Transcript P-Headers - Softarmor

SIPPING
3GPP Requirements
Ad Hoc Meeting
Georg Mayer
IETF#53, Minneapolis
SIP – the Solution for IMS
 Loose Routing adopted
 All IMS entities that forward SIP messages support loose routing
 P/S-CSCF’s are transparent B2BUAs (e.g. network initiated call
release, header removal by P-CSCF)
 Max-Forwards adopted
 DTMF via RTP (RFC2833)
 manyfolks-05 & update drafts – adoption still under discussion
 Path Header – needs further discussion (also in IETF)
Loose Service Binding – Everything is Allowed
 UMTS Network consists of three domains:
 Circuit Switched (CS)
 Packet Switched (PS)
 IP Multimedia Subsystem (IMS)
 IMS is on top of PS domain
 Pure IP / SIP are available via PS domain
 Value added services are available via IMS
 Registration is not necessary to set up SIP calls in UMTS
 Calls to unregistered IMS users are possible (terminated at home
service node, e.g. VoiceMail)
 IMS users can be called from Non-IMS users and vice versa
Privacy – To/From headers
 Request Privacy by an extra header
 Where is the caller identity transported?
 Remote Party ID?
 From header?
 If From header is the solution then
 P-CSCF needs to be able to change it
 P-CSCF should not be mandated to act as B2BUA because of
that, i.e. send the changed value also to the UE in responses.
XML Bodies and P-headers
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3GPP specific information currently is transported in a XML body
IETF: XML should be opaque to Proxies
CSCF’s are transparent B2BUAs
3GPP is basically willing to migrate to P-headers for most of the
information
 It may be more appropriate to transport 3G specific data which is
purely not SIP related (e.g. 3GPP filtering related) within XML-bodies
 Problems?
 ID (intended as informational RFC) will be brought up in the near
future, listing all the 3GPP specific information which should go into
P-headers.
P-Headers
 Charging-Information
 ICID (IMS Charging ID) and GPRS CID for correlation and
identification purposes – ICID generated by first IMS network
entity – globally unique
 Charging Control Function (CCF) Address
 Visited Network ID
 Cell-ID
 Originally dialed Public User ID (Target Address-of-Record)
 3GPP specific or general requirement?
 Relation to Visited Header?
 P-Header?
 Possible to be solved with To-Header manipulation? (Backwards
compatibility …)
Security
 AKA via HTTP-Digest
 How AKA works
 MD5 versus RES
 Integrity Protection
 HTTP-Digest extension
 IPSec
 Draft Arkko Sip-Sec agree
 Key Transport (CK, IK) from S-CSCF to P-CSCF
 (S)MIME?
 P-Header?
 XML Body?
 Tag in existing header?