SGE2010 Does not block ports even with STP enabled

[joe19366]

Good day,

We are experiencing bridge storms and network slow downs and we believe we have traced the issue down to users plugging a cat 5/6 cable between 2 ports on the wall both wired back to a SGE2010 switch.

So we did a test - we plugged a single short cat 6 cable between 2 ports on a SGE2010, our access switch. Suprisingly, even with STP enabled, the switch DID NOT block one of the ports and in a few minutes the ENTIRE NETWORK was down, as CDP, STP, and ARP traffic became a multi-gigabit storm throughout the network.

Why on earth does this switch not block a port that is obviosly looped?

Every other cisco switch since I started on 1900XL's did this in 1999.

Thanks!

-Joe

#19366

[zbenko]

Dear Joe,

STP would conrol multiple links (for redundancy) between switches (endpoints) turning an inactive link on when the active goes down and preventing duplicate active links between them. More about STP at page 258 of the

SFE-SGE2xxx Admin Guide PDF.

The function you might be interested in is called "Storm Control" which limits the number of packets per second so to prevent the switch and the network from storms. See page 82 of the SFE-SGE2xxx Admin Guide PDF available here: http://www.cisco.com/en/US/docs/switches/lan/csbms/sfe2000/administration/guide/SFE-SGE2xxx_Admin_Guide.pdf

Thanks and regards,

Zsolt