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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>

GENERAL: The Art of reading Technical stuff

Today I want to share a very useful technique with you, which I learned during my University times. Most of the time, when we read some new technical stuff, we are not able to understand it in the first go. Suppose if you are reading some great article in Scientific American or in the Economist, you will not be able to understand the article thoroughly in the first go. If you are not a native English speaker like me, you may need to read that article several times to understand it completely.

When I was in university, I was struggling hard to understand the Signals and Systems book by Oppenheim (http://www.amazon.com/Signals-Systems-Edition-Alan-Oppenheim/dp/0138147574). I talked to my professor, and discussed my problem with him. He gave me a wonderful advice. He asked me to us the “re-read” technique. Like if you read a passage and didn't understand it, then re-read that passage. In the first phase, our brain might not be able to understand it. It’s like the baby steps, but once we process the same technical stuff again and again by our brain, you will be amazed to know that you will understand the same stuff which was difficult before.

Believe me Signals and Systems is one of the tough subjects during an engineering degree, but when I begin to use my professor technique to not give up and re-read the passage again and again, then it was the moment of enlightenment. I begin to master and learn the concepts from which I was running.

When I begin my Networking journey, I used the same technique, like I will not leave a highly technical paragraph, until I thoroughly understand it. How many times I will get lost in the technicality of a topic, but I won't stop. Sometimes I feel bored, sometimes I feel that I will not be able to understand this stuff anyhow, but if I stick a little longer and re-read again and again, then believe me the meanings will get open for you and you will master it definitely.

As I am not a native English speaker, I had to struggle hard to understand the highly technical stuff sometimes, but this re-read advice comes in handy and at the end of the day I do understand it. So as a conclusion:

Some difficult passage/technical stuff
                      Re-read it, again and again, don’t give up, don’t feel bad, and don’t get depressed
                                                                                           The End result, you will understand it

At the end of the day, it’s you who need to understand it; no one else will come to put it into your mind J