Command Reference Guide

Administering IP Multicast Routing and Filtering

This chapter provides guidelines and other key information about how to configure and manage IP multicast routing and multicast filtering commands from the Administration Console. You can use the IP multicast features in your system to support an efficient delivery infrastructure for IP multicast applications.

For more information about IP multicast technology, concepts, and implementation procedures, see the Implementation Guide for your system.

For the CoreBuilder 9000 platform, the commands in this chapter apply to Layer 3 switching modules only.

Menu Structure

The commands that you can use depend on the system that you have, your level of access, and the types of modules and other hardware options that are configured on your system. The following diagram shows the complete list of commands for all systems. See the checklist at the beginning of each command description in this chapter for whether your system supports the command.

ip multicast dvmrp

Prompt	Description	Possible Values	[Default]
DVMRP mode	Whether DVMRP mode is enabled or disabled	enabled disabled	disabled (factory default), or current value

ip multicast igmp

For CoreBuilder 9000: Applies to Layer 3 switching modules only.

Enables or disables two modes related to the Internet Group Management Protocol (IGMP), which facilitates router-to-host communication to determine where multicast group members exist in the network. This protocol assists DVMRP in multicast routing and is also used by the system for multicast filtering.

Valid Minimum Abbreviation

: ip m ig

Important Considerations

The IGMP modes that you select apply to the entire system. You cannot enable or disable the two IGMP modes on individual interfaces. You can, however, prevent multicast traffic from being forwarded through individual interfaces. See "ip multicast interface disable" later in this chapter.
Keep both IGMP modes enabled at all times. They add little processing overhead to the system.

Options

Prompt

Description

Possible Values

[Default]

IGMP snooping mode

Whether IGMP snooping mode is enabled or disabled

enabled
disabled

enabled (factory default), or current value

IGMP query mode

Whether IGMP query mode is enabled or disabled

enabled
disabled

enabled (factory default), or current value

Prompt	Description	Possible Values	[Default]
IGMP snooping mode	Whether IGMP snooping mode is enabled or disabled	enabled disabled	enabled (factory default), or current value
IGMP query mode	Whether IGMP query mode is enabled or disabled	enabled disabled	enabled (factory default), or current value

ip multicast interface display

For CoreBuilder 9000: Applies to Layer 3 switching modules only.

Displays information about one or all multicast interfaces in your system.

Valid Minimum Abbreviation

: ip m in disp

Options

Prompt

Description

Possible Values

[Default]

IP interfaces

Index numbers of the IP interfaces for which you want to display information

A valid IP interface index number
all
? (for a list of selectable index numbers)

-

Prompt	Description	Possible Values	[Default]
IP interfaces	Index numbers of the IP interfaces for which you want to display information	A valid IP interface index number all ? (for a list of selectable index numbers)	-

Fields in the IP Multicast Interface Display

Field

Description

DVMRP and IGMP status

Indication of how you have configured DVMRP and IGMP in the system

Index

Number that your system uses to signify the local routing interface (local address) in the next column

Local address

IP address of the local routing interface that is enabled for multicast routing and filtering

Metric

Value that you have assigned as the DVMRP metric for the interface

Port information

Port numbers in the local routing interface and corresponding peer router and multicast group information:

peer - The unicast address of a neighboring router. The additional information in parentheses relates to the version of DVMRP that is operating in the system.

group - The multicast group addresses for which packets are being received or forwarded.

State

Role that the interface plays in multicast delivery. One or more of the following descriptors may appear:

querier - The interface is functioning as the IGMP Querier.

non-querier - The interface is not functioning as the IGMP Querier.

leaf - There are no routers downstream of this interface; multicast group member reside on this subnetwork.

non-leaf - The interface is a branch in the multicast delivery tree. There are one or more multicast routing interfaces downstream of this interface.

one-way - Traffic is moving downstream only.

disabled - No multicast packets are forwarded through this interface, except multicast packets with destination addresses in the reserved range, which is 224.0.0.1 - 224.0.0.225.

Threshold

Value that you have assigned as the time-to-live (TTL) threshold for the interface

Field	Description
DVMRP and IGMP status	Indication of how you have configured DVMRP and IGMP in the system
Index	Number that your system uses to signify the local routing interface (local address) in the next column
Local address	IP address of the local routing interface that is enabled for multicast routing and filtering
Metric	Value that you have assigned as the DVMRP metric for the interface
Port information	Port numbers in the local routing interface and corresponding peer router and multicast group information:
	`peer` - The unicast address of a neighboring router. The additional information in parentheses relates to the version of DVMRP that is operating in the system.
	`group` - The multicast group addresses for which packets are being received or forwarded.
State	Role that the interface plays in multicast delivery. One or more of the following descriptors may appear:
	`querier` - The interface is functioning as the IGMP Querier.
	`non-querier` - The interface is not functioning as the IGMP Querier.
	`leaf` - There are no routers downstream of this interface; multicast group member reside on this subnetwork.
	`non-leaf` - The interface is a branch in the multicast delivery tree. There are one or more multicast routing interfaces downstream of this interface.
	`one-way` - Traffic is moving downstream only.
	`disabled` - No multicast packets are forwarded through this interface, except multicast packets with destination addresses in the reserved range, which is 224.0.0.1 - 224.0.0.225.
Threshold	Value that you have assigned as the time-to-live (TTL) threshold for the interface

ip multicast interface enable

For CoreBuilder 9000: Applies to Layer 3 switching modules only.

Changes the characteristics of an existing IP multicast interface or enables an interface that was previously disabled for multicasting.

Valid Minimum Abbreviation

: ip m in e

Important Consideration

Do not use this command to enable individual interfaces with IP multicast capabilities, because that is achieved when you enable DVMRP and IGMP modes in the system. Use this command only to re-enable interfaces that have been previously disabled or to modify the characteristics of a multicast interface.

Options

Prompt

Description

Possible Values

[Default]

IP interface index

Index number of the routing interface that you want to enable or modify

A valid IP interface index number
? (for a list of selectable index numbers)

-

Interface DVMRP metric

DVMRP cost value that you assign to the interface

1 - 15

1

Interface TTL threshold

TTL threshold value that you assign to the interface

1 - 255

1

Prompt	Description	Possible Values	[Default]
IP interface index	Index number of the routing interface that you want to enable or modify	A valid IP interface index number ? (for a list of selectable index numbers)	-
Interface DVMRP metric	DVMRP cost value that you assign to the interface	1 - 15	1
Interface TTL threshold	TTL threshold value that you assign to the interface	1 - 255	1

: ip multicast interface disable

For CoreBuilder 9000: Applies to Layer 3 switching modules only.

Disables IP multicast functions on an existing IP interface.

Valid Minimum Abbreviation

: ip m in disa

Important Consideration

Disabling an interface through the IP multicast menu is not the same as removing an IP interface. Disabling an interface through the IP multicast menu leaves the routing interface in place, but causes it to filter nearly all multicast packets. Only multicast packets with addresses in the reserved range (224.0.0.1 - 224.0.0.225) are forwarded after an interface is disabled for multicasting.

Options

Prompt

Description

Possible Values

[Default]

IP interface index

Index number of the routing interface that you want to disable for IP multicasting

A valid IP interface index number
? (for a list of selectable index numbers)

-

Prompt	Description	Possible Values	[Default]
IP interface index	Index number of the routing interface that you want to disable for IP multicasting	A valid IP interface index number ? (for a list of selectable index numbers)	-

ip multicast tunnel display

For CoreBuilder 9000: Applies to Layer 3 switching modules only.

Displays information about the IP multicast tunnels that are configured in your system.

Valid Minimum Abbreviation

: ip m t di

Important Considerations

When you define a tunnel, the system assigns a tunnel index number to it. The multicast tunnel display lists tunnels in ascending order by the tunnel index number. Tunnel index numbers provide a way to identify and remove individual tunnels, which is especially useful when multiple tunnel end points are configured on the same routing interface.
When you remove a tunnel, the system does not dynamically re-order remaining tunnels in the multicast tunnel display. For example, if you had three tunnels with tunnel index numbers 1, 2, and 3 and you then removed tunnel 2, the tunnel display lists the remaining tunnels and identifies them with their original tunnel index numbers (1 and 3, in this example). The system does not dynamically re-assign tunnel index numbers (does not change 3 to 2, in this example). The system assigns tunnel index 2 to the next new tunnel that you define. After 2 is used, the system can assign tunnel index 4 for the next new tunnel, and so on.
You can define multiple multicast tunnel end points on the same local routing interface, but each must lead to a different remote interface. To determine if multiple tunnel end points are configured on the same local interface, bring up the multicast tunnel display and look for entries that have the same local address but different remote addresses.
You cannot define multiple IP multicast tunnels between the same two end points (interfaces).

Fields in the IP Multicast Tunnel Display

Field

Description

DVMRP and IGMP status

Indication of how you have configured DVMRP and IGMP in the system.

Index

Tunnel index number, which is different from the routing interface index number that is shown under Index in other displays.

Local address

IP address of the local interface that serves as one of two multicast tunnel end points.

Metric

DVMRP cost that you assigned to the tunnel when you defined it. This value can be different from the DVMRP cost that you assigned to the routing interface.

Pkts in, pkts out

Number of packets traveling through the tunnel. The count starts when you define the tunnel and stops when you remove the tunnel.

Remote address

IP address of the remote interface (a different system, a different subnetwork) that serves as the other multicast tunnel end point.

State

Role played by the local interface in the multicast delivery tree. For possible entries and definitions, see "ip multicast interface display" earlier in this chapter.

Threshold

TTL threshold value that you assigned to the tunnel when you defined it. This value can be different from the TTL threshold value that you assigned to the local interface.

Field	Description
DVMRP and IGMP status	Indication of how you have configured DVMRP and IGMP in the system.
Index	Tunnel index number, which is different from the routing interface index number that is shown under `Index` in other displays.
Local address	IP address of the local interface that serves as one of two multicast tunnel end points.
Metric	DVMRP cost that you assigned to the tunnel when you defined it. This value can be different from the DVMRP cost that you assigned to the routing interface.
Pkts in, pkts out	Number of packets traveling through the tunnel. The count starts when you define the tunnel and stops when you remove the tunnel.
Remote address	IP address of the remote interface (a different system, a different subnetwork) that serves as the other multicast tunnel end point.
State	Role played by the local interface in the multicast delivery tree. For possible entries and definitions, see "ip multicast interface display" earlier in this chapter.
Threshold	TTL threshold value that you assigned to the tunnel when you defined it. This value can be different from the TTL threshold value that you assigned to the local interface.

ip multicast tunnel define

For CoreBuilder 9000: Applies to Layer 3 switching modules only.

Defines a multicast tunnel. One end of the tunnel is located on a multicast routing interface in your local system; the other tunnel end point is a multicast routing interface on a different system and subnetwork. One or more unicast routers lie between these tunnel end points.

Valid Minimum Abbreviation

: ip m t de

Important Considerations

Think of a multicast tunnel end point as being layered on top of a regular multicast routing interface. Therefore, before you can define a multicast tunnel end point in your system, you must first define an IP virtual LAN (VLAN), an IP interface, and enable DVMRP.
The remote tunnel end point that is paired with a local tunnel end point must lie on a different subnetwork.
You must define the tunnel on both end points - that is, on both the local system and the remote system - even though you specify the address of the remote router interface in the local system.
Multicast interfaces and multicast tunnels have similar characteristics. If you configure a multicast interface with certain DVMRP metric and TTL threshold values, and then you later configure a tunnel end point on this interface, the tunnel characteristics do not have to match the interface characteristics.
You can define multiple tunnel end points on the same local routing interface in your system, but these tunnels must lead to different remote routing interfaces. To determine if multiple tunnel end points are configured on the same local interface, bring up the multicast tunnel display and look for entries that have the same local address but different remote addresses.
For the tunnel to function, the interface that is paired with the tunnel end point must not be disabled for multicasting. If you disable an interface for multicasting (using the ip multicast interface disable command) and you had a tunnel end point defined on that interface, the system disables the interface and does not warn you with an error message. The multicast tunnel configuration remains in place, but it does not function.

Options

Prompt

Description

Possible Values

[Default]

IP interface index

Index number of the interface that you want to associate with a multicast tunnel end point

A valid IP interface index number
? (for a list of selectable index numbers)

-

Remote IP address

IP address of the remote multicast tunnel end point. Use standard dotted decimal notation.

A valid remote IP address on a different subnetwork

-

Tunnel DVMRP metric

DVMRP cost that you assign to the tunnel

1 - 15

1

Tunnel TTL threshold

TTL threshold that you assign to the tunnel

1 - 255

1

Prompt	Description	Possible Values	[Default]
IP interface index	Index number of the interface that you want to associate with a multicast tunnel end point	A valid IP interface index number ? (for a list of selectable index numbers)	-
Remote IP address	IP address of the remote multicast tunnel end point. Use standard dotted decimal notation.	A valid remote IP address on a different subnetwork	-
Tunnel DVMRP metric	DVMRP cost that you assign to the tunnel	1 - 15	1
Tunnel TTL threshold	TTL threshold that you assign to the tunnel	1 - 255	1

ip multicast tunnel remove

For CoreBuilder 9000: Applies to Layer 3 switching modules only.

Deletes a multicast tunnel end point from the system.

Valid Minimum Abbreviation

: ip m t re

Important Considerations

To remove a tunnel, you must specify its tunnel index number. This number is different from the routing interface index number. The system assigns tunnel index numbers when you define tunnels and shows them in the multicast tunnel display.
The system does not confirm it has removed the tunnel that you specified. However, you can confirm this by using the ip multicast tunnel display command.
If you try to remove an IP interface in your system, and you have a multicast tunnel defined on that interface, the system warns you with an error message. Before you can remove the IP interface, you must remove the multicast tunnel.
When you remove a tunnel, the system does not dynamically re-order remaining tunnels in the multicast tunnel display. For example, if you had three tunnels with tunnel index numbers 1, 2, and 3 and you then removed tunnel 2, the tunnel display lists remaining tunnels and identifies them with their original tunnel index numbers (1 and 3). The system does not dynamically re-assign tunnel index numbers (does not change 3 to 2). In this example, the system assigns tunnel index 2 to the next new tunnel that is defined. After 2 is used, the system assigns tunnel index 4 (the next consecutive number) to the next new tunnel, and so on.

Options

Prompt

Description

Possible Values

[Default]

Multicast tunnel index

Index number of the multicast tunnel that you want to remove from the system

A valid multicast tunnel index number
? (for a list of selectable tunnel index numbers)

-

Prompt	Description	Possible Values	[Default]
Multicast tunnel index	Index number of the multicast tunnel that you want to remove from the system	A valid multicast tunnel index number ? (for a list of selectable tunnel index numbers)	-

ip multicast routeDisplay

For CoreBuilder 9000: Applies to Layer 3 switching modules only.

Displays all multicast route information that your system uses to receive and forward multicast traffic.

Valid Minimum Abbreviation

: ip m r

Fields in the IP Multicast Route Display

Field

Description

DVMRP and IGMP status

Indication of how you have configured DVMRP and IGMP in the system.

From-gateway

IP address of the router that lies upstream of the local system on the path back to the origin subnetwork. If the origin subnetwork is connected directly to your system, this field is blank.

In-If

Index number of the interface that connects to the upstream router (the From-Gateway). The system receives incoming multicast source traffic through this interface for forwarding. However, your system may also send prune or graft messages or other multicast protocol traffic through this interface to the upstream router. Other important things to know about this column:

Because DVMRP forms a loopless spanning tree to reach all hosts, your system always chooses a single In-If. This interface is called the parent interface.
Either an I or a T precedes the index number:
I indicates a regular multicast interface; T indicates that a tunnel end point is configured on that interface.

Metric

Number of hops from your system back to the origin subnetwork. This value is not the DVMRP metric, which is shown under Metric in other displays.
Occasionally, instead of a numeric value, you may see NR, meaning "network unreachable." Route display entries are refreshed periodically; your system may remember that it has forwarded traffic from a certain address recently, but occasionally it may have trouble computing the hop count because of factors such as an upstream router being temporarily congested. This condition is usually resolved in a short period of time.

Origin-subnet

Subnetwork address and bit-length mask where multicast traffic originates. Both sources and group members generate multicast traffic.

Out-Ifs

Index numbers of the interfaces that communicate with downstream routers or local subnetworks. The system forwards outgoing multicast source traffic through these interfaces. However, your system may also receive prune and graft messages or other information (such as IGMP Host Reports) from these interfaces. Other important things to know about this column:

There can be one or more outgoing interfaces for each multicast source-group pair. These interfaces are called child interfaces.
Either an I or a T precedes the index number:
I indicates a regular multicast interface; T indicates that a tunnel end point is configured on that interface.
An asterisk (*) follows an index number if it is a leaf interface in the multicast delivery tree.

Tmr

Amount of time (in seconds) since each entry was last reset.

Field	Description
DVMRP and IGMP status	Indication of how you have configured DVMRP and IGMP in the system.
From-gateway	IP address of the router that lies upstream of the local system on the path back to the origin subnetwork. If the origin subnetwork is connected directly to your system, this field is blank.
In-If	Index number of the interface that connects to the upstream router (the From-Gateway). The system receives incoming multicast source traffic through this interface for forwarding. However, your system may also send prune or graft messages or other multicast protocol traffic through this interface to the upstream router. Other important things to know about this column: Because DVMRP forms a loopless spanning tree to reach all hosts, your system always chooses a single In-If. This interface is called the parent interface. Either an `I` or a `T` precedes the index number: `I` indicates a regular multicast interface; `T` indicates that a tunnel end point is configured on that interface.
Metric	Number of hops from your system back to the origin subnetwork. This value is not the DVMRP metric, which is shown under `Metric` in other displays. Occasionally, instead of a numeric value, you may see `NR`, meaning "network unreachable." Route display entries are refreshed periodically; your system may remember that it has forwarded traffic from a certain address recently, but occasionally it may have trouble computing the hop count because of factors such as an upstream router being temporarily congested. This condition is usually resolved in a short period of time.
Origin-subnet	Subnetwork address and bit-length mask where multicast traffic originates. Both sources and group members generate multicast traffic.
Out-Ifs	Index numbers of the interfaces that communicate with downstream routers or local subnetworks. The system forwards outgoing multicast source traffic through these interfaces. However, your system may also receive prune and graft messages or other information (such as IGMP Host Reports) from these interfaces. Other important things to know about this column: There can be one or more outgoing interfaces for each multicast source-group pair. These interfaces are called child interfaces. Either an `I` or a `T` precedes the index number: `I` indicates a regular multicast interface; `T` indicates that a tunnel end point is configured on that interface. An asterisk (`*`) follows an index number if it is a leaf interface in the multicast delivery tree.
Tmr	Amount of time (in seconds) since each entry was last reset.

ip multicast cacheDisplay

For CoreBuilder 9000: Applies to Layer 3 switching modules only.

Displays the multicast cache, which is a collection of information about the multicast packets that your system observes.

Valid Minimum Abbreviation

: ip m c

Options

Prompt

Description

Possible Values

[Default]

Multicast source address

Source for which you want to view cache information

Depends on your network
255.255.255.255 for all sources

255.255.255.255 (factory default), or current value

Multicast group address

Multicast group for which you want to view cache information

Depends on your network
255.255.255.255 for all groups

255.255.255.255 (factory default), or current value

Prompt	Description	Possible Values	[Default]
Multicast source address	Source for which you want to view cache information	Depends on your network 255.255.255.255 for all sources	255.255.255.255 (factory default), or current value
Multicast group address	Multicast group for which you want to view cache information	Depends on your network 255.255.255.255 for all groups	255.255.255.255 (factory default), or current value

Fields in the IP Multicast Cache Display

Field

Description

Age

Time since the cache entry was originally created. Time is recorded in hours (h), minutes (m), or seconds (s). Because cache entries are refreshed if traffic is flowing, entries can become very old.

CTmr

Cache timer value, which indicates the remaining life for each entry. Time is recorded in minutes (m) or seconds (s). The system assigns an average life of approximately 7 minutes to each entry (it may be more or less; the system assigns random values between 300 and 600 seconds.) When the cache timer drops to zero, the entry either disappears or is refreshed.

DVMRP and IGMP status

Indication of how you have configured DVMRP and IGMP in the system.

In-If

Index number of the local interface that receives multicast traffic from the origin, as well as the relevant port numbers. One or more of the following symbols may also appear:

Either an I or a T precedes the index number: I indicates a regular multicast interface; T indicates that a tunnel entrance point is configured on that interface.
A P after the index number indicates that a prune message has been sent to an upstream router.
The entry <none> may appear if the system is not able to build the cache entry correctly. This temporary condition corrects itself quickly.

M-cast group

Multicast group address. The cache may contain several entries for the same multicast group because packets addressed to the same multicast group may come from several different subnetworks. Both sources and hosts generate traffic for the same multicast group. From sources, those packets can be application-related; from hosts, those packets can be IGMP Host Membership Reports or Leave-Group messages.

Origin

Information about multicast sources:

Entries preceded by angle brackets (>) are multicast source subnetworks and bit-masks.
Entries without angle brackets are multicast source addresses within the subnetwork that is listed above them.

Out-Ifs

Index numbers to which multicast traffic is being forwarded, as well as the relevant port numbers. One or more of the following symbols may also appear:

A p after an index number indicates that the upstream router has pruned this branch of the delivery tree and no multicast packets are being forwarded through this local interface. Eventually this entry disappears from the cache display.
Either no entry or <none> appears in this column if the system is not able to build the cache entry correctly. This temporary condition corrects itself quickly.

PTmr

Time remaining before the system sends a prune message to an upstream router. Time is shown in seconds (s) or minutes (m). When traffic is actively flowing, a dash (-) indicates that no prune message has been sent upstream.

Field	Description
Age	Time since the cache entry was originally created. Time is recorded in hours (h), minutes (m), or seconds (s). Because cache entries are refreshed if traffic is flowing, entries can become very old.
CTmr	Cache timer value, which indicates the remaining life for each entry. Time is recorded in minutes (m) or seconds (s). The system assigns an average life of approximately 7 minutes to each entry (it may be more or less; the system assigns random values between 300 and 600 seconds.) When the cache timer drops to zero, the entry either disappears or is refreshed.
DVMRP and IGMP status	Indication of how you have configured DVMRP and IGMP in the system.
In-If	Index number of the local interface that receives multicast traffic from the origin, as well as the relevant port numbers. One or more of the following symbols may also appear: Either an `I` or a `T` precedes the index number: `I` indicates a regular multicast interface; `T` indicates that a tunnel entrance point is configured on that interface. A `P` after the index number indicates that a prune message has been sent to an upstream router. The entry `<none>` may appear if the system is not able to build the cache entry correctly. This temporary condition corrects itself quickly.
M-cast group	Multicast group address. The cache may contain several entries for the same multicast group because packets addressed to the same multicast group may come from several different subnetworks. Both sources and hosts generate traffic for the same multicast group. From sources, those packets can be application-related; from hosts, those packets can be IGMP Host Membership Reports or Leave-Group messages.
Origin	Information about multicast sources: Entries preceded by angle brackets (`>`) are multicast source subnetworks and bit-masks. Entries without angle brackets are multicast source addresses within the subnetwork that is listed above them.
Out-Ifs	Index numbers to which multicast traffic is being forwarded, as well as the relevant port numbers. One or more of the following symbols may also appear: A `p` after an index number indicates that the upstream router has pruned this branch of the delivery tree and no multicast packets are being forwarded through this local interface. Eventually this entry disappears from the cache display. Either no entry or `<none>` appears in this column if the system is not able to build the cache entry correctly. This temporary condition corrects itself quickly.
PTmr	Time remaining before the system sends a prune message to an upstream router. Time is shown in seconds (s) or minutes (m). When traffic is actively flowing, a dash (`-`) indicates that no prune message has been sent upstream.