Specifying The Link Type - Cisco Catalyst 4500 Series Configuration Manual

Chapter 20 Configuring STP and MST
Switch# clear spanning-tree detected-protocols
The following example shows how to verify the configuration:
Switch# show spanning-tree summary totals
Switch is in rapid-pvst mode
Root bridge for:VLAN0001
Extended system ID
Portfast Default
PortFast BPDU Guard Default
Portfast BPDU Filter Default is disabled
Loopguard Default
EtherChannel misconfig guard is enabled
UplinkFast
BackboneFast
Pathcost method used
Name
---------------------- -------- --------- -------- ---------- ----------
1 vlan
Switch#

Specifying the Link Type

Rapid connectivity is established only on point-to-point links. Spanning tree views a point-to-point link
as a segment connecting only two switches running the spanning tree algorithm. Because the switch
assumes that all full-duplex links are point-to-point links and that half-duplex links are shared links, you
can avoid explicitly configuring the link type. To configure a specific link type, use the spanning-tree
linktype command.
Restarting Protocol Migration
A switch running both MSTP and RSTP supports a built-in protocol migration process that enables the
switch to interoperate with legacy 802.1D switches. If this switch receives a legacy 802.1D configuration
BPDU (a BPDU with the protocol version set to 0), it sends only 802.1D BPDUs on that port. When an
MSTP switch receives a legacy BPDU, it can also detect the following:
•
•
•
The switch, however, does not automatically revert to the MSTP mode if it no longer receives 802.1D
BPDUs because it cannot determine whether or not the legacy switch has been removed from the link
unless the legacy switch is the designated switch. A switch also might continue to assign a boundary role
to a port when the switch to which it is connected has joined the region.
To restart the protocol migration process on the entire switch (that is, to force renegotiation with
neighboring switches), use the clear spanning-tree detected-protocols commands in privileged EXEC
mode. To restart the protocol migration process on a specific interface, enter the
clear spanning-tree detected-protocols interface command in interface-id privileged EXEC mode.
OL-25340-01
Blocking Listening Learning Forwarding STP Active
A port is at the boundary of a region
An MST BPDU (version 3) that is associated with a different region
An RST BPDU (version 2)
is disabled
is disabled
is disabled
is disabled
is disabled
is disabled
is short
0 0 0
Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
Configuring STP
2 2
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