Exterior Gateway Protocols (EGPs) are also called Inter-Domain Routing Protocols (IDRP). EGPs are dynamic routing protocols used by routers to exchange routing information between 2 distinct Autonomous Systems (AS)
Inter-Domain Routing Protocols: 2 Major Protocols
- Exterior Gateway Protocol (EGP) - not used because it constrained the topology of Internet to a treelike topology and did not allow topology to become more general
- Border Gateway Protocol (BGP) - replaced EGP and is in its fourth generation (BGP-4)
Inter-Domain Routing Protocols: Goals
goals of Inter-Domain Routing:
- find a path from source to destination that is loop free
- paths must be compliant with policies of various ASs (each AS has its own complex routing policies)
- must be scalable
- must be autonomous (the autonomous nature raises trust issues)
Traffic Types
- local traffic - traffic that originates and terminates within an AS
- transit traffic - traffic that passes through an AS
Integrating Inter-Domain Routing & Intra-Domain Routing
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