IPv6 - It Doesn't Just Work.

2008-09-30 imported Tech · ISP · IPv6

I was reading an entry posted by Brett Carr on Nominet’s techblog today entitled “ipv6 It just works”. Unfortunately, for IPv6, and for the sentiment behind this message (IPv6 can be run pretty easily!), in my experience, IPv6 - it doesn’t just work!

It’s easy to dismiss the previous sentence, given that many networks aren’t designed to run IPv6, and there’s kit out there that’s just not IPv6-capable yet. When building the AS29636 network, we specified that IPv6-capability was one of the things that would be a requirement of the kit that was going into the new network, not just something that we’d like to have. We work to a similar specification at my current employer, - which ensures that we can deploy IPv6 within a pre-agreed timeframe once we have some commercial drive for it (either from customers, or for business continuity reasons). I think that this is the best way for a SP network to be a the moment - there’s no revenue in having IPv6 deployed (generally), but there might be lost revenue when a customer comes to your network with IPv6 as a requirement in their RFQ…

Returning to the reason that I started writing this post - the problems for IPv6 deployment don’t just come from the fact that your hardware doesn’t necessarily support it, and it isn’t just that running IPv6 on your kit might have financial implications for the software licensing that you’re going to be deploying (the arbitrary Cisco requirement for advipservices for IPv6 is a completely separate post). There are going to be issues where you don’t necessarily expect them - which can be hard to debug, where IPv6 “should just work”, it doesn’t.

Without mentioning any specifics of a case that was brought to my attention in the last couple of weeks - a customer was having problems getting IPv6 traffic flowing across a layer 2 ethernet circuit. The expectation of this circuit that you can put ethernet frames onto it (and it doesn’t really matter what the ethertype is, just that they’re valid ethernet frames) - and they are going to be punted down the link, to whatever you terminate the L2 circuit on. With IPv4, this not working would be a disastrous failure - the product just wouldn’t be working. However, this particular circuit was not passing frames that contained IPv6 packets. As it turns out, the carrier’s equipment in the path contained a firmware bug that was causing the frames containing IPv6-packets to be dropped - and hence, no neighbour-discovery, and no traffic flow between the two ends of the circuit.

This is just one isolated case - but the question is, where else in your network do you have a problem like this one? How much kit that may, right now, be considered something that shouldn’t be interfering anywhere above L2, is going to exhibit this type of problem? How much load is this going to cause your NOC? How much time liasing with circuit suppliers, and telcos is going to be spent actually deploying IPv6 on your network? I think these questions are starting to form a basis of why SPs should be startng to roll out IPv6 onto your network now. The lack of transition plan from IPv4 to IPv6, and the fact that IPv6 hasn’t had widespread deployment testing across many platforms and transmission media mean that deploying IPv6 in a rush across your network isn’t necessarily going to be as easy as you’ve thought.

Whilst I applaud the fact that Nominet are ensuring that they’re going to be ready to run the UK ccTLD with IPv6 nameservers, and that their infrastructure is ready - I don’t think that IPv6 is going to be quite as easy to deploy as Brett found in his blog post.

Why I'm excited about Di2.

2008-09-14 imported Cycling · Me

There’s a bunch of stuff online about the Shimano Dura-Ace Di2. And there’s a lot of comment online, people saying that they feel electronic-shift is unnecessary, and over-complicated.

I’m mostly interested in why I might want to ride Di2, and I think there’s a bunch of reasons that I would want to, despite all the negative comments that are flying around! So, the big thing that I see as an advantage in the system is the fact that it adjusts on a per-shift basis, this is really handy for those of us that really just want to ride our bikes! Sure, I don’t mind cleaning, and tuning my bike, but there’s some periods when I just want to be riding it, it’s what I love, it’s why I own the bike - so to me, if I get auto-adjustment that means that every shift that I’m doing is accurate, between the times that I either tune my bike up myself, or get it looked over then this sounds great! Cable-stretch is pretty annoying sometimes, and does mean that I end up having some rides where my gears might feel a bit squidgy, or over-tight. This is a problem that could be solved by tuning my bike more often, of course, but really - I just want to ride.

Someone commenting on WIRED has some different thoughts to me - feeling that the battery, and motors are prone to failure - of course they are, everything is. Gear cables snap now already, and derailleurs get worn, and bent. However, I guess with cable systems, I can bend my derailleur back and adjust the tension myself to ride home - the question here is, will Di2 be this flexible? I can get over it if not, because, how often does this really happen (only once, for me)? The battery life of the system shouldn’t be difficult to get right - it should last for a while, and I don’t mind carrying a spare battery, I carry spare tubes already.

There are limitations, sure - however, there are limitations of everything. But, I quite fancy it. �1600 for a groupset isn’t what I’m going to be spending just yet - but once we’re down a bit to more suitable price, then I’d really like to give it a go. Maybe on a ‘09 Orbea Orca - the shape is just bang on:

Rollapaluza Best

2008-09-08 imported Me · Rollapaluza · Photography

As mentioned previously, my new Rollapaluza best time. Not really posted for that reason, but mainly due to test out the new IXUS 960IS I have been given!

1st Shoreditch Invitational Bike Polo

2008-08-25 imported Cycling · London · londonfgss · Rollapaluza · Photography

A week or so ago, I spent a very enjoyable day watching some great bike polo - again with my camera. Enjoy the photos!.

I also managed to knock my Rollapaluza quick-rollers PB down to 22.16s :-D

Rollapaluza XI

2008-08-09 imported Cycling · London · Rollapaluza · Photography

More cycling event photos - a bunch of images from the Rollapaluza XI race last night at the Kingpin Suite in Bloomsbury. Lycra skinsuits meets cycling campaigns meets drunken cyclists. Beer, rollers and endorphins - what more do you need? (Click the image for the full gallery).

Grass Track Racing

2008-08-01 imported Cycling · London · londonfgss · Photography

A couple of Sundays ago I went up to watch the grass track racing in Hackey, arranged by Hackney CC - finally got a moment to upload the photos! Full gallery is here, selected others below!

Handy vim tip

2008-08-01 imported Geek · Work

I’ve been working on a number of bits of code recently, and have found that it’s not entirely practical to check into RCS or SVN for every change that I’ve made. I really like to work by committing when I’ve finished adding a feature to a script, or a project. Hence, I’ve been using the vim “set backup” option. However, this has some limitations, and hence I decided to have a look at what .vimrc could do for me.