variable reduction process

1
Attributes of VOIP Protocols Tradeoffs
SIP versus CMSS
Reference Model
SIP CMSS
Signaling Gateway

• Several versions exist culminating in ? Uses
  SIP version 2.0 with extensions
• RFC3261 usage rules for local
  CLASS services

? Call Control Signaling Protocol ?
(Same as SIP) ? Establishes real-time
connections across diverse network
infrastructure ? For Multimedia
CMS
CMS
CMSS, SIP, H323 (Peer-to-Peer)
Call Agent (CA)
Call Agent (CA)
? Application Level Protocol ? (Same
as SIP) ? Independent of Bearer Protocol (e.g.
IP, ATM, MPLS, ..) ? Independent of
Transmission Tech- nology (e.g. Cable,
DSL, 3G, TDM, ..) ? Network Media
Independent like HTTP or SMTP
Media Gateway Controller (Master)
Media Gateway Controller (Master)
MGCP NCS MEGACO
IP-Phone
MGCP NCS MEGACO
IP-Network
? Extensible, Reliable, Secure (SIPS) ?
Extensible, Reliable. Secure (SIPS)
? Additional Cable Security Spec.
?
MGW
Slave
? IM, Presence, Location, Session-setup, ?
(Same as SIP) Session-management, Negotiation
of user preferences invoking of services
TGW
Slave
PSTN
Fax
? Gate Controller Feature
(DQoS) ? Event Messaging
Feature ? Operations
Provisioning Feature ?
Electronic Surveillance Feature (calea)
Protocols Comparison
Tradeoffs in Master/Slave Peer-to-Peer
Item MGCP MEGACO NCS
SIP H323
Item Master/Slave
Peer-to-Peer
Architecture Master/Slave Master/Slave
Master/Slave Peer-to-Peer
Peer-to-Peer (Physical control)
(Physical control) (Physical control)
(Logical features) (Logical features)
Operation ? Simple/dumb gateway devices ?
Smart GW devices yet simple
to implement ? Application intelligence
in ? Peer interactionSIP processing
network servers does not increase over time
Signaling Master/Slave Master/Slave
Master/Slave Peer-to-Peer Peer-to-Peer
Media RTP RTP RTP RTP
RTP
Service ? Server-based development ?
Device-specific development development only,
generic tools ? Shorter time to
market for ? Possible short time to
market new services across diverse for
new features on specific
networks devices
Conference Yes Yes Yes
No Yes Control
Transport UDP UDP UDP now mostly
TCP mostly TCP ear
lier UDP
Service ? Only update control servers ?
Must update all GW devices deployment
to deploy new features
across the network ?
Services can be managed dynamically
across network
Encoding Text only Text or ASN.1
ASN.1 HTTPish ASN.1, Q931
Application Telephony Multimedia,
Multimedia, Multimedia,
Telephony Emphasis Telephony
Analog Phone Multicast,
Instant Messaging,
Presence
Cost ? Cost-optimized GW devices, ? Higher
cost Smart GWs, leads to lower overall
system higher overall system cost
cost - Especially in large
systems ? Time-frame for obsolescence ?
GW devices may need HW of GW devices is
slower SW upgrades over time
Address Local-name Local-name
Local-name SIP, E164-URLs Flat Alias,
E164 Domain Domain Domain
Suitability Very large Very large Cable
telephony, IP-PBX, Standalone GWs, Used
for Gateways Gateways Analog
Phone IP-Phones, Conferencing-
3G-networks Systems
Examples ? NCS/J.162 ? SIP ?
MGCP ? H.323 ? MEGACO/H.248