Cisco Tips & Tricks

August 27, 2007

Routing Basics

Filed under: IP Routing — ciscotips @ 3:43 am

One of my team member was asking me the question on routing decision. I thought of putting up here ..Any routing decision is based on the following rules.

1) Longest prefix length :- If we have two different routes in a routing table  for a same network, the longest prefix match is selected. lets say we have both & in the routing table.  In this case will be selected.

2) AD ( Administrative distance) :- If longest prefix match cannot be considered for example if we have two routes with same prefix length then Route with lowest AD will be considered. Incase we have a same route learnt from IGRP and OSPF, IGRP route will be considered as it has alower AD(100) then OSPF (110).

3)Meteric:- If routes have same prefix length and same AD then a route with a better meteric is considered. In OSPF, cost~bandwidth is a meteric where as hop count is meteric for RIP.

4) Load sharing:- In case all the above three conditions match then  data  will be load balanced between the routes.



  1. Hi Sikandar,

    Great blog…very informative. I can’t find your contact info, so can you please send me an email if you get a chance? I’d like to speak to you about our industry.


    Comment by Amad — September 4, 2007 @ 6:27 pm

  2. I send you this information, with respect that it will only be this one time. I will not SPAM you in the future. Your assistance or referral would be greatly appreciated.

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    Comment by injones — September 13, 2007 @ 2:46 pm

  3. hi..
    Sikhandar this was good you got a very great interest in
    knowing things i suppose to think. If u can find some thing interesting pls iam requesting u to send those to my mail..

    Comment by gowtham — October 13, 2007 @ 2:09 am

  4. hi great site, i have recently decided at the age of 27 to pursue my dream of working in the it industry i was advised a cisco qualifacation would be a licence to the best jobs and salarys now i have looked into ccna i am slighty concerned i am out of my depth i understand it is more complicated than 1 router linking 2 computers,so i purchased an ebook and the first chapter has almost put me off so i have now got a question
    i can configure a home network using ethernet and wireless technology and set it up for file and printing sharing
    is this any where near the requirements of a network engineer
    is there any advice you could give to somebody who is just starting out

    Comment by daryl staples — October 14, 2007 @ 12:03 am

  5. Hi Daryl,

    Given up already? You’ll not get far like that.

    No, you are nowhere near what the industry needs.

    Get the CCNA and then see what happens.

    Comment by Gary — October 29, 2007 @ 7:44 pm

  6. This is a great website, and I found it very usefull, I took my ccna certification and now am studying CCNP, I finished BSCI,ISCW, and now continue with the BCMSN,……. the world of CISCO is very nice :), I love it, and also I give all repsect to my best best instructor in all over the world Chris Brayant CCIE#12933, his videos is so great.

    Comment by Haissam Jneid — June 13, 2008 @ 3:35 pm

  7. hi guys,

    Can anyone recommend a good book to understand cisco routing basics easily…. how to setup a lab at home and for practice and stuff like that.

    I dont want a cisco press book as that can be tough at times. I would want to start with something that is easy and actually makes routing/router basics fun!!

    i would really appreciate any feedback… please email me on

    thanks alot guys,

    Comment by Asad — September 24, 2008 @ 5:00 pm

  8. Thanks on your marvelous posting! I really enjoyed reading it,
    you happen to be a great author.I will make certain to bookmark your blog and may come back in the future.

    I want to encourage you to continue your great job, have a nice afternoon!

    Comment by Route Your Destination — September 24, 2014 @ 12:14 am

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