Edge-Core ECS2100-10T Reference Manual page 560

Chapter 23
| Multicast Filtering Commands
IGMP Snooping
Command Mode
Global Configuration
Command Usage
IGMP Snooping uses a null IP address of 0.0.0.0 for the source of IGMP query
messages which are proxied to downstream hosts to indicate that it is not the
elected querier, but is only proxying these messages as defined in RFC 4541. The
switch also uses a null address in IGMP reports sent to upstream ports.
Many hosts do not implement RFC 4541, and therefore do not understand query
messages with the source address of 0.0.0.0. These hosts will therefore not reply to
the queries, causing the multicast router to stop sending traffic to them.
To resolve this problem, the source address in proxied IGMP query and report
messages can be replaced with any valid unicast address (other than the router's
own address) using this command.
Rules Used for Proxy Reporting
When IGMP Proxy Reporting is disabled, the switch will use a null IP address for the
source of IGMP query and report messages unless a proxy query address has been
set.
When IGMP Proxy Reporting is enabled, the source address is based on the
following criteria:
◆
If a proxy query address is configured, the switch will use that address as the
source IP address in general and group-specific query messages sent to
downstream hosts, and in report and leave messages sent upstream from the
multicast router port.
◆
If a proxy query address is not configured, the switch will use the VLAN's IP
address as the IP source address in general and group-specific query messages
sent downstream, and use the source address of the last IGMP message
received from a downstream host in report and leave messages sent upstream
from the multicast router port.
Example
The following example sets the source address for proxied IGMP query messages to
10.0.1.8.
Console(config)#ip igmp snooping vlan 1 proxy-address 10.0.1.8
Console(config)#
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