ims and atca james rafferty [email protected]
TRANSCRIPT
3
Agenda• Open Systems for Service Providers• SIP: A Success Story• IP Multimedia Subsystem• ATCA• Where are we on the adoption curve? • IMS and ATCA: The Road Ahead
Open Systems for Service Providers
• Traditional switches (pre-IP) built on proprietary hardware and various quasi-standard telecom protocols
• With advent of IP, a chance to revisit the model• Two key directions emerged:
– Open protocols– Open hardware
• How is that working out?
4
Open Protocols
• Good News– Open protocols are very popular– But, there’s been too many of them
• Circuit-Based: MFR2, ISDN PRI, SS7• H.323, MGCP, H.248, SIP
– From a variety of standards groups and consortia• ITU-T, ANSI, ETSI, IETF, 3GPP, W3C, …
– Fortunately…
5
Winner of the Standards Wars
• SIP (Session Initiation Protocol)
• Two Key Endorsements– Microsoft
– Third Generation Partnership Program (3GPP)
6
SIP and Open Telecom
• Since 2001, VoIP industry has built products that are SIP enabled
• But SIP is pretty complex– Many core standards– Many standard extensions– Many proprietary “de facto” extensions
• How to sort out this puzzle?
7
8
One Answer: 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 Subsystem (IMS) – Developed by Third Generation Partnership Project (3GPP)– Endorsed by both wireless and wireline industry groups
IMS Architecture
P-CSCF
S-CSCFMGCFHSS
Cx
IP Multimedia Networks
IM-MGW
CS Network
Mc
Mb
Mg
Mm
MRFP
Mr
Mb
Legacy mobile signalling Networks
I-CSCF
Mw
Mw
Gm
BGCFMjMi
BGCF
Mk Mk
C, D, Gc, Gr
UE
Mb
Mb
Mb
MRFC
SLFDx
Mp
CS
CS
IMS Subsystem
Cx
Mm
AS
ISCSh
Ut
Mb
Dx
3GPP TS 23.228 V7.2.0 (2005-12)
IP Multimedia Subsystem (IMS) Simplified View
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
Key Elements:
MRFC
HSS/HLR
MRFP
CSCF
MGW
S-CSCF
BGCF
MGCF
MRF
SIP
RTPSS7
SIP
Application Servers
P-CSCF
Benefits of IMS
• Reference Architecture for Vendors and Customers• Provides standard profile of SIP
– 3GPP standards reference core SIP standards and extensions
• No work in process documents are mandated
• Provides focus for SIP and related interop• Updated about every year and one half
– Updates reflect progress in filling standards gaps
11
GamingGaming
SIP MSCML
RTP
SIP
MRF
SIP
SIPSIP w/ VoiceXMLSIP w/ MSCML
SIP
SIPVoiceXML
NFS
HTTP
FTP
NetworkStorage
WebContent
SIP RoutingCloud
3G
2.5G
PSTN
Cable IP Phones
Unified MessagingUnified Messaging AnnouncementsAnnouncements Video MailVideo Mail VideoConferencing
VideoConferencing IP Call CenterIP Call Center
Pre-PaidPre-Paid Voice MailVoice Mail ConferencingConferencing Video RingbackVideo Ringback
S-CSCF/SCIM
IP MSC
CMTS
MGCF/MGW
QuickTime
mp3
Text
MPEG-4
IMS: Foundation for Multimedia Services
IMS: Filling out the Specs
• Work continues on notable IMS components• Example: Internet Engineering Task Force is
developing a SIP based media control protocol– Likely to be adopted by 3GPP for IMS– Will provide a linchpin in the critical interaction between
Application Servers and Media Servers
• Current IMS spec is Release 7 (2007)• Next IMS Release 8 is targeted for 2008
13
IMS and Sorting Out SIP
• The promise of IMS is a reference architecture that many vendors buy into
• Reality is more complex• Vendors ARE deploying pre-IMS or partial IMS
solutions– SIP is widely used, but interoperability issues remain– IMS will help encourage standard profiles of SIP– As a vendor, we’re already seeing more pressure to
adapt the SIP specs endorsed by 3GPP
14
What about Open Hardware?
• PICMG devised the first pass of a telecom architecture early this century
– Used Compact PCI– Had Ethernet backbone – PICMG 2.16– Enabled use of bladed architecture with IP protocols
tying together the blades
• Reaction of Telecom Vendors – Not sufficiently carrier grade– PCI bus is single point of failure
15
ATCA to the Rescue
• PICMG started all over again• Created the Advanced Telecommunications
Computing Architecture (ATCA)• Goals:
– Support very high bandwidth backbones in a chassis– Provide specifications for all key hardware components– Support multiple switch fabrics– Include built-in management tools– Build in robust high availability hardware from the start
16
Apr 20, 2023
ATCA Expanded Board Size
Con
nect
or Z
ones
Con
nect
or Z
ones
CompactPCI55 square inches~50 watts power
AdvancedTCA125 square inches~200 watts power
280mm
8U
6U
160mm
Apr 20, 2023
Bus vs. Switched Fabric Comparison
Shared Bus can jam with one failure
Switched Fabric can have redundant paths
Example: Evolution to ATCA
Rackmount Server
Compact PCI Boards
Software-BasedMedia Server
ATCAHost Blade
Add HW Assist
ATCACarrier Card
ATCAChassis
ATCAAMC Cards
ATCA: Vision and Reality
• ATCA Vision of Open Hardware is a great idea– Encourage creation of open hardware eco-system– Get broad participation of experts in all key components– Build best of breed systems using open components
• The Reality? – The xTCA eco-system has partially taken hold– Lots of competition from private bladed architectures– All of the fabric choices fragmented the vendor
implementations– Many vendors and carriers have not bought in
20
In Perspective
• Can you buy a deployable IMS implementation using xTCA components today?
• In total:– No
• In parts:– Yes
• Does this mean that Open Systems are a failure? – No, not at all
21
Where are we on the adoption curve?
• For SIP– Core SIP RFCs widely adopted– Lots of proven interop between components– Interop via SIPIT and other industry assocations
• For IMS– IMS concepts being used, but standards are incomplete– Hence, adoption of pre-IMS built around SIP
• For ATCA– Sporadic adoption by key vendors– Alternatives have emerged
22
Alternatives to ATCA
• Blade Servers– Platforms developed by several computer vendors– Heavy processing focus; less emphasis on I/O
throughput
• Rack Mounted Servers– Use server as appliance approach– 1 and 2U form factors; expand via rack and stack– Purpose built hardware coupled with open protocols
23
Open Systems Example
• IP Media Servers have been adopted in several form factors
– Began as proprietary, carrier rack systems– Shift toward 1 and 2U appliances, often with standard
CPUs and no DSPs– Blade servers offer high density and scalability– ATCA processor blades can also run media server code
and scale up via addition of more blades– MicroTCA will enable smaller form factor media servers
built on xTCA eco-system
24
So What about ATCA and IMS?
• ATCA has helped spawn an open hardware movement
– But rack mount servers and blade servers have been hugely popular
• IMS is one of the factors driving wide adoption of SIP
– Open protocols have been a big winner, with SIP being the focus
– IMS offers a reference architecture for SIP and ways of gluing SIP components together
25
ATCA and IMS: Evolution, not Revolution
• ATCA still has an uphill climb• Service providers want reliable HA architectures• ATCA has the promise, but needs more adoption
– Smaller xTCA form factors may be more successful– Can build on same eco-system as ATCA
• IMS has lots of vendor mind share, but…– Specifications are still maturing– Still early on the adoption curve– Vendors are using IMS concepts
26
Resources
• IMS Forum – www.imsforum.org• 3GPP – www.3GPP.org • Internet Engineering Task Force – www.ietf.org• ETSI TISPAN -
http://portal.etsi.org/portal_common/home.asp?tbkey1=TISPAN
• PICMG – www.picmg.org• MultiService Forum – www.msforum.org
27
Summary
• Movement toward Open Standards is strong in Telecom
• SIP has been widely adopted• IMS offers promise as a reference architecture, but
still in early stages of deployment• ATCA has supporters but is vying with alternatives
as the basis for next generation hardware• Combination of ATCA and IMS makes sense, but is
not happening yet on a wide scale
28