BPDU / Spanning tree

[Cyberurmel]

Hi all,

just a request to explain to me:
Setting : Network with 6450 Switches which end to 6900 devices and the 6900 are connected to a Cisco Router which should be root for SPT.

just say - 20 vlans per Switch are existing. So what happens in Default Setting when i connect a patch cable in one stack and the ports are:

port 1 example vlan 1 - port 2 example vlan 5

port 1 example vlan 1 - port 2 example vlan 1 ( loop)

the Point is - how to handle such issues at its best to hold them as small as possible. Like Cisco i remember that there exist bpduguard for the Access ports so if a bpdu info arrive such a port - it gets the state of error dissabled.

thanks for help and if i have a missunderstanding for explain

Regards
Cyb

[silvio]

Hi,
there are a lot of possibilities.....
rootguard is in my opinion not the best one.
First you should configure STP with same protocol/mode at all switches (also at cisco). If cisco hat pvst+ than you should at alcatel choose as mode 1x1 and perVlan (it is the same). At the 6450 1x1 is default. At the 6900 it depends from your other config.... disable autofabric (and mvrp) - than you can change to perVlan. Now you can activate at all Alcatel switches pvst+ compatible.
If cisco uses flat than at alcatel too flat mode (all with default protocoll RSTP). And if Cisco uses MSTP than at alcatel too with same CISTs....

To avoid such loops in different vlans with perVlan-Mode you can activate LBD at all the access ports too.
best regards
Silvio