[cisco-voip] speaker sends ttl=16, switch drops it

[Wes Sisk]

Rossella,

Good problem.  The RFC appears to indicate:
http://www.faqs.org/rfcs/rfc2236.html
"All IGMP messages described in this document are sent with IP
   TTL 1, and contain the IP Router Alert option [RFC 2113] in their IP
   header."

The switch is being a bit aggressive in interpretation, but I'd say the 
speaker is out of order here.  When you say "speaker gets all its 
configuration parameters from the server". What server do you mean?

Regards,
Wes

Rossella Mariotti-Jones wrote:
> Hello all, I've been approaching this issue from many different sides, so I figured I'd post on this list too. 
>
> The players are: an Atlas Sound ip speaker model I128SYS (ceiling), a Foundry switch, and Berbee InformaCast v.5.1.1. 
>
> The speaker sends multicast membership group report with ttl=16, as soon as it gets to the switch it gets dropped, see the switch message below: 
>
> IGMP: Error! ttl=16 (!= 1), discard, pkt S=10.22.3.54 to 239.0.1.2, on VL221 (phy 0/1/37), igmp_size=8 
>
> Foundry says that per RFC 2236, IGMP version 2 Membership Report to the group is sent with IP TTL of 1, so whatever is not equal to 1 gets discarded. 
>
> According to Berbee tech support the speaker gets all its configuration parameters from the server however modifying the ttl on the server doesn't change the ttl value that the speaker uses when sending the membership group report, so we think this is a value that's coded in the speaker's firmware. 
>
> The speaker works flawlessly on a Cisco switch. We have already put in a feature request with Foundry because we think the problem is how they are enforcing the RFC, in the meantime we are looking for a different kind of ceiling speakers to try on these switches, any suggestions on any of these points? Anybody has or has had something similar happening? 
>
> Thanks in advance. 
>                                           
>
> ***
> Rossella Mariotti-Jones
> rossella at chemeketa.edu
>
>
> Network Analyst, SS - SPIR - IT TAC
> desk 503-589-7775 - cell 503-480-4255
>
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