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Network Running Slow

Posted on 2009-05-01
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Hi

We have 4 sites here connected by an mpls network managed by a third party supplier.

2 of these sites are identical in terms of amount of users, speed of connection and servers they have to connect to remotely.

However one of the sites is particularly slow, ping runs at the same speed across both the sites, (29ms - 35ms) with no packet loss. However windows share and telnet sessions are very slow at one of the sites.

On reporting this to the third party supplier in typical fashion they have said the line is fine and it is a local issue. Yet no of the other sites are experiencing this, and the servers local to the site are functioning fine. In my mind this proves the issue is with the line, maybe due to something happening locally but this is where the bottleneck is.

I have a feeling something may be using all the bandwidth that shouldn't be, so my question is

Is there some way i can view which IP is using the most bandwidth? I have access to the public snmp strings for the routers (cisco's), I also have remote access to all the computers on the site, i am fairly new to this but could wireshark or a similar product tell me this information?

Thanks




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Question by:marky1984
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by:Roachy1979
ID: 24277839
If you believe the problem to be with the supplier, you could use iPerf to measure the actual throughput on the line.  (http://sourceforge.net/projects/iperf).  You install at both sides and it measures throughput point-to-point.

Wireshark will tell you what protocols are being used - so if for example something obvious (bittorrent, for example) is eating bandwidth this will be a good test.  

You could also implement nTop to give you a breakdown of protocols and usage....http://www.ntop.org/overview.html

MRTG is also worth running so you can see the network utilisation on the routers....http://oss.oetiker.ch/mrtg/index.en.html

Does this help?  If you need any more information, just ask!
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by:marky1984
ID: 24277982
What a great answer, thanks

Will have a play with these tools over the next few days.

Had an engineer ring me back just now, he blamed my switches at the site, granted they are very old netgears but they should really be ok. Annoying the sites around 100miles away so i can't just pop over.

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by:Roachy1979
ID: 24278031
No worries....i tend to find there isn't a 1 stop shop for troubleshooting performance issues....but the links above are a pretty comprehensive toolkit that should give some indication as to the cause of the problems.

For persistent monitoring of sites and alerting I also use Nagios, which will email when faults arise - if you are working with WAN's this is really useful to capture data as it happens (rather than trying to diagnose on the basis of users saying "it seems a bit slow").

Let me know how you get on or if you need any advice setting any of these up (a little linux knowledge may help with this - although you don't need to be a guru, just a little familiar with the command line)...
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by:marky1984
ID: 24278051
i hadn't actually checked the links yet but there linux tools then

no problems, i've never used linux before but the command line can't be more difficult then the exchange cmdlet :P
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by:Roachy1979
ID: 24278136
Wireshark runs in windows and linux....but they are mostly *nix tools, yes. There are some good tutorials out there though, and I'm happy to walk you through getting set up.

If you have a spare machine you can install a linux distro on (it doesn't need to be high end at all) then I'd recommend CentOS, Ubuntu or Fedora as  free distros that you'll be up and running with in no time.

Most of the above are in the repositories for the distributions and can be installed using

yum install packagename(on Centos/Fedora)

or

apt-get install packagename (on Ubuntu)

To edit the config files you can easily do this using nano (at the command line) or a text editor within the gui....

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by:marky1984
ID: 24279030
No worries, thanks very much. I am actually looking forward to getting into this. An area i feel i am some what lacking in if i'm honest.

I got an old p4 box at home so will stick it on there over the weekend and get back to you after bank holiday

I have used ubuntu very briefly before, is there any one you'd choose over the others?



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by:Roachy1979
ID: 24280002
Personally I use Fedora 10 on desktops and notebooks.....I've used Ubuntu before though and it's also good.  Both distributions try to be quite "bleeding edge" though so occasionally you find that packages have been updated before they are mature.  

If it's a box that's going to be running for some time or will be mission critical, go for a long term support version of Ubuntu or CentOS unless you see snazzy new features in the release notes of Fedora or the latest version of Ubuntu that you'd really benefit from.

One point to note is that quality advice on the Ubuntu forums seems to have thinned out a little - with the vast number of users good advice has become a little diluted.  The Fedora and CentOS forums are first class though.  

With any distribution there's a learning curve but Fedora and Ubuntu definitely make a great deal of effort to be user friendly.....

If you have any questions outside the context of this thread over the course of the bank holiday, drop me a mail (contact details in my profile) and I'll advise if I can :)







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by:marky1984
ID: 24280038
you are a star pal, fedora it is

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by:Roachy1979
ID: 24280329
No problem :)

Will you be wanting to do anything with this box other than network testing for the meantime?  If you want multimedia support, dvd playback, flash, etc one of the guys from the Fedora forum has written a handy app that does it all for you....http://dnmouse.org/autoten.html

If not then don't worry about it - on an out-of-the-box install it's straightforward to  install ntop, wireshark, mrtg, etc easily....

dive into a terminal and :

su
yum update
yum install ntop wireshark nagios mrtg iperf
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by:Roachy1979
ID: 24280352
then there's just the minefield that's configuring the apps, but let me know if there are any sticking points as each application has good documentation, and if you're feeling particularly confident, then the man pages for each app can be read by going to

man appname

at the command line :)
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by:diepes
ID: 24285408
my 2c.  If you are installing to a laptop, Ubuntu is brilliant, they have really take the Linux world by storm, by focusing on ease of use and a 6month release cycle.  There motto "Linux for real people"

1. as to the problem, normally on a mpls network the provider provides different classes of service.
I would check with them if this is the case and how they classify the traffic.

2. Have you asked your provider to provide you with detailed statistics on top IP users etc. ?

3. What it the traffic flow ? Is it mostly from a central site to and from the other 3 sites ?
       - If the main servers are central, you should be able to span a port on the central site and using Linux tools determine where the most traffic comes from.  Tools: Wireshark/Etherape
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by:marky1984
ID: 24285486
any input is appreciated, thanks

1. I'm not to sure what you mean, are you talking about prioritising certain traffic over others? like qos

2. Yeah i did ask them this, sadly the routers can't do this apparently. we used to have these compression devices called peribits that could do this perfectly. in the days gone by of outlook 2000 these were very handy.

3. Yeah you are pretty much right, i will check it out

thanks
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by:marky1984
ID: 24295080
now posting from fedora9!

on with the other bits on bobs
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Roachy1979 earned 2000 total points
ID: 24295100
Nice one :)

Welcome to the wonderful world of Linux....

Let me know how you get on with the other stuff!

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by:marky1984
ID: 24449869
Hi

Problem eventually solved, turned out to be a config problem in the suppliers network, but i wouldn't of been able to prove that without being able to prove that with above tools. I now have my lanserver monitoring constantly.

Thanks for the help

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by:Roachy1979
ID: 24451256
No worries Mark.... Glad you got it sorted!
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