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How to optimize LAN traffic

Hi Everyone,

I have a very bad problem of network congestion in my LAN, i am unable to understand how should i solved this problem, kindly find the attached diagram for your understandings.

We have two floor and all the users have internet access along with ip telephones.  We have a very basic flat setup and we also do not have Domain Controller and Email Server. Regarding restricting the urls and downloads i have no such requirements but i do not understand why there is huge congestion in the network. When i do a ping test to the directly connected router i have very bad time response(see the attached).

Kindly suggest me the best solutions.

Regards

@Mohammed 

9 REPLIES
New Member

From the images you sent, you

From the images you sent, you perhaps should include a bit more information, such as a speed test isolated to a computer connected directly to the WAN, how many VoIP phones, etc...

As a general overview, I would say you should first determine how many VoIP lines you have total, and determine how much bandwidth is needed to run all of them at the same time (like each line takes 200k per direction/ch and you have 10 lines... = 2000k min required per direction) then how much data you need for data, (email, IM, video etc...)

This would be the baseline for what you need for your WAN connection, also, you might want to consider running all of your traffic through a router, and enabling and tuning QoS on the upload side to maximize available performance. once that is done, perhaps dealing with securing the network...

 

Good Luck!

 

Seannon

Hi Seanon,I am sorry i did

Hi Seanon,


I am sorry i did not mention that the traffic of VOIP is for internal only, the outgoing goes through analog line connected to the PBX.

When i am connecting my laptop dierctly to the router i have very good ping response of 1ms and the speed is 5Mbps which is we have from ISP.

No. of IP Phones : 30

No. of Workstations : 40

Regards

@Mohammed

Hall of Fame Super Gold

I have no idea what else you

I have no idea what else you can do?  

 

The biggest hurdle you have are the unmanaged switches.  You just can't determine if you're getting STP loop, multi- or broadcast happening, etc.  

 

Another thing, when does this issue happen?  During office hours?  What happens during lunch break?  Does the ping time improve?   Where is this ping originating from?

 

If the ping time improves during lunch break (and gets worst during office hours), without going into much detail, I'd be increasing the bandwidth.  5 Mbps for 40 workstations is just ain't enough. 

 

 

Hi Leo,Yes you are right, i

Hi Leo,

Yes you are right, i am already planning to change these switch to Cisco 2960-X very soon.

This usually occurs during office hours only, when there are less users the ping rate is good and the ping is usually mixed not particularly from one user, but some times there is one user because of him we have a complete internet down, i think this is because there is some virus in his PC. We just then disconnect him from the network for sometime which is not the appropriate way of networking i must say.

Actually the bandwidth is enough but there are some users who are using RTSP all the time i am also preparing to block them using some tools.

Regards

@Mohammed

Super Bronze

DisclaimerThe Author of this

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

You might not have (overall) LAN congestion, but just a busy gateway router.  Network devices, give low priority to responding to pings, so some of your "latency" might be the router is "busy".  The router's LAN port, as it is the gateway for your whole LAN, might also be congested.

Have you tried pinging between a pair of otherwise inactive hosts when the gateway shows high ping latency?

Hi Joseph,Thanks for your

Hi Joseph,

Thanks for your reply, i think what you are saying might be true and yes if i am doing a ping for pair of devices the ping is great, as you said because the router is the gateway for all the device its getting busy. So what are the suggestions for the same ?

Regards

@Mohammed

Super Bronze

DisclaimerThe Author of this

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

It depends on what you're trying to accomplish.

Pinging the gateway IP tells you little about performance.  If fact, on some Cisco devices, they support a "special" responder to much more accurately report on access time to the device's interface vs. using a generic ping.  (NB: the special responder also requires a special sender.)

You didn't describe what model your WAN router is.  Even if your LAN switches are "dumb", maybe your WAN router isn't.  However, if it too is "dumb", then if pinging between other LAN hosts is good, again, you likely don't have a LAN problem.

You may have a WAN congestion problem, most often caused by the amount of bandwidth to/from the Internet.  Sometimes also caused by an "undersized" WAN router.  (The two are not mutually exclusive.)  Without a "smart" router, it will be difficult to analyze your actual situation.

You might trying pinging through the WAN router.  If you can ping to an known outside host, that is relatively inactive, and doesn't have congestion on its side, high ping times to it may indicate WAN congestion.

If you do have WAN congestion, with a "smart" router, you can sometimes provide more predictable performance using QoS.  Often to improve WAN performance, you'll need a higher bandwidth WAN link and/or more "powerful" WAN router.

Hi Joseph,At moment i have

Hi Joseph,

At moment i have only 5 users connected to my LAN and the traffic is very smooth, what all you are saying might be one of the reasons but how should i tackle them ?

I am using Cisco 837 as a WAN router, however i am already in progress to upgrade it to Cisco 1841 very shortly.

What i believe is that because of some users which i do not know the traffic towards the gateway is increasing and now its perfect as they are not active.

Regards

@Mohammed

 

Hall of Fame Super Gold

I am using Cisco 837 as a WAN

I am using Cisco 837 as a WAN router, however i am already in progress to upgrade it to Cisco 1841 very shortly.

837 is NOT designed to run 5 Mbps.  So this could be the potential cause of the issue.  1841 router is sufficient to up to 10 Mbps.

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