Labbing in iTerm

In case you’ve not worked it out yet, I’m an enthusiastic Mac user.  I’ve used them on and off since I met my wife (a long-time and even more passionate Mac user) back in 2000 when she was running OS 9 on a Graphite iMac.  Despite negative initial impressions (“Ugh! Macs?”), she didn’t kick me out of her house and we got married 2 years later.

But I digress…  I’m running OS X Lion on a Macbook Air now and it’s easily my favourite computing environment.  I’ve also recently added an external screen (a Dell 22″ U2212HM) to try and prevent neckache from working on the laptop all the while.  I’m also trying (insofar as I can on the Mac) to replicate the CCIE lab environment.  From what I’ve seen on the web this roughly means:

• No tabbed terminals.
• Single 23″ display only.
• Work with electronic documentation, not hard copy.

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Learn to Teach Yourself

Image by AustinEvan on Flickr

I changed jobs at the end of October and while leaving many of my colleagues behind was difficult it’s been great to get stuck into learning a new network and working with some different technologies.

In the last few weeks I’ve been designing and configuring an expansion of an existing datacentre.  This has given me a great opportunity to sit down and read through design guides and configuration docs on both the Cisco Nexus 5k range of switches and the Cisco ACE4170.  Before this I didn’t really know anything in detail on these devices other than general awareness and various bits and bobs I’d picked up from my compatriots on Twitter.

Both of these technologies gave me plenty to learn about – they both have their fair share of limitations and restrictions on how they can be deployed and both have subtle CLI differences that have entailed scrabbling through documents, scratching heads and asking questions of those better versed in these areas than me (thanks @EriksonIan!).  These gotchas ranged from the trivial (not knowing about the “trunk” parameter to “spanning-tree port type edge”) to the more fundamental (understanding how vPC works).

It was while I was finalising the configs that I realised I’d taught myself an awful lot during the last few weeks – technologies that I had never touched were almost becoming second nature and I was starting to feel vaguely competent (but hopefully not dangerously so).  This thought took me back to my University days – the program leader of the course I was studying had a phrase that he trotted our with regularity that was basically to the effect of:

It’s only now that I can see how true that statement was.  The best people I have ever worked with have all had an extremely good grasp of the fundamentals and the ability to take a new technology, new product, new service – whatever it may be – and make sense of the knowledge and put it to good use.

My personal #1 piece of advice to any aspiring techie would have to be: “Learn how to teach yourself”.  Find out what it takes for you to learn something in-depth and retain that knowledge.  It could be that reading documentation or 3rd party books is enough for you.  You might find that labbing something up and putting practical skills to work works better, or that audio/video-based training is what you need.

Whatever it may be – find a way that works for you and go put it to good use!

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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Free Stuff – BSCI/BCMSN/ONT/ISCW Certification Guides

While I was studying for my CCNP, due to the syllabus changes I ended up with two sets of Cisco Press CCNP Certification Guides.  While I’ll hold onto the SWITCH/ROUTE/TSHOOT set for now, I do have a complete set of BCMSN, BSCI, ONT and ISCW books that I’m looking to get rid of.  If you have a need for these – maybe you’re just attempting CCNA and what to look ahead – and you’re willing to pay the price of postage, get in touch with me and I’ll see what can be done.

There are of course, two caveats – firstly that these books are NOT for the current version of the CCNP certification – they are a year or so out of date.  Secondly, I’m based in the UK, so bear in mind that shipping anywhere outside the UK is likely to be expensive!

If you’re interested, either comment on this post or contact me as @xanthein on Twitter.  It’d be a shame for me to have to just bin them.

The Network Engineer’s Manifesto

By filipe93 on Flickr

Back in 2005, fueled by the growing trend of manufacturers to make their products cheaper, disposable and less home-repairable, Make Magazine published their “Owner’s Manifesto: A Maker’s Bill of Rights“. This document laid out the tenets of the maker/hardware hacking/upcycling movement – essentially the freedom to use your legally-owned goods in whatever way you damn well wanted!

It struck me today that we network engineers could use a similar document – something we can brandish in the faces of vendors when they start doing Stupid Things™ and acting against the interests of those who install, configure, operate, monitor and tweak their products day-in, day-out.  So, without further ado – a manifesto for those on the front-line of the networking industry!

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Testing Multicast

As it’s been a couple of years since I last had to configure multicast, I decided to give it a quick spin in the lab this evening.  There’s plenty of other sites and resources out there for configuring PIM-SM, either with static RP (Rendezvous Point) or by using Auto-RP (proprietary) or Bootstrap Router (BSR – standards-based), so I’m not going to cover that ground here – see the references at the end of this post.

Instead, I want to focus on tools you can use to test multicast from host-to-host via your lab network.  Yes you can use the old standby of:

R5(config-if)#ip igmp join-group 239.1.1.1

and then ping the multicast group address from another router – but where’s the fun in that?  Fortunately there’s some good tools out there you can use to good effect for testing this kind of thing – and there’s two in particular that I’ve been using today – emcast and mnc.

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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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