Cisco 7609 User Manual

16-6
Cisco 7600 Series Router Cisco IOS Software Configuration Guide—12.1E
78-14064-04
Chapter 16 Configuring Optional STP Features
Understanding How EtherChannel Guard Works
Figure 16-5 Adding a Network Device in a Shared-Medium Topology
Understanding How EtherChannel Guard Works
EtherChannel guard detects a misconfigured EtherChannel where interfaces on the Cisco 7600 series
router are configured as an EtherChannel while interfaces on the other device are not or not all the
interfaces on the other device are in the same EtherChannel.
In response to misconfiguration detected on the other device, EtherChannel guard puts interfaces on the
Cisco 7600 series router into the errdisabled state.
Understanding How Root Guard Works
The STP root guard feature prevents a port from becoming root port or blocked port. If a port configured
for root guard receives a superior BPDU, the port immediately goes to the root-inconsistent (blocked)
state.
Understanding How Loop Guard Works
Loop guard helps prevent bridging loops that could occur because of a uni-directional link failure on a
point-to-point link. When enabled globally, the loop guard applies to all point-to-point ports on the
system. Loop guard detects root ports and blocked ports and ensures that they keep receiving BPDUs
from their designated port on the segment. If a loop guard enabled root or blocked port stop a receiving
BPDUs from its designated port, it transitions to the loop-inconsistent blocking state, assuming there is
a physical link error on this port. The port recovers from this loop-inconsistent state as soon as it receives
a BPDU.
You can enable loop guard on a per-port basis. When you enable loop guard, it is automatically applied
to all of the active instances or VLANs to which that port belongs. When you disable loop guard, it is
disabled for the specified ports. Disabling loop guard moves all loop-inconsistent ports to the listening
state.
Switch A
(Root)
Switch C
Switch B
(Designated Bridge)
Added switch
11245
Blocked port

Cisco 7609 Specifications

General

Chassis Slots	9
Switch Fabric Capacity	720 Gbps
Power Supply Options	AC or DC
Product Type	Router
Form Factor	Rack-mountable
Supported Line Cards	Various Cisco 7600 Series line cards
Operating System	Cisco IOS
Management	CLI, SNMP
Forwarding Performance	400 Mpps
Maximum Power Consumption	4000 Watts
Redundancy	Yes
Interfaces/Ports	Various, depending on line cards installed