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This feature allows multiple cable interfaces to share a single IP subnet. Currently, you must use an IP subnet for each cable interface. If you have limited IP address space, interface bundling conserves your IP address resources.
Interface bundling enhances the scalability of the cable network by allowing you to add new cable interface cards without having to reassign IP addresses to the interfaces or to the cable modem users on those interfaces. You can also move cable modems to any cable interface on the bundle without assigning the modems a new IP address. In particular, cable modems being assigned a static IP address can be inserted on to any interface that is part of the assigned bundle.
Cable interface bundling eliminates the need for an IP subnet for each cable interface. With this feature, you only need one IP subnet for each cable bundle. You can also group all the cable interfaces on a Cisco uBR7200 series cable router into a single bundle and configure your uBR7200 router with a single IP subnet. This simplifies network management and conserves IP address space.
Cable interface bundling is only supported on cable interfaces. It is not supported on other interfaces.
Cable interface bundling can be used only in two-way cable installations. It is not supported for telco-return configurations.
One cable interface must be configured as the master interface for the bundle. The other cable interfaces are configured as slave interfaces.
Generic cable configuration commands such as the IP address, DHCP relay, ARP handling, and source-verify checking must be specified on the master interface. Do not specify these commands for the slave cable interfaces. Cable upstream and downstream parameters continue to be specified for each interface.
You must configure interface bundles only by using CLI commands. You cannot use MIB objects to configure cable interface bundles through SNMP sets.
If 1+1 redundancy has been configured, the failure of any card in the bundle moves the entire bundle to the redundant CMTS.
Table 1shows the progression of documented features that have been added to the uBR platform in the Cisco IOS 12.0 time frame.
| Available With: | Category | Feature |
|---|---|---|
The Cisco uBR7200 series cable router is described in Voice, Video, and Home Applications Configuration Guide for Cisco IOS Release 12.0 and in the feature modules that accompany each Cisco IOS Release. Also see the documents in the Broadband/Cable Solutions page on CCO (http://www.cisco.com) and the customer documentation CD-ROM.
No new or modified standards are supported by this feature.
No new or modified MIBs are supported by this feature.
No new or modified RFCs are supported by this feature.
See the following section for configuring cable interface bundling.
| Command | Purpose |
|---|---|
Configures the cable interface to be the master for the interface bundle n |
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Configures the cable interface to be part of the previously created interface bundle n |
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 |
Note Configuring a cable interface to be part of a bundle automatically shuts down and again enables the interface. All modems currently on the interface will go offline and have to reregister with the CMTS before coming back online. |
| Command | Purpose |
|---|---|
This section provides the following configuration examples:
This section documents the new commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command reference publications.
To configure a cable interface to belong to an interface bundle, use the cable bundle interface configuration command. To delete a cable interface bundle definition, use the no form of this command.
Syntax Description
Specifies the bundle identifier. Valid range is from 1 to 255. |
|
(Optional) Defines the specified interface as the master. One cable interface in the bundle must be defined as the master. |
Defaults
No default behavior or values.
Command Modes
Command History
| Release | Modification |
|---|---|
Usage Guidelines
You can configure up to four interface bundles. In each bundle, specify one interface as the master interface by using the optional master keyword. The master interface is configured with layer 3 configuration commands, such as primary and secondary IP addresses and other layer 3 specific configuration commands such as cable arp.
Only configure an IP address on the master interface. Any attempt to add an interface to a bundle will be rejected, if an IP address is configured and the interface is not specified as master interface.
You must specify all generic IP networking information (IP address, routing protocols, switching modes, and so on.) on the bundle master interface. Do not specify generic IP networking information on bundle slave interfaces.
If you attempt to add an interface to a bundle as non-master interface and an IP address is assigned to this interface, the command will fail. You must remove the IP address configuration before you can add the interface to a bundle.
If you have configured an IP address on a bundled interface and the interface is not the master interface, a warning message appears.
Specify generic (that is, not downstream or upstream related) cable interface configurations, such as source-verify or ARP handling, on the master interface. Do not specify generic configuration on non-master interfaces.
Configuring a cable interface to be part of a bundle automatically shuts down and enables the interface. All modems currently on the interface will go offline and have to reregister with the CMTS before coming back online.
If you configure an interface as part of a bundle and it is not the master interface, all generic cable configuration for this interface is removed. The master interface configuration will then apply to all interfaces in the bundle.
If you shut down or remove the master interface in a bundle, no data packets is sent to any of the interfaces in this bundle. Packets will still be physically received from non-master interfaces which have not been shut down, but those packets will be discarded. This means that modems connected to those interfaces will not be disconnected immediately, but modems coming online will not be able to obtain an IP address, download their configuration file, or renew their IP address assignment if the DHCP lease expires.
If you shut down a slave interface, only this shut down interface is affected.
Examples
The following example configures the c3/0 cable interface to be the master interface for bundle 25:
The following example shows the error message you get if you try to configure an interface with an IP address that is not the master interface:
Use the no ip address command to remove to the IP address assignment and reenter the cable bundle command.
Related Commands
To display the forwarding table for the specified interface, use the show cable bundle privileged EXEC command.
Syntax Description
Defaults
No default behavior or values.
Command Modes
Command History
Examples
Table 2 describes the fields shown in the show cable bundle display.
Related Commands
Cable Interface Bundling for the Cisco\xf9 BR7200 Series Cable Router
Release
Modification
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