Important Multicast Concepts Multicast provides support for eficient data delivery to multiple recipients Requirements for IP Multicast routing Keeping track of interested parties Building distribution tree Broadcast/suppression technique Difficult to deploy new IP-layer functionality End system-based techniques can provide similar efficiency Easier to deploy 10/5/06 ecture #12: Inter-Domain Routing
10/5/06 Lecture #12: Inter-Domain Routing 11 Important Multicast Concepts • Multicast provides support for efficient data delivery to multiple recipients • Requirements for IP Multicast routing • Keeping track of interested parties • Building distribution tree • Broadcast/suppression technique • Difficult to deploy new IP-layer functionality • End system-based techniques can provide similar efficiency • Easier to deploy
Routing Review The Story So Far Routing protocols generate the forwarding table Two styles: distance vector, link state Scalability issues: Distance vector protocols suffer from count-to-infinity Link state protocols must flood information through network Today's lecture How to make routing protocols support large networks How to make routing protocols support business policies 10/5/06 ecture #12: Inter-Domain Routing 12
10/5/06 Lecture #12: Inter-Domain Routing 12 Routing Review • The Story So Far… • Routing protocols generate the forwarding table • Two styles: distance vector, link state • Scalability issues: • Distance vector protocols suffer from count-to-infinity • Link state protocols must flood information through network • Today’s lecture • How to make routing protocols support large networks • How to make routing protocols support business policies
Outline Routing hierarchy Internet structure ° External BGP(EBGP) 10/5/06 ecture #12: Inter-Domain Routing 13
10/5/06 Lecture #12: Inter-Domain Routing 13 Outline • Routing hierarchy • Internet structure • External BGP (E-BGP)
Routing Hierarchies Flat routing doesnt scale Storage Each node cannot be expected to store routes to every destination (or destination network) Convergence times increase Communication> Total message count increases Key observation Need less information with increasing distance to destination Need lower diameters networks Solution: area hierarchy 10/5/06 ecture #12: Inter-Domain Routing 14
10/5/06 Lecture #12: Inter-Domain Routing 14 Routing Hierarchies • Flat routing doesn’t scale • Storage → Each node cannot be expected to store routes to every destination (or destination network) • Convergence times increase • Communication → Total message count increases • Key observation • Need less information with increasing distance to destination • Need lower diameters networks • Solution: area hierarchy
Areas Divide network into areas Areas can have nested sub-areas Hierarchically address nodes in a network Sequentially number top-level areas Sub-areas of area are labeled relative to that area Nodes are numbered relative to the smallest containing area 10/5/06 ecture #12: Inter-Domain Routing 15
10/5/06 Lecture #12: Inter-Domain Routing 15 Areas • Divide network into areas • Areas can have nested sub-areas • Hierarchically address nodes in a network • Sequentially number top-level areas • Sub-areas of area are labeled relative to that area • Nodes are numbered relative to the smallest containing area