On Mon, 12 Sep 2005 13:07:11 GMT, "DanR" <dhr22@sorrynospm.com> wrote:

>Jeff, I want to make sure I understand your comments.
>>> Jeff... when you say "A T1 (DS1) is 1.544Mbits/sec. You'll get about
>>> 1.3Mbits/sec thruput in both directions." Does that mean that just one
>>> workstation at a time will see that throughput?
>>
>> No. The bandwidth is distributed roughly equally among the
>> workstations.

>Could the above sentence read "No. The bandwidth is distributed roughly equally
>among the workstations" that are at that moment sending / receiving on the
>Internet.
>In other words... the active workstations share the bandwidth. True? I think
>that is what you said below.

Yes, the active workstations share the bandwidth roughly equally.
Note that this is NOT true with wireless where the distribution varies
with the connection speed.

No, this does NOT mean that one workstation at a time will that
thruput as you previously stated.

>I'm really surprised to learn that a T1 Internet connection has these
>limitations.

You get what you pay for. In the past, it was assumed that a T1(DS1)
came with a superior level of support from the telcos. I still
remember one hour service from Pacific Bell. Now daze, T1 is just
another service and may just be a muxed channel off some telco fiber.
I actually get better service from my DSL lines than I do from the
T1's. The only real benefit of a T1 is the 1.5Mbits/sec outgoing
bandwidth, which cannot be easily supplied via DSL.

>Seems then that (except for upload) it's like having 50 or so
>computers on a home DSL Internet connection.

The conventional rule of thumb for loading is:
100 users doing light web browsing and email.
10 business users doing whatever business users do.
1 file sharing user.

>I would have thought that this
>would have been un-acceptable.

What is unacceptable? Only having 50 computers on a single T1?
Again, it depends on what those users are doing. By todays standards
of bloated and bandwidth hungry applications, a T1 is a small pipe.
If you would kindly dig out the sniffer and see what's moving on your
T1, you might have a better idea of whether you're dealing with a
capacity problem or an abuse problem.

For example, a customer calls me on Sunday morning (yawn) to ask why
their T1 is moving large amounts of traffic when there's nobody in the
office. This is a good question. I expected to find a virus, worm,
or hacker. Instead, I found that a clever user had found a program
that "synchronized" his files between his home computer and his office
machine. He had set it up incorrectly and it was "synchronizing" much
of the corporate server farm as well as gigabytes of junk on his
desktop. Eventually, it would have killed his home computer, but I
didn't want to wait. So, I dived into the managed ethernet switch,
pulled the virtual plug on his machine, and left a nasty voicemail
message. This type of nonsense happens all the time.

Another example. A while back, I noticed that the MRTG traffic graphs
showed that someone was downloading about 25Mbytes of something every
5 minutes. It was causing problems with VoIP traffic and streaming
content. It turned out to be Symantec Live Update trying to update
Norton Antivirus. One problem. Norton AntiVirus had been removed
from that machine, but not Live Update. It would merrily try to
update NAV, fail, and then try again in 5 minutes by downloading
everything over and over and over, etc.

Moral: You need to know what's moving on your network or you can't do
anything useful in the way of troubleshooting and capacity planning.

>My "thought" is not based on technical knowledge

Got it. Your thinking is based on emotion. I have a ladyfriend that
sometimes operates that way. The scarey part is that it often works.
There are books and classes to optimized intuition, crystal ball
gazing, Ouigi Boards, and pseudo science that may help with this way
to non-technical troubleshooting. I've often suspected that the
government also uses this method in their technical ventures.

>but I always assumed that a T1 was the ultimate way to go.

You can't afford the ultimate. At this time, an OC-192 at
9.6Gbits/sec symmetrical is about as fast as commonly available.
Korea has 10Mbit/sec consumer service. Most cable modems and some DSL
vendros will do 6Mbits/sec download and 512Kbits/sec upload. Desktops
will soon have 10Gigabit ethernet cards. Some crude numbers:
http://www.infobahn.com/research-information.htm

Incidentally, if *ONLY* incoming bandwidth is an issue, you might
wanna consider distributing the load. Get several DSL connections and
use one of these to manage the load:
http://www.edimax.com/html/english/p...-PRIrouter.htm
The DSL lines are MUCH cheaper than the T1. However, if your problem
is outgoing bandwidth, a load balancing router will do nothing.

>One more thing. At any given time during the work day we have about 20
>computers using instant messaging. Most of the time there is not traffic but the
>apps are always listening. Is that much of a load?

No load at all. Some IM clients (i.e. AIM) deliver advertising and
stupid videos which grab a small amount of bandwidth, but nothing
disgusting and nothing that's running all the time. However, if
people are using IM for file transfers, the bandwidth use might be
momentarily quite high.

>I am extremely grateful for the time you've spent providing all this good
>information. If we don't have to run all new cable your tip will save our
>company a lot of money and labor.

I still think you need someone with network troubleshooting experience
to impliment monitoring and traffic analysis. Render farms use LOTS
of bandwidth. My guess(tm) is that you're speed problem may be in an
unexpected area.


--
Jeff Liebermann jeffl@comix.santa-cruz.ca.us
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558