16 Aug
2004
16 Aug
'04
12:33 p.m.
At 12:06 PM 8/16/2004, Arnd Vehling wrote:
Jiri Kuthan wrote:
I don't know, I am not a psychologist ;)
Now to provide a complete answer to the question:
the values are supposed to
be unique according to RFC3261 but there is nothing in the world that
prevents broken implementations to generate invalid non-unique values.
There are indeed implementations that are broken. To make CDRs as much
unique as you can, compose the identifier as a triple callid-fromtag-
totag. Composition of values generated by UACs and UASs significantly
reduces the chance of not being unique.
Why does the formulation "significantly reduces the chance of not being unique"
make me nervous? :) May it be that the "SIP RFC Fathers"
neglected the real-word issue of
actually accounting sip-calls a bit? Making accounting dependant on
client side software implementations doesnt seem a basicly good idea
to me.
That's why RFC3261 identifies dialog by the triple, which includes
server-generated to-tag. Obviously if clients and servers agree to
generate stupid triple {from-tag, callid, to-tag}, accounting can
still mess, but I don't see this case as a huge issue.
-jiri