1-3
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-25303-03
Chapter 1 Configuring Optional Spanning-Tree Features
Understanding Optional Spanning-Tree Features
At the interface level, you enable BPDU guard on any port by using the
spanning-tree bpduguard
enable
interface configuration command without also enabling the Port Fast feature. When the port
receives a BPDU, it is put in the error-disabled state.
The BPDU guard feature provides a secure response to invalid configurations because you must
manually put the interface back in service. Use the BPDU guard feature in a service-provider network
to prevent an access port from participating in the spanning tree.
Understanding 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 Port Fast-enabled interfaces by using the
spanning-tree portfast bpdufilter default
global configuration command. This command 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.
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 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.
You can enable the BPDU filtering feature for the entire switch or for an interface.
Understanding 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.
Summary of Contents for Catalyst 3560-X Series
Page 12: ...Contents 10 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 13: ...Contents 11 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 14: ...Contents 12 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 15: ...Contents 13 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 16: ...Contents 14 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 17: ...Contents 15 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 18: ...Contents 16 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 19: ...Contents 17 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 20: ...Contents 18 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 21: ...Contents 19 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 22: ...Contents 20 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 23: ...Contents 21 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 24: ...Contents 22 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 25: ...Contents 23 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 26: ...Contents 24 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 27: ...Contents 25 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 28: ...Contents 26 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 29: ...Contents 27 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 30: ...Contents 28 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 31: ...Contents 29 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 32: ...Contents 30 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 33: ...Contents 31 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 34: ...Contents 32 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 35: ...Contents 33 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 36: ...Contents 34 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 37: ...Contents 35 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 38: ...Contents 36 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...
Page 42: ...56 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 Preface ...
Page 1538: ...Index IN 58 Catalyst 3750 X and 3560 X Switch Software Configuration Guide OL 25303 03 ...