Transcript AttributesVoIP

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