Media and ISUP Signaling Transition for IMS and Next-Gen Networks - PowerPoint PPT Presentation

About This Presentation
Title:

Media and ISUP Signaling Transition for IMS and Next-Gen Networks

Description:

How Does it Work Now? VoIP relies strongly on a variety of network elements. Media Gateways ... Skype is the 1st big success story. SIP PTP is being standardized ... – PowerPoint PPT presentation

Number of Views:38
Avg rating:3.0/5.0
Slides: 25
Provided by: LMEL
Category:

less

Transcript and Presenter's Notes

Title: Media and ISUP Signaling Transition for IMS and Next-Gen Networks


1
(No Transcript)
2
Media and ISUP Signaling Transition for IMS and
Next-Gen Networks
  • James Rafferty, Cantata Technology
  • Jraff_at_cantata.com

3
Agenda
  • Introduction Networks in Transition
  • Needs for Translation
  • Signaling
  • Media
  • How Does it Work Now?
  • How will it Work in the IMS?
  • The Way Forward
  • Summary

4
Introduction Networks in Transition
  • IP has excellent momentum in both carriers and
    enterprises
  • Voice and other services will run over IP in the
    future
  • The transition is underway
  • But it will take many years
  • SIP has won the IP standards war
  • But it needs to interwork with the current
    networks
  • Traditional circuit based signaling is still
    prevalent for both landline and wireless networks
  • IP Multimedia Subsystem has won mind share as a
    next-gen service architecture
  • But implementations are still at the trial stage

5
Network Evolution for Service Delivery
Network Traditional TDM Transition Hybrid Next-Gen IP
Architecture Centralized Integrated Design Open distributed TDM-IP Migration Open distributed Pure IP (IMS)
Signaling/Functions SS7, ISDN, CAS SS7-SIP ISDN-SIP CAS-SIP SIP-SIP H.323-SIP
Media/Functions TDM TDMcircuit to circuit TDM - IP conversion circuit to packet IP - IP packet to packet
Applications TDM enhanced services Discrete applications IP-based transport SS7 services over IP IP services over TDM IP-enable/extend TDM services Multimedia services on common service platform (IMS) Blended SIP services
6
Needs for Translation
  • Signaling
  • SIP is likely to be the protocol of choice for
    next generation IP communications
  • It will need to interwork with other signaling
    methods
  • Circuit
  • SS7 network overlays for Intelligent Network
    services
  • ISDN User Part (ISUP) for call control
  • TCAP for Database Services like Caller ID
  • ISDN PRI
  • Channel Associated Signaling (tonal)
  • IP
  • H.323 was rolled out starting in 1998
  • Still found in many carriers and enterprises
  • MGCP is the gateway protocol of choice for Cable
    networks
  • H.248 is used for gateway control in the IP
    Multimedia Subsystem

7
Needs for Translation (2)
  • Media
  • Next generation IP architectures envision
    end-to-end trancoding-free voice operations
  • This is the ideal / Reality is messier
  • Why?
  • Most common VoIP voice codecs
  • G.711, G.729A, G.723.1
  • Up and coming
  • iLBC
  • Most common Wireless codecs
  • CDMA, GSM-FR, GSM-EFR, AMR
  • Fax
  • Both T.38 and G.711 IP coding are common
  • Result
  • Need to translate media across network boundaries

8
Needs for Translation (3)
  • Situation is not much better for video
  • H.324-3G translates media between IP and first
    gen 3G phones
  • Special gateways needed to multiplex the media
    for transmission to the handset
  • A variety of different video codecs in use
  • H.263 (2000), H.263
  • MPEG-4 Advanced Simple Profile
  • H.264 (aka MPEG-4 Advanced Video Coding)
  • And more are being produced all the time

9
How Does it Work Now?
  • VoIP relies strongly on a variety of network
    elements
  • Media Gateways
  • Translate media and typically some signaling
  • Signaling Gateways
  • Usually translate from circuit signaling to IP
    signaling
  • Session Border Controllers
  • May translate between IP signaling protocols
  • For example, H.323 to SIP
  • Softswitches
  • Provide control over media and signaling gateways
    in a distributed architecture
  • Sometimes these elements are combined
  • For example, media signaling -gt
  • Integrated Media Gateway

10
Typical VoIP Architecture
IMG 1010 Media Gateway
IMG 1010 Media Gateway
SIP / H.323
SIP / H.323


IP Network
SS7
ISDN / CAS
SS7
ISDN / CAS
Class 5 Switch
Class 5 Switch
Media Gateway Functions PSTN-to-IP Connection
gtMedia gtSignaling gtRouting
End Users
End Users
11
VoIP Using Softswitch Architecture
Softswitch
SIP - T
Softswitch
SIP - T


IP Network
SS7 / M3UA
Signaling GW
H.248 / MGCP
H.248 / MGCP
SS7
Class 5 Switch
Media GW
Media GW
IP Network
RTP
RTP
TDM / IMT
SS7
Media Gateway Functions PSTN-to-IP Connection
gtMedia
TDM / IMT
Signaling GW Functions TDM-to-IP connection
gtSS7 to SS7 over SIGTRAN
End Users
End User
12
Voice over Broadband
SIP
Telco Class 5 Switch
RTP
IP Backbone
SIP
Media Gateway Functions PSTN-to-IP Connection
gtMedia gtSignaling gtRouting
RTP
TDM Phone
IP Phone
13
VoIP Peering
Session Border
Controller
SIP
SIP / H.323
SS
7

TDM
IP Carrier 1
SIP
TDM Carrier
SIP / H.323
ISDN / CAS

RTP
IMG 1010 Media Gateway
Peering Fabric
Media Gateway Functions PSTN-to-IP Connection
gtMedia gtSignaling gtRouting IP to
IP Connection gtTranscoding gt ENUM address
translation
SIP
IP Carrier 2
SBC Functions IP-to-IP connection gtFirewall
and NAT traversal gtPolicy enforcement
gtSecurity gtSignaling Interwork (SIP, H.323)
Peering Fabric offers simpler connections among
carriers
14
Whats Next IMS
  • Wireless Vendors worked to produce standards for
    Multimedia Services over SIP
  • Design Criteria
  • Provide common architecture for multiple services
  • IP at the core
  • Offer access to users on existing networks
  • Need to interwork between IP and circuit switched
    at the edges
  • Result IP Multimedia Subsytem (IMS)
  • Developed by Third Generation Partnership Project
    (3GPP)
  • Endorsed by both wireless and wireline industry
    groups

15
IMS Architecture
16
IMS for the Rest of US
Application Servers
Key Elements
  • AS Application Server
  • SCIM - Service Capability Interaction Manager
  • MRFC - Multimedia Resource Function Controller
  • MRFP - Multimedia Resource Function Processor
  • MRF Media Resource Function
  • CSCF- Call Session Control Function
  • BGCF - Breakout Gateway Control Function
  • MGCF - Media Gateway Control Function
  • MGW - Media Gateway
  • HSS - Home Subscription Server
  • HLR - Home Location Register

SIP
MRFC
CSCF
RTP
MRF
17
IMS and Signaling Translation
  • All signaling converted from circuit to IP at the
    edges
  • Integrated Approach
  • Convert SS7 ISUP, PRI, CAS directly to SIP
  • Follows TS 29.163 which is based on ITU-T
    Q.1912.5
  • Distributed Approach
  • Signaling GW Convert SS7 ISUP and PRI to run
    over IP
  • Use the SIGTRAN suite of adaption layers that run
    over SCTP
  • For example, ISUP runs over M3UA
  • Media Gateway Control Function
  • Terminates SS7 over IP and converts to SIP

18
IMS and Media Translation
  • Ideally, media is NOT converted from end to end
  • For example, use AMR codec for voice over entire
    3G UTMS network from end to end
  • Conversions needed to connect to existing
    networks
  • Media Gateways
  • Landline Connection - Will convert G.711 to AMR
    or EVRC
  • 2G to 3G Wireless Will convert GSM series to AMR
  • Voice over Broadband to Wireless IP
  • May need conversions such as G.729A, iLBC, or
    G.723.1 to AMR or EVRC

19
State of the Standards
  • SIP is a many splendored thing
  • Core 3261 specification and many, many others
  • Hitchhikers Guide to SIP outlines the Core SIP
    (draft)
  • IMS is standardized on SIP, But
  • Several different versions, each offering its own
    profile of SIP and other related specifications
  • Release 5 First real specs for IMS in 2003
    introduces the architecture
  • Release 6 More complete IMS specs in late
    2004, but still incomplete
  • Release 7 Just being standardized now Rollout
    probably 2 years away
  • More complete, but some areas are very immature
  • For example, no standard for media control
    between application servers and Media Resource
    Functions

20
State of the Marketplace
  • VoIP Rollout is not waiting for IMS
  • SIP has overtaken H.323 for new VoIP deployments
  • SIP enabled Media Gateways very popular
  • H.323 mainly needed to tie into legacy
    deployments
  • Distributed Gateway model
  • Many of the large gateways use the distributed
    approach
  • Media Gateway controlled by Softswitch
  • Softswitch Protocols of choice are MGCP and H.248
  • Usually have separate signaling gateways to
    terminate SS7 and convert to IP signaling
  • Integrated Media Gateway Model
  • Incorporate both signaling and media translation
    in GW
  • Include SS7 termination and conversion to SIP or
    SIP-T in one box for better economics

21
The Way Forward
  • IMS will continue to mature and is well regarded
    by Tier 1 carriers
  • Pressures on Landline vendors such as BT will be
    the early IMS implementors
  • Wireless vendors have less incentive to make the
    investment except for new applications
  • Voice over Cable vendors start transition to IMS
    as well, but currently using SIP and MGCP
  • Tier 2 and below vendors will continue to use SIP
    and only convert to IMS if obvious advantages
  • Peer to Peer models will also compete with the
    IMS Client Server approach
  • Skype is the 1st big success story
  • SIP PTP is being standardized
  • Slow transition from hybrid to all-IP networks

22
Resources
  • Internet Engineering Task Force www.ietf.org
  • Provides RFCs for SIP, RTP and some aspects of
    SS7 / IP interworking
  • Hitchhikers Guide to SIP
  • http//www.ietf.org/internet-drafts/draft-ietf-sip
    -hitchhikers-guide-02.txt
  • International Telecommunications Union
    www.itu.int
  • Develops H.248 / Megaco and SS7 series of
    recommendations
  • Third Generation Partnership Program (3GPP)
    www.3GPP.org
  • Develops IP Multimedia Subsystem and related
    standards
  • Cablelabs www.cablelabs.org
  • Develops standards for Cable use of IMS and MGCP

23
Summary
  • Transition underway from Circuit to IP
    communications networks
  • SIP is the IP Communications protocol of choice
  • Both Signaling and Media Conversion needed today
    and for years to come
  • IMS has good mind share, but still at early stage
    of deployments
  • In the meantime, a variety of network elements
    will fuel the transition to IP
  • Both distributed and integrated models popular
    methods for signaling and media translation

24
  • Thank You!
Write a Comment
User Comments (0)
About PowerShow.com