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SIP Connection Reuse Efficiency. Rohan Mahy—Airespace (rohan@ekabal.com). Existing Connection Reuse Draft. Per WG consensus in San Diego, now only talks about connection reuse of mutually authenticated TLS connections for efficiency purposes
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SIP Connection Reuse Efficiency Rohan Mahy—Airespace (rohan@ekabal.com)
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 • 1.2.3.4 • server22.example.org
SIP Outbound Connections Cullen Jennings (fluffy@cisco.com)
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
Biloxi Alice Bob REGISTER (on conn 33) 2. INV 3. INV (on conn 33) Solution • When UA registers, the proxy keeps track of “connection” and uses this connection for things that the proxy forwards to this UA
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
Biloxi Edge Alice Bob REGISTER (on 33) 2. REGISTER (on 44) 3. INV 3. INV (on 44) 3. INV (on 33) Intermediate Edge Proxies • Solution works the same way with proxies between registrar and UA Path header with unique value for this AOR, Contact, connection-id, instance-id Mapping installed on 200 to REGISTER Map using data from path header