IP Network

Network upgrade

Simon Woodhead

Simon Woodhead

22nd January 2010

In late 2009 we added a further data centre to our network, in Manchester, UK. This email is notice of the work we will soon be doing to bring that facility fully on-line and the reasons behind it.


Earlier in 2009 we opened our second site in Maidenhead, just outside the London M25 orbital. Our goal was and is to operate at least two sites in the UK to afford redundancy and independence of London. Whilst Maidenhead has partly fulfilled that remit we have had concerns with the facility itself and have been unable to make adequate progress with establishing connectivity independent of London to maintain network accessibility in the event of a catastrophic event affecting multiple London data centres.

Our new facility in Manchester is set in the heart of the Science Park, home to the major northern data centres. We have been able to interconnect with two major carriers – Cogent and Tinet – there. Tinet are the only major provider who are able to offer transit which does not have to traverse London in some way – they have connectivity directly from Manchester to the US via Dublin.

We have also joined Edge-IX (formerly and better known as ManAP), a Manchester centric but now national peering exchange, and we will be actively peering with local and regional ISPs to improve the quality and performance of the network from Manchester in the same way as we do in London.

Naturally we have ample private connectivity joining the two sites although as you will see below intend to distribute traffic slightly differently across the network to improve service levels to those customers who are themselves or who are with northern UK ISPs.

Scheduled maintenance notice

On the weekend of the 29th January we will be relocating equipment from Maidenhead to Manchester. From Friday 29th, calls will be routed exclusively through our London site enabling Maidenhead to clear down. It is anticipated that new service in Manchester will be brought on-line late Saturday and calls will be redistributed once adequate testing has been carried out. Maidenhead will be taken offline permanently.

This is non-service-affecting although any customer monitoring running against equipment currently in Maidenhead will show it as offline until it is restored in Manchester. No customer action is required as no IP addresses will change.

The future

This move takes us closer to our goal of a totally independent two site network, although there remains more to do.

We will continue to balance most voice traffic 50/50 across the two sites, with either site capable of carrying all of it, but Manchester’s distance from London (7ms) does afford additional opportunities for UK customers. We will enable customer outgoing traffic to be assigned to a specific site on an IP address basis, e.g. one piece of customer equipment can have media handled in Manchester and another in London. For the many customers who have equipment co-located in Manchester, or data centres further north which hang off-it, this may make a lot of sense as it avoids the trip from us in Manchester down to London and then back. Signalling will still be handled by the same global proxies enabling media to be moved by us without customer intervention.

Those wishing to take advantage of this may wish to periodically monitor a traceroute to our primary Manchester router ( and primary London router ( In advance of this work Manchester is heavily de-preferenced to avoid traffic entering the network there unecessarily but once work is complete this will be adjusted. As we add peerings on EdgeIX those with northern ISPs who we come to peer with should should find their traffic entering Simwood in Manchester rather than London. In this case, it makes sense to set the media to be handled there. If you require any guidance, please open a support ticket with a traceroute to the two addresses above and we will be happy to help.

Customers who run their own AS are encouraged to consider peering with us in either location, or ideally both. We will accept physical cabling in either site, whilst we are reachable in London over LONAP and Manchester over EdgeIX.

Finally, we have ample co-location space available in Manchester for customers wishing to host equipment directly on the Simwood network. It is available by the U, quarter-, half- or full-rack.

We hope you will share our excitement at this step and our efforts to make the Simwood network as highly available and stable as possible. Please do contact us with any questions or concerns.

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