Convergence After A Link Failure - Dell PowerConnect B-FCXs Configuration Manual

Now, Port3/Switch 3 is currently in a discarding state and is negotiating a port role. It received RST
BPDUs from Port3/Switch 2. The 802.1W algorithm determines that the RST BPDUs Port3/Switch
3 received are superior to those it can transmit; however, they are not superior to those that are
currently being received by the current Root port (Port4). Therefore, Port3 retains the role of
Alternate port.
Ports 3/Switch 1 and Port5/Switch 1 are physically connected. Port5/Switch 1 received RST
BPDUs that are superior to those received on Port3/Switch 1; therefore, Port5/Switch 1 is given
the Backup port role while Port3 is given the Designated port role. Port3/Switch 1, does not go
directly into a forwarding state. It waits until the forward delay time expires twice on that port before
it can proceed to the forwarding state.
Once convergence is achieved, the active Layer 2 forwarding path converges as shown in
FIGURE 41
Bridge priority = 1500
Bridge priority = 2000

Convergence after a link failure

What happens if a link in the 802.1W topology fails?
For example, Port2/Switch, which is the port that connects Switch 2 to the root bridge (Switch 1),
fails. Both Switch 2 and Switch 1 notice the topology change
PowerConnect B-Series FCX Configuration Guide
53-1002266-01
Active Layer 2 path
Switch 2
Port3
Designated
port
Port3
Alternate
port
Port4
Switch 3
Root port
Indicates the active Layer 2 path
Configuring STP related features
Port3
Designated
port
Port2
Port2
Designated
Root port
port
Port4
Designated port
(Figure
Figure
Port5
Backup port
Switch 1
Bridge priority = 1000
42).
8
41.
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