Volker Hilt

1
Session-Independent Policiesdraft-ietf-sipping-se
ssion-indep-policy-02

• Volker Hilt
• volkerh_at_bell-labs.com
• Jonathan Rosenberg
• jdrosen_at_cisco.com
• Gonzalo Camarillo
• Gonzalo.Camarillo_at_ericsson.com

2
Status

• Session-independent policy delivery mechanism
• Minor editorial changes.
• Policy document format
• Major revision to simplify format
• New section about policy format design
• Basic Session Policy Format (BSPF)
• Minimal policy format.
• Covers aspects defined in requirements draft
  only.
• Can be extended to cover other aspects as needed.

3
BSPF Design

• Policy Structure
• Policies are defined as XML elements.
• Flat structure (i.e. no combined policies).
• "policy" attribute
• Mandatory, allowed, denied
• Optional "direction" attribute (defined
  per-element).
• Optional "label" attribute (defined per-element).
• Merging policies
• Merging rules are defined individually for each
  policy element.

4
Open Issue 1 BSPF Elements

• Included elements
• Media types
• Codecs
• Media intermediary
• QoS
• Max bandwidth

• Proposed media elements
• Max no of streams
• Max no of sessions
• Max no of streams per session
• Max bandwidth per session
• Max bandwidth per stream
• External address and port
• Media transport protocol
• Proposed protocol elements
• Outbound proxy
• SIP methods
• SIP option tags
• SIP transport protocol
• Body format/disposition
• Body encryption

5
Open Issue 2 Policy Conflicts

• Merging policies may result in conflicts.
• Example
• Policy 1 only G.711 / Policy 2 only G.729
• If policies are enforced in the network, setting
  up a call might not be possible.
• Can this be prevented or resolved?
• Define a default value for a baseline call that
  must be allowed (e.g. G.711)?

6
Session-Specific Policiesdraft-hilt-sipping-sessi
on-spec-policy-02

• Volker Hilt
• volkerh_at_bell-labs.com
• Jonathan Rosenberg
• jdrosen_at_cisco.com
• Gonzalo Camarillo
• Gonzalo.Camarillo_at_ericsson.com

7
Status

• Minor editorial changes.
• Mechanism to hand out policy server URI in INVITE
  transaction.
• Minor changes.
• Removed use of tokens in Policy-Id header.
• Removed interaction with policy server on BYE.
• Policy Channel Protocol
• Open issue.

8
Open Issue Policy Channel Protocol (1)

• 1 SIP SUBSCRIBE/NOTIFY
• UA subscribes to session policies using provided
  URI.
• UA submits session description in SUBSCRIBE body.
• Policies are returned in NOTIFY messages.
• Asynchronous policy updates via NOTIFY messages.
• Use (possibly long-lived) TLS connection to proxy
  or policy server.
• 2 SIP SUBSCRIBE/NOTIFY PUBLISH
• Same as 1.
• UA submits session description in PUBLISH.

9
Open Issue Policy Channel Protocol (2)

• 3 HTTP
• UA retrieves policies using provided URI.
• No asynchronous policy updates.
• 4 COPS
• UA has the role of a COPS Policy Enforcement
  Point (PEP), policy server has role of Policy
  Decision Point (PDP).
• UA submits policy requests to the policy server.
• Policies can be updated at any time by the policy
  server.
• 5 BEEP
• UA establishes a BEEP channel to the policy
  server.
• The UA sends the session description to the
  policy server and receives policies through this
  channel.
• Policies can be updated at any time by the policy
  server.

10
Other Issues

• Allow the use of alternative policy channel
  protocols?
• Example HTTP if asynchronous updates are not
  needed.
• Proxy provides multiple URIs to UA.
• Which information does the UA submit to the
  policy server?
• Session description
• Policy-specific data