Tuesday, October 8, 2013

BGP Conditionally Injected Loops

While writing up the previous post on BGP Conditional Route Injection I got an idea while I was verifying the information in the post. I thought I saw a way for a loop to form in that the injected route would be learned by a router making it send traffic in the wrong direction.

It turns out I was right.

BGP Conditional Route Injection

This is one of those “complicated” configs. There’s a bunch of typing involved, and the syntax need to be just so.  I labbed this up tonight and it didn’t work. I proceeded to stare at my config for the next 30 minutes before I saw my error. This, my friend, is how you fail the TS section. So in the hopes that I don’t pull the same stunt with this feature come Lab day you folks are now treated to another blog post!

Sunday, September 22, 2013

RIP Distribute-lists and the Extended ACL

Here’s a neat trick that’s an easy one to screw up or forget the syntax on.  In RIP (and EIGRP as well I believe) you can use an extended access-list to filter out specific routes advertised by specific neighbours.  This is done using the source and destination fields of the extended ACL to specify source of the routing update, and the route(s) you want to filter respectively.

Example after the jump.

Thursday, September 19, 2013

Meraki MR12 Initial Setup and First Thoughts

I managed to get myself a Meraki MR12 access point after attending one of their webinars simply because I am an IT professional.  For free.  Pretty good deal eh?

http://meraki.cisco.com/lp/free-demo

Since I have a blog I thought I'd post up some thoughts on the MR12, and Meraki in general.  In the interests of full disclosure I do work for a Meraki partner, though to date I'm not aware of any deals we've completed.  And of course, they gave me this AP for attending their webinar. 

Thursday, September 5, 2013

Help Please: PPP Multilink

I'm going to try something a little different for this post.  Usually I take something that I've been labbing that I find interesting, or challenging, and document it for memory retention and your reading enjoyment.  This time I've got a config-let for PPP Multilink that I found quite by accident that I don't know is "right" or not.  It works, so that would mean it's right enough, but I'm hoping that someone out there can point me at some supporting documentation that can clarify what the difference is between this method and what I'll call the more traditional method, and why you would use one over the other.


Monday, September 2, 2013

VTP Transparent Mode Relay Caveat

As I get my fingers back in shape for the Lab I figured a little VTP practice tonight was in order.  VTP is fairly straightforward, so I wasn't expecting anything unusual when I started in on a little bit of config with a transparent VTP switch...

I've previously run under the assumption that a VTP transparent switch will relay VTP frames as long as it is in the same domain as the VTP frame it receives.  If there's a mismatch then the frame is discarded.  Well, this is still true, but there's a third scenario that I hadn't ever really considered before: the domain is set to NULL.

Thursday, August 29, 2013

MPLS and the Next Hop

This week I discovered that in all my labbing it would seem that I have never tried to run L3VPN MPLS over a Frame Relay hub and spoke configuration using OSPF and the provider IGP with a broadcast network type.  The reason that I know I’ve never done this before is because it just doesn’t work.  This seems like a sneaky little scenario for a TS task so here’s what things look like should you ever encounter it.

Sunday, February 24, 2013

I hate LAX.

I hate LAX.

If ever there was an airport that sits on the edge of a land the $Diety forgot, this is that airport.  I'd call it Hell, but it's more of a special type of Purgatory where people go to be forgotten, wandering between terminals having to go out of and into security between flights, where you sit in armpit terminals waiting for your aircraft for hours while watching the delayed time increment by 15 minute intervals every 15 minutes.  Best of all, even once your plane finally gets to the gate you're informed over the amazingly unintelligible PA system that there are mechanical issues and they're getting a mechanic to come out and look at the problem.

And that about sums up my afternoon sitting in the American Eagle terminal.

When Dreams Die (Or at least get put on hold)

On February 21st, 2013 I failed the CCIE R&S lab for the 5th time.

I've been working towards the CCIE for about 2.5 years now.  I passed the written in Jan 2011, and I've been working on the lab ever since.  I've put nearly my entire life, both personal and professional, on hold while I've chased this dream.  That's been a luxury that has caught up with me finally and now my attention must be focused in other areas.  I am no longer able to spend weekday evenings, and the majority of my weekends in my den, with my rack, furiously typing away on the CLI.

I'm hoping I can still get a hour or two here and there to at least keep things fresh in my mind.  Maybe come late fall or winter I will be better prepared to ramp up again for another attempt.  But in the meantime I need to look at buying a house, move to a new city, focus on work and some partner related certifications that my employer would like me to get, and deal with a couple neglected customers.

I still plan to post up here as much as I can.  I had always intended to keep this going post CCIE.  I even have a few ideas about some things I'd like to do in making this more of a full site beyond simple blog posts.  Maybe this hiatus will allow me to do some of that.

Thanks to everyone who stops by here and reads what I put out.  And thanks to everyone who's helped me along the way so far.  With a little luck I can be back on the trail sooner rather than later.