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Intrigue Surrounds SMW4 Cut


It has been a rough few weeks for the global Internet, given numerous submarine cable failures and the largest DDOS attack ever reported. While we’re hard-pressed to find evidence of the purported global Internet slowdown due to the DDOS attack, the dramatic impacts of yesterday’s SMW4 submarine cable cut were profound. Recent reports that the cable break was the result of sabotage make the incident even more intriguing. In this blog, we detail what happened to some of the providers in four countries along the route of the cable: Egypt, Saudi Arabia, Pakistan and India.

Impacts of the loss of SeaMeWe-4

This month’s submarine cable outages have profoundly degraded connectivity to the Middle East, Asia and Africa. In particular, last week’s EASSy and SEACOM outages wiped out connectivity in parts of East Africa from Djibouti to South Africa. As if that weren’t bad enough, the biggest submarine cable connecting Europe and Asia, SeaMeWe-4, suffered a failure at 6:20 UTC, 27 March.

Later in the day, the Egyptian Naval forces claimed that they had caught divers sabotaging a submarine cable off the coast of Alexandria, Egypt. In any event, SMW4 clearly suffered a major failure, and as we will see below, caused widespread disruption of Internet services from Egypt to Pakistan.

These plots of latency measurements below show that westbound transit to Europe for many of these providers was either degraded or unavailable due to the SMW4 cut off the coast of Alexandria, Egypt. These providers fell back on eastbound transit through the Far East, but these backup paths weren’t always up to carrying the load.


Immediately following the cut (marked with a red line), Egyptian incumbent, Telecom Egypt, experienced a brief disruption in Internet transit followed by a reshuffling of its transit providers as it lost service from Level3 and NTT.

8452latencies_Frankfurt_bgp02.fra1_s.png 8452latencies_SG_vps01.sin1_s.png

The loss of service from Level3 and NTT and gain of eastbound providers Bharti and Singapore Telecom (SingTel) is much clearer when the same data is viewed as a stacked graph of counts of traceroutes crossing through various providers into TE’s network:


Saudi Arabia

Saudi Arabian incumbent, Saudi Telecom (STC), experienced dramatic increases in latencies to Europe as traffic shifted away from the severed submarine cable.

39386latencies_Amsterdam_vps01.ams2_s.png 39386latencies_LAX_bgp02.lax1_s.png

Headed the other direction from Saudi Arabia to Hong Kong, the cut caused STC to reshuffle its transit, but without the dramatic rises in latencies.

39386latencies_HKG_vps01.hkg1_s.png 39386latencies_SG_vps01.sin1_s.png

UAE (added 2 April)

As was the case with other Middle Eastern providers, Etisalat experienced a dramatic shift in traffic from Europe and the west, but less so from the east.

8966latencies_AMS_vps01.ams2_s.png 8966latencies_LAX_bgp01.lax1_s.png
8966latencies_FRA_bgp02-1.fra1_s.png 8966latencies_HKG_vps01.hkg1_s.png

Emirates Integrated Telecommunications Company also known by its retail name, “Du”, appears to have weathered the cable cut without significant disruptions to either the west or the east.

15802latencies_LHR_bgp02.lhr1_s.png 15802latencies_AMS_vps01.ams2_s.png
15802latencies_HKG_vps01-1.hkg1_s.png 15802latencies_LAX_bgp01.lax1_s.png


The impact of the SMW4 cut on the Pakistani Internet has been severe, as reported by the Pakistani media.

Pakistani incumbent, PTCL, was already struggling due to the recent loss of another major submarine cable. The graph on the left shows that latencies from Frankfurt to PTCL went through the roof as traffic was re-routed around the world to get to Pakistan. From Singapore, (on the right) there was a minor disturbance, but not nearly as crippling as for westbound traffic.

45595latencies_Frankfurt_bgp02.fra1_s.png 45595latencies_SG_vps01.sin1_s.png

For Pakistan’s other international gateway, Transworld, the impacts were severe when connecting to both the west and the east.

38193latencies_NYC_vps01.nyc1_s.png 38193latencies_HKG_vps01.hkg1_s.png


With the loss of SMW4, India-based Bharti lost its main route to the west. Delays for Internet traffic coming from western Europe spiked. From the east, things were fine.

9498latencies_Frankfurt_bgp02.fra1_s.png 9498latencies_HKG_vps01.hkg1_s.png

Like Bharti, Vodafone India experienced dramatic increases in latencies for connections to and through Europe.

55410latencies_Frankfurt_bgp02.fra1_s.png 55410latencies_London_bgp02.lhr1_s.png

When connecting through the East, Vodafone India was largely stable. In fact, from Los Angeles, latencies improved slightly as traffic from LA was allowed to go a slightly shorter (and presumably more expensive) path across the Pacific Ocean instead of the Atlantic to get to India.

55410latencies_HKG_vps01.hkg1_s.png 55410latencies_LAX_bgp02.lax1_s.png


For me, one of the takeaways from the above analysis is that many of these providers have carefully engineered geographic diversity into their submarine cable strategy. However, the backup paths don’t always deliver relief. In Pakistan, for example, the loss of westbound transit has virtually crippled the Internet despite the fact that eastbound routes stayed up. It is almost the mirror image of the impact on Bangladesh in last year’s SMW4 cable cut near Singapore. In that case, Bangladesh lost eastbound transit due to the cable cut and the westbound backup just didn’t have the bandwidth to handle the load, leaving the country essentially cut off.

Finally, I’ll be giving a talk next month in Paris about visualizing the impacts of submarine cable breaks such as yesterday’s SMW4 cut at Suboptic 2013, the world’s largest conference about the submarine cable business. We obviously have a lot more to discuss now as an industry. If you are attending, please stop by and introduce yourself.

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Doug Madory
Whois: Doug Madory

Doug Madory is a Director of Internet Analysis at Oracle Dyn where he works on Internet infrastructure analysis projects. Doug has a special interest in mapping the logical Internet to the physical lines that connect it together, with a focus on submarine cables.