MegaStream Ethernet uses an ATM core network for the secure transport of the data between your sites. Connection between your site NTE and the BT Node is via optical fibre.

Core network bandwidth is configured such that the ATM PVCs carrying the MegaStream Ethernet circuits ensure your bandwidth is guaranteed with the ATM PCR set to the same value as the SCR. The value of the ATM PVC bandwidth shall be greater than the chosen Ethernet circuit bandwidth to account for ATM overheads.

If your traffic exceeds the ordered value of the MegaStream Ethernet circuit bandwidth then the frames will be stored in ingress buffers until they can be put to line or will be discarded if the buffers are full. This will cause increased latency and traffic discards. We recommend traffic shaping by your CPE.

The MegaStream Ethernet service has been designed so that the end-to-end latency does not exceed 30ms with some typical latencies as shown below:

Route

Distance

Typical latency

London - London

30km

12ms

London - Birmingham/Bristol

250km

17ms

London - Manchester

320km

17ms

London - Edinburgh

640km

19ms

London - Londonderry

750km

22ms

London - Inverness

940km

22ms

 
 

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