1. Jonathan Rosenberg dynamicsoft
GRUU
Jonathan Rosenberg
dynamicsoft

2. Issues URN Equality Comparison GRUU and 425 SIPS Administrative GRUU
Registration tree

3. URN Equality
Registrar has to compare instance IDs to detect if it’s already been registered.
Comparison requires URN equality rules
But we don’t mandate a baseline URN scheme!
Solution
If registrar supports URN scheme, use its equality rules
If not, use lexical equality

4. GRUU and 425 Ramp-Up Problem
Want to minimize messaging when recovering from catastrophic client failures
Proxy failure
NAT failure
Require 4 message exchanges – ¼ capacity cost!
Message exchanges are required to ensure a single contact for each instance gets registered to the AOR

5. Solutions Automatically override old registration with new Keep both
Ping-pong overrides (shouldn’t happen!)
Keep both
Does this violate GRUU property
GRUU routes to a single INSTANCE, ok to take multiple ROUTES

6. SIPS Under what conditions does server allocate a sips GRUU?
If Contact URI is sips [yes]
If contact is reachable over TLS [yes]
Depends on connect reuse
If Contact is sip [no]
If a sips URI is allocated, should a SIP URI also be allocated?
Does a sip AOR equal a sips AOR?
Yes: sips contact, sips gruu, can hand out sip gruu
No: separate contacts, separate gruus

7. Administrative GRUU Configuring these will be ugly
Remove the text (Cullen)
Prefer to keep
Want endpoints that don’t register to have *some* way to use GRUU
We can do better downstream

8. Reg Tree Currently, AOR registration tree unaffected by GRUU
AOR-> Contact
Proxying from AOR OK, but redirects won’t work
Contact unreachable
Is this a problem?
Will we want to redirect to these types of contacts??
GRUU
AOR
Contact

9. Alternate Reg Tree
If you want to fix this, you need to bind GRUU to AOR
Questions
What is in Contact of request? GRUU or client-supplied URI
Client-supplied URI
What goes in Contact header field of 200 OK
Both
What is refreshed
AOR->GRUU mapping persists as long as a contact is associated with GRUU
How does reg-event look?
AOR
GRUU
Contact