How to solve a slow network issue in a Lan segment? Interview question

[deepak1304]

Hi,

There was 2 questions in my interview. Can somebody answer these questions with explaination? Plz

1)  There were 20 switches connected to each other in a lan segment, they were running fine but now there is a compaint that there is a network slow issue, how you will solve the problem? (Internet as well as routers are not there)

2) One FTP server  and 10 clients are connected to one switch, every day each client uploads a 10 Mb of file which takes hardly some min, But now they are complaing that it is taking more than 10-15 min to upload the same file. What could be the reason and how you will solve it?

Thanks

Deepak

[Leo Laohoo]

1.  Run ping tests with large packets.  Traceroute to ensure no routing loop.  Try to replicate the issue.  Check to make sure there are no line errors, link flapping, speed and/or duplex mismatch.

2.  Check for line errors on the FTP and clients.  You can also check for speed and/or duplex mismatch.  Check for link flaps. You can also use TDR to ensure the cabling to your FTP and clients are working fine.

[jimmysands73_2]

Interesting, see this at work all the time, but at an interview, ... under the gun.

First I would ask, what changed and when then why?

Then I would look for bridgeing loops.  Extreme has ELRP, great for this, do not know CIsco's equivilant.  I would then look at the logs of the switches/routers, port utilization on the per port basis.  A bad NIC can flood the network also.  Look to make sure your root bridge is still the same.

The FTP server, maybe the port went from full to half duplex.  I would concentrate on the uplink between the sw and server, if it is happening to all 10 users, then they are proabably not the issue.

Good questions.

[jimmysands73_2]

Deepak,

How did you answer it?

Just curious...

[wilrow113]

The first I would look at switch logs an check spanning tree to see if loops

Also needed to look at the topology of the 20 switches

Second would be check interfaces of the server and clients for errors and load

Sent from Cisco Technical Support iPad App

[Ven Taylor]

Since those problems are never cut and dry in the real world, I expect they were just asking them to see if you'd start asking the right questions.  Either that or the people interviewing you don't understand troubleshooting.

JimmySands had some good answers.