1000 Page Views!

Sometime last night while I was sleeping the page view count for this month hit the 1000 mark.  While this is a very small number compared to any real site out there it is for this site I think a milestone that I'm going to make a post about.

I'm pretty sure that about half of the 1000 page views so far this month were wirerat trying to solve the Networking-Forum Easter Egg Contest.

If you read this blog regularly then thank you.  If you're just passing by then I hope you come back, but thanks for checking things out.

The previous monthly page view high mark was last month at 853.

IPexpert IOU Topology

IOU has been leaked.  L2IOU has been leaked. It was only a matter of time before someone did this...  Might as well be me :)

Here's a NETMAP file that recreates the IPexpert CCIE R&S topology, and a wrapper script to start it. And as my special gift, a bash script to convert the config files provided by IPexpert to a format that (L2)IOU can work with.

I might do up some diagrams at some point, but for now you'll have to figure it out from these text files. 

Enjoy!

IPv6 for Enterprise Network Book Review

Networking-Forum and CiscoPress hooked me up with a promo copy of this new book in return for a review.  That review has no been published and you can find it at http://www.networking-forum.com/blog/?p=2162.

So I have this book lying around doing nothing...

Right before I started this blog, and my path to the CCIE, I was a newly minted CCNP looking for my next step.  At the time I had thought that I wanted to go after a CCSP in the short term, with a CCIE after that.  Well, life doesn't always work out the way you think it will.  Instead of this path I ended up being head-hunted by my current employer who was looking to make me a CCIE.

Great story eh?  What does this have to do with you?  I'm glad you asked.

In preparation to go after the CCSP I bought myself a copy of the CCNA Security Official Exam Cert Guide (IINS 640-553).  I've never read it.  I've barely ever opened it.  The CD in the back is still sealed.  And it's extremely unlikely that I'm ever going to read it.

So I'd like you to have it.

IP Subnet-Zero

I thought it would be interesting to take a little stroll through history and look at something that really isn't relevant to today's network, but was something that you weren't allowed to use in days gone by.  As the blog title says, that something is IP Subnet-Zero.

ZER0 ZER0 ZER0 ZER0

What is IP Subnet Zero?  Well, it's a legacy command on Cisco routers the controls whether or not the use of the all zeros subnet is permitted.  What's the all zeros subnet?  To properly understand what the all zeros subnet is we need to first remember what classful networking was, and how things all got started in IP beginning with RFC 791. 

ZER0 ZER0 ZER0 ZER0

IOU Lab Topology #2

As I mentioned in my first IOU topology post I more frequently use another topology that has turned out to be better suited for my labbing needs than my first attempt.  Well, here is that topology.

Networking-Forum.com CCNA Specialization Scholarship

Just like the previous NF CCNA Scholarship Steve is again offering up to provide someone with the materials and costs associated with obtaining a Cisco CCNA certification, but this time it's for one of the specialization tracks.  Are you already holding a valid CCNA? Do you want a CCNA Security?  Or voice?  Well here's your chance.

http://www.networking-forum.com/viewtopic.php?f=29&t=23933

Good luck to everyone!

IOU Lab Topology #1

Some time ago Cisco's IOU was leaked out to the web.  I was able to get a copy (don't ask where, I won't help you) and have managed to get it set up on a spare box at home.  There are a couple of really good tutorials on the Web that explain how to get it set up and working and how to build a lab topology.  I've built two topologies so far that I use to lab things up when needed, and I'd like to share the first with you now.

Lock-and-Key Security (Or how I learned to love the Dynamic ACL)

After a great February of blogs (for me anyway) I didn't manage to get a single post out in March.  Oddly enough March turned out to be a new record for pageviews...  Weird eh?

At any rate, I did do up another guest blog post for Steve on Networking-Forum.com on Lock-and-Key security..  If you're interested I encourage you to head on over and check it out.


http://www.networking-forum.com/blog/?p=2108

I hope you enjoy it.

IPv6 Will Make You Think Differently: We Don't Need No Stinking FHRP

I got into a discussion about the availability of HSRP for IPv6 being in higher end Cisco platforms but not the lower ones.  I didn't think too much of the question when first saw it, but in reading up on IPv6 last night I came across some of the details in Neighbour Discovery that I thought might be a good replacement.  Deep within RFC 2461 lies section 6.3.6:

6.3.6.  Default Router Selection

   The algorithm for selecting a router depends in part on whether or
   not a router is known to be reachable.  The exact details of how a
   node keeps track of a neighbor's reachability state are covered in
   Section 7.3.  The algorithm for selecting a default router is invoked
   during next-hop determination when no Destination Cache entry exists
   for an off-link destination or when communication through an existing
   router appears to be failing.  Under normal conditions, a router
   would be selected the first time traffic is sent to a destination,

   with subsequent traffic for that destination using the same router as
   indicated in the Destination Cache modulo any changes to the
   Destination Cache caused by Redirect messages.

   The policy for selecting routers from the Default Router List is as
   follows:

     1) Routers that are reachable or probably reachable (i.e., in any
        state other than INCOMPLETE) SHOULD be preferred over routers
        whose reachability is unknown or suspect (i.e., in the
        INCOMPLETE state, or for which no Neighbor Cache entry exists).
        An implementation may choose to always return the same router or
        cycle through the router list in a round-robin fashion as long
        as it always returns a reachable or a probably reachable router
        when one is available.

     2) When no routers on the list are known to be reachable or
        probably reachable, routers SHOULD be selected in a round-robin
        fashion, so that subsequent requests for a default router do not
        return the same router until all other routers have been
        selected.

        Cycling through the router list in this case ensures that all
        available routers are actively probed by the Neighbor
        Unreachability Detection algorithm.  A request for a default
        router is made in conjunction with the sending of a packet to a
        router, and the selected router will be probed for reachability
        as a side effect.

     3) If the Default Router List is empty, assume that all
        destinations are on-link as specified in Section 5.2.

Let's take a look at how we can use this to our advantage.