[Serusers] 483 - Too many hops

Chintan Thakker cthakker at ipnetfusion.com
Sat Jun 21 00:18:16 CEST 2003

 Consider the following scenario. UA1 is trying to call UA2 both 
registered with the same proxy. (UA1 -> 'ser' -> UA2)

 UA1 sends INVITE to the proxy with request uri set to UA2. It also sets 
the Route header in the invite to that of the proxy.
 This returns a 483 - too many hops to UA1

 It seems that in the above mentioned scenario, the proxy loops back the 
INVITE multiple times locally. This decrements the Max Forwards value 
every time until it becomes zero and hence sends 483 back to UA1. It 
seems to me this is not the correct behavior of the server. It should 
forward the request to UA2.

Thanks in advance,


-- Start trace --

U 2003/06/20 15:24:42.362466 ->
  INVITE sip:9727610001 at SIP/2.0.Via: SIP/2.0/UDP;b
  ranch=z9hG4bK421668676.Max-Forwards: 70.From: 9727619271 
<sip:9727619271 at 19>;tag=421668676.To: 9727610001 
<sip:9727610001 at>.Call-ID:
   421668676 at 1 INVITE.Contact: 
<sip:9727619271 at>.C
  ontent-Type: application/sdp.Content-Length: 138.Route: 
  ..v=0.o=username 421668676 421668676 IN IP4 
  P4 0.m=audio 54454 RTP/AVP 0.a=rtpmap:0 PCMU/8000.

U 2003/06/20 15:24:42.363813 ->
  SIP/2.0 100 trying -- your call is important to us..Via: SIP/2.0/UDP 
  2.88:5060;branch=z9hG4bK421668676..From: 9727619271 
<sip:9727619271 at 192.1.2
  .88>;tag=421668676.To: 9727610001 <sip:9727610001 at>.Call-ID: 
  68676 at 1 INVITE.Server: Sip EXpress router 
(0.8.11pre29 (i3
  86/linux))..Content-Length: 0..Warning: 392 "Noisy 
   tells:  pid=15107 req_src_ip= req_src_port=5060 
  10001 at out_uri=sip:9727610001 at via_cnt==1"....
U 2003/06/20 15:24:42.794681 ->
  SIP/2.0 483 Too Many Hops..Via: SIP/2.0/UDP;branch=z9hG4bK4
  21668676..From: 9727619271 
<sip:9727619271 at>;tag=421668676.To: 97
<sip:9727610001 at>;tag=b27e1a1d33761e85846fc98f5f3a7e58.4
  632.Call-ID: 421668676 at 1 INVITE.Server: Sip EXpress 
   (0.8.11pre29 (i386/linux))..Content-Length: 0..Warning: 392
  0 "Noisy feedback tells:  pid=15107 req_src_ip= 
   in_uri=sip:9727610001 at out_uri=sip:9727610001 at 

-- End trace --

ps: We checked it with loose routing(suceeding ';lr' present in URIs in 
Route) as well as strict routing(suceeding ';lr' not present in URIs in 
Route). Should the type of routing used matter ?

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