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Configuring Optional Spanning-Tree Features
Information About Configuring the Optional Spanning-Tree Features
Caution:
Configure Port Fast only on ports that connect to end stations; otherwise, an accidental topology loop
could cause a data packet loop and disrupt switch and network operation.
You also can use the
spanning-tree bpduguard enable
interface configuration command to enable BPDU guard on any
port without also enabling the Port Fast feature. When the port receives a BPDU, it is put it in the error-disabled state.
BPDU Filtering
The BPDU filtering feature can be globally enabled on the switch or can be enabled per interface, but the feature operates
with some differences.
At the global level, you can enable BPDU filtering on PortFast-enabled interfaces by using the
spanning-tree portfast
bpdufilter default
global configuration command. This command prevents interfaces that are in a PortFast-operational
state from sending or receiving BPDUs. The interfaces still send a few BPDUs at link-up before the switch begins to filter
outbound BPDUs. You should globally enable BPDU filtering on a switch so that hosts connected to these interfaces do
not receive BPDUs. If a BPDU is received on a PortFast-enabled interface, the interface loses its PortFast-operational
status, and BPDU filtering is disabled.
At the interface level, you can enable BPDU filtering on any interface by using the
spanning-tree bpdufilter enable
interface configuration command without also enabling the PortFast feature. This command prevents the interface from
sending or receiving BPDUs.
Caution:
Enabling BPDU filtering on an interface is the same as disabling spanning tree on it and can result in
spanning-tree loops.
You can enable the BPDU filtering feature for the entire switch or for an interface.
Enabling BPDU Filtering
When you globally enable BPDU filtering on Port Fast-enabled interfaces, it prevents interfaces that are in a Port
Fast-operational state from sending or receiving BPDUs. The interfaces still send a few BPDUs at link-up before the
switch begins to filter outbound BPDUs. You should globally enable BPDU filtering on a switch so that hosts connected
to these interfaces do not receive BPDUs. If a BPDU is received on a Port Fast-enabled interface, the interface loses its
Port Fast-operational status, and BPDU filtering is disabled.
Caution:
Configure Port Fast only on interfaces that connect to end stations; otherwise, an accidental topology loop
could cause a data packet loop and disrupt switch and network operation.
You can also use the
spanning-tree bpdufilter enable
interface configuration command to enable BPDU filtering on any
interface without also enabling the Port Fast feature. This command prevents the interface from sending or receiving
BPDUs.
Caution:
Enabling BPDU filtering on an interface is the same as disabling spanning tree on it and can result in
spanning-tree loops.
UplinkFast
Switches in hierarchical networks can be grouped into backbone switches, distribution switches, and access switches.
shows a complex network where distribution switches and access switches each have at least
one redundant link that spanning tree blocks to prevent loops.
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 ...