353
Cisco Systems, Inc.
www.cisco.com
Configuring Optional Spanning-Tree
Features
Prerequisites for the Optional Spanning-Tree Features
You can configure all of these features when your switch is running the per-VLAN spanning-tree plus (PVST+). You can
configure only the noted features when your switch is running the Multiple Spanning Tree Protocol (MSTP) or the rapid
per-VLAN spanning-tree plus (rapid-PVST+) protocol.
Restrictions for the Optional Spanning-Tree Features
You can configure the UplinkFast or the BackboneFast feature for rapid PVST+ or for the MSTP, but the feature remains
disabled (inactive) until you change the spanning-tree mode to PVST+.
Information About Configuring the Optional Spanning-Tree
Features
PortFast
PortFast immediately brings an interface configured as an access or trunk port to the forwarding state from a blocking
state, bypassing the listening and learning states. You can use PortFast on interfaces connected to a single workstation
or server, as shown in
, to allow those devices to immediately connect to the network, rather than
waiting for the spanning tree to converge.
Interfaces connected to a single workstation or server should not receive bridge protocol data units (BPDUs). An interface
with PortFast enabled goes through the normal cycle of spanning-tree status changes when the switch is restarted.
Note:
Because the purpose of PortFast is to minimize the time interfaces must wait for spanning-tree to converge, it is
effective only when used on interfaces connected to end stations. If you enable PortFast on an interface connecting to
another switch, you risk creating a spanning-tree loop.
You can enable this feature by using the
spanning-tree portfast
interface configuration or the
spanning-tree portfast
default
global configuration command.
Содержание IE 4000
Страница 12: ...8 Configuration Overview Default Settings After Initial Switch Configuration ...
Страница 52: ...48 Configuring Interfaces Monitoring and Maintaining the Interfaces ...
Страница 108: ...104 Configuring Switch Clusters Additional References ...
Страница 128: ...124 Performing Switch Administration Additional References ...
Страница 130: ...126 Configuring PTP ...
Страница 140: ...136 Configuring CIP Additional References ...
Страница 146: ...142 Configuring SDM Templates Configuration Examples for Configuring SDM Templates ...
Страница 192: ...188 Configuring Switch Based Authentication Additional References ...
Страница 244: ...240 Configuring IEEE 802 1x Port Based Authentication Additional References ...
Страница 274: ...270 Configuring SGT Exchange Protocol over TCP SXP and Layer 3 Transport Configuring Cisco TrustSec Caching ...
Страница 298: ...294 Configuring VLANs Additional References ...
Страница 336: ...332 Configuring STP Additional References ...
Страница 408: ...404 Configuring DHCP Additional References ...
Страница 450: ...446 Configuring IGMP Snooping and MVR Additional References ...
Страница 490: ...486 Configuring SPAN and RSPAN Additional References ...
Страница 502: ...498 Configuring Layer 2 NAT ...
Страница 559: ...555 Configuring Network Security with ACLs How to Configure Network Security with ACLs Creating a Numbered Extended ACL ...
Страница 770: ...766 Configuring IPv6 MLD Snooping Related Documents ...
Страница 930: ...926 Configuring IP Unicast Routing Related Documents ...
Страница 956: ...952 Configuring IPv6 Unicast Routing Configuring IPv6 network 2010 AB8 2 48 network 2010 AB8 3 48 exit address family ...
Страница 976: ...972 Configuring Cisco IOS IP SLAs Operations Additional References ...
Страница 978: ...974 Dying Gasp ...
Страница 990: ...986 Configuring Enhanced Object Tracking Monitoring Enhanced Object Tracking ...
Страница 994: ...990 Configuring MODBUS TCP Displaying MODBUS TCP Information ...
Страница 996: ...992 Ethernet CFM ...
Страница 1030: ...1026 Working with the Cisco IOS File System Configuration Files and Software Images Working with Software Images ...
Страница 1066: ...1062 Using an SD Card SD Card Alarms ...