Secure your OOB!

As anyone who has had to work with remote datacenters or remote offices will tell you, you can never have too much OOB (Out-Of-Band) access.  Whether it be because you’ve fudged an ACL on a firewall or fat-fingered your route filtering, some form of remote access to your network devices comes under the heading of “bacon saver”.

A terminal server doesn’t necessarily have to be a dedicated device: as many network engineers know, a Cisco router equipped with some manner of async card makes a fairly basic but serviceable terminal server.  I’ve used both 2800 and 2900 series routers equipped with HWIC-8A and HWIC-16A modules at work, while my home lab uses a 2600XM (which does double duty as one of the “BB” routers in the IPexpert topology) with an NM-16A.  I’ve then equipped these devices with some kind of alternative network access – sometimes an old-school analog dialup or ISDN connection, other times a cheap ADSL connection – so that you can still get access to the site to troubleshoot when all other routes to the site are down.

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Short-Term Memory Loss

When I started preparing for the CCIE lab, I made a decision to build my own physical hardware lab at home.  Partly because I’m a geek and that’s the sort of thing we do, and partly because it made my life easier.  The ability to decide on the spur of the moment to fire up the rack and do an hour or two of labbing was very attractive to me, especially as most of the lab rental providers are US-based and work on 8 hour slots – this doesn’t always translate to friendly labbing hours here in the UK.

My lab is based loosely on the IPexpert topology – but built mostly using 1841s.  After a successful evening of labbing I’d shut down the rack and gone to bed.  The next day I’d fired it up again only to be caught by several of the 1841s getting stuck in a loop of stack traces and reboots.  The main error of any use was:

SYSTEM INIT: INSUFFICIENT MEMORY TO BOOT THE IMAGE!

Houston, we have a problem…

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Getting Started with Cisco Nexus

One of the cool things about working as a network engineer is learning and investigating new technologies.  At my place of work we’ve recently been looking long and hard at the Cisco Nexus product line for both 10Gb Ethernet and FC.  In fact, as soon as the new 5596UP and 5548UP (Universal Port) models were released, we knew these switches would meet our needs.

The Nexus range, for those who’ve missed this bandwagon entirely, is based on the NX-OS software platform rather than the traditional Cisco IOS.  I don’t think any experienced network engineer could find a reason to dislike this – IOS has many glaring faults (both architecturally and from a CLI perspective) and NX-OS (which was originally the SAN-OS software from the MDS line of SAN switches) has built a pretty good reputation for reliability.  This is hardly surprising; storage engineers tend to get somewhat excited when their hosts’ storage paths are pulled out from underneath them due to a fabric switch dying…

One “not-really” problem of this is that engineers need to get their head around NX-OS and the Nexus platform and while the learning curve isn’t steep, it’s worth knowing the differences between the two platforms and having a good idea of the product range before you go shopping.  To this end I’ve put together a list of useful Nexus resources that I’ve been working with over the last month or two while we investigated the capabilities of these products.  I hope it’s useful to you!

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CCIE R&S Reading List

As I was finishing up my CCNP a couple of months back, I started to put some serious considerations as to what certification I wanted to attempt next.  One option was to go for CCIE R&S and it didn’t take me long to decide that was what I wanted to do. The technical challenge and career benefits made it a very simple choice for me!

As virtually everyone in the industry knows, the CCIE certification is based on a day-long practical examination held at various Cisco facilities worldwide. In order to take that exam, you first have to pass the CCIE written test – a qualification exam to ensure that those sitting the lab exam really do know the theory behind the practice.  While I’ve not taken this exam yet, general consensus seems to be that while it isn’t particularly difficult or require über-deep knowledge, it is very broad in what it expects the candidate to know.

Sure enough, consulting the CCIE R&S v4.0 Blueprint (login/registration required) shows the breadth of material required. All the major enterprise IPv4 and IPv6 IGPs are there, together with BGP.  Layer 2 topics include Spanning Tree and Frame Relay, with MPLS being a new addition.  Multicast, QoS, Security and Network Services round out the technical topics quite nicely.

Obviously to learn all these topics to the required level of detail is going to take more than a single book and I’ve done a fair bit of research into what people recommend as reading material for the CCIE written exam. I’ve included this information here in the hope that it’ll be useful to those looking to take this exam soon.

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CCNP – Complete!

After a couple of false starts I’ve finally completed my CCNP – I passed TSHOOT on Friday 19th November 2010, having completed that exam, ROUTE and SWITCH in the last 12 months.  Having gone through that I wanted to share a few general thoughts about the exam program in general – obviously I can’t say anything too specific about the exams themselves due to Cisco’s legal agreements.

First off – TSHOOT.  As many have said, this exam is a fairly major departure for the CCNP-level exams. Candidates face a number of questions, the majority of which will be trouble-ticket type questions based on a known topology and a known list of technologies (exam blueprint).  This information gives the candidate a vast resource of information that can be used to direct his/her studying.  I would also invite candidates for this exam to look at Kevin Wallace’s TSHOOT Videos.  They really do help clarify techniques that will be useful in the exam itself.  I looked at them the morning before I took the exam and it helped me get my mind into exam gear, given that I’d done no preparation in the 2 weeks before the exam (I was traveling for work and as a result was insanely busy).

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CCNP – and why you shouldn’t let it expire!

As I mentioned in my previous post, I’m studying towards my CCNP – Cisco Certified Network Professional.  However, this isn’t the first time I’ve had to do this.  According to the Cisco certification tracker, I first gained my CCNP back in July 2003 and my CCNA in July 2000.  This was at the end of my industrial placement while at Uni – a year that I spent working for Cisco doing various consultancy-type things.  I was very fortunate and was able to get a lot of training – the joys of the dot-com boom era!

This placement (and my background) left me with skills in both Linux/UNIX Admin and Networking.  I ultimately ended up in a job as a UNIX admin and my Cisco skills atrophied – I eventually let my CCNA and CCNP lapse in 2006.

Roll on a few years – I’ve now managed to move into a network admin role at the same company.  I re-certified my CCNA in 2007 and started towards CCNP in 2008.  CCNP is a very different ball game now compared to back then: while the core technologies are the same there are many differences in the syllabus to reflect products, technologies and protocols in use today.  Being out of the loop for a few years means that it’s taking me far longer to get through the exams and having a family now means  I don’t have as much time to study as I used to.  Letting my CCNP lapse has cost me a lot of time and money to re-certify – but given my circumstances it was probably unavoidable!

Things seem to be going pretty OK at the moment.  I passed the ISCW exam in December 2009 (after failing it in April) before the syllabus change was announced – however it did serve the purpose of re-certifying my CCNA.  I took SWITCH earlier this month and passed and am now working towards ROUTE.

If I can get ROUTE and TSHOOT sorted this year, I’ll be very happy indeed!

Blog Reboot

So having neglected this blog since 2007, I’ve decided it’s time for a reboot.  I’m currently studying for my Cisco CCNP certification and want to try and share some of that with the web at large.  Hopefully it’ll be useful for other folks in a similar situation and if nothing else I hope to invite some useful comments.

I’m debating if I can try and do some video blog entries too – mixture of video and screencaps perhaps.  Have to be careful not to let it get in the way of studying itself though!