Routing Protocol Flashcards
Router
A router Primary function is to move an IP packet from one network to a different network.
It learns about nonattached networks through the configration of status routes and through dynamic ip routing protocols
Dynamic IP Routing Protocols
Dynamic IP routing protocols distribute network topology information between routers and provide updates without intervention when a topology change in the network occurs.
Autonomous System (AS)/routing domain
A network interconnected routers and related systems managed under a common network administration
Common Dynamic Routing Protocols
1) Routing Information Protocol Version 2 (RIPv2)
2) Enhanced Interior Gateway Routing (EIGRP)
3) Open Shortest Path First (OSPF)
4) Intermediate System-to-Intermediate System (IS-IS)
5) Border Gateway Protocol (BGP)
Interior Gate Protocols (IGP)
The protocols are designed and optimized for routing within a autonomous system
Exterior Gateway Protocols (EGP)
The protocols route between autonomous system
Distance Vector Algorithms
Distance Vector routing protocols such as RIP, adverstise routes as vectors where distance is a metric (Cost) such as hop count, and vector is the next -hop router ip used to reach the destination
Distance
The distance is the route metric to reach the network
Vector
The vector is the interface or direction to reach the network
Bellman-Ford and Ford-Fulkerson
Distance Vector Algorithms
Enhanced DIstance Vector Algorithms
EIGRP
Diffusing update algorithm (DUAL) is an enhanced vector algorithm that EIGRP uses to calculate the shortest patch to a destination within a network
It offers rapid convergence time for changes in the network topolgy
It sends update only when there is a change in the network, it does not send full routing table updates ina perodic fashing as distance vector protocols
It uses Hellos and forms neighbour relationships just as link state protocols do
it uses bandwidth, delay, reliability, load and maximum transmission unit (MTU) size instead of hop count for path calculations
It has option to load balance traffice across equal or unequal cost paths
Link State Algorithms
A Link state dynamic IP protocol advertises the link state and link metric for each for its connected links and directly connected routers to every router in the network
Link state advertisements
OSPF > Link state advertisement (LSA)
IS-IS > Link state packets (LSP)
Link State Database (LSDB)
as a router receives an advertisement from a neighbour it sotes the information in a local database and advertises the link state information on to each of its neighbour routers exactly as it was received
Dijkstra Shortest path first
after updating LSDB the SPF algorithm calcualte the best shortest loop-free paths, this link state algorithm then populates the routing table with this information
Distance Vector vs Link state
Link state usually requrie more cpu and memory than distance vector protocols. less prone to routing loops and make better routing path decisions.
Routing Protocol
Protocol used by routers talking routers to each other and exchange network information and fill the routing table.
Routable/Routed Protocol
Once the router table is populated, send the traffic to particular network they use routed/routable protcol like IP v4 ip V6
Path Vector Algorithm
Similar to distance vector algorithm, the difference is that instead of looking at the distance to determine the best loop free path it looks at various BGP path attributes .
1) Automonous system path (AS_path)
2) Multi-exit discriminator (MED)
3) Origin
4) Next Hop
5) Local Preference
6) Atomic Aggregate
7) Multi-exit aggregator
Path Vector Protocol
A Path Vector Protocol gurantees loop free paths by keeping a record of each autonomous system that is the routing advertisement traverses.
