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IGMP Proxy

IGMP proxy enables the system to issue IGMP host messages on behalf of hosts that the system discovered via standard IGMP interfaces. The system acts as a proxy for its hosts.

Overview

Figure 3-3 shows a system in an IGMP proxy configuration. You enable IGMP proxy on one interface, which connects to a router closer to the root of the tree. This interface is the upstream interface. The router on the upstream interface should be running IGMP.

You enable IGMP on the interfaces that connect the system to its hosts that are farther away from the root of the tree. These interfaces are known as downstream interfaces.


Figure 3-3 Upstream and downstream interfaces

As described in IGMP Operation, earlier in this chapter, hosts interact with the system through the exchange of IGMP messages. Similarly, when you configure IGMP proxy, the system interacts with the router on its upstream interface through the exchange of IGMP messages. However, when acting as the proxy, the system performs the host portion of the IGMP task on the upstream interface as follows:

Configuring IGMP Proxy

To configure a downstream interface, enable IGMP on that interface. To configure IGMP proxy on the system, complete the following tasks:

  1. Enable IP multicasting.
host1(config)#ip multicast-routing
  1. Identify the interface that you want to act as the upstream interface.
host1(config-if)#interface atm 3/0
  1. Enable IGMP proxy on that interface.
host1(config-if)#ip igmp-proxy
  1. (Optional) Specify how often the system should send unsolicited reports to routers on the upstream interface.
host1(config-if)#ip igmp-proxy unsolicited-report-interval 
600
  1. (Optional) Specify how long the system should assume that there is an IGMPv1 querier router on the subnet after the system receives an IGMP V1 query on this interface.
host1(config-if)#ip igmp-proxy V1-router-present-time 600

    ip igmp-proxy



Note: You can enable only one upstream interface.

host1(config-if)#ip igmp-proxy

    ip igmp-proxy unsolicited-report-interval



Note:
Issue this command only on the upstream interface. Otherwise, this command will have no effect.

host1(config-if)#ip igmp-proxy unsolicited-report-interval 
600

    ip igmp-proxy V1-router-present-time



Note:
Issue this command only on the upstream interface. Otherwise, this command will have no effect.

host1(config-if)#ip igmp-proxy V1-router-present-time 600

Setting the IGMP Proxy Baseline

You can set the counters for the numbers of queries received and reports sent on the upstream interface to zero. This feature allows you to establish a reference point for IGMP proxy statistics.

    baseline ip igmp-proxy interface



Note:
Issue this command only on the upstream interface. Otherwise, this command will have no effect.

(host1)#baseline ip igmp-proxy interface

Monitoring IGMP Proxy

To display IGMP proxy parameters, use the following show commands.

    show ip igmp-proxy

host1#show ip igmp-proxy
Routing Process IGMP Proxy, Administrative state enabled, 
Operational state enabled
total 1 upstream interface, state enabled
    6 multicast group 

    show ip igmp-proxy groups

host1#show ip igmp-proxy groups

Grp Address     Interface       Member State
--------------- --------------- --------------
225.1.1.1       atm3/0.2          Idle
225.1.1.2       atm3/0.2          Idle
225.1.1.3       atm3/0.2          Idle
225.1.1.4       atm3/0.2          Idle
225.1.1.5       atm3/0.2          Idle
225.1.1.6       atm3/0.2          Idle
count 6

host1#show ip igmp-proxy group 225.1.1.1
Grp Address     Interface       Member State
--------------- --------------- --------------
225.1.1.1       atm3/0.2        Idle
host1#show ip igmp-proxy group count
Count: 6 groups

    show ip igmp-proxy interface

host1#show ip igmp-proxy interface atm 3/0.2
Interface atm3/0.2 address 21.1.1.1/255.0.0.0
Administrative state enabled, Operational state enabled
Interface parameters: 
    Version 2
    State No v1 Router Present
    Unsolicited report interval 10 secs
    Version 1 router present timeout 400 secs
    0 multicast group
Interface statistics: 
    Rcvd:  0 v1 query, 6 v2 queries
           0 v1 report, 0 v2 report
    Sent:  0 v1 report, 48 v2 reports, 0 leave

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