Subject: RE: draft-nair-sip-dhcp-00.txt

From: Bernie Volz <[email-masked]>
Date: Mon, 7 Feb 2000 11:59:33 -0500

I've only taken a brief look at this, but have a question:

Is the intent of the suboption 3 (IP address sub-option) that a client
randomly picks one address and if that server doesn't respond, it goes
to the backup server (suboption 4)? Why not have it try all of the
servers in suboption 3 (round-robin fashion, starting with a randomly
picked one). That way, you might even be able to drop suboption 4 and
simplify configuration a bit?

Or, is suboption 4 intended for use in all cases (even when or if
suboption 1 (DNS SRV) or suboption 2 (DNS 'A') are specified and used
but that server fails to respond or the DNS server isn't responding)? In
that case, are the clients not allowed to use suboption 3 anyway?

- Bernie Volz
  Process Software

---

From: Gautam Nair <[email-masked]>
Date: Mon, 07 Feb 2000 13:10:51 -0500

Bernie Volz wrote:

> picked one).

You're right. The selection is to  be done in round-robin fashion starting
with a randomly picked one.

> That way, you might even be able to drop suboption 4 and
> but that server fails to respond or the DNS server isn't responding)?

Sub-option 4 is intended for use as a last resort option in all cases
(sub-options 1, 2 and 3) if the SIP server fails to respond. Sub-option 4 is
used after all the SIP servers specified in the sub-options 1,2 and 3 have
been tried and have failed.

> In

They are allowed to use sub-option 3. Only after an unsuccessful sub-option
3 attempt, does the client try sub-option 4. Sub-option 4 is required in
addition to sub-option 3 because there's no easy way to specify the *backup
only* server in the random round-robin selection scheme.
In case of failure of only the DNS server, sub-option 3 will be used.

>   Process Software

Thank you for your comments and suggestions,

Gautam Nair.
Columbia University.