Wednesday, March 31, 2010

Some BGP Basics

Right now I am preparing for CCIP BGP exam before facing Beast CCIE SP Lab. BGP was the only Routing Protocol (Although an Application Technically :) ) which always scared me in the past. So finally I decided to prepare for CCIP BGP exam in order to get rid of this old fear.

So while preparing for it now I also prepared some notes for those who are new to big world of BGP. 

So here you go...

Deepak Arora

Tuesday, March 23, 2010

Bootable GNS Live CD - AKA SLAX

I am not sure if you guys knows this or not but there is GNS bootable version that exists called SLAX. SLAX comes in form of IOS image which you can download and write this Image into CD. The CD contains bootable version of SLAX. The advantage of using SLAX over GNS in windows is that SLAX runs very customizable version of GNS over linux BSD. So it consumes far less CPU and Memory resources compare to GNS Windows version.


Most Detailed CCIE R&S Ver 4.0 Blueprint - From Ruhann, CCIE 24163

Best Regards,
Deepak Arora

Thursday, March 18, 2010

Off Topic - Some Non Technical Stuff from Childhood days

I guess this is the second off topic or non-technical topic so far on my blog, but what else can say except I simply can't resist myself to do this.

This is regarding a a book on Children Stories called "Roosi Lok Kathayein" AKA "Russian Folk Tales". This book was basically written by Russian Writers around 70's I guess. Later some people translated this into Hindi and gave it this hindi name. 
I think I was of 10 when my Grandpa gave me this book. I read each story several times. But as i grew up I lost it some where with time. I tried to find it out many times later with no luck.

But finally I googled it today and found it's PDF. I wish I'll be able to find it's hard copy somewhere as well.

So If you still love and remember those great stories of your childhood, you will definitely like this :)

Deepak Arora

Tuesday, March 16, 2010

No OEQs for Cisco 360 degree program students

Beginning April 1, 2010, Cisco will allow Cisco 360 Learning Program students who attend a Cisco CCIE® Routing and Switching or CCIE Voice workshop to request a waiver and skip the Core Knowledge Section of the CCIE lab exam.  All waiver requests must be approved by the workshop instructor.  No end date for the Core Knowledge Waiver has been announced, but Cisco will provide at least 60 days’ notice before discontinuing the waiver.

During a Cisco 360 Learning Program workshop, students complete a series of performance assessments that demonstrate their understanding of the CCIE material and serve the same purpose as the Core Knowledge section of the exam.  Therefore, Cisco 360 Learning Program students who use the waiver will not be required to type out answers to the Core Knowledge questions and will be allowed to move immediately to the next section of the lab exam.

To qualify for the waiver, workshop students should contact their instructor 45 days in advance of their scheduled lab exam and provide the following information:

  • Student's name
  • Student's email address
  • Student’s username
  • Name, date, and location of workshop attended
  • Student’s scheduled lab date and location

Monday, March 15, 2010

CCIE R&S/SP Switching Study Plan

Here today I am gonna share the study plan which I used myself to prepare for R&S/SP lab switching portion preparation. It worked pretty well for me and now I feel quite comfortable with this section. During this preparation I used Narbik's workbooks as I didn't have INE/IP Expert Workbooks, but if you like INE/IPX too much like many others then there shouldn't be any problem with that :)

So here we go:
1. CCNP BCMSN EXAM Cert Guide  - From David Hucaby
    skip following chapters including TCAM Details

a. Network Design
b. Wireless portion
c. Multicasting portion

2.while reading any topic in the workbook make sure 

you can find all these topics in the DOC CD under 
3560 Configuration guide:

3. Go through the following switching articles:

4. Finish Train Signal BCMSN Videos from Chris bryant

5. Finish INE AT COD Switching sessions - Old ver (10 Days)

6. Finish IP Expert VODs on Switching - old ver (From Scott)

7. Your favourite workbook switching labs on Rack 

    (Use DOC CD whenever needed to configure solution)

8. Make notes about new findings learned during lab session

9. Read CCIE Short notes from Ruhann on Switching

10. Free V Lectures on Switching : From IPX

11. Repeat Step 7 
     (Use DOC CD whenever needed to configure solution)

Happy Studying...

Best Regards,
Deepak Arora

Thursday, March 11, 2010

Mysterious EIGRP Router ID and It's Significance

Today I am gonna discuss one of the EIGRP detail which not many people know about. It's about Mysterious EIGRP Router ID. Have you ever heard about such thing earlier ?

Yes, In EIGRP world Router ID does exist. However the significance of the EIGRP Router ID is not as important as Router ID in OSPF or BGP. But there are some situations where you might need to take a look at it in order to troubleshoot EIGRP connectivity/reach-ability issues. 

Yeah I know, it sounds kind of weird but it's really not that ugly.

So the first thing that comes in mind is How can I see EIGRP Router ID ?

Simple, just use the following command "sh ip eigrp topology" and you can find it right there :)

Now next thing comes in mind is what's it's significance and how it can create problem ?

Now before that I would like to tell you guys the Router ID selection criteria in EIGRP is same as in OSPF.

Now lets talk about it's significance for a moment. EIGRP Router ID don't have any local significance as far I know based on my different testing scenarios. Even if it's DUPLICATE within AS, it's not gonna hurt. But on the other hand in OSPF - duplicate router id can create lots of Database inconsistency issues because as per Link State protocol theory - All routers within the OSPF area must have same set of Link State Database copies and LSA's are tracked by sending Router's router id.

Now if talk about problems, based on my different testing scenarios I found that EIGRP router id can create problems when we are redistributing external prefixes like redistributing Static routes, Other EIGRP AS, OSPF , Connected Subnets etc....

Below I am attaching all my testing results one by one. Hopefully everything is simple and straight to understand but incase you need some more explanation then just drop me an email at -

Don't forget to click on images to view better :)

Also read outputs starting from left side and later from right side *Up side Down too*

Image 1 - Order->R1, R2 
Image 2 - Order->R3, R4
Image 3 - Order->R1, R2, R4, R3
Image 4 - Order->R4, R3, R4
Image 5 - Order->R3, R1, R1, R3, R2
Image 6 - Order->R3

Happy Studying...

Best Regards,
Deepak Arora

Tuesday, March 9, 2010

Free OEQs For CCIE R&S

I am not sure if you guys knows this already, but one of the famous CCIE R&S Workbook seller/ Cisco CCIE R&S 360 partner NMC shares one OEQ free of charge everyday on it's website. 

This is actually part of their CCIE Written Preparation Product which costs around 99 USD for full version.

But if you visit their website everyday, you can find one New OEQ everyday free of charge :)

Deepak Arora

Tuesday, March 2, 2010

OSPF Area 555 - Now what the hack is that ?

Here is another OSPF twist. Although in my point of view it's just a stupid router trick which can appear in CCIE R&S lab cause that's the lab where they ask lots of Router tricks too along with the deep understanding of different Internetwork Technologies. But in some other people's opinion it could be something related to deep understanding of OSPF protocol.

Anyways here is your CCIE Lab task under OSPF Section worth 5 Points: :)
Q - Router R2 has been configured under OSPF AREA 555. Now configure Router R1 to peer with Router R2 using OSPF. But do not use "area 555" key-word any where in configuration.

Hmmm....Isn't that interesting enough ?

Looks like that proctor is not happy with you and that's why he asked for this.

Any-ways...lets try to find this under DOC CD (12.4T - As per lab version)

I quickly browse through DOC CD and didn't find anything helpful there...So what now? ...As our best friend in Exam - DOC CD - is not able to help us with this.

Now lets come back to the we can configure ospf area on router...Hmmm....1.) Under the OSPF Process...2.) Under the interface configuration mode using " ip ospf" command...hmmm...but in both ways commands asks for " area 555" key-word to be entered.

So are we gonna loose 5 Point Now ?

and Answer is ....YES...I mean chances are pretty high for that if you haven't read about this earlier somewhere. Also this may lead us to loose further points along the way if this peering needs to be functional for BGP, Multicast, QOS and other tasks to work properly.

So lets talk about how we can do it now :)

Well...Actually Area IDs are 32-bit numbers. Although they can be expressed into Decimal format for our sake but they can also be expressed in a Dotted-Decimal format. Also some vendors does support the Dotted Decimal format as default way to configure OSPF Area IDs.

So lets convert 555 into binary first:

555 = 1000101011 <- Used windows Calculator Here :)

so in better way we can write it as follows:

00000000.00000000.00000010.00101011  <- Now lets break it further

00000000 = 0

00000000 = 0

00000010 = 2

00101011 = 32+8+2+1 = 43

00000010.00101011 = 2.43 or

Hmmm....wasn't that fun ?????

Now lets put the following command under OSPF router configuration mode, but same format will also work for OSPF interface configuration mode too.

R1(config)#router ospf 1
R1(config-router)#net a

So soon after this you will see the magical peering coming UP :)

So I hope you will enjoy it. Below is the complete config though for detailed review:


R1(config)#do sh prot | e do
Global values:
  Internet Protocol routing is enabled
Serial0/0 is up, line protocol is up
  Internet address is < - This is another fun too :) to add here
Loopback11 is up, line protocol is up
  Internet address is

R1(config)#router ospf 1
R1(config-router)#net 0.0.00 a


R2(config-router)#do sh prot | e do
Global values:
  Internet Protocol routing is enabled
Serial0/0 is up, line protocol is up
  Internet address is
Loopback22 is up, line protocol is up
  Internet address is

R2(config-router)#net a 555

R2(config-router)#do sh run | s rout
router ospf 1
 network area 555

R2(config-router)#do ping r 10 so lo 22

Type escape sequence to abort.
Sending 10, 100-byte ICMP Echos to, timeout is 2 seconds:
Packet sent with a source address of
Success rate is 100 percent (10/10), round-trip min/avg/max = 4/24/140 ms

Happy Studying...

Best Regards,
Deepak Arora

Monday, March 1, 2010

Troubleshooting OSPF Adjacency - MTU Mismatch Issue

Today I am gonna focus little more on OSPF Adjacency Troubleshooting. One of the criteria which should match to form Neighborship is Interface MTU Size. In case two ospf neighbors trying to form neighborship are getting failed and you get the following message on console "Too many retransmissions". Chances are pretty high that it's a common ospf MTU size mismatch issue. I have seen many books talking about OSPF so far which didn't mention that MTU size of neighbors should also match in order to form adjacency. So in this short post I am going to tell you how to fix it by putting the command under the interface " ip ospf mtu-ignore". After entering this command OSPF basically doesn't consider MTU size to form neighborship and ignores it. Although this command can be entered on one side but it's better to enter it on both routers. Other way of course is to configure MTU size manually on both sides to match.

Here is another quick command to add more fun into ospf, I'll discuss this command in detail soon in my next post. Have you ever seen something like this earlier under OSPF config :) are other details that you may wanna look at. In my topology I just connected R1 to R2 with serial interfaces (S0/0) on both sides.

Deepak Arora