SIP Session Policiesdraft-hilt-sipping-session-indep-policy-00draft-hilt-sipping-session-spec-policy-00

Volker Hiltvolkerh@bell-labs.com

Co-Authors: Jonathan Rosenberg, Gonzalo Camarillo

Session-Independent Policies - Issues• Who provides policies for which scope?

1.Home network for AOR.2.Local network for AOR.3.Local network for devices.

• Can the event package of the Profile Delivery Framework be used?– Selective subscription to policy packages.– Support different policy packages (XML/text-

based).

• Use Profile Delivery Framework?– Add support for multiple packages and local

network AOR subscriptions.• Keep XML policy format?

– Use within Profile Delivery framework.

• WG-Item?

How to Proceed?

• Piggyback model (current draft).– Proxies insert policies into INVITE transaction.

• Policy MFOs are inserted in the message containing the SDP.• Preconditions used to avoid “ghost rings” if UAC CANCELs

because of policies. – Pro’s: call setup delay independent of number of proxies; small number

of messages.– Con’s: policies traverse entire network (encryption to hide them).

• Re-direct model.– Proxies use INVITE transaction to tell UAs to retrieve policies.

• UAC: proxy rejects INVITE and provides policy URI.• UAS: proxy inserts policy URI in INVITE.• UAs submit MIOs to policy server and retrieve policies.

– Pro’s: policies for local UAs stay in local network; reuse session-independent mechanisms.

– Con’s: reject cascade with multiple proxies; increased setup delay.

Session-Specific Policies – Models

Open Issues• Which model (redirect vs. piggybacking)?• User approval needed for policies?

– Automated decisions by UA may simplify flows.• Encryption of MIOs and MFOs?

– Align with e2m and sec-inserted drafts.