Some Random Notes about EIGRP, OSPF, DV Protocols and Linkstate Protocols
Some Random notes, that are still very useful :)
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EIGRP = Enhance Interior Gateway Routing Protocol
Ok, what are the most common words that I hear about EIGRP?
Neighbor table, Topology table, Routing table, successor (primary
route), feasible successor(secondary route), backup routes, DUAL, Diffused
Update Algorithm, auto summarization, unequal cost load balancing, easy to
configure.
Routing protocol based on: DV plus some features of Link
State protocol
Hello sent every 5 seconds = >
Hold down timer = > set according to hello packets received
Have very speedy convergence time and easy on processor.
#router eigrp 10
#network <network to be advertised> <eigrp wild card bits- optional>
Some commands to remember:
#show ip eigrp neighbors
#show ip eigrp topology
#show ip eigrp route
In EIGRP we can summarize anywhere. Load balance over
unequal cost paths. Null0 created automatically to tackle the routing
efficiently, in other words null garbage container, to through away the garbage
routes.
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Distance Vector Routing Protocols, Linkstate routing
protocol. Hybrid protocols.
DV protocols send their entire routing table after a
specific interval, while linkstate protocols make neighbor adjacencies and event
triggered updates are sent.
DV protocols have looping issues
Count down to infinity loop!
Loop preventions mechanism in a CISCO router: like route
poisoning, split horizon, hold down timer,
Link state routing protocol: OSPF: not more than 50
routers/area
ABR, ASBR, Backbone router
All routers in an area have the same topology table but they
will have different routing table.
Localize updates within an area. Requires a hierarchical
design, you must design network keeping in mind the hierarchical design!
Hello messages in ospf: sent every 10 seconds on broadcast/p-2-p
links, once every 30 seconds on NBMA networks ie frame relay. Best practice is
to tune the hello packet sending time, most case its set to 1 second.
And to make adjacency routers must agree on some specific parameters
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OSPF general syntax and configurations
Modifying the router ID
#router ospf < processs ID>
#network <Network> <wildcard mask> area <area
#>
#show ip ospf
#show ip protocols
#show ip ospf neighbors
To advertise a summary route:
#area <area #> range
<sumar ip> <mask>
