Monday, April 30, 2012

Cisco CAT OS - Still Alive

In my current project my customer has still got plenty of 2900s,4k,5k and 6500 switches running on CAT OS. For me, working with CAT OS is little hectic. The major reason being that it's kinda hard to find CAT OS documentation. Also no Cisco Networking course teaches CAT OS anyways so technically I was never been trained on this. But still customer has got plenty of those so I got to support these.

So I was looking for a consolidated reference/study material to learn CAT OS for quite some time and finally I found a nice book from Cisco Press:

The thing I very much liked about this book is that it has a parallel command reference for IOS vs Cat OS. Which makes it easy to find the right commands as if you know equivalent IOS command.

Further Readings:

Deepak Arora

Sunday, April 1, 2012

Basic ASA Configuration - NAT,PAT & ACL (Coming Soon)

Solution -> OSPF AREA Challenge - A Little Tricky Stuff

Two months back I posted "OSPF Area Challenge" - Which so far only one person was able to solve - Siddharth Bhatia -

Siddharth is a Dual CCIE in both R&S & Sec Tracks.

Now lets talk about solution indeed. The solution was actually simple one. If you look closely at the diagram & requirement you basically see multiple OSPF Area 0 islands separated by other areas. Now for lack of better term, lots of time you will see this called as "Dis-contiguous Area 0". Now technically it's only Area 0 which can not be dis-contiguous, but any other area can be dis-contiguous and there is absolutely no problem about it at all.

Now to connect these OSPF Area 0 islands we can use Virtual Links. But there is another hidden problem introduced in Area 34 by configuring it as stub area. By default Stub area doesn't allow you to run virtual links. Or if you have configured virtual links across area and later configure it as "Stub". The virtual link eventually will get break. Solution to this problem - Configure Tunnel and Run virtual link inside the tunnel.

Lets see how topology will look like now :

so lets review configurations now:

Further Readings :

Deepak Arora