Cisco Catalyst 4500 Series, Руководство по настройке программного обеспечения

Страница: 777 / 2086

26-7
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 26 Configuring Optional STP Features
About STP PortFast Port Types
To disable the EtherChannel guard feature, use the no spanning-tree etherchannel guard misconfig
global configuration command.
Use the show interfaces status err-disabled privileged EXEC command to show which switch ports are
disabled because of an EtherChannel misconfiguration. On the remote device, you can enter the show
etherchannel summary privileged EXEC command to verify the EtherChannel configuration.
After the configuration is corrected, enter the shutdown and no shutdown interface configuration
commands on the port-channel interfaces that were misconfigured.
About STP PortFast Port Types
You can configure a spanning tree port as an edge port, a network port, or a normal port. A port can be
in only one of these states at a given time. The default spanning tree port type is normal. You can
configure the port type either globally or per interface.
Depending on the type of device to which the interface is connected, you can configure a spanning tree
port as one of these port types:
•
A PortFast edge port—is connected to a Layer 2 host. This can be either an access port or an edge
trunk port (
portfast edge trunk ). This type of port interface immediately transitions to the
forwarding state, bypassing the listening and learning states. Use PortFast edge on Layer 2 access
ports connected to a single workstation or server to allow those devices to connect to the network
immediately, rather than waiting for spanning tree to converge.
Even if the interface receives a bridge protocol data unit (BPDU), spanning tree does not place the
port into the blocking state. Spanning tree sets the port’s operating state to
non-port fast even if the
configured state remains port fast edge and starts participating in the topology change.
Note
If you configure a port connected to a Layer 2 switch or bridge as an edge port, you might
create a bridging loop.
• A PortFast network port—is connected only to a Layer 2 switch or bridge.
Bridge Assurance is enabled only on PortFast network ports. For more information, see About
Bridge Assurance, page 26-11 .
Note
If you configure a port that is connected to a Layer 2 host as a spanning tree network port,
the port will automatically move into the blocking state.
•
A PortFast normal port—is the default type of spanning tree port.
Note
Beginning with Cisco IOS Release 15.2(4)E, or IOS XE 3.8.0E, if you enter the spanning-tree portfast
[trunk] command in the global or interface configuration mode, the system automatically saves it as
spanning-tree portfast edge [trunk].