[cisco-voip] UDP 2000 from SRST router to IP phone?

[Bernhard Albler]

Hi all,

 

Well, one of the interesting aspects of SRST and CME is, that they use
UDP 2000 as the source Port for all RTP traffic to locally registered
phones. I believe this is connected to the fact, that cme/srst proxies
all RTP traffic from the phones to other destination.

e.g. if you have another Dial-peer to a h323 system, the rtp will
actually flow from the phone to udp 2000 on the router, which then
reoriginates the traffic with a udp high port to the other entity. 

 

 

Regards

bernhard

------------------------------------------
DI (FH) Bernhard Albler, NTS AG
Tel.: +43 (1) 867 67 76 -0, email: balbler at nts.at

________________________________

Von: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] Im Auftrag von Ed Leatherman
Gesendet: Freitag, 6. Juli 2007 14:37
An: Lelio Fulgenzi
Cc: cisco-voip at puck.nether.net; Matt Slaga (US)
Betreff: Re: [cisco-voip] UDP 2000 from SRST router to IP phone?

 


I would think that your IP phone would send to the UDP range 16384-32767
on the gateway for RTP traffic rather than port 2000. It sounds like the
call is already setup.



On 7/5/07, Lelio Fulgenzi <lelio at uoguelph.ca> wrote:

That's was our understanding, TCP 2000.

I don't think we've ever heard about the sequential ports though. We've
only
opened up TCP 2000.

----- Original Message -----
From: "Matt Slaga (US)" < Matt.Slaga at us.didata.com>
To: "Paul Choi" <asobihoudai at yahoo.com>; "Lelio Fulgenzi"
< lelio at uoguelph.ca <mailto:lelio at uoguelph.ca> >;
<cisco-voip at puck.nether.net>
Sent: Thursday, July 05, 2007 9:09 PM
Subject: RE: [cisco-voip] UDP 2000 from SRST router to IP phone?


> Cisco contends that SCCP uses TCP 2000 - 2002 (one port for each
> CallManager in it's failover list).  Not sure about UDP 2000.
>
> -----Original Message-----
> From: cisco-voip-bounces at puck.nether.net
> [mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Paul Choi
> Sent: Thursday, July 05, 2007 9:01 PM
> To: Lelio Fulgenzi; cisco-voip at puck.nether.net
> Subject: Re: [cisco-voip] UDP 2000 from SRST router to IP phone?
>
> I could be full of shit but I'm pretty sure that SCCP 
> uses UDP 2000 to communicate with CCM.
>
>
> --- Lelio Fulgenzi <lelio at uoguelph.ca> wrote:
>
>> We're just setting up some ACLs and found that while 
>> in SRST mode, the SRST router (or at least the
>> loopback address that we bind MGCP to) tried to
>> communicate to the IP phone that was registered. We
>> had not allowed for this and as a result, the call 
>> out the gateway was one way audio. But we didn't see
>> any other denies come out of the logs.
>>
>> I see that in the SRST config, it asks for a port,
>> and it is 2000. But it's still wierd to see UDP 2000 
>> being used.
>>
>> Can anyone comment?
>>
>> 2d08h: %SEC-6-IPACCESSLOGP: list voice_in_kc denied
>> udp 10.104.122.141(17624) -> 10.104.34.48(2000), 1
>> packet 
>>
>>    ^- IP phone              ^- SRST router
>>
>>
>>
>
------------------------------------------------------------------------
> --------
>> Lelio Fulgenzi, B.A.
>> Senior Analyst (CCS) * University of Guelph *
>> Guelph, Ontario N1G 2W1
>> (519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
>>
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

>>
>> "Buffalo buffalo Buffalo buffalo buffalo buffalo
>> Buffalo buffalo."      WJR
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>
>
>
>
>
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-- 
Ed Leatherman
Senior Voice Engineer
West Virginia University
Telecommunications and Network Operations 

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