41902 Lecture Notes - Lecture 9: Interior Gateway Routing Protocol, Routing Information Protocol, Routing Protocol
Network Fundamentals
Chapter 5: Network Layer: The Control Plane
Chapter 5.2: Routing Protocols
Routing protocol goal: determine good paths/routes from sending hosts to receiving host, through
network of routers. A path is the sequence of routers packets will travers in going from given initial
source host to given final destination host. Good – least cost, fastest, least congested.
Routing algorithm Classification:
- Global or centralised:
- All routers hae oplete topology, lik ost iforatio through lik state algoriths
- Decentralised or distributed:
- Router knows physically-connected neighbours, link costs to neighbours
- Iterative process of computation, exchange info with neighbours
- Distae etor algoriths
- Static: Routes change slowly over time
- Dynamic: Routes change more quickly, periodic update, in response to link cost changes
Link State:
- Dijkstra’s algorith lik-state routing algorithm): net topology
Distance Vector: (or mail readers) compose, edit, read and mail messages. E.g. Outlook,
Thunderbird, iPhone mail client
Chapter 5.3: Intra-AS routing in the Internet: OSPF
Hierarchical addressing allows efficient advertisement of routing information.
When looking for forwarding table entry for given destination address, use longest address
prefix that matches destination address.
Making routing scalable: ith illios of destiatios, they a’t all e stored i routig
tables. Routing table exchange would swamp links. The internet is a network of networks
and each network admin may want to control routing in its own network.
Therefore, the internets approach to scalable routing is turning aggregate routs into regions
known as autonomous systems (AS) (aka domains)
Intra-AS routing:
- Routing is among hosts and routers in the same autonomous system (AS/network).
- All routers in an AS must run the same intra-domain protocol. Routers in different AS
can run different intra-domain routing protocols. Within an AS there are getaway
routers. These are at the edge of the autooous syste ad has liks to routers
in other autonomous systems.
- Intra-AS routing determine entries for external destinations and destinations within AS.
- Uses Interior gateway protocols (IGP). Most common intra-AS routing protocols:
- RIP: Routing Information Protocol
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
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