Source: Comms Business July 2011
One of the advantages of the new MSANs (Multi-Service Access Nodes) carriers are installing to replace the old DSLAMs (Digital Subscriber Line Access Multiplexors) is that as the name suggests they can be used to supply more than just DSL to the end user. The same pair of copper wires can be used for voice or, the focus of this article, Ethernet. As with DSL the speed of the Ethernet circuit delivered to an end user depends on their distance from the exchange however unlike DSL, copper wires can be ‘bonded’ at the exchange to improve both the speed and resilience of the service.
EFM (Ethernet First Mile) is generally preferred to DSL because it is symmetrical, un-contended, more reliable and has a better SLA. Also when sold as part of an MPLS network many suppliers will offer QoS (Quality of Service) over EFM but not over DSL. BT Wholesale (BTW) and Talk Talk Business (TTB) probably have the largest numbers of POPs (Points of Presence) in the UK with BTW launching their product early in 2010 and TTB in March this year. Although both products use essentially the same technology there are differences in the range of speeds offered, coverage and SLAs. See below;
|SLA||7 hours||6 hours|
|Copper pairs||1 to 8 pair options||2 or 4 pair option|
|Lead time||From 25 working days||From 25 working days|
|EFM footprint ||1080 exchanges built to deploy EFM||1900+ exchanges EFM and Ethernet enabled now, with additional 700 exchanges being deployed|
|Live exchanges (@ 1/6/2011)||720||200+ exchanges on 25 day lead time, 1100+ available with 45 day lead time, 600 + on 70/90 day lead time|
To simplify the proposition and the pricing TTB have opted to stick with the ‘up to’ method of describing the speed the end user can expect to enjoy, historically used for broadband. Essentially if you buy the 2-pair product you get up to 10Mb Ethernet and if you buy the 4-pair product this improves to ‘up to’ 20Mb. BTW on the other hand try and determine the exact speed the end user will get before the order is placed and price accordingly. This makes it difficult to directly compare pricing between the two for all the different available speeds. When I looked at the last 20, 10Mbit/s EFM quotes we had done for Griffin Partners TTB came out around 60% cheaper on rental. Both BTW and TTB have ambitious plans for EFM and they expect to roll out hundreds more exchanges over the next few months. Other networks like O² and C&W that have similar equipment in exchanges are bound to follow which can only be good news for resellers that want a wider choice and lower prices.
Due to the fact that it uses multiple copper pairs, EFM is considered by some to be more reliable than DSL, and even fibre Ethernet. If one pair fails the circuit will usually stay up, albeit at a reduced speed whereas with DSL and fibre Ethernet if the single copper pair or fibre develops a fault the circuit is usually inoperable.
EFM may be the technology that the Cloud evangelists have been waiting for. SMEs are hesitant about moving their applications and data into a remote data centre if they have to sacrifice their 100Mb LAN for a best-effort, contended DSL circuit between them and their supplier. EFM offers a better alternative for around the price of an SDSL circuit.