ip multicast-routing

To enable IPv4 Multicast routing on all IP-enabled interfaces of the router and to enable Multicast forwarding, use the ip multicast-routing command in global configuration mode. To stop Multicast routing and forwarding, use the no form of this command.

Syntax

ip multicast-routing [pim | igmp-proxy] no ip multicast-routing

Parameters

• pim—Enable Multicast routing using Protocol Independent Multicast (PIM).
• igmp-proxy—Enable Multicast routing using IGMP Proxy.

Default Configuration

Multicast routing is not enabled.

Command Mode

Global Configuration mode

User Guidelines

Use the ip multicast-routing command with parameter to specify the needed IP Multicast Routing Protocol.

The ip multicast-routing command without parameter enables PIM.

To forward IPv4 Multicast packets on an interface, IPv4 Multicast forwarding must be enabled globally and an IPMv4 Routing protocol must be enabled on the interface.

Example

The following example enables IP Multicast routing using IGMP Proxy:

switchxxxxxx(config)# ip multicast-routing igmp-proxy

ip multicast ttl-threshold

To configure the time-to-live (TTL) threshold of packets being forwarded out an interface, use the ip multicast ttl-threshold command in Interface Configuration mode. To return to the default TTL threshold, use the no form of this command.

Syntax

ip multicast ttl-threshold ttl-value no ip multicast ttl-threshold

Parameters

• ttl-value—Time-to-live value, in hops. It can be a value from 0 to 256.

Default Configuration

The default TTL value is 0.

Command Mode

Interface Configuration mode

User Guidelines

Multicast packets with a TTL value less than the threshold will not be forwarded on the interface.

The default value of 0 means all Multicast packets are forwarded on the interface.

A value of 256 means that no Multicast packets are forwarded on the interface.

You should configure the TTL threshold only on border routers. Conversely, routers on which you configure a TTL threshold value automatically become border routers.

Example

The following example sets the TTL threshold on a border router to 200:

switchxxxxxx(config)# interface vlan 100 switchxxxxxx(config-if)# ip multicast ttl-threshold 200 switchxxxxxx(config-if)# exit

show ip mroute

To display the contents of the Multicast routing (mroute) table, use the show ip mroute command in user EXEC or privileged EXEC mode.

Syntax show ip mroute [group-address [source-address]] [summary]

Parameters

• group-address—Destination Multicast IP address.
• source-address—Source IP address.
• summary—Filters the output to display a one-line, abbreviated summary of each entry in the mroute table.

Command Mode

User EXEC mode

Privileged EXEC mode

User Guidelines

Use the show ip mroute command to display information about Mroute entries in the mroute table. The switch populates the Multicast routing table by creating (S, G) entries from (*, G) entries. The asterisk (*) refers to all source addresses, the “S” refers to a single source address, and the “G” is the destination Multicast group address. In creating (S, G) entries, the switch uses the best path to that destination group found in the Unicast routing table (that is, through Reverse Path Forwarding [RPF]).

Examples

Description of Significant fields in the examples below

Flags:—Provides information about the entry.

• C—Connected. A member of the Multicast group is present on the directly connected interface.
• L—Local. The router itself is a member of the Multicast group.
• S—Sparse. Entry is operating in sparse mode.
• s—SSM Group. Indicates that a Multicast group is within the SSM range of IP addresses. This flag is reset if the SSM range changes.
• R—RP-bit set. Indicates that the (S, G) entry is pointing toward the RP. This flag typically indicates a prune state along the shared tree for a particular source.
• F—Register flag. Indicates that the software is registering for a Multicast source.
• T—SPT-bit set. Indicates that packets have been received on the shortest path source tree.
• J—Join SPT. For (*, G) entries, indicates that the rate of traffic flowing

down the shared tree is exceeding the SPT-Threshold set for the group. (The default SPT-Threshold setting is 0 kbps.) When the J – Join shortest path tree (SPT) flag is set, the next (S, G) packet received down the shared tree triggers an (S, G) join in the direction of the source, thereby causing the router to join the source tree.

For (S, G) entries, indicates that the entry was created because the SPT-Threshold for the group was exceeded. When the J – Join SPT flag is set for (S, G) entries, the router monitors the traffic rate on the source tree and attempts to switch back to the shared tree for this source if the traffic rate on the source tree falls below the SPT-Threshold of the group for more than 1 minute.

Note. The router measures the traffic rate on the shared tree and compares the measured rate to the SPT-Threshold of the group once every second. If the traffic rate exceeds the SPT-Threshold, the J – Join SPT flag is set on the (*, G) entry until the next measurement of the traffic rate. The flag is cleared when the next packet arrives on the shared tree and a new measurement interval is started.

If the default SPT-Threshold value of 0 kbps is used for the group, the J – Join SPT flag is always set on (*, G) entries and is never cleared. When the default SPT-Threshold value is used, the router immediately switches to the shortest path source tree when traffic from a new source is received.

• I—Received Source Specific Host Report. Indicates that an (S, G) entry

was created by an (S, G) report. This (S, G) report could have been created by Internet Group Management Protocol Version 3 (IGMPv3), URD, or IGMP v3lite. This flag is set only on the designated router (DR).

Timers:Uptime/Expires—“Uptime” indicates per interface how long (in hours, minutes, and seconds) the entry has been in the IP Multicast routing table. “Expires” indicates per interface how long (in hours, minutes, and seconds) until the entry will be removed from the IP Multicast routing table.

(*, 224.0.255.1) and (192.168.37.100/32, 224.0.255.1)—Entry in the IP Multicast routing table. The entry consists of the IP address of the source router followed by the IP address of the Multicast group. An asterisk (*) in place of the source router indicates all sources.

Entries in the first format are referred to as (*, G) or “star comma G” entries. Entries in the second format are referred to as (S, G) or “S comma G” entries. (*, G) entries are used to build (S, G) entries.

Incoming interface: —Expected interface for a Multicast packet from the source. If the packet is not received on this interface, it is discarded.

RPF neighbor or RPF nbr—IP address of the upstream router to the source. Tunneling indicates that this router is sending data to the RP encapsulated in register packets. The hexadecimal number in parentheses indicates to which RP it is registering. Each bit indicates a different RP if multiple RPs per group are used. If an asterisk (*) appears after the IP address in this field, the RPF neighbor has been learned through an assert.

Outgoing Interface List (OIF):—Interfaces through which packets will be forwarded.

Example 1. The following is sample output from the show ip mroute command with the summary keyword:

switchxxxxxx# show ip mroute summary   Timers: Uptime/Expires   IP Multicast Routing Table   (172.16.160.67/32, 224.2.127.254), 00:02:46/00:00:12, OIF count:2 (172.16.244.217/32, 224.2.127.254), 00:02:15/00:00:40, OIF count:   (172.16.8.33/32, 224.2.127.254), 00:00:25/00:02:32, OIF count:2   (172.16.2.62/32, 224.2.127.254), 00:00:51/00:02:03, OIF count:2   (172.16.8.3/32, 224.2.127.254), 00:00:26/00:02:33, OIF count:2   (172.16.60.189/32, 224.2.127.254), 00:03:47/00:00:46, OIF count:2

Example 2. The following is sample output from the show ip mroute command when IGMP Proxy is enabled:

switchxxxxxx# show ip mroute Timers: Uptime/Expires   IP Multicast Routing Table   (*, 224.0.255.3), 5:29:15/00:03:01   Incoming interface: vlan2   Outgoing interface list:     vlan100, 5:29:15/0:02:57   (192.168.46.0/24, 224.0.255.3), 05:29:15/00:02:59   Incoming interface: vlan2   Outgoing interface list:     vlan5, 05:29:15/00:02:57

Example 3. The following is sample output from the show ip mroute command when PIM is enabled:

switchxxxxxx# show ip mroute   Flags: C - Connected, L - Local,   S - Sparse, s - SSM Group, R - RP-bit set,   F - Register flag, T - SPT-bit set, J - Join SPT,   I - Received Source Specific Host Report   Timers: Uptime/Expires   IP Multicast Routing Table   (*, 224.0.255.3), 05:29:15/00:03:23, RP is 192.168.37.2, flags: SC   Incoming interface: vlan2, RPF neighbor 10.3.35.1   Outgoing interface list:     vlan100, 05:29:15/00:02:57   (192.168.46.0/24, 224.0.255.3), 05:29:15/00:02:59, flags: C   Incoming interface: vlan2, RPF neighbor 10.3.35.1   Outgoing interface list:     vlan5, 05:29:15/00:02:57

Example 4. The following is sample output from the show ip mroute command with the IP Multicast group address 232.6.6.6 specified when PIM is enabled:

switchxxxxxx# show ip mroute 232.6.6.6   Flags: C - Connected, L - Local,   S - Sparse, s - SSM Group, R - RP-bit set,   F - Register flag, T - SPT-bit set, J - Join SPT,   I - Received Source Specific Host Report   Timers: Uptime/Expires   IP Multicast Routing Table   (*, 232.6.6.6), 00:01:20/00:02:59, RP 224.0.0.0, flags:sSJP   Incoming interface:Null, RPF nbr 224.0.0.0   Outgoing interface list:Null   (10.2.2.2, 232.6.6.6), 00:01:20/00:02:59, flags:CTI   Incoming interface:vlan33, RPF nbr 224.0.0.0   Outgoing interface list:     vlan30, 00:00:36/00:02:35

Example 5. The following is sample output from the show ip mroute command with the summary keyword when PIM is enabled:

switchxxxxxx# show ip mroute summary Flags: C - Connected, L - Local,   S - Sparse, s - SSM Group, R - RP-bit set,   F - Register flag, T - SPT-bit set, J - Join SPT,   I - Received Source Specific Host Report   Timers: Uptime/Expires   IP Multicast Routing Table   (*, 224.255.255.255), 2d16h/00:02:30, RP 172.16.10.13, OIF count:1, flags: SJ   (*, 224.2.127.253), 00:58:18/00:02:00, RP 172.16.10.13, OIF count:2, flags: SJC   (*, 224.1.127.255), 00:58:21/00:02:03, RP 172.16.10.13, OIF count:2, flags: SJ   (*, 224.2.127.254), 2d16h/00:00:00, RP 172.16.10.13, OIF count:2, flags: SJCL   (172.16.160.67/32, 224.2.127.254), 00:02:46/00:00:12, OIF count:2, flags: CLJT   (172.16.244.217/32, 224.2.127.254), 00:02:15/00:00:40, OIF count:2, flags: CLJT   (172.16.8.33/32, 224.2.127.254), 00:00:25/00:02:32, OIF count:2, flags: CLJT   (172.16.2.62/32, 224.2.127.254), 00:00:51/00:02:03, OIF count:2, flags: CLJT   (172.16.8.3/32, 224.2.127.254), 00:00:26/00:02:33, OIF count:2, flags: CLJT   (172.16.60.189/32, 224.2.127.254), 00:03:47/00:00:46, OIF count:2, flags: CLJT

show ip multicast

To display general information about IP Multicast configuration, use the show ip multicast command in user EXEC or privileged EXEC mode.

Syntax show ip multicast [interface interface-id]

Parameters

• interface—Displays IP Multicast-related information about an interface configured for IP Multicast.
• interface-id—Interface identifier for which to display IP Multicast information.

Command Mode

User EXEC mode

Privileged EXEC mode

User Guidelines

Use the show ip multicast command without the interface keyword to display general information about the state of IP Multicast on the router.

Use the show ip multicast command with the interface keyword to display the IP Multicast information about the specified interface.

Examples

Example 1. The following is sample output from the show ip multicast command without the interface keyword when no IP Multicast Routing protocol is enabled:

switchxxxxxx# show ip multicast   IP Unicast Forwarding: enabled   IP Multicast Protocol: No

Example 2. The following is sample output from the show ip multicast command without the interface keyword when IGMP Proxy is enabled:

switchxxxxxx# show ip multicast IP Unicast Forwarding: enabled  IP Multicast Protocol: IGMP Proxy

Example 3. The following is sample output from the show ip multicast command about the given interface. IGMP Proxy is enabled on the interface and the interface is an IGMP Proxy Upstream interface:

switchxxxxxx# show ip multicast interface vlan 200   IP Unicast Forwarding: enabled IP Multicast Protocol: IGMP Proxy vlan 200   TTL-threshold: 0   IGMP Protocol: IGMPv3   PIM: disabled   IGMP Proxy: Upstream

Example 4. The following is sample output from the show ip multicast command about the given interface. IGMP Proxy is enabled on the interface and the interface is an IGMP Proxy Downlink interface:

switchxxxxxx# show ip multicast interface vlan 100   IP Unicast Forwarding: enabled IP Multicast Protocol: IGP Proxy vlan 200   TTL-threshold: 0   IGMP Protocol: IGMPv3   PIM: disabled   IGMP Proxy: DownStream (Upstream: vlan 200)

Example 5. The following is sample output from the show ip multicast command about the given interface. IGMP Proxy is disabled on the interface:

switchxxxxxx# show ip multicast interface vlan 100   IP Unicast Forwarding: enabled IP Multicast Protocol: IGMP Proxy vlan 200   IP Status: enabled  hop-threshold: 100   IGMP Protocol: IGMPv3   PIM: disabled   IGMP Proxy: disabled

Example 6. The following is sample output from the show ip multicast command about the given interface. PIM is enabled on the interface:

switchxxxxxx# show ip multicast interface vlan 100   IP Unicast Forwarding: enabled IP Multicast Protocol: PIM vlan 200  IP Status: enabled  hop-threshold: 100   IGMP Protocol: IGMPv3   IGMP Proxy: DownStream (Upstream: vlan 200)