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  1. Emergency Service Identifiersdraft-ietf-ecrit-service-urn-01 Henning Schulzrinne Columbia University hgs@cs.columbia.edu IETF65 - ECRIT

  2. Open Issues • Identifying the call post-resolution • Server resolution IETF65 - ECRIT

  3. UA recognition & UA resolution location information mapping mapping may recurse DHCP LLDP-MED 9-1-1 (dial string) leonianj.gov INVITE sip:psap@leonianj.gov To: urn:service:sos Accept-Contact: *;sip.service="urn:service:sos" <location> INVITE sip:psap@leonianj.gov To: urn:service:sos Accept-Contact: *;sip.service="urn:service:sos" <location> IETF65 - ECRIT

  4. UA recognition & proxy resolution mapping 9-1-1 provider.com INVITE urn:service:sos To: urn:service:sos Accept-Contact: *;sip.service="urn:service:sos" <location> INVITE sip:psap@leonianj.gov To: urn:service:sos Accept-Contact: *;sip.service="urn:service:sos" <location> IETF65 - ECRIT

  5. UA recognition & proxy resolution(proxy location determination) mapping 9-1-1 provider.com INVITE sip:psap@leonianj.gov To: urn:service:sos Location: <location> Accept-Contact: *;sip.service="urn:service:sos" INVITE urn:service:sos To: urn:service:sos Accept-Contact: *;sip.service="urn:service:sos" IETF65 - ECRIT

  6. Proxy recognition & proxy resolution mapping 9-1-1 provider.com INVITE sip:psap@leonianj.gov To: sip:911@provider.com;user=phone Location: <location> Accept-Contact: *;sip.service="urn:service:sos" INVITE sip:911@provider.com;user=phone To: sip:911@provider.com;user=phone IETF65 - ECRIT

  7. Problems with approach • No authentication  call alice@yahoo.com, mark as emergency call  get free call • assumes that IP calls are charged • unlikely that providers will just gateway to E.164 PSAP numbers • if mapping done by outbound proxy, next entity will be PSAP URL anyway • no home routing for emergency services! (visited service in IMS) •  only problem for UA rec/res • thus, could we punt? IETF65 - ECRIT

  8. only trust Accept-Contact from same trust domain see P-Asserted-Identity model (RFC 3325)  brittle or use Identity model  signed by outbound proxy unfortunately, not covered by doesn’t help with UA rec/res model! creating a new header likely to have similar issues re-do mapping and ensure that URL matches server can learn list of “legal” URLs after a while can fail if mapping is dynamic (advertisement changes) then just replaces URL forces each outbound proxy to do mapping check external source that URL is indeed a PSAP use draft-ietf-sipping-certs for destination URL, but would need to have a role-based cert “this is a bona-fide PSAP” easy to posit, harder to deploy globally can incur significant delay but only needed when there’s service differentiation new TLD for PSAPs only  Call identification alternatives IETF65 - ECRIT

  9. Resolution: DDDS • (Most) URNs have a resolution mechanism  DDDS • Extract service part, e.g., “sos.fire” • Get domain D from local source: • DHCP  ISP as service provider • domain part of AOR  VSP as service provider • SIP configuration • Resolve NAPTR record for D:example.com. ; order pref flags service regexp replacement IN NAPTR 50 50 "u" "LOST+D2T" "!urn:service:(.*)!http://example.com/map/\1!i" . IETF65 - ECRIT

  10. Summary • Only two (known) open issues: • marking  can be separated, if needed • DDDS  needs NAPTR expert advice IETF65 - ECRIT