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 172.16.0.0/16 & 172.16.16.0/24 in the routing table.  In this case 172.16.16.0/24 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.

Advertisements

8 Comments »

  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.

    Thanks,
    Amad

    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.

    Now that you can claim yourself to be CCIE, its time to make your mark in the Telecom Industry working for the Best.

    Are you ready?

    Cisco Services/-HTTS Group
    High Touch Technical Support
    The High Touch Technical Support (HTTS) is a premium service that provides customers with technical assistance 24 hours a day, 7 days a week, from Cisco Advanced Services engineers who have a comprehensive understanding of their network, operations procedures, business processes, past problems, and present concerns. This is your opportunity to be exposed to new cutting edge technologies, multiple, diverse network environments all over the global. Are you ready to take your certification to the next level…..be the Expert in your field?

    Cisco Systems, Inc. is seeking a Consulting Support Engineers for Phoenix-Arizona, Columbus-Ohio and Somerset-New Jersey campuses. We will relocate the preferred candidate. You must be a US citizen.

    The following responsibilities are associated with this High Touch Technical Support Engineer position:

    –Role is dedicated support function providing reactive technical support to large Enterprise customer.
    –Will have a strong background in Routing Protocols and Large scale Architecture.
    –Acts as a technical expert in LAN Switching specific to CAT6K.
    –Provides second line phone/email/fax consultation to independently debug complex product problems.
    –Will provide systems/product training both internally and externally.
    –Acts as a focal point for large account network problem resolution.
    –Provides support on a world-wide basis.
    Successful candidate has the following experience, knowledge or proven capabilities:
    –Ability to work independently, as the position only receives minimal supervision with no instruction on routine work and general instruction on new assignments.
    –Ability to analyze, use and configure small to medium networks.
    –Proven crisis management skills.
    –Works on problems of diverse scope where analysis requires evaluation of identifiable factors.
    –Applies known solutions to solve problems.

    The following technical skills are required:
    –Routing Protocols
    –Large scale Architecture
    –LAN switching expertise specific to CAT6K

    Typically requires BS in CS or EE or equivalent plus 7-10 years related experience. You must have a current, completed CCIE to be considered. Candidate must be willing to be tested on strengths. Salary will be commensurate with experience, with exceptional Benefits and Stock options. We are competitive on our total compensation offerings. If you are interested in working for Cisco in this capacity then please submit your details and CV to injones@cisco.com. Only those candidates that meet the requirements will be contacted.

    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
    thanks
    daryl

    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 icemate76@hotmail.com

    thanks alot guys,
    Regards
    asad

    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


RSS feed for comments on this post. TrackBack URI

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Create a free website or blog at WordPress.com.

%d bloggers like this: