Hi All,
I notice during the NGREP session , there is this field called Call-ID . It is something like this format :- 9ce97fd3-1a800040@172.16.1.123 mailto:9ce97fd3-1a800040@172.16.1.123 .
According to the RFC , it is said that this field is generated by the UA who started the request. I was just wondering, how did they get the IP Address at the back ? Which IP Address did they reference it from ?
From the RFC, it also says that the all request/response in the dialog
should use the same Call-ID. When they say this, does it mean the entire field with the ip address (eg. 9ce97fd3-1a800040@172.16.1.123 ) or just the front part of it (eg. 9ce97fd3-1a800040 ) ?
I notice that during a dialog session from a UA to the server going to the PSTN gateway, it was refering to this Call-ID until the point when the request was forwarded to the PSTN gateway. When the PSTN gateway replies, it replied with a same Call-ID with a different IP address at the back (9ce97fd3-1a800040@123.234.123.234 )
172.16.1.123 - Private address of the UA 123.234.123.234 - Public address of the UA
Strange ? Give your comment. Somehow i feel that this implementation is wrong.
Regards, Sam
Hello,
On 05/24/06 13:53, Sam Lee wrote:
Hi All,
I notice during the NGREP session , there is this field called Call-ID . It is something like this format :- 9ce97fd3-1a800040@172.16.1.123 mailto:9ce97fd3-1a800040@172.16.1.123.
According to the RFC , it is said that this field is generated by the UA who started the request. I was just wondering, how did they get the IP Address at the back ? Which IP Address did they reference it from ?
The Call-ID should be unique, so many devices uses the local IP address to try to avoid as much as possible the duplicity of the call-id with other phones. Hoeever, this does not apply with devices running in private networks.
From the RFC, it also says that the all request/response in the dialog should use the same Call-ID. When they say this, does it mean the entire field with the ip address (eg. 9ce97fd3-1a800040@172.16.1.123 mailto:9ce97fd3-1a800040@172.16.1.123 ) or just the front part of it (eg. 9ce97fd3-1a800040 ) ?
The whole string including the IP address is the call-id.
I notice that during a dialog session from a UA to the server going to the PSTN gateway, it was refering to this Call-ID until the point when the request was forwarded to the PSTN gateway. When the PSTN gateway replies, it replied with a same Call-ID with a different IP address at the back (9ce97fd3-1a800040@123.234.123.234 mailto:9ce97fd3-1a800040@123.234.123.234 )
That is very wrong. Maybe there is an ALG in the path which replaces the private address with public ones, but that should not apply to the call-id. The caller should reject the reply.
Cheers, Daniel
172.16.1.123 - Private address of the UA 123.234.123.234 - Public address of the UA
Strange ? Give your comment. Somehow i feel that this implementation is wrong.
Regards, Sam
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On Wednesday 24 May 2006 07:01, Daniel-Constantin Mierla wrote:
I notice that during a dialog session from a UA to the server going to the PSTN gateway, it was refering to this Call-ID until the point when the request was forwarded to the PSTN gateway. When the PSTN gateway replies, it replied with a same Call-ID with a different IP address at the back (9ce97fd3-1a800040@123.234.123.234 mailto:9ce97fd3-1a800040@123.234.123.234 )
That is very wrong. Maybe there is an ALG in the path which replaces the private address with public ones, but that should not apply to the call-id. The caller should reject the reply.
I have actually seen an ALG do exactly that before, and my client dropped all messages coming back through it, as expected.
---Mike
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Daniel-Constantin Mierla -
Mike Williams -
Sam Lee