4 May
2005
4 May
'05
3:32 p.m.
Hi Zeus!
Maybe there's a misunderstandiung: I for myself have no problem with
looping packets but I've problems with ACKs and Via-HF with branch=0 -
and that's the UAS (SER) to be blamed for. The UA sends a normal - and
in my eyes correct - ACK after an 200 OK, and this ACK is forwarded by
SER with a Via-HF containing "branch=0".
So far I didn't get a clue how I could take influence on SER writing bad
branch parameters - even if I wanted SER to do that. IMHO branch=0 isn't
legal according to the metioned sections of RFC3261.
I've attached a ethereal plaintext export of a call. Packet #13 is the
ACK from the initiating UA to SER, packet #14 is the bad ACK with
branch=0. Sorry for the crumbled view, but I have almost no influence on
ethereal's export format.
Alex Mack
Zeus Ng schrieb:
When I mention section 12.2, I was referring your UA,
not SER. I do have a
typo on alias as well.
To better troubleshoot your problem, ser.cfg and debug would help. By
looking at your ngrep, I believe there is something wrong with your ser.cfg.
The ACK from SER to Asterisk should not have a Record-Route header added.
-----Original Message-----
From: serdev-bounces(a)lists.iptel.org
[mailto:serdev-bounces@lists.iptel.org] On Behalf Of Alex Mack
Sent: Wednesday, 4 May 2005 8:29 PM
To: Zeus Ng
Cc: serdev(a)lists.iptel.org; serusers(a)lists.iptel.org
Subject: Re: [Serusers] Re: [Serdev] Problem with Via
Branch/Strange Looping Problem with ACK's
Hi Zeus!
Zeus Ng schrieb:
First, the ACK should follow section 12.2 (indeed
12.2.1.1),
Requests
within a Dialog, not section 12.1.2 according to
section
13.2.2.4, 2xx
Responses.
------
The UAC core MUST generate an ACK request for each 2xx received from
the transaction layer. The header fields of the ACK are constructed
in the same way as for any request sent within a dialog
------
I disagee: the SER is an UAS not an UAC.
IMHO, the concernig chapters are 16.6 subpoint 8 ("16.6 Request
Forwarding"; "8. Add a Via header field value") and 8.1.1.7 ("8.1.1.7
Via"). Both chapters state the UAS (SER) MUST add a Via with a branch
parameter starting with the magic cookie "z9hG4bK".
The ACK generated by the UAC looks good to me, anyway.
Second, do you happened to have a line like this
in your SER config.
aliase=your_proxy_name:5080 or aliase=your_proxy_ip:5080?
Are you sure about the trailing 'e' in "aliase"? I've two
alias-definitions (one for the IP, one for the realm) in my
ser.cfg. But
they don't have the port added. I've already added the ports in the
listen statements.
Alex Mack
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