HP ProCurve 9304M Installation And Configuration Manual page 250

Installation and Basic Configuration Guide
Routing Switch 5 sends an RST BPDU that contains a proposal flag to Port5/Routing Switch 2. When handshakes
are completed in Routing Switch 5, Port5/Routing Switch 2 is selected as the Root port on Routing Switch 2. All
other ports on Routing Switch 2 are given Designated port role with discarding states.
Port5/Routing Switch 2 then sends an RST BPDU with an agreed flag to Routing Switch 5 to confirm that it is the
new Root port and the port enters a forwarding state. Port7 and Port8 are informed of the identity of the new Root
port. 802.1W algorithm selects Port7 as the Designated port while Port8 becomes the Backup port.
Port3/Routing Switch 5 sends an RST BPDU to Port3/Routing Switch 6 with a proposal flag. When Port3/Routing
Switch 5 receives the RST BPDU, handshake mechanisms select Port3 as the Root port of Routing Switch 6. All
other ports are given a Designated port role with discarding states. Port3/Routing Switch 6 then sends an RST
BPDU with an agreed flag to Port3/Routing Switch 5 to confirm that it is the Root port. The Root port then goes
into a forwarding state.
Now, Port4/Routing Switch 6 receives RST BPDUs that are superior to what it can transmit; therefore, it is given
the Alternate port role. The port remains in discarding state.
Port5/Routing Switch 6 receives RST BPDUs that are inferior to what it can transmit. The port is then given a
Designated port role.
Next Routing Switch 2 sends RST BPDUs with a proposal flag to Port3/Routing Switch 4. Port3 becomes the Root
port for the bridge; all other ports are given a Designated port role with discarding states. Port3/Routing Switch 4
sends an RST BPDU with an agreed flag to Routing Switch 2 to confirm that it is the new Root port. The port then
goes into a forwarding state.
Now Port4/Routing Switch 4 receives an RST BPDU that is superior to what it can transmit. The port is then given
an Alternate port role, and remains in discarding state.
Likewise, Port5/Switch 4 receives an RST BPDU that is superior to what it can transmit. The port is also given an
Alternate port role, and remains in discarding state.
Port2/Routing Switch 2 transmits an RST BPDU with a proposal flag to Port2/Routing Switch 1. Port2/Routing
Switch 1 becomes the Root port. All other ports on Routing Switch 1 are given Designated port roles with
discarding states.
Port2/Routing Switch 1 sends an RST BPDU with an agreed flag to Port2/Routing Switch 2 and Port2/Routing
Switch 1 goes into a forwarding state.
Port3/Routing Switch 1 receives an RST BPDUs that is inferior to what it can transmit; therefore, the port retains
its Designated port role and goes into forwarding state only after the forward delay timer expires twice on that port
while it is still in a Designated role.
Port3/Routing Switch 2 sends an RST BPDU to Port3/Routing Switch 3 that contains a proposal flag. Port3/
Routing Switch 3 becomes the Root port, while all other ports on Routing Switch 3 are given Designated port roles
and go into discarding states. Port3/Routing Switch 3 sends an RST BPDU with an agreed flag to Port3/Routing
Switch 2 and Port3/Routing Switch 3 goes into a forwarding state.
Now, Port2/Routing Switch 3 receives an RST BPDUs that is superior to what it can transmit so that port is given
an Alternate port state.
Port4/Routing Switch 3 receives an RST BPDU that is inferior to what it can transmit; therefore, the port retains its
Designated port role.
Ports on all the bridges in the topology with Designated port roles that received RST BPDUs with agreed flags go
into forwarding states instantly. However, Designated ports that did not receive RST BPDUs with agreed flags
must wait until the forward delay timer expires twice on those port. Only then will these port move into forwarding
states.
The entire 802.1W topology converges in less than 300 msec and the essential connectivity is established
between the designated ports and their connected root ports.
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