How to disable Spanning Tree on some ports

[cmarmonier]

Hello,

I would like to disable Spanning Tree on some ports (but Spanning tree must operate on the others ports) : I want egress and ingress BPDU trame are blocked
=> If I disable ports in flat Spanning Tree configuration : is it good ?

How must I do ?

[silvio]

if your switch is in flat mode than: > spantree cist port 1/1/1 disable

if the switch is in PerVlan-mode (1x1) than you must do it for every vlan at your port:
spantree vlan 1 port 1/1/1 disable

regards
Silvio

[cmarmonier]

I thank you

[cmarmonier]

I have an another question but it concerns RSTP standard.
When RSTP is enable (single mode), switch handle only 802.1Q untagged packets. If packets are tagged they are ignored and blocked, isn't it ? ... I don't find this information is the RSTP standard (all switches work the same way ?).

[silvio]

in flat mode bpdu between the switches where always send untagged. I uses the default vlan. If you have at all uplinks between the switches the same default vlan than this will deside which ports are blocked (if you have a loop). Blocked means that all vlan will be in blocking (also if one of the tagged vlan isn't a loop).
In my experience the best way is to have at all switches same mode (per vlan or flat) and same protocoll (rstp or mstp). So that at switch in flat mode don't receive tagged bpdu.
regards
Silvio

[cmarmonier]

ok but if a person (not me) install behind my switch 2 others switches (study case) :
switch 1 (my switch) - port 1 (VLAN 100 tagged) <---> port 1 (VLAN 100 tagged) - switch 2 (without RSTP) - port 2 (VLAN 100 untagged) <-----> port 1 (VLAN 100 untagged) - switch 3 (flat RSTP)


switch 3 send untagged BPDU to switch 2
switch 2 transmit BPDU of switch 3 to switch 1 with VLAN tag
=> I think switch 1 will block BPDU (and ignore it) but I don't find this information in the RSTP standard...

[silvio]

it depends....
(1) sw1 in flat or pvlan mode and sw2 is filtering bpdu: no effect in stp at both sites
(2) sw1 in flat mode und sw2 is bridging bpdu (transarent in untagged vlan 1): bpdu will be exchanged between sw1 vlan1 and sw3 vlan100
(3) sw1 in perVlan mode und sw2 is bridging bpdu (transarent in untagged vlan 1): bpdu will be exchanged between sw1 vlan1 and sw3 vlan100

normally (2) and (3) should work without issue. But I have often seen issue with stp between switches from different vendors, so that communication between the switches where not possible. F.e.incompatible bpdu -> port blocked in dispute mode or every 2 seconds (stp hello timer) there are interrupts...

You have to deside: all switches in same protocoll/mode like MSTP or disable STP between the switches.

regards
Silvio

[cmarmonier]

ok , I thnak you