Description

On a network running PIM dense only mode, integrating new multicast feed from 232.0.0.0/8 range, you might encounter the following error.

Feb 20 05:06:06 router-l8 rpd[9351]: RPD_IGMP_SSM_REPORT_MODE_INVALID: Interface irb.103: Group record with invalid mode for SSM group 232.0.38.1 ignored.

Symptoms

Junos by default does not support PIM SSM range 232.0.0.0/8 as ASM.

Solution

There are 2 possible solutions in this case.

1. Assume SSM range as ASM range - asm-override-ssm

This option assumes the incoming feed from 232.0.0.0/8 range to be ASM. The source device once receives the feed from 232.0.0.0/8 range, it will consider this feed as ASM and will flood it just like dense groups.

# set routing-options multicast asm-override-ssm

Enable the routing device to accept any-source multicast join messages (*,G) for group addresses that are within the default or configured range of source-specific multicast groups.

2. Run PIM SSM and ASM together by implementing RP to handle PIM SSM flows.
This option discusses about parallel implementation of both dense and sparse mode. The RP will facilitate the SSM traffic with PIM while dense multicast traffic groups gets flooded across the network.
 
All the interfaces in the network should be configured with sparse-dense mode.
 
Following document can help explore more in PIM SSM mode - https://www.juniper.net/documentation/us/en/software/junos/multicast/topics/concept/multicast-pim-ssm.html

 

Modification History

2024-02-20 : Article Created