Dynamic Routing Protocol -> Routing protocols are used to facilitate the exchange of routing information between routers, also allow routers dynamically share information about remote networks and automatically add this information to their own routing tables.
Pro's & Con's
Dynamic Routing Protocols Classification
AS (Autonomous System) : a collection networks under a common administration sharing a common routing strategy.
IGP VS EGP
IGP : are used for intra-autonomous system routing - routing inside an autonomous systemEGP : are used for inter-autonomous system routing - routing between autonomous systems
Distance Vector
- Distance = How far, Vector = Next hop address
- Road sign
- Periodically send routing tables updates
- Doesn’t allow to get exact topology of an internetwork
- No neighbor discovery
- Fast convergence is no big concern
Link State
- Link = Interface on a router, State= information regarding the link, (IP,Type Network,Cost)
- Road Map
- Update only when there is a change in network topology
- Can create complete-view topology map of the network
- Neighbor discovery
- Fast convergence is crucial
Classful :
- Don’t send subnet mask information in routing updates
- Don’t support VLSM
- Contiguous network
- RIPv1, IGRP
Classless :
- Include subnet mask with the network address in routing updates
- Support VLSM
- Discontiguous network
- RIPV2,EIGRP,IS-IS,OSPF,BGP
Routing Convergence : when all routers' routing tables are at a state of consistency. The network has converged when all routers have complete and accurate information about the network. A network is not completely operable until the network has converged; therefore, most networks require short convergence times.
Slow : RIP, IGRP
Fast : EIGRP, OSPF
Metric
Its used by routing protocols to select best path, each routing protocols uses its own metric, for example; RIP -> Hop Count, EIGRP -> ‘K’ Value, Bandwidth & Delay is default, OSPF -> Cost
Administrative Distance
Is integer value from 0 to 255, 0 is the most preferred (Directly-connected), 255 will not install to routing table. The lower the administrative distance value the more trustworthy the route. Also determine which route to install in routing table. And its used when a router has learned routes to same destination from two or more different route sources, Important because not all route source are equal.
Source : CCNA Exploration 4.0 – Routing Protocols and Concepts