23-06-2015 09:34:15

In the past few months, BIT has replaced its core routers with new models. Due to the growth of the internet, not only in bandwidth but also in the size of the routing tables, new models needed to be placed with more capacity for bandwidth, calculating power and memory. BIT has been using Juniper routers in its core network to their full satisfaction for the past 15 years, so it was logical to choose the replacement routers from the new models of the Juniper MX-range.

The routers in London and Frankfurt have been replaced in April. On these locations connections are made with LINX and the DE-CIX to exchange local traffic with other existing networks. Additionally, connections are made with transit providers that provide us with routes to the entire internet. The replacement of these two routers by travelling engineers went smoothly and without noticeable disruption for clients. First the traffic was temporarily routed through different paths so the routers could be replaced. The new routers were checked and then put into operation according to a previously developed action plan, making sure this could also happen without disrupting our client’s course of business.

On June 17, the two core routers in BIT-1 and BIT-2 in Ede were replaced. These routers are the linchpin in BIT’s network: they are linked to the routers in London and Frankfurt, have connections to the Amsterdam Internet Exchange (AMS-IX) and Neutral Internet Exchange (NL-ix), are also connected to transit providers and take care of the access to the access network.

BIT’s access network delivers the services to the clients. The switches to which clients are connected in BIT-1 and BIT-2 are switched out and BIT’s services like email and DNS are then hosted there. So actually, the access network is a collection of many small networks with their own configurations and the core routers are the gateway to these networks. This makes replacing these routers a lot more complex than replacing the routers in London or Frankfurt, because naturally the replacement needs to take place with a minimal impact on our clients.

Fortunately, these two core routers in Ede have been thusly designed to be able to take on each other’s functions. This prevents troubles in case of failures in one of the routers, but also makes it easier to replace them if need be. So on June 17, a little after midnight, we started routing all traffic to and from the access network through BIT-1. About half an hour later all checks had been done and the router in BIT-2 was no longer active. Then it could be taken from the rack and replaced by the new router. Putting the new router into operation was then executed according to a comprehensive action plan with many checks. This all took a little over an hour, but then the router was fully operational. After a few more checks, the same plan was followed for BIT-1. Around 4 AM this router had also been replaced and was up and running, so the access network was fully redundant again. After this, a series of final checks was done and simultaneously various systems for administration, monitoring, statistics, billing and DDoS detection were altered to get all that information available and up to date again.

All in all, this maintenance has been very successful: the new routers are running properly and the inconvenience for our clients has been kept to a minimum. With the execution of such migrations, having good network diagrams, a good action plan and carrying out the proper checks is essential. Prior to each replacement, all relevant information (for example route tables, BGP session statuses, ARP tables) is saved, so it was possible to check whether the effects after each step in the action plan were as expected. Of course good preparation and testing (where possible) is also highly advisable in case of new configurations.

The replacement of the routers not only has the advantage of enabling the network to accommodate the growth of the internet: the old core routers in BIT-1 and BIT-2 were the size 12 rack units (50 cm high) and weighed around 50 kilograms each. The new core routers are only 2.5 rack units high (15 cm) and weigh less than 15 kilograms. The new routers also need 2.5 Ampère (600 Watts) less than the old ones. With the new routers we save on our electricity consumption and we have a lot more space in our racks.