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T1/E1 Inverse Multiplexing over ATM

T1/E1 Inverse Multiplexing over ATM

This feature module describes the Cisco IOS Inverse Multiplexing over ATM (IMA) features that are available for the Cisco 6015 and Cisco 6160 digital subscriber line access multiplexers (DSLAMs) with installed DS3+T1/E1 IMA NI-2 cards. The IMA feature is available for the Cisco 6015 DSLAM in Cisco IOS Releases 12.1(4)DA and above. The IMA feature is available for the Cisco 6160 DSLAM in Cisco IOS Releases 12.1(5)DA and above.

This document includes the following sections:

Feature Overview

The T1/E1 inverse multiplexing over ATM (IMA) feature uses IMA technology to aggregate multiple low-speed links (T1/E1) into one or more IMA groups at speeds between 1.5 Mbps 16 Mbps. IMA breaks up the ATM cell stream and distributes the cells over the multiple physical links of an IMA group and then recombines the cells into a single stream at the other end of the connection. The multiple links of an IMA group increase the logical link bandwidth to approximately the sum of the individual link rates.

How IMA Works

IMA links transmit IMA control protocol (ICP) cells, which enable the reconstruction of the original ATM cell stream. ICP cells define and separate IMA frames passing through each physical link in an IMA group. ICP cells also control the operation of IMA by accounting for cell delay variation (CDV), which is introduced by ICP cells, and the link differential delays on physical links to ensure the proper reassembly of IMA frames. Using an IMA frame length of 128 cells, one out of every 128 cells on a physical link is an ICP cell. In this scenario, a frame containing fewer than 128 cells is injected with filler cells. The receiving end of an IMA group extracts the ICP and filler cells as the IMA stream is reconstructed into an ATM cell stream and passed to the ATM layer. IMA operation is transparent to ATM layer protocols. Therefore, the ATM layer operates as if a single physical interface were being used.

Figure 1 illustrates IMA with three bundled links.


Figure 1: IMA Inverse Multiplexing and Demultiplexing


Depending upon the installed I/O module (1DS3+8T1 I/O or 8xE1 I/O), IMA can be configured by grouping the following physical links (refer to the "Supported Platforms" section):

The DS3+T1/E1 IMA NI-2 supports three modes of operation:

The eight links on the DS3+T1/E1 IMA NI-2 can be independent ATM links or can be configured into one or more IMA groups. There are four static IMA groups. Each IMA group can contain from zero to eight T1/E1 links. Any combination of independent T1/E1 links and IMA groups is allowed, up to eight T1/E1 links total.

Some examples of allowed combinations are

Benefits

The T1/E1 IMA features for the Cisco 6015 and the Cisco 6160 offer the following benefits:

Restrictions

The DS3+T1/E1 IMA NI-2 card supports the trunk selection feature for IOS Release 12.1(4)DA. This feature allows you to configure any WAN interface (the DS3, any T1 link, any E1 link, or any IMA group) as the trunk.

Note   When you configure a T1 link or an IMA group as the trunk (1DS3+8xT1 I/O module only), the DS3 port is disabled. When you select the DS3 port as the trunk, the T1 links and IMA groups are all treated as subtended ports.

E1 IMA group bandwidth is limited to six links. Cell loss will occur if an IMA group has more than six links and more than 12 Mbps are sent through it. The loss only occurs on groups with greater than six E1 links. All eight links can be used in different groups, however (for example, six in group 0, two in group 1). This does not affect T1 operation (that is, all eight T1 links may be used in a group). Refer to the Release Notes for Cisco IOS Release 12.1(4)DA for Cisco DSLAMs with NI-2 DDTS report CSCdr45623 for more information.

Related Documents

Hardware Documents

A complete list of all DSL hardware product related documentation is available on the World Wide Web at http://www.cisco.com/univercd/cc/td/doc/product/dsl_prod/index.htm.

Software Documents

A complete list of all DSL IOS software product related documentation is available on the World Wide Web at http://www.cisco.com/univercd/cc/td/doc/product/dsl_prod/ios_dsl/rel121/index.htm.

In the following ATM software guides, look for information pertaining to the Cisco LightStream 1010, which uses the same software base as the NI-2 DSLAMs:

Supported Platforms

This Cisco 6015 and Cisco 6160 DSLAMs and the following components support the IMA feature:

NI-2 Chassis I/O Module Minimum IOS Release

DS3+T1/E1 IMA

6015

1DS3+8xT1

12.1(4)DA

DS3+T1/E1 IMA

6015

8xE1

12.1(4)DA

DS3+T1/E1 IMA

6160

1DS3+8xT1

12.1(5)DA

DS3+T1/E1 IMA

6260

8xE1

Future

Supported Standards, MIBs, and RFCs

Standards

The IMA feature supports the ATM Forum Technical Committee: Inverse Multiplexing for ATM (IMA) Specification Version 1.1 (AF-PHY-0086.001).

The IMA feature supports the ATM Forum Technical Committee: Inverse Multiplexing for ATM (IMA) Specification Version 1.0 (AF-PHY-0086.000).

MIBs

For descriptions of supported MIBs and how to use MIBs, see the Cisco MIB web site on CCO at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

RFCs

The IMA feature supports RFC 1406 and RFC 1407 (for DS3 trunks).

Prerequisites

Before you can configure a Cisco 6015 or Cisco 6160 DSLAM to provide T1/E1 IMA service, you must perform the following tasks:

Configuration Tasks

Perform the following tasks to configure ATM interfaces for IMA. Each task in the list is required.

Each link can be used as an independent T1/E1 ATM link with all the properties and functionality of ATM interfaces. When the link becomes part of an IMA group, its independent ATM functionality ceases; however, the IMA group can use ATM commands.

Configuring a Trunk Interface

The DS3+T1/E1 IMA NI-2 card supports the trunk selection feature for Release 12.1(4)DA. This feature allows you to configure any WAN interface (the DS3, any T1 link, any E1 link, or any IMA group) as the trunk. When you configure a T1 link or an IMA group as the trunk, the DS3 port is disabled. When you select the DS3 port as the trunk, the T1 links and IMA groups are all treated as subtended ports.

Command Purpose

Step 1 

DSLAM> enable Password: <password> DSLAM#

Enter enable mode.

Enter the password.

You have entered enable mode when the prompt changes to DSLAM#.

Step 2 

DSLAM# configure terminal

Enter global configuration mode. You have entered global configuration mode when the prompt changes to DSLAM (config)#.

Step 3 

DSLAM(config)#atm ni2-switch trunk atm 0/1

Select the interface to use as the trunk.

Step 4 

DSLAM(config)#interface atm 0/1

Enter interface configuration mode. You have entered interface configuration mode when the prompt changes to DSLAM (config-if)#.

Step 5 

DSLAM(config-if)#shutdown

Disable the individual link by enabling the shutdown command.

Step 6 

DSLAM(config-if)#clock source network-derived

Select the transmit clock source for the link.

Step 7 

DSLAM(config-if)#framing m23adm

Select the framing type for the link.

Step 8 

DSLAM(config-if)#scrambling cell-payload

Enable DS3 cell payload scrambling on the link.

Step 9 

DSLAM(config-if)#lbo short

Specify the line build out (short or long), followed by the length. You can view the acceptable lengths by including the? option after the long or short commands.

Step 10 

DSLAM(config-if)#no shutdown

Enable the individual link by canceling the shutdown state.

Step 11 

DSLAM(config-if)#end

Return to enable mode when you finish configuring interfaces.

Verifying the Trunk Interface

Use the show running-config command to verify that the DSLAM running configuration contains the atm ni2-switch trunk ATM0/1 statement.

If the trunk interface is not the interface you meant to select, using the atm ni2-switch trunk command, repeat the "Configuring a Trunk Interface" procedure.

Configuring T1/E1 Interfaces

To configure a T1 or E1 interface, use the following procedure:

Command Purpose

Step 1 

DSLAM> enable Password: <password> DSLAM#

Enter enable mode.

Enter the password.

You have entered enable mode when the prompt changes to DSLAM#.

Step 2 

DSLAM# configure terminal

Enter global configuration mode. You have entered global configuration mode when the prompt changes to DSLAM (config)#.

Step 3 

DSLAM(config)#interface atm 0/2

Enter interface configuration mode. You have entered interface configuration mode when the prompt changes to DSLAM (config-if)#.

Step 4 

DSLAM(config-if)#no shutdown

Enable the individual link by canceling the shutdown state.

Repeat steps 3 through 8 if your DSLAM has more than one interface that you need to configure.

Step 5 

DSLAM(config-if)# linecode ami

NoteIf ami linecoding is selected, enable scrambling on thelink.

DSLAM(config-if)# linecode hdb3

Select the linecode type of the T1 link.





Select the linecode type of the E1 link.

Step 6 

DSLAM(config-if)# framing esf DSLAM(config-if)# framing pcm30

Select the frame type for the T1 data link.
Select the frame type for the E1 data link.

Step 7 

DSLAM(config-if)#lbo short 133

Specify the line length (short or long), followed by the length. You can view the acceptable lengths by including the ? option after the long or shortcommands.

Step 8 

DSLAM(config-if)#clock source loop-timed

Select the transmit clock source for a link.

Step 9 

DSLAM(config-if)#end

When you finish configuring interfaces, return to enable mode.

Verifying T1/E1 Interfaces

After configuring your T1/E1 interfaces, use the following commands to verify their operational status.

Command Purpose

Step 1 

DSLAM# show interface atm0/2

Displays the interface configuration, status, and statistics of the ATM interface.

Step 2 

DSLAM# show controller atm0/2

Displays diagnostic information for the specified interface.

If an interface is down and you configured it as up, or if the displays indicate that the hardware is not functioning properly, make sure that the T1/E1 interface is properly connected and configured.

Configuring IMA Interfaces

To configure an IMA interface, you must use configuration mode (manual configuration). In this mode, you enter Cisco IOS commands at the DSLAM prompt.

Command Purpose

Step 1 

DSLAM> enable

Enter enable mode.

Step 2 

DSLAM# configure terminal

Enter global configuration mode. You have entered global configuration mode when the prompt changes to DSLAM (config)#.

Step 3 

DSLAM(config)#interface atm 0/2

Enter interface configuration mode. You have entered interface configuration mode when the prompt changes to DSLAM (config-if)#.

Step 4 

DSLAM(config-if)#ima-group 2

Assign the ATM interface to an IMA group (numbered from 0 to 3). After the interface is assigned to an IMA group, individual ATM functionality is no longer available on the link.

Step 5 

DSLAM(config-if)#no shutdown

Enable the individual link by canceling the shutdownstate.

Repeat Step 3 through Step 5 if your DSLAM has more than one interface that you need to configure.

Step 6 

DSLAM (config-if) # interface atm0/ima2

Begin configuring the IMA interface.

Step 7 

DSLAM(config-if)#ima clock-mode independent

Select the transmit clock mode for the selected IMAgroup.

Step 8 

DSLAM(config-if)#ima differential-delay-maximum 68

Enter the maximum differential delay in milliseconds for the selected IMA group.

Step 9 

DSLAM(config-if)#ima active-links-minimum 2

Enter the minimum number of links that need to be operational for the selected IMA group.

Step 10 

DSLAM(config-if)#no shutdown

Enable the IMA group by canceling the shutdownstate.

Step 11 

DSLAM(config-if)#end

When you finish configuring interfaces, return to enable mode.

Verifying the IMA Configuration

After configuring your IMA interfaces, use the following commands to verify their operational status.

Command Purpose

Step 1 

DSLAM# show interface atm0/ima2

Displays interface configuration, status, and statistics for the IMA interface.

Step 2 

DSLAM# show controller atm0/ima2

Displays diagnostic information for the specified IMA group.

Step 3 

DSLAM# show ima interface atm0/ima2

Displays configuration information and operational status for the specified IMA group.

Step 4 

DSLAM# show ima interface atm0/2

Displays information for a single link in an IMAgroup.

If an interface is down and you configured it as up, or if the displays indicate that the hardware is not functioning properly, make sure that the new interface is properly connected and configured.

Troubleshooting Tips

Use the following general guidelines to troubleshoot IMA groups and the individual links of an IMA group.

Make Sure T1/E1 Links are Error Free

Command Purpose

Step 1 

DSLAM# show interface atm0/2

Use the show interface atm command to verify the status of a T1 link. Verify that the administrative and protocol statuses are both up. Also, check for CRC errors and loopback status.

Step 2 

DSLAM# show running-config interface atm0/2

Verify that the interface is not shutdown. Also, compare the interface configuration with the far end interface to ensure that there are no configuration mismatches.

Step 3 

DSLAM# show controllers

Use the show controllers command to verify the port status and view any active alarms states.

Troubleshoot the IMA Groups and Links

Command Purpose

Step 1 

DSLAM# show ima interface atm0/ima0

Verify that the IMA group status is up. Also, use the command output to verify the IMA configuration at the near and far end.

Step 2 

DSLAM# show ima interface atm0/2

Verify that the member links of the IMA group are up.

Step 3 

DSLAM# show ima counters

The show ima counters command reports IMA statistics in 15 minute intervals with 24 hour totals.

See http://www.cisco.com/univercd/cc/td/doc/product/dsl_prod/6015/user/hig/index.htm for troubleshooting information.

Monitoring and Maintaining IMA

This section describes commands that you can use for monitoring and maintaining IMA configurations. Table 1 lists the commands.


Table 1: Commands for Monitoring and Maintaining IMA
Command Purpose
DSLAM#show ima interface

Displays information about all IMA groups and the links in those groups.

DSLAM#show ima interface atm0/imaima-group-number

Displays information about a single IMA group and the links in that group.

DSLAM#show controllers

Displays information about current settings and performance at the physical level.

DSLAM# show ima interface atm0/atm-interface-number

Displays IMA information for an individual link in an IMA group.

Configuration Examples

This section contains example configurations describing how to configure:

IMA Trunk with IMA Subtended Chassis

The following sample configuration describes how to configure:

Figure 2 illustrates the network topology being configured in the following configuration sample.


Figure 2: IMA Trunk with IMA Subtended Chassis


Note   Comments are written in boldface type and encapsulated with exclamation points.
... atm ni2-switch trunk ATM0/IMA0 !Configures interface ATM0/IMA0 as the trunk! ! ! ! interface ATM0/0 no ip address no ip route-cache atm maxvp-number 0 atm maxvc-number 4096 atm maxvci-bits 12 ! interface Ethernet0/0 ip address 192.168.1.1 255.255.255.0 no ip route-cache ! interface ATM0/1 no ip address no ip route-cache shutdown no atm ilmi-keepalive ! interface ATM0/2  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive  clock source loop-timed  scrambling cell-payload linecode ami lbo short 133 ima-group 0 !Adds this interface to IMA group 0! ! interface ATM0/3  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive  clock source loop-timed  scrambling cell-payload linecode ami lbo short 133 ima-group 0 !Adds this interface to IMA group 0! ! interface ATM0/4  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive  clock source loop-timed  scrambling cell-payload linecode ami lbo short 133 ima-group 0 !Adds this interface to IMA group 0! ! interface ATM0/5  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive  clock source loop-timed  scrambling cell-payload linecode ami lbo short 133 ima-group 0 !Adds this interface to IMA group 0! ! interface ATM0/6  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive clock source loop-timed  scrambling cell-payload linecode ami lbo short 133 ima-group 1 !Adds this interface to IMA group 1! ! interface ATM0/7  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive  clock source loop-timed  scrambling cell-payload linecode ami lbo short 133 ima-group 1 !Adds this interface to IMA group 1! ! interface ATM0/8  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive clock source loop-timed  scrambling cell-payload linecode ami lbo short 133 ima-group 2 !Adds this interface to IMA group 2! ! interface ATM0/9  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive clock source loop-timed  scrambling cell-payload linecode ami lbo short 133 ima-group 2 !Adds this interface to IMA group 2! ! interface ATM0/IMA0 !IMA group 0 configuration!  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive  ima active-links-minimum 2 ima clock-mode independent ima differential-delay-maximum 68 ! interface ATM0/IMA1 !IMA group 1 configuration!  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive  ima active-links-minimum 2 ima clock-mode independent ima differential-delay-maximum 68 ! interface ATM0/IMA2 !IMA group 2 configuration!  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive  ima active-links-minimum 2 ima clock-mode independent ima differential-delay-maximum 68 ! interface ATM0/IMA3 no ip address no ip route-cache shutdown no atm ilmi-keepalive ...

DS3 Trunk with IMA and T1 Subtended Chassis

The following sample configuration describes a network topology containing a mixture of IMA, T1, and DS3 interfaces. It is relevant only to IMA on platforms with the 1DS3+8xT1 I/O module installed.


Figure 3: DS3 Trunk with IMA and T1 Subtended Chassis


... atm ni2-switch trunk ATM0/1 !DS3 is the default trunk! ! ! ! interface ATM0/0 no ip address no ip route-cache atm maxvp-number 0 atm maxvc-number 4096 atm maxvci-bits 12 ! interface Ethernet0/0 ip address 192.168.1.1 255.255.255.0 no ip route-cache ! interface ATM0/1 no ip address no ip route-cache no atm ilmi-keepalive ! interface ATM0/2 no ip address no ip route-cache no atm ilmi-keepalive ima-group 0 !Adds this interface to IMA group 0! ! interface ATM0/3 no ip address no ip route-cache no atm ilmi-keepalive ima-group 0 !Adds this interface to IMA group 0! ! interface ATM0/4 no ip address no ip route-cache no atm ilmi-keepalive ima-group 0 !Adds this interface to IMA group 0! ! interface ATM0/5 no ip address no ip route-cache no atm ilmi-keepalive ima-group 0 !Adds this interface to IMA group 0! ! interface ATM0/6 !T1 configuration!  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive  clock source loop-timed  scrambling cell-payload linecode ami lbo short 133 ! interface ATM0/7 !T1 configuration!  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive  clock source loop-timed  scrambling cell-payload linecode ami lbo short 133 ! interface ATM0/8 !T1 configuration!  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive  clock source loop-timed  scrambling cell-payload linecode ami lbo short 133 ! interface ATM0/9 !T1 configuration!  no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive  clock source loop-timed  scrambling cell-payload linecode ami lbo short 133 ! interface ATM0/IMA0 !IMA group 0 configuration! no ip address no ip route-cache no ip mroute-cache no atm ilmi-keepalive  ima active-links-minimum 4 ima clock-mode independent ima differential-delay-maximum 68 ! interface ATM0/IMA1 no ip address no ip route-cache shutdown no atm ilmi-keepalive ! interface ATM0/IMA2 no ip address no ip route-cache shutdown no atm ilmi-keepalive ! interface ATM0/IMA3 no ip address no ip route-cache shutdown no atm ilmi-keepalive ...

Command Reference

This section documents the new and modified commands that are specific to the T1/E1 IMA feature. All other commands used with this feature are documented in the Command Reference for Cisco DSLAMS with NI-2. For information on other Cisco IOS commands that can be used on the NI-2 DSLAMs, see the Cisco ATM Switch Router Command Reference Guide.

atm ni2-switch trunk

To select the interface to use as the trunk, use the atm ni2-switch trunk command. To reset this command to the default value, use the no form of this command.

atm ni2-switch trunk {atm0/1 | atm0/2 | atm0/3 | atm0/4 | atm0/5 | atm0/6 | atm0/7 | atm0/8 | atm0/9 | atm0/ima0 | atm0/ima1 | atm0/ima2 | atm0/ima3}

Syntax Description

{atm0/1 | atm0/2 | atm0/3 | atm0/4 | atm0/5 | atm0/6 | atm0/7 | atm0/8 | atm0/9 | atm0/ima0 | atm0/ima1 | atm0/ima2 | atm0/ima3}

Select the interface to use as the trunk.

Defaults

The DS3 link is the default trunk interface on the 1DS3+8xT1 I/O network I/O module (atm ni2-switch trunk atm0/1).

The first E1 link (atm0/2) is the default trunk interface on the 8xE1 network I/O module (atm ni2-switch trunk atm0/2).

Note   Before you reassign trunk status from an active link or IMA group to a different link or IMA group, you must administratively shut down both the current trunk and the interface to be assigned trunk status.

Command Modes

Interface configuration.

Command History

Release Modification

12.1(4)DA

This command was introduced.

Usage Guidelines


Table 2: Interface Name
Interface Name

DS3 link

atm 0/1

T1/E1 link 0

atm 0/2

T1/E1 link 1

atm 0/3

T1/E1 link 2

atm 0/4

T1/E1 link 3

atm 0/5

T1/E1 link 4

atm 0/6

T1/E1 link 5

atm 0/7

T1/E1 link 6

atm 0/8

T1/E1 link 7

atm 0/9

IMA group 0

atm 0/ima0

IMA group 1

atm 0/ima1

IMA group 2

atm 0/ima2

IMA group 3

atm 0/ima3

Examples

In the following example, the trunk interface is set to T1/E1 link 2.

atm ni2-switch trunk atm0/4

Related Commands

Command Description

show atm interface

Shows ATM-specific information about all ATM interfaces.

clock source

To select the transmit clock source for a link, use the clock source interface command. When you assign a link to an IMA group interface, this command has no effect unless the link is the common clock source in the CTC IMA group. When you change the link back to g.804 mode, the system reflects the changes. To restore the default values, use the no form of this command.

clock source {loop-timed | network-derived}

Syntax Description

loop-timed

Configures the link to use the received clock as the transmit clock.

network-derived

Configures the link to use the network clock source as the transmit clock.

Defaults

The clock source is network-derived by default (clock source network-derived).

Command Modes

Interface configuration.

Command History

Release Modification

12.1(4)DA

This command was introduced.

Examples

The following example shows how to set the clock source to loop-timed.

interface atm 0/1  clock source loop-timed

Related Commands

Command Description

show controllers

Displays information about a physical port device.

framing

To select the frame type for the data link, use the framing interface configuration command. To restore the default values, use the no form of this command.

framing framingmode

Syntax Description

framingmode

Specifies framingmode as follows:

  • For E1: pcm30 | crc4

  • For T1: esf | sf

  • For DS3: cbitadm | cbitplcp | m23adm | m23plcp

Defaults

For E1: pcm30

For T1: esf

For DS3: cbitadm

Command Modes

Interface configuration.

Command History

Release Modification

12.1(4)DA

This command was introduced.

Usage Guidelines

In the E1 environment, the framing command allows selection of the E1 frame type to CRC4 enabled framing mode (crc4) or CRC4 disabled framing mode (pcm30).

In the T1 environment, the framing command allows selection of the T1 frame type to extended super frame (esf) or super frame (sf).

In the DS3 environment, the framing command allows the selection of the DS3 frame type to C-Bit ADM, C-Bit PLCP, M23 ADM, or M23 PLCP.

Note   The framing type must match on both sides of a link.

Examples

The following example shows how to select m23plcp as the frame type.

interface atm 0/1  framing m23plcp

Related Commands

Command Description

show controllers

Displays information about a physical port device.

ima active-links-minimum

To configure the minimum number of active links required for an IMA group to function, use the ima active-links minimum interface configuration command. To restore the default value, use the no form of this command.

ima active-links minimum number

no ima active-links minimum

Syntax Description

number

Configures the minimum number (1 to 8) of active links for an IMA group to function.

Defaults

No minimum links is the default (no ima active-links-minimum or ima active-links-minimum 1).

Command Modes

Interface configuration.

Command History

Release Modification

12.1(4)DA

This command was introduced.

Usage Guidelines

This command sets the minimum number of links that must be in the active state before the IMA group interface will become active. If at any time the number of active links is less than this value, then the IMA group interface will no longer be active.

Examples

The following example uses the ima active-links-minimum command to configure the minimum number of active links that must be active for the IMA group to function correctly.

interface atm 0/ima0  ima active-links-minimum 2

Related Commands

Command Description

show ima interface

Displays information about all IMA groups and the links in those groups.

show ima interface atm0/ima group-number

Displays information about a single IMA group and the links in that group.

ima clock-mode

To set the transmit clock mode for an ATM IMA group, use the ima clock-mode interface configuration command. To restore the default value, use the no form of this command.

ima clock-mode {common {2-9} | independent}

no ima clock-mode

Syntax Description

common

Configures the group with a link number that is used as a common clock source to all other links in the IMA group. If the specified link is not available, another link in the group will be used until the specified link is added.

independent

Configures the group so that each link in the group is clocked independently based on its own clock source setting.

Defaults

By default, the first link added to the group is used as the common clock source (ima clock-mode common).

Command Modes

Interface configuration.

Command History

Release Modification

12.1(4)DA

This command was introduced.

Usage Guidelines

This command controls the clock for the IMA group as a whole. When you set the independent keyword, the clock source interface configuration command is used under each interface to determine clocking individually. When you set the common keyword, the clock source interface configuration command for the common link determines clocking for all the links in the group.

Note   The IMA clock mode must match on both sides of an IMA link.

Examples

The following example uses the ima clock-mode command to configure the IMA group clocking mode as independent.

interface atm 0/ima0  ima clock-mode independent

Related Commands

Command Description

clock source

Selects the transmit clock source for a link.

ima differential-delay-maximum

To set the maximum allowable differential delay in milliseconds allowed between links for the IMA group to be considerable, use the ima differential-delay-maximum interface configuration command. To restore the default value, use the no form of this command.

ima differential-delay-maximum {msecs}

no ima differential-delay-maximum

Syntax Description n

msecs

Configures the maximum differential delay in milliseconds as follows:

  • For T1 the range is 25 to 69 milliseconds.

  • For E1 the range is 25 to 55 milliseconds.

Defaults

The default is 25 milliseconds.

Command Modes

Interface configuration.

Command History

Release Modification

12.1(4)DA

This command was introduced.

Usage Guidelines

The transmitter on the T1/E1 IMA port adapter must align the transmission of IMA frames on all interfaces that are members of the IMA group. This allows the receiver to adjust for differential link delays among the interfaces that are members of the IMA group. Based on this required behavior, the receiver can detect the differential delays by measuring the arrival times of the IMA frames on each link.

At the transmitting end, the cells are transmitted continuously. If no ATM layer cells need to be sent between ICP cells with an IMA frame, then the transmit IMA sends filler cells to maintain a continuous stream of cells at the physical layer.

Examples

The following example configures the maximum allowable differential delay to 55 milliseconds for all interfaces assigned to the IMA group.

interface atm 0/ima0  ima differential-delay-maximum 55

Related Commands

Command Description

show ima interface

Displays information about all IMA groups and the links in those groups.

show ima interface atm0/ima group-number

Displays information about a single IMA group and the links in that group.

DSLAM# show ima interface atm0/interface-number

Displays information for a single link in an IMA group including delay on that link.

ima frame-length

To set the IMA frame length in cells per frame, use the ima frame-length interface configuration command.

ima frame-length {32 | 64 | 128 | 256}

no ima frame-length

Syntax Description

32

Configures IMA frame length to 32 cells.

64

Configures IMA frame length to 64 cells.

128

Configures IMA frame length to 128 cells (default).

256

Configures IMA frame length to 256 cells.

Defaults

The default is 128 cells.

Command Modes

Interface configuration.

Command History

Release Modification

12.1(4)DA

This command was introduced.

Usage Guidelines

An IMA group uses the frame length parameter to set the insertion of the ICP cells at the beginning of frames in the transmit direction. Normally, one ICP cell is sent per IMA frame. The larger the IMA frame the less overhead there is at the expense of a decrease in allowable timing differences between the lengths.

Examples

The following example uses the ima frame-length command to configure the frame length transmitted as 64 cells for the IMA group.

interface atm 0/ima0  ima frame-length 64

Related Commands

Command Description

show ima interface

Displays information about all IMA groups and the links in those groups.

ima group

To assign a T1/E1 link to an IMA group, use the ima-group interface configuration command. To remove a link from an IMA group, use the no form of this command.

ima group number

no ima group

Syntax Description

number

Specifies the IMA group number (0 to 3).

Defaults

The links do not belong to any IMA group by default.

Command Modes

Interface configuration.

Command History

Release Modification

12.1(4)DA

This command was introduced.

Usage Guidelines

Use the ima-group interface command to configure a T1/E1 port adapter interface as part of an IMA group. IMA allows you to aggregate multiple low-speed links into one larger virtual trunk or IMA group and appears to your ATM switch router as one logical pipe. This IMA group provides modular bandwidth for user access to ATM networks for connections between ATM network elements that are at rates between traditional multiplexing levels, such as between T1/E1, and DS3/ E3.

IMA requires inverse multiplexing and demultiplexing of ATM cells in a cyclical fashion among links grouped to form a higher-bandwidth logical group with a rate of approximately the sum of the link rates. This grouping is called an IMA group.

Examples

The following example uses the ima group command to assigns link 0 to IMA group 0.

interface atm 0/2  ima-group 0

Related Commands

Command Description

show controllers

Displays information about a physical port device.

show ima interface

Displays information about all IMA groups and the links in those groups.

show ima interface atm0/ima group-number

Displays information about a single IMA group and the links in that group.

ima test

To configure an IMA group test pattern transmitted in the ICP cells, use the ima test interface configuration command. To restore the default value, use the no form of this command.

ima test [link link-value] [pattern pattern-value]

no ima test

Syntax Description

link

Configures the link that is transmitting the test pattern.

link-value

Specifies which IMA group member link (2 through 9) is transmitting the test pattern.

pattern

Configures the test pattern.

pattern-value

Specifies the test pattern (0 through 255) transmitted in the ICP cells.

Defaults

The link-value is 2.

The pattern-value is 0xa6.

The default is no ima test.

Command Modes

Interface configuration.

Command History

Release Modification

12.1(4)DA

This command was introduced.

Usage Guidelines

The test pattern procedure verifies the connectivity of a link within an IMA group. The procedure uses a test pattern sent over one link to verify the connectivity to the other links in the IMA group. The test pattern should be looped over all the other links in the group at the far end of the connection. All of the IMA test pattern procedures are performed over the ICP cells exchanged between both ends of the IMA virtual links. After the test is configured on the IMA group, the test continues explicitly until configured to the default.

Examples

The following example uses the ima test command to configure the test pattern of 100 to transmit over ATM interface 0 of IMA group 0.

interface atm 0/ima0  ima test link 2 pattern 100

Related Commands

Command Description

show ima interface

Displays information about all IMA groups and the links in those groups.

ima version

To set the operating mode of an IMA group, use the ima version interface configuration command. To restore the default value, use the no form of this command.

ima version {1.0 | 1.1}

no ima version

Syntax Description

1.0

Specifies that the group run in version 1.0 mode.

1.1

Specifies that the group run in version 1.1 mode.

Defaults

The default is version 1.0 mode.

Command Modes

Interface configuration.

Command History

Release Modification

12.1(4)DA

This command was introduced.

Examples

The following example uses the ima version command to set the IMA version to 1.1.

interface atm 0/ima0  ima version 1.1

Related Commands

Command Description

show ima interface

Displays information about all IMA groups and the links in those groups.

show ima interface atm0/ima group-number

Displays information about a single IMA group and the links in that group.

lbo

To set the line build-out to various lengths, use the lbo interface configuration command. To restore the default values, use the no form of this command.

lbo {short {133 | 266 | 399 | 533 | 655} | long {gain10 | gain36} {0db | -7.5db | -15db | -22.5db}}

no lbo

Syntax Description

short

Specifies a short cable length. Must be followed by a length value. The range mapping for each value is shown below:

Value        Range (feet)

133          0 to 133

266          134 to 266

399          267 to 399

533          400 to 533

655          534 to 655

long

Specifies a cable length line build out. Long must be followed by a gain and a margin value.

Defaults

The default setting is long haul with gain36 and 0db (lbo long gain36 0db).

Command Modes

Interface configuration.

Command History

Release Modification

12.1(4)DA

This command was introduced.

Usage Guidelines

This command is applicable to T1 links.

Examples

The following example shows how to select long as the cable length.

interface atm 0/2  lbo long gain36 -15db

The following example shows how to select short as the cable length.

interface atm 0/2  lbo short 266

Related Commands

Command Description

show controllers

Displays information about a physical port device.

linecode

To select the linecode type of the T1/E1 link, use the linecode interface configuration command. To restore the default values, use the no form of this command.

linecode {ami | b8zs | hdb3}

no linecode {ami | b8zs | hdb3}

Syntax Description

ami

Specifies alternate mark inversion (AMI) as the linecode type. Valid for T1 or E1 controllers.

b8zs

Specifies B8ZS as the linecode type. Valid for T1 controller.

hdb3

Specifies HDB3 as the linecode type. Valid for E1 controller.

Defaults

T1 = b8zs

E1 = hdb3

Command Modes

Interface configuration.

Command History

Release Modification

12.1(4)DA

This command was introduced.

Usage Guidelines

Use this command to match the line code of the far end device.

Examples

The following example specifies AMI as the linecode type.

interface atm 0/ima0  linecode ami

Related Commands

Command Description

show controllers

Displays information about a physical port device.

scrambling

To enable or disable T1/E1 cell payload scrambling on a link, use the scrambling interface configuration command. To restore the default values, use the no form of this command.

scrambling cell-payload

no scrambling cell-payload

Syntax Description

cell payload

This is the scrambling mode.

Defaults

Scrambling cell-payload is disabled.

Usage Guidelines

The scrambling type must match on both sides of a link.

Command Modes

Interface configuration.

Command History

Release Modification

12.1(4)DA

This command was introduced.

Examples

The following example uses the scrambling command to enable scrambling on the specified interface.

interface atm 0/ima0  scrambling cell-payload

Glossary

A

AAL-1

ATM Adaption Layer. This layer maps higher layer user data into ATM cells, making the data suitable for transport through the ATM network.

AAL-5

ATM Adaption Layer. This layer maps higher layer user data into ATM cells, making the data suitable for transport through the ATM network.

AIS

Alarm Indication Signal. In a T1 transmission, an all-ones signal transmitted in lieu of the normal signal to maintain transmission continuity and to indicate to the receiving terminal that there is a transmission fault that is located either at, or upstream from, the transmitting terminal.

Asynchronous Transfer Mode

See ATM.

ATM

Asynchronous Transfer Mode. A cell-based data transfer technique in which channel demand determines packet allocation. ATM offers fast pack technology, real time, demand led switching for efficient use of network resources.

B

broadband

Characteristic of any network that multiplexes independent network carriers onto a single cable. This is usually done using frequency division multiplexing (FDM). Broadband technology allows several networks to coexist on one single cable; traffic from one network does not interfere with traffic from another since the "conversations" happen on different frequencies in the "ether" rather like the commercial radio system.

C

CCO

Cisco Connection Online.

chassis

The card cage (housing) where modules are placed.

Cisco Connection Online

See CCO.

D

digital signal level 3

See DS3.

Distributed Defect Tracking System

See DDTS.

DS3

digital signal level 3. Framing specification used for transmitting digital signals at 44.736 Mbps on a T3 facility.

DSLAM

Digital Subscriber Line Access Multiplexer. Concentrates and multiplexes digital subscriber line signals at the telephone service provider location to the broadband wide area network. Replaces ADSLAM.

E

E1

A digital carrier that is used to transmit a formatted signal at 2.048 Mbps.

E3

A digital carrier that is used to transmit a formatted signal at 34.368 Mbps.

F

frame

A packet as it is transmitted over a serial line. The term derives from character oriented protocols where special start-of-frame and end-of-frame characters were added when transmitting packets.

I

IMA

inverse multiplexing over ATM. Standard protocol defined by the ATM Forum in 1997.

M

Management Information Base

See MIB.

MIB

Management Information Base. A collection of objects that can be accessed via a network management protocol, such as SNMP and CMIP (Common Management Information Protocol).

N

NI-2

A second generation network interface card.

S

Simple Network Management Protocol

See SNMP.

slot

A numbered location within a chassis capable of housing a module.

SNMP

Simple Network Management Protocol. The network management protocol of choice for TCP/IP-based internets.

T

T3

A digital carrier that is used to transmit a DS3 formatted digital signal at 45 Mbps.

U

UNI

User-Network Interface. ATM Forum specification that defines an interoperability standard for the interface between ATM-based products (a router or an ATM switch) located in a private network and the ATM switches located within the public carrier networks. Also used to describe similar connections in Frame Relay networks.

UNI signaling

User-Network Interface signaling for ATM communications.

V

VC

Virtual Circuit. A logical circuit created to ensure reliable communication between two network devices. A virtual circuit is defined by a VPI/VCI pair, and can be either permanent (PVC) or switched (SVC). In ATM, a virtual circuit is called a virtual channel. Sometimes abbreviated VC. See also PVC, SVC, VCI, and VPI.

virtual circuit

See VC.

VPI

Virtual Path Identifier. An 8-bit field in the header of an ATM cell. The VPI, together with the VCI, is used to identify the next destination of a cell as it passes through the network. See also VCI.


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Posted: Wed Jul 17 08:23:45 PDT 2002
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