Guys,
I was able to figure out why I was getting occasional sl_send_reply errors with some ACK messages. I don't know if this is something that needs to be corrected at a deeper level, but I'll give you the rundown:
1. UA Makes a call to a bad number 2. Bad number is actually valid so it gets routed to the GW 3. GW responds 404 4. ACK loop occurs.
When the ACK loop happens, SIP captures reveal the following (watch the Max-Forwards):
#1 .. Max-Forwards: 9 Record-Route: sip:ser;ftag=0014a934057d001145ed0fa2-6f6f2e8e;lr=on Via: SIP/2.0/UDP ser;branch=0 Via: SIP/2.0/UDP 192.168.249.83:5060;received=otherip;branch=z9hG4bK140d833e .. #2 .. Record-Route: sip:ser;ftag=0014a934057d001145ed0fa2-6f6f2e8e;lr=on Max-Forwards: 8 Record-Route: sip:ser;ftag=0014a934057d001145ed0fa2-6f6f2e8e;lr=on Via: SIP/2.0/UDP ser;branch=0 Via: SIP/2.0/UDP ser;branch=0 Via: SIP/2.0/UDP 192.168.249.83:5060;received=otherip;branch=z9hG4bK140d833e ..
Etc. etc. until Max Forwards counts down to 0, at which point:
if (!mf_process_maxfwd_header("10")) { sl_send_reply("483", "Too Many Hops"); break; };
And naturally: sl_send_reply: I won't send a reply for ACK!!
So, I've obviously been able to avoid this by changing to:
if (!mf_process_maxfwd_header("10")) { if (method!="ACK") { sl_send_reply("483", "Too Many Hops"); }; break; };
Now, the greater question: is the ACK loop being generated by a defective message. If so, is it anything to worry about? And in either case is putting the method check in there a valid solution?
Can anyone advise?
Thanks, -Corey
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Not that this will help much, but, I've seen a problem like this when loose_route() fails to identify the message as being to ser (that is myself). For example if the GW is at the same IP address but a different port and the port is not included in an alias.
Mark
On 9/9/05, Corey S. McFadden csm-lists@csma.biz wrote:
Guys,
I was able to figure out why I was getting occasional sl_send_reply errors with some ACK messages. I don't know if this is something that needs to be corrected at a deeper level, but I'll give you the rundown:
- UA Makes a call to a bad number
- Bad number is actually valid so it gets routed to the GW
- GW responds 404
- ACK loop occurs.
When the ACK loop happens, SIP captures reveal the following (watch the Max-Forwards):
#1 .. Max-Forwards: 9 Record-Route: sip:ser;ftag=0014a934057d001145ed0fa2-6f6f2e8e;lr=on Via: SIP/2.0/UDP ser;branch=0 Via: SIP/2.0/UDP 192.168.249.83:5060 http://192.168.249.83:5060 ;received=otherip;branch=z9hG4bK140d833e .. #2 .. Record-Route: sip:ser;ftag=0014a934057d001145ed0fa2-6f6f2e8e;lr=on Max-Forwards: 8 Record-Route: sip:ser;ftag=0014a934057d001145ed0fa2-6f6f2e8e;lr=on Via: SIP/2.0/UDP ser;branch=0 Via: SIP/2.0/UDP ser;branch=0 Via: SIP/2.0/UDP 192.168.249.83:5060 http://192.168.249.83:5060 ;received=otherip;branch=z9hG4bK140d833e ..
Etc. etc. until Max Forwards counts down to 0, at which point:
if (!mf_process_maxfwd_header("10")) { sl_send_reply("483", "Too Many Hops"); break; };
And naturally: sl_send_reply: I won't send a reply for ACK!!
So, I've obviously been able to avoid this by changing to:
if (!mf_process_maxfwd_header("10")) { if (method!="ACK") { sl_send_reply("483", "Too Many Hops"); }; break; };
Now, the greater question: is the ACK loop being generated by a defective message. If so, is it anything to worry about? And in either case is putting the method check in there a valid solution?
Can anyone advise?
Thanks, -Corey
This message has been scanned for viruses and dangerous content, and is believed to be clean.
Serusers mailing list serusers@lists.iptel.org http://lists.iptel.org/mailman/listinfo/serusers
This is a known problem. It is your responsibility to detect invalid numbers before sending them to the GW... However, you should catch the bad ACK earlier (not wait until the loop has occurred). You didn't include the full, original ACK that starts the loop, but I assume you should be able to detect the 404 from your GW. I must admit I'm not really able to picture the dialog that occurs, but I assume the loop is between SER and the GW or is it a loop within SER itself? g-)
Corey S. McFadden wrote:
Guys,
I was able to figure out why I was getting occasional sl_send_reply errors with some ACK messages. I don't know if this is something that needs to be corrected at a deeper level, but I'll give you the rundown:
- UA Makes a call to a bad number
- Bad number is actually valid so it gets routed to the GW
- GW responds 404
- ACK loop occurs.
When the ACK loop happens, SIP captures reveal the following (watch the Max-Forwards):
#1 .. Max-Forwards: 9 Record-Route: sip:ser;ftag=0014a934057d001145ed0fa2-6f6f2e8e;lr=on Via: SIP/2.0/UDP ser;branch=0 Via: SIP/2.0/UDP 192.168.249.83:5060;received=otherip;branch=z9hG4bK140d833e .. #2 .. Record-Route: sip:ser;ftag=0014a934057d001145ed0fa2-6f6f2e8e;lr=on Max-Forwards: 8 Record-Route: sip:ser;ftag=0014a934057d001145ed0fa2-6f6f2e8e;lr=on Via: SIP/2.0/UDP ser;branch=0 Via: SIP/2.0/UDP ser;branch=0 Via: SIP/2.0/UDP 192.168.249.83:5060;received=otherip;branch=z9hG4bK140d833e ..
Etc. etc. until Max Forwards counts down to 0, at which point:
if (!mf_process_maxfwd_header("10")) { sl_send_reply("483", "Too Many Hops"); break; };And naturally: sl_send_reply: I won't send a reply for ACK!!
So, I've obviously been able to avoid this by changing to:
if (!mf_process_maxfwd_header("10")) { if (method!="ACK") { sl_send_reply("483", "Too Many Hops"); }; break; };
Now, the greater question: is the ACK loop being generated by a defective message. If so, is it anything to worry about? And in either case is putting the method check in there a valid solution?
Can anyone advise?
Thanks, -Corey
This message has been scanned for viruses and dangerous content, and is believed to be clean.
Serusers mailing list serusers@lists.iptel.org http://lists.iptel.org/mailman/listinfo/serusers
-
Corey S. McFadden -
Greger V. Teigre -
Mark Aiken