Internal Querier; When To Use An Internal Querier; Internal Querier Default Configuration - Cisco ASR 9000 Series Configuration Manual

Implementing Layer-2 Multicast with IGMP Snooping

Internal Querier

When to Use an Internal Querier

In a network where IP multicast routing is configured, the IP multicast router acts as the IGMP querier. In
situations when no external querier exists in the bridge domain (because the multicast traffic does not need
to be routed), but local multicast sources exist, you must configure an internal querier to implement IGMP
snooping. The internal querier solicits membership reports from hosts in the bridge domain so that IGMP
snooping can build constrained multicast forwarding tables for the multicast traffic within the bridge domain.
An internal querier might also be useful when interoperability issues with non-Cisco equipment prevent IGMP
snooping from working correctly with an external querier. In this case, you can:
1 Prevent the uncooperative external querier from being discovered by placing the router-guard command
on that port.
2 Configure an internal querier to learn group membership interests from the ports in the bridge domain.
3 Configure static mrouter ports to receive multicast traffic.

Internal Querier Default Configuration

The minimum configuration for an internal querier is:
• Add the internal-querier command to a profile attached to the bridge domain. The default configuration
• Add the system-ip-address command to a profile attached to the bridge domain to configure an address
Table 7: Internal Querier Default Configuration Values
Configuration Command
system-ip-address
internal-querier max-response-time
internal-querier query-interval
internal-querier robustness-variable
internal-querier tcn query count
internal-querier tcn query interval
is shown in Table 7: Internal Querier Default Configuration Values, on page
other than the default 0.0.0.0.
Cisco ASR 9000 Series Aggregation Services Router Multicast Configuration Guide, Release 6.0.x
Default Value
0.0.0.0. The default address is invalid for the
internal-querier.
10
60 (seconds)
This is a nonstandard default
Note
value.
2
2
10 (seconds)
Internal Querier
19.
19