Subject: [SIP] URL comparison

From: "Stuart Wray" <[email-masked]>
Date: Mon, 20 Nov 2000 15:14:34 +0000

Henning Schulzrinne suggested that I submit the following questions about URL
comparison to the SIP list.

On page 21 of rfc2543bis02 , it says

(call this clause A)
"user, password, host, port and any url-parameter parameters of the URI must
match. If a component is omitted, it matches based on its default value."

So far, this is clear, but the paragraph goes on to say that

(call this clause B)
"Components not found in both URLs being compared are ignored"

Now consider these two URLs:

     sip:[email-masked]:6666
     sip:[email-masked]

Clause A means that these URLs compare as unequal, but clause B means that they
compare as equal.

Should clause B actually start with the word "other"?

(clause B')
"Other components not found in both URLs being compared are ignored"

(If so, is this actually the correct judgement? I would have thought that a URL
should not compare equal to a URL with an extra component. Why is it useful for
them to compare equal?)

And now another separate point: the text on page 21 goes on to say:

"Note that the two URLs example.com and example.com:5060, while considered
equal, may not lead to the same server, as the former causes a DNS SRV lookup,
while the latter only uses the A record".

However, this is not true --- on page 12 it says:

"3. The Request-URI is examined. If it contains an explicit port number other
than 5060, the next two steps are skipped".

The A record is only used if there is a port number other than 5060 ---- so
example.com and example.com:5060 both use the SRV record. (Of course this may
result in different machines actually being contacted, but that's a different
matter entirely, not to do with A records).

  Stuart Wray

_______________________________________________
SIP mailing list
[email-masked]
http://lists.bell-labs.com/mailman/listinfo/sip