[Gerald Combs <gerald@xxxxxxxxxxxx>]

On Tue, 7 Oct 2003, Mah Horng Liang wrote:

> I could understand all the traffic capture! but 1 of the type of traffic I couldn't understand.. 
> 
> Destination: xxx (Spanning-tree-(for-briges)_01) 
> 
> I guess this is the traffic generate by ethernet switch!! The destination & source MAC addr couldn't found inside my network ! Wish u can explain the status !! 

You're correct -- this is being generated by your switch.  Loops in
a bridged or switched environment can retransmit frames indefinitely
and flood your network.  The spanning tree algorithm detects loops and
removes them by blocking traffic on ports where needed.  It does this
in a way that ensures your network doesn't get split in half.

The following URLs have more detailed information on spanning tree:

    http://www.oreillynet.com/pub/a/network/2001/03/30/net_2nd_lang.html

    http://www.cisco.com/univercd/cc/td/doc/product/rtrmgmt/sw_ntman/cwsimain/cwsi2/cwsiug2/vlan2/stpapp.htm

    http://support.baynetworks.com/library/tpubs/html/router/soft1000/bridge/2950A-19.html