show interfaces pos
  • show controllers pos

Managing Interface Naming

The following sections describe how to manage interface naming on the Cisco ASR 900 Series Router optical interface module.

Identifying Slots and Subslot

To specify the physical address for controller or interface configuration, use the interface and controller sonet commands, where:

  • slot—Specifies the chassis slot number where the interface module is installed; the slot number is always 0 for interface modules on the Cisco ASR 900 Series Router.
  • subslot—Specifies the subslot where the interface module is installed.
  • port—Specifies the SONET port number.

For example, if the optical interface module is installed in slot 0 of the chassis, the controller configuration address is specified as controller sonet 0/0/0 .

For channelized configuration, the interface address format is: slot/subslot/port:channel-group, where:

  • channel-group—Specifies the logical channel group assigned to the time slots within the T1 link.

Configuring Multilink Point-to-Point Protocol

Multilink Point-to-Point Protocol (MLPPP) allows you to combine interfaces which correspond to an entire T1 or E1 multilink bundle. You can choose the number of bundles and the number of T1 or E1 lines in each bundle in any combination of E1 and T1 member link interfaces.

This section describes how to configure MLPPP on the optical interface module and includes the following topics:

MLPPP Configuration Guidelines

When configuring MLPPP, consider the following guidelines:

  • Only T1 and E1 links are supported in a bundle.
  • Enable PPP encapsulation before configuring multilink-related commands.
  • Interfaces can be grouped into the MLPPP bundle if they belong to same interface module.
  • A group can have a maximum of 16 interfaces.

Creating a Multilink Bundle

To create a multilink bundle, use the following commands:

 

 
Command
Purpose

Step 1

Router# configure terminal

Enters global configuration mode.

Step 2

Router(config)# interface multilink group-number

Creates a multilink interface and enters multilink interface mode, where:

  • group-number—The group number for the multilink bundle.

Step 3

Router(config-if)# ip address address mask

Sets the IP address for the multilink group, where:

  • address—The IP address.
  • mask—The subnet mask.

Assigning an Interface to a Multilink Bundle

To assign an interface to a multilink bundle, use the following commands:

 

 
Command
Purpose

Step 1

Router# configure terminal

Enters global configuration mode.

Step 2

Router(config)# interface serial slot / subslot / port

 

Selects the interface to configure and enters interface configuration mode, where:

  • slot / subslot / port —Specifies the location of the controller.

Step 3

Router(config-if)# encapsulation ppp

Enables PPP encapsulation.

Step 4

Router(config-if)# ppp m ultilink group group-number

Assigns the interface to a multilink bundle, where:

  • group-number—The multilink group number for the T1 or E1 bundle.

Step 5

Note Repeat these commands for each interface you want to assign to the multilink bundle.

 

Configuring Fragmentation Size and Delay on an MLPPP Bundle

To configure the fragmentation size on a multilink PPP bundle, use the following commands:

 

 
Command
Purpose

Step 1

Router# configure terminal

Enters global configuration mode.

Step 2

Router(config)# interface multilink group-number

Creates a multilink interface and enters multilink interface mode, where:

  • group-number —The group number for the multilink bundle. Range 1-2147483647

Step 3

Router(config-if)# ppp multilink fragment size fragment-size

Sets the fragmentation size in bytes. Fragmentation is disabled by default. Valid values are 42 to 65535 bytes.

Step 4

Router(config-if)# ppp multilink fragment-delay delay

Sets the configured delay on the multilink bundle that satisfies the fragmentation size, where:

  • delay —Delay in milliseconds.

The following example of the show ppp multilink command shows the MLPPP type and the fragmentation size:

Router# show ppp multilink
Multilink1, bundle name is test2
Bundle up for 00:00:13
Bundle is Distributed
0 lost fragments, 0 reordered, 0 unassigned
0 discarded, 0 lost received, 206/255 load
0x0 received sequence, 0x0 sent sequence
Member links: 2 active, 0 inactive (max not set, min not set)
Se4/2/0/1:0, since 00:00:13, no frags rcvd
Se4/2/0/2:0, since 00:00:10, no frags rcvd
Distributed fragmentation on. Fragment size 512. Multilink in Hardware.
.
 

Changing the Default Endpoint Discriminator

To override or change the default endpoint discriminator, use the following command in interface configuration mode:

 

Command
Purpose

Router(config-if)# ppp multilink endpoint { hostname | ip IP-address | mac LAN-interface | none | phone telephone-number | string char-string }

Overrides or changes the default endpoint discriminator the system uses when negotiating the use of MLP with the peer.

Disabling Fragmentation on an MLPPP Bundle

By default, PPP multilink fragmentation is enabled. To disable fragmentation on a multilink bundle, use the following commands:

 

 
Command
Purpose

Step 1

Router# configure terminal

Enters global configuration mode.

Step 2

Router(config)# interface multilink group-number

Specifies the multilink interface and enters multilink interface mode, where:

  • group-number —The group number for the multilink bundle. Range 1-2147483647

Step 3

Router(config-if)# ppp multilink fragment disable

Disables PPP multilink fragmentation.

Configuring BERT

BERT (Bit-Error Rate Testing) is used for analyzing quality and for problem resolution of digital transmission equipment. BERT tests the quality of an interface by directly comparing a pseudorandom or repetitive test pattern with an identical locally generated test pattern.

The BERT operation is data-intensive. Regular data cannot flow on the path while the test is in progress. The path is reported to be in alarm state when BERT is in progress and restored to a normal state after BERT has been terminated.

For information about configuring BERT, see “$paratext>” section

Configuring Automatic Protection Switching

For information on how to configure Automatic Protection Switching (APS) on the optical interface module, see Configuring Automatic Protection Switching on the Cisco ASR 900 Series Router .

Verifying Interface Configuration

Besides using the show running-configuration command to display your Cisco ASR 900 Series Router configuration settings, you can use the show interface serial and the show controllers sonet commands to get detailed information on a per-port basis.

Verifying Per-Port Interface Status

To find detailed interface information on a per-port basis on an optical interface module, use the show interface serial and show controllers sonet commands.

For examples of the show commands here, see the Cisco IOS Interface and Hardware Component Command Reference .

Troubleshooting

You can use the following commands to verify your configuration:

  • show cem circuit —shows information about the circuit state, administrative state, the CEM ID of the circuit, and the interface on which it is configured. If xconnect is configured under the circuit, the command output also includes information about the attached circuit.
  • show cem circuit 0-504— Displays the detailed information about that particular circuit.
  • show cem circuit summary— Displays the number of circuits which are up or down per interface basis.
  • show controller sonet x/y/z—Displays the alarm information.
  • show hw-module subslot transceiver— Displays information about the optical transceiver
  • show mpls l2transport vc —Displays the state of local and peer access circuits
  • show running configuration —Shows detail on each CEM group
  • show xconnect all —Displays the state of the pseudowire and local and peer access circuits
  • show interfaces pos—Displays all the current interface processors and their interfaces.
  • show controllers pos—Displays status information about the OC POS interface

To provide information about system processes, the Cisco IOS software includes an extensive list of EXEC commands that begin with the word show, which, when executed, display detailed tables of system information. Following is a list of some of the common show commands for the APS feature.

To display the information described, use these commands in privileged EXEC mode.

 

Command or Action
Purpose

Router# show aps

Displays information about the automatic protection switching feature.

Router# show controller sonet slot / port-adapter / port

Router# show controllers pos

Displays information about the hardware.

Router# show interfaces

Displays information about the interface.

For examples of the show commands here, see the Cisco IOS Interface and Hardware Component Command Reference .

Configuration Examples

This section includes the following configuration examples:

Example of Cyclic Redundancy Check Configuration

The following example configures CRC on a T1 interface:

! Specify the interface to configure and enter interface configuration mode.
!
Router(config)# interface serial 2/0/0.1
!
! Specify the CRC type.
!
Router(config-if)# crc 32
 

Example of Facility Data Link Configuration

The following example configures FDL on a T1 interface:

! Specify the interface to configure and enter interface configuration mode.
!
Router(config)# interface serial 1/0/0.2
!
! Specify the T1 number and select fdl.
!
Router(config-controller)#t1 2 fdl ansi

Example of Invert Data on T1/E1 Interface

The following example inverts the data on the serial interface:

! Specify the interface to configure and enter interface configuration mode.
!
Router(config)# interface serial 3/0/0.1/2/1:0
!
! Configure invert data.
!
Router(config-if)# invert data
 

Additional Resources

For more information about configuring ATM, see

For additional information on configuring optical interfaces, see