Quick circuit question.

Tue Jul 6 17:43:24 UTC 2004

Drew Weaver <drew.weaver at thenap.com> wrote:
[...]
> We have 1 DS-3, that if we get close to 45Mbps IN/OUT the other
> direction will be completely unusable. We have another DS3, that we
> have seen doing 45Mbps IN, and 15Mbps Out at the same time. This is
> going to sound dumb, but is duplex a consideration with lines of
> these types? I thought you could do either 45Mbps in, 45Mbps out, or
> a mix of both, not 45Mbps In, and 45Mbps out at the same time
> (90mbps)..

The underlying link should be doing both 45Mb/s in and 45Mb/s out at
the same time. However, with TCP/IP, if the downstream (say) link is
so saturated with downloads that the acknowledgements to uploads are
heavily delayed or lost, this can cause uploads to be throttled.

The extent to which this occurs depends on all sorts of factors, such
as the TCP stacks on the hosts at either end, the routers on the link,
and whatnot.

-- 
Another tradition is to soak the pudding in brandy and then set fire to it.
One year we couldn't find any brandy so we used whisky. This produced a
flame which scorched the ceiling above the table.
					-- Edward Pierce in the Monastery