welz400
05-18-03, 08:45 AM
Hi,
as a recent user/requester of help on this site, I have frequently said that my MTU is set at 1430, used to be 1458.
I have also said that it has been advised by users on the pipex support NG.
Anyway, I copied the following from one of the messages on that NG:
(This all refers to Pipex, not any other ISP:)
'The maximum raw speed is 576,000 bits/sec, but the AAL5 cell
overheads mean that there is only approx 521,660 bits/sec for
'data', including PPP, IP and TCP overheads. 521,660 bits/sec
is 65,208 bytes/sec, but after you take the PPP, IP and TCP
overheads into account this reduces to around 62,943 bytes/sec
for an MTU of 1390, and slightly less for an MTU of 1458 due
to the fact that IP packets plus PPP overheads will not fill
an an exact number of AAL5 cells.'
Cheers
as a recent user/requester of help on this site, I have frequently said that my MTU is set at 1430, used to be 1458.
I have also said that it has been advised by users on the pipex support NG.
Anyway, I copied the following from one of the messages on that NG:
(This all refers to Pipex, not any other ISP:)
'The maximum raw speed is 576,000 bits/sec, but the AAL5 cell
overheads mean that there is only approx 521,660 bits/sec for
'data', including PPP, IP and TCP overheads. 521,660 bits/sec
is 65,208 bytes/sec, but after you take the PPP, IP and TCP
overheads into account this reduces to around 62,943 bytes/sec
for an MTU of 1390, and slightly less for an MTU of 1458 due
to the fact that IP packets plus PPP overheads will not fill
an an exact number of AAL5 cells.'
Cheers