Any networking guru's out there?

[original PM]

Hi All,

I have a query which i am hoping someone can help me with.

One of our outllying locations has a 2MB IP clear line running into it.

It uses this line to connect to our companies central storage and LAN.

It seems that the max usage on that line only seems to get to about only seems to peak at about 1.0 Mbps yet given that some large files are pulled across this part of the network and so when this happens we would expect to see the line being maxed out.

So the questions really are

1) Am I getting my MB and Mb's mixed up?
2) What else within a LAN can slow down the network (switches??)
3) Would disk access speed potentially mean that the data cannot get off the disk quick enough to max out the line?
4) Anything else anyone can add which may be of use!

Thanks in advance

[TestMangler]

Christ Almighty. A possesive apostrophe in gurus ? Why ???????

[v8gaz]

Which variant of IP CLear is it? It's sometimes delivered over ADSL, and that version typically has a 5:1 contention. Also, check that BT havent billed you for 2Mb and only supplied 1Mb. It happens.

[doodab]

Telecoms providers usually work in megabits per second, so it's probably 2mbit/s, unless it's 16mbit/s.

What protocol are you using for the file transfers? SMB / CIFS (windows file sharing protocol) and wide area networks are very uncomfortable bedfellows in my experience. It's very latency sensitive. Actually a lot of everyday protocols designed for LANs are worse than useless over higher latency WAN links.

[petergriffin]

It seems that the max usage on that line only seems to get to about only seems to peak at about 1.0 Mbps

How did you get to that figure? How far is the location from the exchange?

Is the speed you mention for downloads or uploads? ADSL means asymmetric, that is the supposed 2 Mbps is only when you download a file not when you upload it. If you need to frequently synchronize files between sites you need SDSL not ADSL.

[wxman]

When you say a 2Mb clear line - what actually is it?

Can you provide any more details?

[doodab]

When you say a 2Mb clear line - what actually is it?

Can you provide any more details?

It's an IP over MPLS service. Individual sites use ethernet, ADSL or leased line to access the network.

[original PM]

Hi All,

Cheers for the replies so far.

The only other info I have is that when doing a speed test (using one of the speedtest websites) it gives me about 1.87 MB for both uploads and downloads.

Probably a bit misleading when I say file transfers - what I mean is opening a file (such as word or excel) at the outlying location when the file is stored in the datacentres as opposed to an actual file transfer using ftp etc.

When I am within the LAN the time taken to open the file is small it is only when using the WAN that we have a large increase in time taken to open the file - obviously I would expect that because within the LAN I think we have 1 GIG backbone(?) but the link to the outlying site is as about 2MB - however the tests never seem to show the peak loading being above 100 mb/s - now I would expect when large file transfers are taking place for this to be maxing out - but it is not!

Does any of this help?

(oh apologies for the apostrophe - completely unforgivable!)

Cheers

[doodab]

Hi All,

Cheers for the replies so far.

The only other info I have is that when doing a speed test (using one of the speedtest websites) it gives me about 1.87 MB for both uploads and downloads.

Probably a bit misleading when I say file transfers - what I mean is opening a file (such as word or excel) at the outlying location when the file is stored in the datacentres as opposed to an actual file transfer using ftp etc.

When I am within the LAN the time taken to open the file is small it is only when using the WAN that we have a large increase in time taken to open the file - obviously I would expect that because within the LAN I think we have 1 GIG backbone(?) but the link to the outlying site is as about 2MB - however the tests never seem to show the peak loading being above 100 mb/s - now I would expect when large file transfers are taking place for this to be maxing out - but it is not!

Does any of this help?

(oh apologies for the apostrophe - completely unforgivable!)

Cheers

Yes. It's the latency. The underlying protocol that Windows file sharing uses is very latency sensitive because it does a lot of requests and responses and it waits for a response before sending another request. Iirc it does this for every 64k of data in a file as well as when fetching metadata etc. So if your latency is 20ms it will take 40ms to transfer each 64k however much bandwidth you have.

Version 2 is supposed to be better but you need a modern client and server OS to use it i.e. server 2008 and Vista or 7.

[original PM]

cheers doodab much appreicated.