EAB-05:006037 Uen Rev A ... Gonzalo.Camarillo@ericsson.com - PowerPoint PPT Presentation

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EAB-05:006037 Uen Rev A ... Gonzalo.Camarillo@ericsson.com

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EAB-05:006037 Uen Rev A ... Gonzalo.Camarillo_at_ericsson.com Contents Interfaces The Cx and Dx interfaces DIAMETER The Sh and Si interfaces The Mw and ISC interfaces ... – PowerPoint PPT presentation

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Title: EAB-05:006037 Uen Rev A ... Gonzalo.Camarillo@ericsson.com


1
IMS Interfaces and Protocols
  • Gonzalo.Camarillo_at_ericsson.com

2
Contents
  • Interfaces
  • The Cx and Dx interfaces
  • DIAMETER
  • The Sh and Si interfaces
  • The Mw and ISC interfaces
  • The Go interface
  • COPS
  • The Mi, Mj, Mk, Mm, Mr, Mg and Mc interfaces
  • The Ut interface

3
Interfacesof IMS
SIP Application Servers
OSA Application Server
CSE(SCP)
Home IMS Network
ISC
Sh
OSA-SCS
Sh
ISC
ISC
Cx
HSS
Cx
Mi
Mw
Mw
Mr
Mg
Gi
Mw
MGW
Gi
ISUP/BICC
Visited IMS Network
Visited Access Network
GGSN
4
Cx Interface
  • I-CSCF or S-CSCF to HSS
  • Allocation of S-CSCF, authentication, retrieval
    of subscriber information
  • Diameter protocol, with a specific application
    Diameter Multimedia Application

SIP Application Servers
OSA Application Server
OSA-SCS
IM-SSF
SLF
HSS
P-CSCF
S-CSCF
I-CSCF
GGSN
MRF
5
Dx Interface
  • I-CSCF or S-CSCF to SLF
  • Used to find the HSS, either by
  • CSCF queries SLF, and SLF returns HSS address or
  • CSCF sends Cx request to SLF which proxies the
    request on to the relevant HSS
  • Diameter protocol, with a specific application
    Diameter Multimedia Application

HSS
6
DIAMETER protocol
  • The RADIUS protocol (Remote Access Dial In User
    Services) has been widely and successfully
    deployed to provide authentication,
    authorization, and accounting (AAA) services in
    the internet. However, inherent shortcomings of
    the RADIUS protocol have limited its ability to
    adapt to the ever-increasing capabilities of
    routers and network access servers, and the
    ever-expanding set of desired AAA services. A
    number of requirements for AAA protocols were
    identified and these requirements drove the
    design of the Diameter protocol.
  • Below are listed some characteristics of the
    Diameter Protocol
  • It is a Query-Response type protocol so, it could
    be used for retrieving user or service
    information.
  • Diameter operates over TCP (Transmission Control
    Protocol) or SCTP (Stream Control Transmission
    Protocol). TCP and SCTP are connection-oriented
    transport protocols with flow control and
    congestion avoidance mechanisms.
  • Diameter includes support for capability
    negotiation so, although clients and servers are
    not aware of each other's capabilities, they
    may be able to successfully negotiate a mutually
    acceptable service.
  • It is capable of transporting of user
    authentication information, transporting of
    service specific authorization information,exchang
    ing resource usage information,relaying, proxying
    and redirecting of Diameter messages through a
    server hierarchy.
  • Diameter is a peer- to-peer protocol so any node
    can initiate a request.

7
Sh and Si Interfaces
  • Sh Interface
  • AS to HSS
  • Read from or write to HSS records
  • DIAMETER
  • Si Interface
  • HSS to IM-SSF
  • Query CAMEL subscription information from HSS
  • DIAMETER

Sh
Si
HSS
8
Mw and ISC Interfaces
  • Mw Interface
  • CSCF to CSCF
  • Communication between CSCFs. Considered as a
    proxy from the SIP point of view
  • SIP
  • ISC Interface
  • S-CSCF to AS
  • ISC IMS Service Control. Needs to carry
    charging information.
  • SIP

ISC
HSS
Mw
Mw
9
Go Interface
  • PDF to GGSN
  • QoS Authorisation
  • COPS

HSS
Gi
Go
P-CSCF
PDF
Go
Gi
GGSN
PEP
10
COPS protocol
  • It is a simple query and response protocol that
    can be used to exchange policy information
    between a policy server (Policy Decision
    Point-PDP) and its clients (Policy Enforcement
    Points-PEP). In 3GPP, the client (Policy
    Enforcement Points) is the GGSN and the server
    (Policy Decision Point) in the PDF residing in
    the P-CSCF.
  • The characteristics of the COPS protocol are
  • The protocol employs a client/server model where
    the PEP sends requests, updates, and deletes to
    the remote PDP and the PDP returns decisions back
    to the PEP.
  • The protocol uses TCP as its transport protocol
    for reliable exchange of messages between policy
    clients and a server.Therefore, no additional
    mechanisms are necessary for reliable
    communication between a server and its clients.
  • It allows the server to push configuration
    information to the client, and then allows the
    server to remove such state from the client when
    it is no longer applicable.
  • The PEP is responsible for initiating a
    persistent TCP connection to a PDP. The PEP uses
    this TCP connection to send requests to and
    receive decisions from the remote PDP.
    Communication between the PEP and remote PDP is
    mainly in the form of a stateful request/decision
    exchange, though the remote PDP may occasionally
    send unsolicited decisions to the PEP to force
    changes in previously approved request states.
    The PEP also has the capacity to report to the
    remote PDP that it has successfully completed
    performing the PDP's decision locally, useful for
    accounting and monitoring purposes. The PEP is
    responsible for notifying the PDP when a request
    state has changed on the PEP. Finally, the PEP is
    responsible for the deletion of any state that is
    no longer applicable due to events at the client
    or decisions issued by the server.

11
Mi,Mj,Mk,Mm,Mr, Mg Mc reference points
  • Mr Interface
  • CSCF to MRFC
  • SIP
  • Mg Interface
  • MGCF to CSCF
  • SIP
  • Mc Interface
  • MGCF to MGW
  • Megaco (H.248)
  • Mp interface
  • MRFC to MRFP
  • Megaco (H.248)
  • Mi Interface
  • CSCF to BGCF
  • SIP
  • Mj Interface
  • MGCF to BGCF
  • SIP
  • Mk Interface
  • BGCF to BGCF
  • SIP
  • Mm Interface
  • CSCF to Other SIP
  • SIP

HSS
Mi
Mr
Mg
Mj
Mc
Mp
12
The Ut interface
  • UE to AS interface
  • Available in Release 6
  • Used to do data manipulation, such as
  • Configuration of presence list
  • Configuration of conference participants
  • Configuration of watcher access
  • This interface is not used for traffic.
  • The protocols are HTTP and XCAP

HSS
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