how to troubleshoot a switch

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goodcooper

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i've been having a lot of issues with a site i've got 5 different core switches, all seem to be exhibiting similar problems, basically becoming unresponsive to all traffic, cutting in and out, being all around unreliable with passing traffic...

they aren't the best switches, cheapy Cisco SF200-24

i really like the features on it and the price was definitely right on them, but like i said, nothing but problems...

reboots will fix the issues for a few minutes and then out again...

i realized now that i'm going to have to take some steps to troubleshoot all of the problems, and i really don't know what to look for...

i know to get started i'll probably be using a port mirroring feature and wireshark, but what exactly should i be looking for?

how do i troubleshoot these switches? exactly what should my methodology be, and what am i looking for with regards to diagnostics?

pretty simple topology, one switch is uplinked to 4 others, all the same model
 
Sounds like you are experiencing a loop of some sorts. Is Spanning Tree enabled on all of the switches?
 
You started the post by saying you have five core switches, but then you stated you have one switch linked to four others. In my mind, when you say you have five core switches, that means you have five layer three switches that provide service to multiple layer two switches below them. Can you elaborate?
 
Maybe give a more detailed network diagram, but it sounds like something funky is going on once the switches are converged.
 
Shadowspawn said:
You started the post by saying you have five core switches, but then you stated you have one switch linked to four others. In my mind, when you say you have five core switches, that means you have five layer three switches that provide service to multiple layer two switches below them. Can you elaborate?
Click to expand...

you're right, i realized that was sort of confusing after i posted it...

i have one core switch, feeding 4 other switches...

all SF200-24p

there are some dumb switches at some desks under some of those switches, and i've been working towards eliminating all of those with my wiring guy, still a couple around though....

i'll take a closer look at those... somebody may have one plugged into itself, or plugged into one of the main switches twice or something

but i did pull this from my core switch, found it kind of interesting:



port 20 is my #5 switch
port 21 is my #4 switch
port 22 is my #3 switch
port 23 is my #1 switch

(core is #2, from which this screenshot is taken....)

so it looks like i'm recieving an alarming number of broadcast and multicast packets from my #3 switch

the odd thing is, i think that's my switch that i havn't got any other switches plugged into, it's on it's own....

i'll run the same page on that switch and see if it will give me any clues....
 
Can you provide a visio diagram of some kind so we can visually see what's going on?
 
Run "sh cdp n" on each switch. If you see itself in the report, you have a loop. Do you have BPDUguard enabled on all interfaces except the trunks?
 
FE22 for example has nearly 50% broadcast packets, that's a bad sign. You want to aim for no more than 20%
 
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