394 BigIron RX Series Configuration Guide
53-1002253-01
Displaying RSTP information
13
Designated Bridge Identifier The bridge from where the root information was received. It can be from the
root bridge itself, but it could also be from another bridge.
Root Port The port on which the root information was received. This is the port that is
connected to the Designated Bridge.
Max Age The max age is derived from the Root port. An RSTP-enabled bridge uses
this value, along with the hello and message age parameters to compute
the effective age of an RST BPDU.
The message age parameter is generated by the Designated port and
transmitted in the RST BPDU. RST BPDUs transmitted by a Designated port
of the root bridge contains a message value of zero.
Effective age is the amount of time the Root port, Alternate port, or Backup
port retains the information it received from its peer Designated port.
Effective age is reset every time a port receives an RST BPDU from its
Designated port. If a Root port does not receive an RST BPDU from its peer
Designated port for a duration more than the effective age, the Root port
ages out the existing information and recomputes the topology.
If the port is operating in 802.1D compatible mode, then max age
functionality is the same as in 802.1D (STP).
Hello The hello value derived from the Root port. It is the number of seconds
between two Hello packets.
Fwd Dly The number of seconds a non-edge Designated port waits until it can apply
any of the following transitions, if the RST BPDU it receives does not have an
agreed flag:
• Discarding state to learning state
• Learning state to forwarding state
When a non-edge port receives the RST BPDU it goes into forwarding state
within 4 seconds or after two hello timers expire on the port.
Fwd Dly is also the number of seconds that a Root port waits for an RST
BPDU with a proposal flag before it applies the state transitions listed
above.
If the port is operating in 802.1D compatible mode, then forward delay
functionality is the same as in 802.1D (STP).
RSTP (IEEE 802.1W) port parameters
Port Num The port number shown in a slot#/port# format.
Pri The configured priority of the port. The default is 128 or 0x80.
Port Path Cost The configured path cost on a link connected to this port.
P2P Mac Indicates if the point-to-point-mac parameter is configured to be a
point-to-point link:
• T – The link is configured as a point-to-point link.
• F – The link is not configured as a point-to-point link. This is the
default.
Edge port Indicates if the port is configured as an operational Edge port:
• T – The port is configured as an Edge port.
• F – The port is not configured as an Edge port. This is the default.
TABLE 80 CLI display of RSTP summary (Continued)
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