EIGRP
EIGRP
- Enhanced Interior Gateway Routing Protocol
- #Cisco-Proprietary routing protocol, called "advanced" Distance Vector routing protocol
- Much better than RIP, but still a DV protocol
- EIGRP routers need to have the same Autonomous System (AS) number
Config# router eigrp (AS number)Config-router# network (Network address) (Wildcard mask)
Calculating routes
- EIGRP Metric = Bandwidth of slowest link + delay of all links
- Terminology
- Feasible Route is any route that has a path to the destination
- Feasible Distance is the router's metric value to the route's destination
- Advertised Distance is the neighbor device's Feasible Distance
- Successor is the route with the lowest metric to the destination
- Feasible Successor an guarantied loop-free alternate route should the Successor go down that has a lower Advertised Distance than the Successor's Feasible Distance
- The "Lower AD than Successor's FD" is known as the Feasibility condition
NOTE: I need a graph here to help illustrate all the EIGRP terms.
Unequal-Cost Load-balancing
- This is different from ECMP
- By default, EIGRP uses ECMP
- You can tell EIGRP to load balance between the Successor and the Feasible Successor routes (ONLY the S and FS routes will be load balanced)
- Change this via Metric variance Multiplier
config-router# variance 2- Variance 2 = Feasible Successor with an FD up to 2x the Successor route's FD can be used to load balance
- Change this via Metric variance Multiplier