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)…
I couldn’t find this exact info on the net anywhere.
-Drew
the directions are independent.
are you sure when you run the line at 100% in one direction you're not either a)
returning the ping/traffic down the congested DS3 or b) disrupting control
traffic - ospf, keepalives etc that is upsetting the link
Steve
Date: Tue, 6 Jul 2004 11:42:32 -0400
From: Drew Weaver
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)..
No no no. DSx circuits are full duplex.
Eddy
when you measure utilization X by five minute samples, it is highly
likely that it bursts at least 30% above that, or at least tries
to.
randy
[...]
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.
Date: Tue, 6 Jul 2004 17:43:24 +0000 (UTC)
From: Peter Corlett
The underlying link should be doing both 45Mb/s in and 45Mb/s
out at the same time.
Errr? Most providers can only dream of 1:1 ratios.
Eddy
> Date: Tue, 6 Jul 2004 17:43:24 +0000 (UTC)
> From: Peter Corlett> The underlying link should be doing both 45Mb/s in and 45Mb/s
> out at the same time.Errr? Most providers can only dream of 1:1 ratios.
I interpret this as the SDH will run as 45Mb in both directions.. you're talking
about peering?
Steve
I meant the underlying circuit itself. Much like my telephone line
does 64k each way in both directions, but it doesn't mean I'm chatting
away on it constantly 
: 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)..
:
: I couldn't find this exact info on the net anywhere.
Anyone happen to know of where TTC's online library went a few years ago
after they merged with someone? (I've forgotten whom) There was a great
deal on T1s, T3s, etc. I have hard copies at home, but it'd sure be nice
to get some online copies, if they still exist.
scott
No no no. DSx circuits are full duplex.
^ usually
Date: Tue, 6 Jul 2004 15:59:10 -0700
From: Randy Bush
> No no no. DSx circuits are full duplex.
^ usually
True. I meant to state that TX traffic doesn't come at the
expense of RX traffic, and that a talker needn't wait to ensure
the other end is listening.
Eddy
Date: Tue, 6 Jul 2004 16:25:28 +0100 (BST)
From: Stephen J. Wilcox
> We have 1 DS-3, that if we get close to 45Mbps IN/OUT
> the other direction will be completely unusable.
Calculated on what time interval? If that's a five-minute
average, you probably have some serious backpressure spikes that
you're missing. (Are you running xRED to get traffic to back
off?)
are you sure when you run the line at 100% in one direction
you're not either a) returning the ping/traffic down the
congested DS3 or b) disrupting control traffic - ospf,
keepalives etc that is upsetting the link
How about less exotic things... like ACKs? 
Or perhaps DNS
resolution is slow. I don't know exactly what the problem is, as
a "my Internet isn't working" post is rather vague. 
At any rate, this thread probably fits better on isp-bandwidth,
perhaps isp-tech... maybe even i-a. Posting to list just in case
there are lurkers who didn't know, but the other lists are more
fitting for questions like this.
Eddy