Foundry NetIron M2404C and M2404F Metro Access Switches
Configuring RSTP (Rev. 03)
Rapid Spanning Tree Protocol (RSTP)
© 2008 Foundry Networks, Inc.
Page 16 of 34
This functionality is provided in order to permit bridge ports that are (administratively) known
to be at the edge of the Bridged LAN to transition to Forwarding without delay.
However, as the presence of a bridge on a port that has been marked as an edge port could
potentially cause a loop in the active topology, it is necessary to qualify the value of the
administrative state variable according to the port knowledge of whether or not any BPDUs
have been received on the port.
•
EdgePort
The Bridge Detection state machine controls the value of the corresponding operational
state variable, operational EdgePort, which may be used in order to determine whether a port
that becomes Designated is permitted to transition directly to Forwarding. A value of
enabled
in the show commands indicates that this state transition is permitted to occur.
If a BPDU is received on the port, then the value of operational EdgePort is set to
disabled
.
Following a port initialization, or following a link-up event, operational EdgePort is set to the
value of admin EdgePort.
Hence, if a port that has been marked as an edge-port proves not to be one (due to the presence
of another bridge), then it will cease to behave like an edge-port until such a time as it is
reinitialized (either by a link up/down event or by reissuing the CLI command).
NOTE
If a BPDU is received on a port that is configured as an edge port that port
automatically reverts to
edge-port disabled
status. After link up/down, the port
returns to the admin status.
Command Syntax
device-name
(config-if
UU/SS/PP
)#
rapid-spanning-tree edge-port
device-name
(config-if
UU/SS/PP
)#
no rapid-spanning-tree edge-port
Setting the Link Type
The
rapid-spanning-tree link-type
command, in Interface Configuration mode, sets the RSTP
port administrative
link-type
. The
no
form of the command resets the link type to its default value
(auto).
There are two statuses of link state: operational and administrative.
1. Admin Link-Type:
Auto
From the point of view of determining the value of the link-type, the device is considered
to be connected to a point-to-point LAN segment if any of the following conditions are
true:
The device concerned supports auto-negotiation, and the auto-negotiation function has
determined that the LAN segment is to be operated in full-duplex mode.