SessionSpecific Policies drafthiltsippingpolicyscenarios00'txt

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Session-Specific Policiesdraft-hilt-sipping-polic
y-scenarios-00.txt

• Gonzalo.Camarillo_at_ericsson.com
• Volker Hilt ltvolkerh_at_bell-labs.comgt

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Scenario

• Proxy inserts a firewall in the media path
• Proxy inserts a NAT (e.g., v4/v6)
• Proxy instructs the UA to disclose the transport
  addresses of all the m lines
• UA discloses its transport addresses
• Proxy provides the UA with new transport
  addresses to be used
• UA informs proxy about the remote UAs transport
  addresses

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Scenario
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Assumptions

• The remote UA does not support session policies
• The piggyback model uses UPDATEs instead of
  re-INVITEs
• So that the flows work with provisional responses
  and with preconditions as well

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PA and INVITE with offer
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PA and empty INVITE
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PB and INVITE with offer
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PB and empty INVITE
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Asynchronous Policy Changes

• For example, rules related to codec or media type
  restrictions change in the middle of a session
• Not supported by the piggyback model

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Security

• Separate channel
• Can use end-to-end authentication and encryption
• Piggyback
• Requires end-to-middle and middle-to-end security

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Conclusions

• Which model do we choose to develop a solution
  mechanism for session-specific policies?
• Piggyback
• Separate Channel