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

[Rossella Mariotti-Jones]

When I say server I mean the Berbee InformaCast server (v. 5.1.1).

I talked with Atlas Sound, the speaker manufacturer, and they say they
don't do the coding, I think the firmware is made by Berbee, I asked the
engineer that was helping us if it can be upgraded, we'll see. And yes,
I also think that the Foundry switch is being a little too tight about
the following the specs in this RFC.

Does anybody use ceiling speakers with Berbee? If so which kind? We're
looking to try a different brand and we need ceiling speakers because we
want to keep them out of reach as much as possible.

Thanks.

 

***

Rossella Mariotti-Jones

rossella at chemeketa.edu <mailto:rossella at chemeketa.edu> 

 

  <http://www.chemeketa.edu/> 

Network Analyst, SS - SPIR - IT TAC

desk 503-589-7775 - cell 503-480-4255

 

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From: Scott Voll [mailto:svoll.voip at gmail.com] 
Sent: Monday, June 16, 2008 10:12 AM
To: Wes Sisk
Cc: Rossella Mariotti-Jones; cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] speaker sends ttl=16, switch drops it

 

berbee InformaCast

 

Rossella--

 

Does the Altas speaker have a firmware on it you can get and update?

 

Scott

On Mon, Jun 16, 2008 at 9:49 AM, Wes Sisk <wsisk at cisco.com> wrote:

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
<http://10.22.3.54/>  to 239.0.1.2 <http://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

**** PRIVILEGED AND CONFIDENTIAL COMMUNICATION  **** This electronic
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prohibited.

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