Overview:
Dynamic routing protocols are categorized as either distance-vector protocols or link-state protocols
Study Notes:
Distance-Vector Routing Protocols
- The full routing table is sent in periodic updates to neighbors, which requires more bandwidth
- Distance is the main metric used to calculate routes
- RIP uses hop count
- IGRP uses bandwidth and delay
- Slower to converge because it has to wait for the periodic updates
- More susceptible to loops
- Distance-Vector Protocols - RIP, IGRP
- Routers rely on neighbors for route information - routing by rumor
Link-State Routing Protocols
- Created to avoid the convergence and loop issues of Distance-Vector protocols
- Routers send updates that advertise the state of their links. The full routing table is not sent, which saves on bandwidth.
- Cost is the metric used to calculate routes
- Areas are used to define which routers share updates with each other
- Routers know the state of all links within their area
- Routers use different tables to maintain an understanding of the Link-States
- Neighbor table - list of neighbor routers and the interface
- Topology table - the Link-State table, map of all links within an area and their status
- Shortest-Path table - best rotues to each particular destination - this is the routing table
- Convergence is quick
- Loops are avoided
- Because of the three tables needing to be maintained, it could use more RAM and CPU resources