David Mytton

Building the Server Density office network

Published (updated: ) in Server Density Archive.

Originally published on the Server Density blog.

In February we moved into our new London office we started building in December last year. As a tech startup, one of the most important things is a good network and fast internet connectivity. It’s easy to upgrade internet speed as we grow so we can start with a lower cost option but the internal network needs to be considered before it’s all wired up. Rewiring an entire office in the future would be a massive pain!

So we went straight for Cat6 gigabit ethernet. We briefly considered fibre but decided that would be too expensive and overkill because of the total office capacity and that the actual internet speed would be limited by the WAN connection, which is unlikely to be fast enough any time soon. We’re not running a data centre so 1Gbps is fast enough.

As mentioned in the final part of our first series, our first internet connection is supplied by BT. This is a standard ADSL connection rated to up to 20MB. In real world tests we get 15.5Mbps downloads and 0.82Mbps upload. It also includes an SLA so any faults are guaranteed to be fixed within 24 hours.

ADSL is provided through a normal phone line which goes directly into our Draytek Vigor2830 ADSL2/2+ Firewall Router. This connects into a 24 port Netgear GS724TP switch on the ground floor. These switches provider power over ethernet, 10/100/1000 switching and VoIP priority. 

Netgear Switch Control Panel – my old cinema display has no gigabit network port so I’m connected via a USB ethernet port, which is 10/100 only. The Airport Express is also 10/100. These show in yellow and the green ports are the trunk 1Gbps ports.
Every desk has x2 L6J CAT6 ports – 1 for a computer and 1 for a VoIP phone which are wired through trunking to a termination point in a cupboard. The ground floor has its own cupboard and the first and second floors all terminate in a cupboard on the second floor. Each cupboard therefore has a patch panel which acts as the connection point to the switch.

The floors are connected by two trunk cables which are independent and correctly shielded and spaced from power cables to prevent interference. This connects the ground foor switch to the second floor switch. 

Currently we’re only using the first and second floor so have a simple Apple Airport Express plugged in on the second floor, providing 802.11n (2.4Ghz) in bridge mode. However, because every floor has network ports in addition to the desk ports, we can position one or more wireless routers throughout the building to cover all floors. This is better than having wifi built into the DSL router hidden in a cupboard on the ground floor.

Currently the Draytek router provides DHCP to the entire office but we can segment the switches so that different floors can have different networks for further security and access to different services. Roadmap for expansion includes providing network backup for all our Macs (probably via a Time Capsule), a guest wifi network to separate the networks for visitors and additional internet providers for additional combined speed and redundancy.

Wiring up the patch panels into the switch
24 hours of bandwidth usage
Downstairs cabinet with router
Cabinet plus wires coming from the wall trunking
Downstairs cupboard containing the switch and cabinet
Desks with power and network panels
Floor panels with power and network