Igmp Snooping Packet Checks; Startup Query Configuration - Cisco ASR 9000 Series Configuration Manual

Implementing Layer-2 Multicast with IGMP Snooping

IGMP Snooping Packet Checks

By default, IGMP snooping performs the following validations. If your network performs these validations
elsewhere, you can disable the IGMP snooping validations.
• IGMP snooping checks the time-to-live (TTL) field in the IGMP header and drops packets where TTL
is not equal to 1. The TTL field should always be set to 1 in the headers of IGMP reports and queries.
You can disable this check using the ttl-check disable command, in which case IGMP snooping processes
all packets without examining the TTL field in the IGMP header.
• IGMP snooping checks for the presence of the router alert option in the IP packet header of the IGMP
message and drops packets that do not include this option.
You can disable this check using the router-alert-check disable command, in which case IGMP snooping
does not perform the validation before processing the message.

Startup Query Configuration

The startup query feature is configured using new igmp snooping profile parameters. You can configure the
startup query processing in response to the following events:
• MC-LAG Port goes active
• Topology-change
• Port-up
• Process start
The above parameters are specific to MC-LAG feature. These are apart from the existing bridge domain level
parameters such as count, MRT, and query interval. For more information about these CLI, refer the
Cisco ASR 9000 Series Aggregation Services Router Multicast Command Reference.
• For IGMP snooping to work on MC-LAG properly, the IGMP snooping configuration on both the
Note
POAs must be the same.
• In the case of downstream MC-LAG, when MC-LAG is configured and up and running, the MC-LAG
port has to be added in IGMP Snooping enabled Bridge-domain.
• In the case of upstream MC-LAG, where POAs are attached to multicast router, the static mrouter
port has to be configured on the multicast router that is towards both the POAs so that traffic is drawn
to both the POAs.
Cisco ASR 9000 Series Aggregation Services Router Multicast Configuration Guide, Release 6.0.x
IGMP Snooping Configuration at the Bridge Domain Level
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