Archived from groups: comp.dcom.lans.ethernet (
More info?)
In article <ctllao$jqq$1@panix5.panix.com>, Al Dykes <adykes@panix.com> wrote:
:In article <3670g5F4uacnkU1@individual.net>,
:jpd <read_the_sig@do.not.spam.it.invalid> wrote:
:>Begin <ctj55g$9tj$1@canopus.cc.umanitoba.ca>
:>On 2005-01-30, Walter Roberson <roberson@ibd.nrc-cnrc.gc.ca> wrote:
:>> There is, though, one user on one port of one of the switches who
:>> is producing more data than the rest of the users combined: that one
:>> user should have a gigabit port and gigabit backbone to the server.
:>I'd start with putting him on netnanny or something suitably annoying
:>to see if that doesn't reduce the traffic to something reasonable.
As the OP of that statement, I can say that it would not be an
appropriate solution to the situation.
:How are you measuring your network ?
Well, since you ask, I have Fluke's Network Inspector monitoring
all of the switches and producing 5-minute trend graphs. I also
sometimes turn on MRTG and watch the graphs for awhile. More often
though, I record the packet counters and examine the packet volumes
along the various links, cross-correlating from each end of the
link to avoid making mistakes.
:You've got to give us more information before I'll say that your
:requirement exceeds a plain 100Mb full duplex switched network. It's
:a no-braiener to make the server-switch connection a Gbe interface,
:but beyond that you need to do some work to understand what your
:bottleneck is. The physical plant has lots to do with the design. If
:you're in one building with a few floors then pulling a run from the
:main equipment room to a switch on each floor gives you a colapsed
:backbone for not a lot of money.
We have a building with 4 floors and two "wings", with a traditional
star topology to a basement LAN router. One of the two wings is
within the 100 meter copper limit, but due to the way the cross-connect
between the wings run, the switches in the other wing are near or
exceed the 100 m limit, so those have fibre to the core router.
Fibre was also installed on the other side for future expansion, with
all the fibre terminating in that basement room.
ulling fibre is a no-brainer and
:100Mb to each floor may be enough and save the price of a an expensive
:Gbe switch in the center, but a couple years from now when you need it
:it will be an easy upgrade path, and cheaper.
Our measurements show we need the "expensive Gbe switch" anyhow, in
order to keep up with our backups -- we've just gone from ~ 1 TB
of storage to ~12 TB of storage capacity [not all used yet!!]
The question was whether it would be best to install a managed gigabit
switch in the wing where only one user is producing a great amount
of data. Our conclusion was that it would be cheaper to pull
copper [and fibre too since most of the cost is in the labour
of putting the cables into the trays] over to our mini-NOC where
we intend the new core router to live.
:"more traffic than the rest of the network, combined" is meaingless
:for the purposes of this discussion
I didn't say "than the rest of the network combined", I said
"than the rest of the users combined". There's a difference.
:unless you give us numbers.
The one user produces ~50 gigabytes per day, usually 6 days a week,
250-350 Gb per week total. Assuming 50% transfer efficiency
[allowing for overheads and architectural limitations as you
get towards gigabit], that is half a working day of continuous
data transfer at 100 Mb/s. By way of comparison, all of our other
servers combined [other than the one the above user data is stored on]
backed up this morning into 437 Gb of tape. If you need more exact
numbers, such as number of packets and bytes transfered per port, then
I can supply several months worth of that information in ~5 minute
increments, but it would be a bit of a nuisance to extract it in
detail out of the database it is in.
Personally though, I don't think it'd be productive to dig up the
details. I monitored the system carefully before making decisions
about which portions needed upgrading and which did not. You should not,
though, neglect the influence of power politics: if my measurements show
that an entire subdepartment could easily fit into 10 Mb/s whilst
a different subdepartment is overflowing 100 Mb/s, the first
subdepartment will tend to feel that it is owed a network upgrade
when the second gets one...
:also suggests that that you have a small # of machines since the
:larger the base the harder it is for one machine to exceed the
:aggregate unless he's very different, such as the only diskless
:workstation, or does daily full backups to the servfer.
Look@Lan tells me I have 324 different devices intermittantly on the
network. Over 600 devices are assign IP addresses, but they
don't all necessarily get used in the same month. We probably
average close to 4 networked devices per person.
:It would be worth the time to see if he's got a virus or spyware.
:Then you should try to understand his business and what makes him
:special.
You ass-u-me'd that I don't understand his business and what makes him
special. I have a fairly good idea of what makes him special.
:I would, before I asked for the money got Gbe. If the
:netowrk connection isn't his bottleneck then there is no reason to
:spend money on him.
:A desktop machine generating enough data for a 100MB/sec net
:connection to be a bottleneck is a rare thing in business.
Again you have ass-u-me'd. You failed to look at my email address
and take a step such as visiting our web site. We aren't -in-
business: we are public sector biomedical research.
For what it's worth, the user is involved in Proteomics and is,
if I recall correctly, doing automated DNA sequence analysis.
The rate of data production swamps our previous high-point
of projects having to do with Functional Imaging of the Brain
in MRI machines, a typical run of which was only 1/2 Gb.
--
I don't know if there's destiny,
but there's a decision! -- Wim Wenders (WoD)
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