Transcript Comparison of SIP Proxy and Redirect Servers

Comparison of SIP
Proxy and Redirect Servers
Presented By:
Greg Osterhout
Sr. Mgr, SIP Services Development and Evolution
SIP Reference Architecture
I2004
EtherSets SIP Soft Client
User
Proxy
SIP
USB Phone
Terminal Endpoints
• SIP User Agent for
user devices
SIP
User
Proxy
Network/User Proxy
• Registration of SIP
endpoints
• Provides endpoint mobility
• User specific services
• Domain resolution
SIP Network Nodes
SIP
SIP
SIP
Mobil Oil
Network
User
Proxy
PSTN
SS7/PRI
PSTN Gateway
• SIP User Agent for PSTN Trks
• SIP services for PSTN terminations
SIP User Proxy
• Primarily exist in customer IP networks
• Provides endpoint mobility services via SIP registration
methods
• Provides wide range of user specific services
— simple canned service
— full user controlled services via CGI or CPL scripts or servlets
Network User Proxy
• Provides Domain mapping for network endpoints
• Could provide SIP services to customers that can’t feasibly
manage their own user proxy
Proxy Capability Driven By Network
1. INVITE sip:[email protected] SIP/2.0
From: sip:[email protected]
2. INVITE sip:pulver@von1 SIP/2.0
From: sip:[email protected]
3. SIP/2.0 200 ok
From: sip:pulver@von1
pulver.com
nortel.com
[email protected]
jeff.pulver
Location Server
pulver@von1
4. SIP/2.0 100 OK
From: sip:[email protected]
5. ACK sip:[email protected] SIP/2.0
From: sip:[email protected]
6. ACK sip:pulver@von1 SIP/2.0
From: sip:[email protected]
Proxy server
SIP Proxy Servers
• “Network Servers” that Proxy requests to other server
• User Proxies manage sets of SIP users
• Provides dynamic association of SIP endpoints
• Proxy capabilities:
— outgoing calls
— address lookup
— policy management
— firewalls
— call path hiding
• Proxy servers can be stateful or stateless
Proxies Provide SIP User Management
Stateful Proxy Servers
• Maintains call context
• Replicates User Agent Server/User Agent Client to process
requests/responses
• Call state and transaction state can be maintained
• Forking proxies require state
• TCP proxies must be stateful for reliability
• Enhanced services require state for execution
• Can populate billing information
Services Dictate Statefulness of Proxy
Stateless Proxy Servers
• No call context
• Response is not based on User Agent replication
• Provides client anonymity
• Restricted gateway access
• High processing capacity
• Allows for easier replication than stateful proxy
• Can have semi-stateful proxy for ultimate benefits
Stateless Proxies Geared for Capacity
pulver.com
Location Server
Jeff.pulver
nortel.com
[email protected]
Pulver@von1
Redirect Server
1. INVITE sip:[email protected]
From: sip:[email protected]
2. SIP/2.0 320 Moved temporarily
Contact: sip:[email protected]
4. INVITE sip:[email protected]
From: [email protected]
5. SIP/2.0 200 OK
To: [email protected]
3. ACK sip:[email protected]
From: sip:[email protected]
6. ACK sip:[email protected]
From: sip:[email protected]
SIP Redirect Servers
• Accept SIP requests, map the address into new addresses,
and return these addresses to the client
• Do not initiate requests
• Do not accept calls
• Lower state overhead required than proxy servers
• High processing capacity due to fewer messages to process
• Services are client device dependent
Service Dependence on Client
• Can be stateful or stateless
• High capacity
• Flexible, network service
• Minimal state overhead
implemenations
• Reliability achieved through
• Service execution pushed to
client
replication
• Scalability achieved through
partitioning
• Overload potential if not properly
scaled
• Hybrid (semi-stateful) model
provides maximum benefits
Hybrid Proxy Is Best Alternative