Network Tuning

[amacdos]

Hi guys ,

I am sorry , I am still a new Network Administrator . I have question , on how to tune the network .

I am a LAN Environment . We have servers , pc and printers .

Can anyone help me on how to monitor the network and tune the network , to make faster .

Regards

Alman

[David Stanford]

This isn't something that can be answered easily, but have a look at this link for some ideas:

http://www.cisco.com/warp/public/126/perfmgmt.htm

[amacdos]

Hi thanks Davis ,

Is there any tools available like Ciscoworks or anything to check the network .

Regards

Amacdos

[Danilo Dy]

Hi Amacdos,

Start with a freely available utilities to monitor your device. Check MRTG http://oss.oetiker.ch/mrtg/, it can monitor Cisco devices port bandwidth utilization, CPU and Memory utilization. It can also monitor LINUX/W2K3 Network Card, CPU, Memory, and partition utilization and some application processes.

Dandy

[amacdos]

Thanks Dandy ,

I am using MRTG to monitor the link utilisations . Basically from MRTG we can see the utilisations , there's a sudden change on the network ,but how do we check the changes ...

Just curious ..

[Danilo Dy]

What change? Take note that MRTG can't do what commercial application able to do like auto-map the network.

[amacdos]

Medan ,

The change ,that I am trying to say is for example internet link utilisation was up from 70 % and 90 % . From here , how do I investigate and check the cause of the heavy utilisation . I did not ask anything about an automap the network by using MRTG .

I am aware that MRTG will only give you , the link utilisation , pure monitoring , you can't do anything else .

My question was how to investigate the cause of the problem . From MRTG reading , what is the next thing to check , like appplication layer and protocol layers . Such tcp window size , or anything like that .

As I am introduced myself as a new guy in networking .I am not a Consultant

[Danilo Dy]

If you monitor all ports bandwidth utilization from the router down to the access switches, you can compare the pattern in the graph to point to which host or network is suddenly utilizing more bandwidth. Another way is enable IP Accounting in the router, when suddenly you have high bandwidth utilization, you can identify the IP Address of the host that causes it. Once you identify the host, you can find application or services running on it that may have cause the high bandwidth utilization.

If you don't have company policy for use of internet access or doesn't have a proxy to control internet access, you may be surprise to find out that some users are using P2P like emule, edonkey, etc..

There are products like Packetseeker and Packetshaper from Packeteer that can monitor bandwidth utilization of any application. The later can even shape it.

People administering network, pro or new should work with a cool head! The internet will not reach to what it is today if the network administrators who manages small to large networks that build up the internet works with a hot temper!

[amacdos]

If I use a Etherreal kind of product , which can even give information on protocols like tcp , does it help . Do I need to look into protocols also .

The rules are very simple , if don't feel like answering anybody's question in this discussion forum . You can chose not to answer the question , it's not a compulsory for anyone to answer to someone's question .

It's just a discussion forum .

[rajasha.cisco]

Hello David,

The given URL is locked. Could you please suggest other than this which will be much helpful. Thanks

[Marvin Rhoads]

David's URL posting is old and should redirect you to the new location:

http://www.cisco.com/en/US/customer/tech/tk869/tk769/technologies_white_paper09186a008014fbf3.shtml

The concepts there are pretty sound ones still.

If you can tell us a little bit about what kind of Cisco equipment you are using we can better help by making out suggestions specific to the type of equipment you have installed. The various types all have different capabilities with respect to performance management.

[rajasha.cisco]

Hi Marvin,

The response I'm getting is page is forbidden so I cant access the URL.

Anyways we are using catalyst 3560, 3750, 2950 and n number of IBM servers and Dell, printers. So please suggest a tool for network management/monitroing in this scenario. Thanks.

[Marvin Rhoads]

I've attached a PDF copy of the web page I linked above. Hopefully you will be able to access it that way.

For the layer 2 switches you describe, performance management visibility is generally limited to querying interfaces for utilization. Any number of tools can do also this - Cisco Network Assistant is a free one that offers some limited ability to do it in real time. There are some open source products (Cacti, PRTG etc.) that offer a package that will query, graph and let you call up historical data. The paid products (What's Up Gold, SolarWinds NPM, Cisco Prime LMS, etc.) offer increasing levels of sophistication for more cost.

The best data for performance monitoring is most easily gotten via Netflow technology. It is built into Cisco products - primarily the routers (full featured), ASAs (good support) and layer 3 switches (limited). Netflow just collect raw data and requires export to a 3rd party application for storage and analysis. Those include ntop (open source), SolarWinds Netflow Traffic Analyzer, Csico Prime LMS and other commercial products from companies like Plixer and ManageEngine.