Subject: [Fwd: DHCP options for locating outbound SIP servers]

From: Gautam Nair <[email-masked]>
Date: Mon, 07 Feb 2000 00:36:00 -0500

Subject: DHCP options for locating outbound SIP servers
From: Henning Schulzrinne <[email-masked]>
To: [email-masked]
Cc: [email-masked]
Date: Fri, 04 Feb 2000 11:17:45 -0500

Gautam Nair and I have submitted an Internet draft for using DHCP to
configure SIP clients with the address of outbound SIP servers.

Until the draft appears in the I-D directories, it can also be found at
http://www.cs.columbia.edu/sip/drafts/draft-nair-sip-dhcp-00.txt

(For the DHCP experts: SIP, the Session Initiation Protocol, is used for
setting up, modifying and terminating multimedia sessions, including
Internet telephone calls. It is an IETF Proposed Standard document in
RFC 2543, with information available at http://www.cs.columbia.edu/sip)

We have documented a number of approaches in the draft, some of which
may well be dropped if deemed to be redundant. A particular concern of
ours are low-complexity embedded systems (such as
http://www.cs.columbia.edu/~hgs/ephone) that may not support DNS and do
not have the computational resources to host an SLP implementation.
(Indeed, the outbound SIP server may well handle DNS resolution for the
client.)

Since SIP domains can be rather large (a whole ISP), we considered it
important to provide a load balancing mechanism. Since this operates in
a telephony context, reliability is very important, leading us to
include the notion of backup servers and the ability to operate even
when local DNS service is interrupted. There may well be better
mechanisms to address either of these concerns.

Feedback and comments are appreciated.

Henning