[afnog] Channelising E1s

Mark Tinka mtinka at globaltransit.net
Tue Jul 8 10:35:36 UTC 2008

On Tuesday 08 July 2008 18:17:59 Bernard Wanyama wrote:

> Peter,
> If you are not constrained on serial capacity, go ahead
> and give the client 512Kbps at Layer 1/2, then you can
> provision the 256 up / 256 down at Layer 3 on the
> bandwidth manager.

But the customer has to pay for a 512Kbps leased line, yet 
he's purchasing 256Kbps of IP.

> That way, you will not have a bottleneck on the line.
> Fixing the bandwidth to 256Kbps on the line will subject
> the user to HDLC/PPP overhead (approx 6-8 Kbps per
> timeslot).

Granted, there is Layer 2 overhead; perhaps the first 
question we should have asked Peter is how much sustained 
throughput the customer can actually achieve.

> Mark,
> In UG, ISPs have the tendency of selling Internet
> bandwidth in a fashion like - 256Kbps down / 256Kbps up
> means 512Kbps.

Well, as ISP's, I think we should be the wiser. It's bad 
enough that customers contest bandwidth provisioning 
without having to explain to them that the total offered 
capacity is the summation of either direction.


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