Assessing the benefits to Sri Lanka of direct connection to SEA-ME-WE 5

Posted on September 27, 2014  /  1 Comments

All these years Sri Lanka was connected to its main international communication conduits (SEA-ME-WE 2, 3 and 4) from Colombo and Mount Lavinia (a suburb of Colombo) over branch cables. In the case of SEA-ME-WE 5, the new consortium cable that is expected to come online in 2016, the connection will be direct, in that the Alcatel built cable will terminate in Brown’s Hill in Matara (close to the southernmost point of Sri Lanka) and the eastern component to be built by NEC will commence from the same location.

This will shave off several milliseconds from the delivered latency partly because of the use of superior regenerators and partly because of the reduced distance. This is what Wikipedia says:

Latency is largely a function of the speed of light, which is 299,792,458 meters/second in vacuum. This would equate to a latency of 3.33 microseconds for every kilometer of path length. The index of refraction of most fibre optic cables is about 1.5, meaning that light travels about 1.5 times as fast in a vacuum as it does in the cable. This works out to about 4.9 µs of latency for every kilometer. In shorter metro networks, the latency performance rises a bit more due to building risers and cross-connects and can bring the latency as high as 5 µs per kilometer.

It follows that to calculate latency of a connection, one has to know the distance traveled by the fibre, which is rarely a straight line, since it has to traverse geographic contours and obstacles, such as roads and railway tracks, as well as other rights-of-way. Due to imperfections in the fibre, light degrades as it is transmitted through it. For distances of greater than 100 kilometers, either amplifiers or regenerators need to be deployed. Passive amplifiers typically add less latency than regenerators, at the cost of compounding attenuation, though in both cases it can be highly variable, and so needs to be taken into account. In particular, legacy spans are more likely to make use of higher latency regenerators.

The question is whether the new cable will deliver measurable benefits to the IT and BPM industries (other than those not located in Matara) and whether there will be noticeable improvements in broadband quality of service experience. We will provide some answers in the coming weeks.

1 Comment