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Backup Connectivity – GSM Failover

1 min read

Fibre to the home (FTTH) lines usually come with a ‘best effort’ SLA from the fibre network, and it can sometimes take 3 business days to restore a fibre line.

If you work from home or have critical services like alarm systems, we recommend adding a backup internet connection.

🥈 Backup connectivity options #

  • 2nd fibre line – 1st prize, but more expensive, check coverage in your area
  • GSM / LTE router – cost-effective, wide coverage, but needs monitoring
  • Fixed LTE – fixed monthly cost, check coverage in your area
  • WISP / FWA – fixed monthly cost, check coverage in your area

⚙️ Hardware required #

You’ll need to get a router that has more than one WAN port and can detect a failure on the primary WAN port. The router will then switch over to the backup link and also switch back to the primary link once that’s available again. Please email our support team if you need advice on a router which supports a backup link.

💸 Cost #

Expect to pay about R2000 for the hardware and about R700/m for the backup link. There are less expensive options. Keep in mind that if you choose a service which is billed per MB – you could run up a big bill or quickly run out of data on a SIM card.

⏱️ Monitoring and Notifications #

If you use a service that does not have a fixed monthly fee (cost per MB), we suggest enabling monitoring and notifications. Routers can often warn you when they are running on the backup link. Have a look at:

SIM Control: https://simcontrol.co.za/pricing

🚦 Static IP(s) when the primary link fails #

If you are hosting services on your side of the fibre line and you have static IPs, you probably need a VPN on SD-WAN solution to keep your IPs on the internet when your primary link goes down.

You’ll need a router on the datacentre side of your two fibre lines. This can be a virtual machine or a physical router. You can then run something like a Wireguard tunnel or an SD-WAN solution from a company like UI.com, Meraki or Fusion (local).

Example: You have a static /29 of IP space from Atomic and you have two fibre lines from different fibre networks. When the primary link fails, the /29 still gets routed to your office via the backup fibre line.

The above solution gives you fibre line redundancy, but the /29 is not portable IP space, so both fibre lines need to connect to one ISP. You can also look at BGP multi-homing solutions using multiple ISPs, but you will need your own IP address space. Keep in mind, running tunnels adds complexity and you may not have the usual 1500 Byte MTU on your fibre service.