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

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

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

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?

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

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

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

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

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

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

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

Information Resource Jonathan Rosenberg jdrosen@dynamicsoft.com +1 732.741.7244