Learning and understanding policy routing is crucial knowledge for any good network engineer. You’ll find quite a bit of policy routing going on in today’s production networks.  But what exactly is policy-based routing?
Policy routing
Policy-based routing, generally referred to as “policy routing”, is the use of route maps to determine the path a packet will take [...]

With the advent of new technologies as well as the ability to have multi-layer switches at the access layer, Cisco is starting to change the game.  New network designs are pushing layer 3 routing out to the access switches creating a routed edge.
Most campus and data center network designs have been following the standard 3 [...]

Authentication, Authorization, and Accounting… Otherwise Known as AAA (triple A).  Most people who have had to implement AAA on a router or switch probably know very little about the commands they copy to the router config.  Most simply grab the AAA configs from another working router or switch and be done with. But have [...]

Many engineers (at one time myself too) believe they understand wild card masks. If you ask someone they will most likely tell you that a wild card mask is just the opposite or reverse of a subnet mask. Unfortunately this isn’t quite correct. Yes, at first glance a wild card mask “looks” [...]

For anyone who has ever needed to test a new network architecture, implement a new routing protocol or simply study for a Cisco exam has needed access to a real live router or a router simulator.  But buying a bunch of routers just test up an idea or for study is expensive.  And until recently [...]

So, Your the senior network engineer for a nice large network. Everything is running smoothly until one day a primary link goes down and you seem to be the last one to know about it!  Everyone is running to you to find out whats going on and expecting you to know what and why things [...]

When you are running BGP on two or more routers that border your network to the outside world, you will need to configure iBGP between all of these BGP peer routers. Just as a quick refresher, iBGP routers are routers that are in the same AS, eBGP routers are in different AS’s.  Of course there [...]

That’s right, run Linux right on your Cisco router! That’s what Cisco’s new Application eXtension Platform or AXP is doing. Now using a network card like a standard AIM module or network module for your ISR router you can load and run Linux on your router to run your applications and even intergrate [...]

Recently during an upgrade of a Cisco router I ran into a strange problem where my OSPF neighbors that were working prior to the upgrade stopped working after the upgrade. I also noticed that the broken neighbors were only to non-Cisco devices, namely Nortel Contivity VPN devices.
I could see this by checking the neighbor [...]