Why adjacency matters

People think of the internet as one big network. In a sense it is, because the man in the street rarely gets to look under the bonnet at its engine and all the good work of network techies everywhere makes it seem so. In reality the internet is made up of over 60,000 “Autonomous Networks” (ASNs) from all around the world.

The biggest region, in terms of number of ASNs, as you might reasonably imagine is the USA, but there are one or two surprises. A few surprises I’d say. I leave you to decide which ones:

• United States – 21,510
• Russian Federation – 4,688
• Ukraine – 2,103
• UK – 1,913
• Brazil – 1,884
• Poland – 1,770
• Germany – 1,698
• Canada – 1,557
• Romania – 1,555
• Australia – 1,419

With the fourth most ASNs in the world, the UK is an important place to be on the internet and this is reflected in the size of the membership of the London Internet Exchange (LINX). LINX is one of the main places in the UK where ASNs are interconnected at peering points. We are currently present at LINX Juniper and LINX Extreme (two independent LINX networks), and LONAP, and spend a fairly significant amount of engineering time each month managing our peering.

The reason why this is important is in maintaining good links to other ASNs so we can provide our customers with day-to-day speed and responsiveness in reaching their data, wherever it is in the world. It is also important in the event of network problems – the more routes (and peers) you have, the more likely you can keep carrying network traffic when others might fail. We’re planning to add more peering outside of London during 2013 to protect ourselves, and our customers, from a London-based network disaster!

Hurricane Electric are a major connectivity partner for Timico and they have just released a list of the most connected peers, ranked by the number of adjacencies. Network nodes are considered adjacent if they can reach each other with a single hop across a link layer. A high number of adjacencies means that accessing resources (servers/websites) on those networks is usually very fast so the more adjacencies you have to your own network the better. The high number of adjacencies is achieved by peering. This is the process whereby companies agree to share each other’s traffic free of charge on the basis that it is cheaper than paying a commercial network to carry the data (a service/process known as internet “transit”). The connectivity infrastructure for peering still has to be paid for and this is what is provided by LINX.

Timico comes in at 10th in the UK for IPv4 and ninth for IPv6 (but IPv6 still has a far smaller presence on the internet). So that means we, and our customers, are pretty damn well connected to the rest of the internet. At Timico we use a tool called as-stats to give a view of our top peers by bandwidth, which clearly shows if traffic is over peering networks or via transit provider, and target to have peering with as many of the high up peers as possible.  We have also aimed to peer with as many networks with open peering policies as possible as having this attitude benefits the community of network operators, adding a level of competition to transit providers to keep them from driving costs up.

Most of our peers are content providers, or other network providers of similar magnitude of size, where it's mutually beneficial to peer between our networks to reduce cost of global backbone transit connectivity. Organisations with large global backbones will tend to be lower in the list of 'most connected' peers as they will usually be more restrictive (than completely open), and only peer with other operators who pass comparatively large amounts of traffic.

So being adjacent is all about being close. And that’s a nice thing to be at this time of year.

To find out more about our network please leave a comment on this blog or tweet us @TimicoUK.