Question

IPMC log messages recommendation steps


Userlevel 4
09/18/2014 11:21:31.53 Slot-1:
Unable to set IPMC index for s,G,v=ac13b243,effffffa,233 IPMC 8, unit 0 Invalid parameter

09/18/2014 11:21:31.53 Slot-1: Bcm not found SetBCM IPMC index for s,G,v=ac13b243,effffffa,233 IPMC 8, unit 0 00000000 00000000

09/18/2014 11:21:31.53 Slot-1: Unable to set IPMC index for s,G,v=ac13b242,effffffa,233 IPMC 8, unit 0 Invalid parameter





Such errors are frequently logged for multiple customers when IGMP & IPMC compressions are enabled by default which is not a hardware issue.



This logs are due to IPMC hardware entries which cannot be seen through the normal CLI.



The same can be cleared on following below recommendation,



1. disable igmp snooping - - -> By default enabled – this command disables igmp snooping.

2. configure forwarding ipmc compression off - -- > By default enabled – to reduce IPMC entries – this command disables compression

3. configure igmp snooping filters per-vlan - - -- reduces igmp entry – by default it was per-port – which will have more IPMC entries

4. configure igmp snooping forwarding-mode group-vlan - - -> reduces igmp entry – by default it was source,group,vlan – which will have more IPMC entries

5. configure forwarding ipmc compression group-table - -  enable back compression to reduce IPMC entries

6. enable igmp snooping - - -> enabling back igmp snooping



Steps 3 to 5 to have reduced IPMC entries.



The reason these messages are seen in the switch is due to lots of clearing and re-learning of group table entries events happening which results in few entries failing to get re-learnt. At this stage we see those IPMC related errors. This is the situation where we see mismatch of entries with software and hardware.

In order to overcome the issue, turning off the IPMC compression is the only solution.

When IPMC Compression is turned off, switch will not try to clear all the entries and re-learn instead it clears only the particular group table entry and will not impact other existing S,G,V entries.

Now a little on the IP multicast compression .

IP multicast compression provides additional IP multicast scaling when multiple IP multicast FDB entries have the same egress subscriber list.

1 reply

Userlevel 4
There are much better options available in 15.x Latest versions. Best one is upgrade code which will have multicast control packets flood in hardware .(fast path)

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