GRUU%20Mechanism%20and%20Device%20ID

1
GRUU Mechanism andDevice ID

• Jonathan Rosenberg
• dynamicsoft

2
GRUU Changes

• Removed requirement that GRUU be constructed so
  that AOR or Contact cannot be learned
• Privacy is not a requirement here
• Indicate that a GRUU can be obtained from other
  unspecified mechanisms
• GRUU now bound to instance ID
• Caller prefs instance ID defined and registered

3
Issue 1 Registration Conflict

• Problem Case
• UA with instance ID A registers
• UA crashes
• UA reboots, obtains a new IP, re-registers
• Registration conveys the same instance ID
• Result would be two contacts with the same
  instance ID
• Three behavior options
• Requests for the GRUU fork
• Registrar should reject the registration
• Registrar should delete the older registration

4
Pros/Cons

• Behavior 1 is not desirable
• Violates fundamental assumption about a GRUU
• HERFP
• Behavior 3 has server decide on resolution,
  behavior 2 has client
• Its possible that the client may want the old to
  persist
• Proposal specify behavior 2
• New response code a good idea

5
Issue 2 caller prefs param?

• Currently, instance ID is a callee capability
  parameter
• Implication can use it in Accept or Reject
  Contact header fields
• Would allow routing to instance ID without GRUU,
  sort of
• Caller prefs routing not reliable, no guarantees
• This is part of reason why original instance
  approach for transfer was rejected in favor of
  GRUU
• Proposal
• Keep as callee cap (it IS a characteristic)
• Add text advising strongly against usage with
  Accept/Reject contact use a GRUU instead

6
Issue 3 Format of instance ID

• Is it a URN?
• Do we specify how its computed?
• Use a HIP ID?
• GUID?
• Proposal
• Do not specify how its computed
• Must be formatted as quoted string allows
  anything
• Merely require temporal and spatial uniqueness

7
Issue 4 GRID usage outside of GRUU?

• GRID has the property of surviving proxy
  translations
• Is a form of sub-addressing
• Is there value in having this as a generic URI
  parameter?
• Proposal
• It is a generic URI parameter
• Since GRUU can be obtained outside of
  registrations, can be applied to other mechanisms
• Only makes sense in context of URIs that
  represent an instance though

8
Issue 5 Other usages?

• Billing? Diagnostics?
• Need requirements and use cases SIPPING problem
  right now
• We should proceed with GRUU instance ID separate
  from that
• Is a very specific feature for a very specific
  extension