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Sustained Badwidth Usage

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by aaron_wurthmann

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So I am moving my own personal Exchange server into a collocation facility.

The colo has given me several quotes (and yeah I have collected from several vendors) these quotes have limits on sustained bandwidth use. What I think that means is thatif I suck up more bandwidth than allocated I will be charged extra. So lets say they give me 1Mbps sustained and it is burstable to 10Mbps, lets say for what ever reason be it huge data transfer what ever I use 5Mbps for a short period. From what I read I am going to be charged for that, and trust me the penalties are scary.

So.. two questions.

1) How can I monitor or take an average of how much bandwidth I actually use on this a system? I assume there is something in preffmon, what I am looking for are basically the average bandwidth used over a few days.

2) Is it possible to limit the systems' NIC speed or how much bandwidth can be used. Like for example if I tell the card to do half duplex, only in this case I would actually want to tell the card to do like quarter duplex. (YES I KNOW TERRE IS NOT QUARTER DUPLEX, it is kinda a joke, but I think the analogy still holds). I need to limit the possible bandwidth to like 1 Mbps.

8 replies

by aaron_wurthmann

I think you mis-read my question. I am not trying to see how much bandwidth is available to me. I know the answer to that. I am trying to see how much is being used by my system. So lets say right now on my XP system I am using 1% according to the network monitor of the 100Mbps available, that would be 1 MB. Of course I am not using 1%, the networking monitor does not tell me anything lower than 1% and.. oh wait I think I answered my own question.. I need to install netmon on my system then usepreffmon.

by timwalsh

Aaron, there may not be any real need for concern. You mention that it is "personal" Exchange server. What else is it being used for? How many people are using this Exchange server? I hope you realize that your allowable sustained bandwidth is two thirds of a T-1 line.

In perfmon, you want to add a counters for the network interface performance object. You can add counters for bytes received/sec, bytes sent/sec, and total bytes/sec (combination of the first two).

None of the NICs that I have experience with have a capability of throttling bandwidth. You might want to check with the vendor and tell them you don't want/need burstable and just throttle your bandwidth (if possible) at 1Mbps.

Hope this helps.

by aaron_wurthmann

Preffmon does the trick. It compiles an average as well so that I can get some understanding of what exposure is. Now of course I need a way to run preffmon after I log out of a the system but that is another question.
*see below for other comments*

by aaron_wurthmann

Comment for Answer 2, Tim,

Actually they quoted me 256 Kbps. There will will be half a dozen users using Outlook Web Access with SSL as their primary way of checking e-mail. I will admin the system with Terminal Service and ftp. There will be several applications on the system including FW, Vscan, etc that require regular updates, not to mention Windows updates. I can set the updates to check at night when no one else is on the system.

I'll run preffmon with those counters and see what I am using currently.

What scares me of curers is the whole penalty if I go over 256Kbs idea.

by oldefar

I am curious as to the colo definition of sustained use and bursting. On the LAN, you will always clock out at 100% of the media speed.

MS OS has no directly configurable throttle for the NIC, although Linux has. This creates a problem based onthe colo accounting method. You can add a router at your LAN port and use its capabilities to throttle what you pass on to the colo systems. A performance issue comes into play since once you max the router buffers, packets are discarded.

The colo time period for accounting is important since if the time duration is large enough, you may have no concern. Too small, and you will be either idle or in violation of your rate.

by aaron_wurthmann

Correct there is no way in Windows to do it natively. There are some third party apps that do it and I could do it with a Cisco router and or a BSD or Linux router as well. But I think you hit the nail on the head. What is sustained usage? I looked at a few Colo's web site and near as I can tell what they all do is take a 5 minute sampling of the bandwidth being used. At the end of the month they compile this sampling and if it is 95% over 256 Kbps or about 500 Kbps then I am charged. So far the highest the average has gotten on my test system that has more users and more exposure than my personnel one will ever have has has gotten to an average of 100 kbps.

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