Category Archives: Computer Networking

Fibre Connection Between the House and the Outbuildings

Posted on by
Reply

After initially thinking I wanted a fibre optic network link, I’d mostly settled on using a copper Cat 5E Ethernet link between the House and the Outbuildings, to connect their separate computer networks together. The reasons for favouring a copper Ethernet link were:

  • I happen to have about 150m of Ubiquiti outdoor grade Cat 5E Ethernet cable going spare, from when I bought a 305m reel to install outdoor cabling for the CCTV cameras that monitored the site and the construction of the House 10 years ago – so this enables the buildings to be linked ‘for free’
  • This network link will directly-connect the network Routers1 in each building, which (currently) only offer 1Gbit/s copper Ethernet ports and so would need Media Converters to connect over a fibre link
    • When these Routers need to be replaced, I would expect to purchase devices which have SFP+ ports which would take an SPF+ module to enable a fibre cable to be connected directly to each Router and synchronise at 10Gbit/s
    • Media Converters aren’t especially expensive – roughly £25 each – but need mounting somewhere and need their own power supply
  • The physical cable route between the two Routers takes ‘the long way round’ but is less than 100m, so the Cat 5E cable should enable a 1000BASE-T connection, at 1Gbit/s
  • 1Gbit/s will be plenty of bandwidth, given the planned use of the Outbuildings

However, I have just installed 85m of outdoor grade 8-core bulk fibre cable, because:

  • I had to install another cable along the same route, to extend a Current Transformer clamp connection to enable the Tesla PowerWall 32 to monitor the existing AC-connected solar PV inverter’s generation output
    • About 1/3 of the cable run is through the now-fully-insulated loft space above the Workshop, so it’s quite a difficult job to balance on the roof trusses (while unable to stand upright) and attach the cable to the cable baskets using the existing releasable cable ties – and it’s no harder to do that for 2 cables than for 1
  • Unterminated bulk fibre cable is surprisingly cheap – less than 50p per metre – so it’s not a major problem if the fibre doesn’t get used for a while – or ever

I’m still planning to use the copper Cat 5E initially, so I won’t pay to have the fibre spliced to pre-terminated ‘pigtails’ until I see how that performs (or doesn’t). If the Cat 5E works OK I’ll wait until I upgrade the Routers to light up the fibre link.

I selected Single Mode (OS2) fibre, with an outdoor-grade PE sheath (since about 25m of the run is in an underground duct between the buildings) and 8-core because it was only fractionally more expensive than 4-core.

Initially I found the many variants of fibre types and connectors quite confusing but this forum post by an amateur astronomer, in relation to network-connecting an observatory. proved very helpful in cutting through the jargon and homing in on the right solution – although they advocate using pre-terminated fibre which can be difficult to install when there’s not much space available in an existing duct.

  1. I’m using the term “Router” in the strict sense of its computer networking definition: a device that provides OSI Layer 3 connectivity, routing TCP/IP packets between Layer 2 network segments ↩︎
  2. Strictly speaking it’s the Tesla Backup Gateway 2 which does the monitoring – and then passes the measurement to the PowerWall 3 ↩︎

Outdoor WiFi for the Outbuildings

Posted on by
Reply

While there are several Wireless Access Points inside the House (and there will be several more inside the Outbuildings) those do not provide a good WiFi signal outside, since the walls are quite effective at blocking the radio signals. Hence there are also two outdoor Wireless Access Points mounted on the House, which are Ubiquiti UniFi UAP-AC-M devices:

  • One on the West-facing elevation, covering the wildflower meadow and the driveway to the lane
  • One on the East-facing elevation, covering the Courtyard and the Southern side of the Outbuildings

One disappointment is that those provide almost zero coverage to the South and North of the House. South isn’t too much of an issue, since there’s only a small ‘blind spot’ (the site boundary is quite close), but North is more of a problem since there’s a much bigger area with poor WiFi coverage.

In an attempt to address that ‘blind spot’, the Outbuildings will have one additional UAP-AC-M, facing North-West, to cover the parking area North of the Garage doors and the driveway as it passes the North side of the House. To try to cover both North and West, it makes sense to mount the access point on the corner of the building. Mounting brackets are supplied with the access point to attach directly to a wall or to a pole, but mounting on an external corner is more problematic.

Fortunately, somebody has addressed this issue by designing an excellent 3D printed corner bracket. The same STL file is published:

Rendering of 3D Model of a Corner Mount for a Ubiquiti UAP-AC-M Outdoor Wireless Access Point

At first glance this bracket looks very ‘big’ since it places the unit 100mm out from the corner, but that’s no bad thing from an RF signal standpoint. It has fixing holes perfectly placed to suit the supplied wall mounting bracket – then further (countersunk) holes to fix the bracket to the wall.

Before purchasing the additional UAP-AC-M, I did review whether to install a more modern outdoor access point instead. The UAP-AC-M conforms to the WiFi 5 standard (for about £75) and there are alternatives which support WiFi 6 (for about £150) or WiFi 7 (for about £200). Given that significant price differential – and given that I have two UAP-AC-M units already – I decided to go with the cheaper option.

A smartphone or similar device will ‘roam’ between different access points while moving around the buildings or between inside and outside. While doing so, it is not expected to lose its WiFi connection (each access point presents the same set of SSIDs) or change its IP address. (The VLANs which correspond to each SSID are ‘stretched’ between the House and the Outbuildings, so once allocated an IP address via DHCP the WiFi client can continue using that same IP address with different access points – because they’re all on the same VLAN and hence the same subnet.)