Resource Priority Header

1
Resource Priority Header

• draft-ietf-sip-resource-priority-05
• James M Polk
• Henning Schulzrinne
• 7 March 05
• (2 weeks shy of 5 year anniversary for this
  effort)

2
Resource Priority Header quick review

• A means of addressing congestion in SIP elements
  (proxies, UAS)
• does not address IP-level congestion
• Gives prioritized access to proxy or UAS
  resources
• e.g., trunk
• access-controlled using SIP authentication/authori
  zation
• Priority names organized into namespaces
• no globally agreed-upon ordering across
  namespaces
• typically, each element supports only 1-2
  namespaces

3
Changes from previous (-05) version

• removed all the modes (strict, semi-strict and
  loose)
• Provide semantics for the priority-queue based
  behavior
• Articulated element specific behaviors (UAC, UAS
  endpoint, UAS GW, proxy...) for preemption or
  priority-queue namespaces
• New sections on each namespace with any special
  behaviors that are expected
• Added a Future Namespace definition section

4
Version -05 IANA Registry Table
Behaviors Namespaces dsn drsn q735
ets wps --------- ---
---- ---- --- --- Number of
Priority-values 5 6 5 5
5 Reference this RFC (if
ever published) Preemption Policy
yes yes yes no no Queue Based
Policy no no no yes
yes New Error Code 417 417
417 417 417 ...and the list goes on...

• This was ugly, and everyone knew it, even me

5
Version -06 IANA Registry Table
Intended New
New Error Namespace Levels Operation
Rej. code code Reference --------- ------
---------------- --------- ---- ---------
dsn 5 preemption no
no This RFC drsn 6
preemption no no This RFC
q735 5 preemption no
no This RFC ets 5
priority-queue no no This RFC
wps 5 priority-queue no
no This RFC

• This is prettier, and everyone should see this,
  even me

6
Version -07 IANA Registry Table
Intended New
New Error Namespace Levels Operation
warning code code Reference ---------
------ ---------------- --------- ----
--------- dsn 5 preemption
no no This RFC drsn 6
preemption no no This RFC
q735 5 preemption no
no This RFC ets 5
priority-queue no no This RFC
wps 5 priority-queue no
no This RFC

• This is even better, and everyone should see
  this, even me

7
Changes going into -07 version

• Version -07 will be submitted Monday, March 14th
• Combined the rejection text with the error text
  (cleaner)
• Reduced the text in each namespace section
  (cleaner)
• Responses are no longer prioritized (doesnt work
  reliably or securely)
• Clarified Unknown namespaces are ignored
• Rewrote section on where multiple namespaces are
  used, giving further semantics
• Will add a bit more introductory motivational
  text
• Moved part of the Security Considerations section
  that warned of poor implementations
• not that the Security Considerations section ever
  gets ignored by anyone... doh!

8
Multiple Namespaces
Legend Foo.A Bar.1 (Highest priority) Foo.B
Bar.2 Foo.C Bar.3 (least priority)