Iceland falls off the edge of the web

On Saturday night, Iceland lost much of its Internet connectivity after one of two submarine cables that serve landings on the island failed. Downstream customers including a major hospital, the national academic network and thousands of DSL users were affected by the outage.

International telecoms connectivity to Iceland is dependent on two links – either a spur of the CANTAT-3 cable from Newfoundland to the Faeroes and then on to Scandinavia or Scotland, which lands near Reykjavik, or else the FARICE-1 link from Scotland via the Faeroes to the east coast.

It was CANTAT-3 that dropped out, with the link failing entirely some 1,500 kilometres south-west of Iceland in 3,000 metres of water for reasons that remain unclear. Although Icelandic AS operators could reannounce their prefixes via FARICE, this meant that not only was the available bandwidth drastically reduced, but traffic to and from North America had to route via European ASNs (autonomous system numbers) – suboptimal to say the least, especially for transit to Asia that would normally have gone transpacific.

The fault seems to have occurred around 23.23 on Saturday, or at least that’s what the BGP (Border Gateway Protocol) updates would suggest.

It’s not the first time either – earlier this year, FARICE went down after the proverbial backhoe cut the overland portion of the link near Inverness. So far, the worst-case scenario of both cables being lost is yet to occur, although fingers are crossed until CANTAT-3 is operational once more.