SIP Connection Reuse Efficiency Rohan Mahy—Airespace

Existing Connection Reuse Draft Per WG consensus in San Diego, now only talks about connection reuse of mutually authenticated TLS connections for efficiency purposes Includes informative reference to “outbound-connection” document One open issue just received from Cullen

Open Issue on Alias Name (1 of 2) Current Text (Option 1): – Name of the alias (advertised value) is from the sent- by part of the Via header field value. Verify TLS peer name corresponds with sent-by –Via: SIP/2.0/TLS proxy-farm.example.org;alias –TLS cert could contain: proxy-farm.example.org and proxy-farm.example.com

Open Issue on Alias Name (2 of 2) Cullen’s Proposal (option 2): – Name of the alias (advertised value) is from the TLS peer name. Verify sent-by part of the Via header field value corresponds with peer name –TLS peer name is sip.example.org –Via sent-by could be: sip.example.org server22.example.org

SIP Outbound Connections Cullen Jennings

Proxy UA Problems Several things stop proxies from forming a new connection to an UA: –Lack of stable endpoint address –No TLS Certificate –Firewall –NAT

Solution When UA registers, the proxy keeps track of “connection” and uses this connection for things that the proxy forwards to this UA 1.REGISTER (on conn 33) 2. INV 3. INV (on conn 33) Alice Biloxi Bob

TCP Keep Alive Option 1: CRLF Option 2: existing method (REGISTER) Option 3: new method (PING) Recommendation: CRLF

UDP Keep Alive Option 1: CRLF or 0 byte message Option 2: REGISTER Option 3: STUN Recommendation: STUN –Deals with case where residential NAT reboots

Redundant Connections Approach: Allow multiple registrations to indicate that they are equivalent connections to the device and any connection can be used This allows connection to separate farm members for building high availability systems Requires a unique device id in the registration Question: to allow or not allow Recommendation: Allow

Quick Reconnect When a device reboots, should it be able to kill previous registrations to this device This reduces load on proxies after widespread device reboots Approach is provide device id and connection id and new registration replaces any previous connection with same tuple Recommendation: Yes

What to use for Device ID? Hard phones could use MAC or other hardware identifier that was administratively unique Soft phone could use random number UUID encompasses both of these and more in a NIH way Recommendation: –Draft should suggest using UUID

Backup Slides

Intermediate Edge Proxies Solution works the same way with proxies between registrar and UA 1.REGISTER (on 33) 3. INV 3. INV (on 44) Alice Biloxi Bob Edge 2. REGISTER (on 44) 3. INV (on 33) Mapping installed on 200 to REGISTER Path header with unique value for this AOR, Contact, connection-id, instance-id Map using data from path header