HP ProCurve 9304M Installation And Configuration Manual page 238

Installation and Basic Configuration Guide
• Agreed – The Root port sends back an RST BPDU containing an agreed flag to its peer Designated port and
moves into the forwarding state. When the peer Designated port receives the RST BPDU, it rapidly
transitions into a forwarding state.
Figure 8.7 Agree Stage
Routing Switch 300
At this point, the handshake mechanism is complete between Routing Switch 100, the root bridge, and Routing
Switch 200.
Routing Switch 200 updates the information on the Routing Switch 200's Designated ports (Port2 and Port3) and
identifies the new root bridge. The Designated ports send RST BPDUs, containing proposal flags, to their
downstream bridges, without waiting for the hello timers to expire on them. This process starts the handshake
with the downstream bridges.
For example, Port2/Routing Switch 200 sends an RST BPDU to Port2/Routing Switch 300 that contains a
proposal flag. Port2/Routing Switch 300 asserts a proposed signal. Ports in Routing Switch 300 then set sync
signals on the ports to synchronize and negotiate their roles and states. Then the ports assert a synced signal and
when the Root port in Routing Switch 300 asserts it's synced signal, it sends an RST BPDU to Routing Switch 200
with an agreed flag.
This handshake is repeated between Routing Switch 200 and Routing Switch 400 until all Designated and Root
ports are in forwarding states.
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Port1
Designated port
Forwarding
RST BPDU
sent with
Port1
an Agreed
Root port
flag
Synced
Forwarding
Port2
Synced
Discarding
Port2
Indicates a signal
Routing Switch 100
Root Bridge
Routing Switch 200
Port3
Synced
Discarding
Port3
Routing Switch 400