05-24-2022 11:35 PM
Hi,
I'm having difficulties with the relationships between (R)STP port roles and states and which works with Uplinkfast.
STP port roles: Root, Designated and Blocking
STP port states: Blocking, listening, learning and forwarding
Can all port role types be in all states?
A STP non-designated port can have the blocking port role and only the blocking port role, right?
RSTP port roles: Root, Designated, Alternate, Backup
RSTP port states: Discarding, learning and forwarding
Can all port role types be in all states?
A RSTP non-designated port can have the alternate port role or the backup port role, right?
About UplinkFast:
STP: When UplinkFast is enabled, the non-designated Port transitions to the Forwarding state immediately without going through the Listening state and Learning state, as in normal Spanning Tree operation.
RSTP: A switch's ability to immediately move its best Alternate port from Blocking to Forwarding (without first going through Listening and Learning), functions like a classic STP optional feature called UplinkFast.
Does this mean that STP Uplinkfast only works on the blocking port role?
Does this mean that RSTP's ability only works on the alternate port role? Why not the backup?
I tried searching for these answers, but did not find anything that could definitely confirm how this is connected.
05-25-2022 12:24 AM
Hello
@trane.m wrote:
Does this mean that STP Uplinkfast only works on the blocking port role?
Yes it does work on a blocking port-its a backup (alternate) port towards the root switch, it transitions into the forwarding state after a root port on the same switch fails
@trane.m wrote:
Does this mean that RSTP's ability only works on the alternate port role? Why not the backup?
An alternate port is a backup port the difference between the two is an alternate port is a backup port towards the root switch, However a backup port provides an alternate link but not primarily towards the root switch.
05-25-2022 01:11 AM
Hello
@trane.m wrote:
Does this mean that STP Uplinkfast only works on the blocking port role?
Yes it does work on a blocking port-its a backup (alternate) port towards the root switch, it transitions into the forwarding state after a root port on the same switch fails
@trane.m wrote:
Does this mean that RSTP's ability only works on the alternate port role? Why not the backup?
An alternate port is a backup port the difference between the two is an alternate port is a backup port towards the root switch, However a backup port provides an alternate link but not primarily towards the root switch.
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