Some More Cool Dancing - Off Topic

EIGRP Offset-List Not Working - Troubleshooting Series(Ticket 1)

Today I am going to start a 12 ticket long troubleshooting series for all readers. The tickets will be posted in every week or two followed by solutions for old ones every week too. There will be 48 Hrs time line for solving each ticket starting from time of posting. Who so ever will solve all 12 tickets within the time line with following details will win exiting gift :-)

1. What is root cause of problem ?
2. How we can fix it with minimal changes in pre-configuration?

The winner will win CCNP TSHOOT Exam Certification Guide Hard Copy.

Take a look at topology and configuration below and determine why EIGRP offset-list is not working.

HTH...
Deepak Arora

I wish I could dance like this - Fun Post

How To Prepare For CCNA - An Insight Look

In Recent months I have received so many email from all around the world from people asking about how to prepare for CCNA.

So today as I am resuming blogging back so thought to start with this. I mean how I passed my CCNA back in sep 2005.

Back in 2005 there were not much resources available to prepare for CCNA like today. I was working for a company as System Support Engineer (Desktops, Servers, High Speed Line Printers etc). Life was pretty hard and income was quiet less...actually 75 USD a month. At that time a close friend and mentor SUSHIL SHARDA who was working for same client like I was on behalf of another company asked me to try my luck in Networking Industry. He encouraged me to go for CCNA. I took his suggestion and started preparing for CCNA 640-801 exam.

I used the following material or In brief CCNA Complete Study package written by great CCIE Instructor Chris Bryant (CCIE#12933).

http://www.thebryantadvantage.com/UltimateCCNAStudyPackage.html

The CCNA package has got everything you need to pass CCNA exam like :

1. CCNA Study Book
2. CCNA Lab Book (Containing CCNA Lab Scenarios for practice and to put  
    your theory and skills on test for practice)
3. Binary Maths book which covers all you need to know about Subnetting
4. A book covering how to convert from Binary to hex and decimal   
   and vice versa.
5. CCNA Practice Engine
6. CCNA command handbook etc

This all stuff is gonna cost you just 25 USD.

Apart from this I used CCNA Book from Todd Lammle. In those days GNS was not available so I used most of time on real equipments and Boson's CCNA Simulator. But for current CCNA most of stuff can be practiced on GNS. But still getting some hands on with real equipment will be an added advantage.

Here is link to another subnetting quiz tool which I found extremely helpful to get rid of my bad subnetting calculation skills:

http://www.nybi.org/subnet-2.php

Apart from this I would suggest you to join some instructor lead class in-case you have enough money to spend on it to gain hands on experience with real equipments.

But there are certain things which I would like to suggest you before joining instructor lead classes.

1. How many CCNA students have passed so far from them. Try to get in touch with someone among those and take feedback.

2. Do they have enough equipments so that you don't need to sit and wait for too long to wait for your turn to practice on real equipments.

3. The equipments they have are able to run all IOS command set and features which you need to practice for CCNA.

I have heard about many CCNA institutes which have old equipments that can't run features like SDM, No Wireless Equipments to practice wireless section, Old routers and IOS which cannot run IPv6 etc.

4. Read from books about basics of networking and ask for a demo class session to see if you and instructor have good understanding.

Just don't go blank to attend any certification class...that's the tip of the day.

Remember that practice is the key. But make sure you are good enough with theory before getting into lab and practice stuff.

Also don't under estimate CCNA exam like many other who claims it's an easy one to pass. From my personal experience I can tell you that It's not an easy exam to pass.

Also make sure you test all theory you read using equipments or GNS to make sure there is no gap. One common mistake I have seen people making while learning Cisco (including me) is that some times we take things on little grant and assumes what's written in book can't be wrong. Also it depends upon how you inter prate Author's wording. It might look to you that particular thing is gonna work one way while author was trying to tell it's gonna work in that particular way under particular conditions.

Also in case you have any CCNA queries you can always come back to me and I'll try to help you guys with those in best way I can. But there is another forum forum where you can post your queries and to get help.

www.ieoc.com

All you need to do is to create a free login and post your queries on forum.

So best of luck with your CCENT and CCNA study guys... Enjoy every moment of learning.

Further Ref : https://learningnetwork.cisco.com/thread/15662

HTH...
Deepak Arora

OSPF Troubleshooting Lab - It's All About LSA Magic

Yesterday I got this OSPF Troubleshooting Challenge sent by one CCIE candidate friend on email. So I thought to share it with you guys.


With that being said , here is the topology {Which I redraw to look better of course :-) } & quick requirements.

Note: Click Images To Enlarge

Requirements :
---------------------


On R3 we have redistribute the Loopback interfaces into OSPF process using "redistribute connected subnets" command. Over R2 we have configured "Summary x.x.x.x x.x.x.x" command under OSPF process to summarize these loopbacks of R3. But R1 is still seeing the all more specific routes for R3's loopbacks. In short it's not getting the summary route from R2. 


So how we gonna fix it ?


Ummm.... Interesting ? .... May Be :-)


Lets hop on to all three routers and check the basic configuration already done for us.

So based on this we can see that it's just a normal misconfiguration. Because to summarize the External Routes we need to put this command on R3 since it's the one who is ASBR. Or in short - Only ASBR can summarize the external prefixes not ABR. It looks simple and meaningful though but I have seen many people with this misconception that since as most of books we read says in OSPF the summarization can only be done at Boundary Routers so they assume that external routes can also be summarized by ABR. Which we can see here is that not the case. Or may be they should have mentioned this behavior explicitly :-)

So by that same token if we configure "Summary x.x.x.x x.x.x.x" command on R3 instead of R2 in that case it will work just fine.

But that will be two simple... how about if we are not allowed to put this command on R3 ?

Ummm.... that will actually make life more complicated. Lets check the database on R2 and see how it looks like with command "sh ip ospf database"

 So R2 sees those prefixes as LSA Type - 5 and we are Adv router (Originator) is 33.33.33.33 which is Router ID (RID) of R3 which I setup manually.

Ummm.... so only LSA 5 Originator can summarize the prefixes by using "Summary" command. 

Is there any way we can take charge of these prefixes and convert them to LSA Type 5 with Originator set being Ourself ?

How about NSSA ? :-) 

Because if convert Area 1 into NSSA in that case we will see those external prefixes being advertised by R3 as Type 7 LSA. Since R2 is the ABR it will convert LSA 7 into LSA 5 before advertising into Area 0. So in that sense we are now originator of LSA - 5 and very well can use summary command.

Lets see this on command line by configuring AREA 1 as NSSA on R2 & R3:

Now lets take a look at database on R2 again:

Lets see if this worked for us just fine by taking a look at R1's Routing Table.

So far so good. :-) Time for Celebration

But what if we are not even allowed to make Area 1 as NSSA ? ..... horrible ?


See if you can make it work with this restriction before I present the solution which came from a great Network Engineer and friend Michael Miller.


Take it as challenge and see if you can make this work with this last restriction by not configuring Area 1 as NSSA. 


I'll post the solution though some time next week.


And Of course.... Merry Christmas Everyone

HTH...

Deepak Arora

CCIE - 0::0/0 Null0