Layer 2 loops

[anuragvats]

am wondering how to detect layer 2 loops in a network, can somebody help me out the way to detect layer 2 loop in the network...

[scottmac]

The most notable sign is broadcast storms.

The switch will cycle from zero to one hundred percent (in some cases) or go to one hundred percent and stay there.

"Real" network traffic slows considerably, or halts altogether as the switch process overloads and vapor-locks.

On most of the Cisco switches I've seen, the LEDs start off, blink at an increasing rate, lock on solid, then go out (protection kicks in and shuts down the ports) ... repeat until resolved.

Good Luck

Scott

[dgahm]

Scott,

You left out the general state of panic, and the boss hovering wanting to know when the network will be back up :-)

Dave

[scottmac]

That's a "Layer 8" problem .... deal with the lower layer problems, and the upper layer problems go away .....;}

It also give you the opportunity, while doing the RFO (Reason For Outage)to bring up that budget request you submitted (that layer 8 denied or severely cut back) that would have prevented the issue ...(whether it would have or not, but usually would have).

"Every dark cloud has a silver lining"

Thanks for the additional insight!

Good Luck

Scott