IP Network

Network upgrade

Simon Woodhead

Simon Woodhead

12th March 2009

Last week we lit our second UK data centre – BlueSquare.

Located in Maidenhead, this is outside of both central London and the M25 orbital and some 33 miles from our primary location in Telehouse East. With 10GB of diverse fibre between the two sites, our Maidenhead network is just 1ms from our primary London equipment.

Our goal is to mirror all services in our primary location in BlueSquare, such that in the event of a major disaster affecting London data centres, or problems on our own network, Maidenhead can carry the full load of our IP network and services built on it. This includes ensuring that any external connectivity from Maidenhead is similarly independent of London.

It will take some time to fully achieve our goal but some services are already mirrored in Maidenhead and others will come on stream soon. This will unfortunately mean additional IP addresses and configuration changes. We have outlined these below but we will keep you notified as further action becomes necessary.

Ordinarily you will see service from either site as the two sites will run in active-active configuration, with each utilised to no more than 50% of capacity for the service concerned. In the event of a failure, or increasingly in the event of planned maintenance, we will switch service exclusively to one site.

Colocation customers are encouraged to consider replicating or splitting equipment between the two sites to maintain availability in the unlikely event of an outage in one location.

Changes to make immediately:

You will need to accept SIP and RTP traffic from two new addresses ( and for incoming calls from Simwood numbers. This needs to be in place before March 20th. We recommend you authorise through to as further hosts will be added in due course.
No firewall changes are required if you have authorised traffic from as we recommend – Maidenhead will run entirely within this subnet.
Outbound traffic sent to our global proxy at needs no change, although a second IP address representing signalling in BlueSquare will be added soon, together with a dynamic host name. Customers will need to either use the hostname or be able to use the second IP should the first be unavailable.
Customers on alternative configurations and sending signalling to any of our Los Angeles or New York equipment should contact us to discuss changes.
Finally, 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 Telehouse East from most London (and many European) data centres over Datahop, and most London data centres over LONAP. Customers on-site in a BlueSquare data centre can also reach us over their fibre ring, or by direct cabling in Maidenhead.

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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