2. Realities of Multi-Domain Gateway Network Management
Jonathan Rosenberg
Chief Scientist

3. Limitations of Single Provider VoIP
Single Provider VoIP Networks are a Barrier to Entry
Difficult for a single carrier to get national or international coverage
Wide coverage needed for cost advantages
Capital investment of many international POPs is significant
Solution - Multi-Provider
Each provider owns a set of POPs
Calls originating in POP of one provider can terminate in POP of another A B C D

4. Multi-Provider Agreements
P2P
Multi-Provider Case Requires Agreements Between Entities
Many Possible Organizations of Agreements
Peer to peer bilateral
Settlement House (star)
Confederation (full mesh)
Each Organizational Arrangement is a Series of Bilateral Agreements
Results in a Requirement of Bilateral Information Flow
Settlement
House
Confederation

5. Information Exchange Main Question: Where to Route an Incoming Call?
Depends on a Number of Factors:
The set of phone numbers each provider is willing to terminate
Cost/billing/pricing arrangements
Preferences for a particular provider
POLICY
Decision Must be Made Quickly
Affects call setup time
How is it Accomplished?

6. Solution: TRIP Telephony Routing over IP
Being Developed in IP Telephony Working Group in IETF
Specification is Mature, RFC Shortly
What does it do?
Exchange of routing information between peer providers
Exchange happens outside of call setup
Routing information consists of phone prefixes and associated data
Allows for aggregation and redistribution
Strong policy support

7. TRIP Components Internet Telephony Administrative Domain (ITAD)
Gateways
Internet Telephony Administrative Domain (ITAD)
Owner of GW, LS, users
Location Server (LS)
Primary component
Exchanges routing information with internal and external peers
Front End
Protocol mechanism used to access TRIP data
Typically SIP
Location
Server
ITAD B
TRIP
End
Users
ITAD A
Front
End

8. What are its main features?
Based on Scalable IP Routing Technology
Combination of BGP4 and IS-IS
Proven algorithms and operation
Support for LNP and Routing Numbers
includes international codes with hex values
Works for both SIP and H.323
Can even enable routing through conversion boxes

9. What are its Main Features cont.
Capabilities Exchange
Agree upon address family for routing
Send Only, Receive Only, Bidirectional Modes
Allows for domains that wish to only export or import routes
Extensibility
Support for new attributes built in
Attributes provide parameters for a route

10. How does it work?
An LS is Statically Configured with its Internal and External peers
No autodiscovery
External relationships need to be driven from business needs
LS Connects to Peers
TCP connection
Basic capabilities negotiation
Address families
Send/Receive/Send-only
Agree on keepalive interval
Route Exchange
Complete synchronization of routing tables with external peers
Sharing of learned routes with internal peers
Only happens initially
Keepalives
After route exchange, period keepalives
Small in size
Updates
If route changes, modified route is sent
Incremental updates

11. Location Server Processing
Internal Routes
An LS Will Receive Routes from Many Sources
External Peers
Internal Peers
Statically configured
Needs to Generate
Local Telephony Routing Information Base (TRIB)
Routes to send to peers
Accomplished with Decision Process
Combines routes from sources
Generates Local TRIB
Outputs Routes
Adj. TRIB
Adj. TRIB
Local Routes
Adj. TRIB In
Decision Process
Policy
Local TRIB
Adj. TRIB Out
Adj. TRIB Out
Adj. TRIB Out

12. Summary Problem: Solution: Single provider cannot own all gateways
Need for a way to support multi-provider operation
Solution:
Telephony Routing over IP (TRIP)
Protocol for inter-domain exchange of routes bilaterally

13. Information Resource Jonathan Rosenberg jdrosen@dynamicsoft.com