Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide - Manual (Page 177)

NOTE
The LAG IDs are only significant locally and need not match on the two ends of a LAG.
The LACP system ID in the MCT-supporting device normally comes from the port MAC address. To
support LACP over MCT, the ID must be obtained in another way. MCT uses a pre-defined algorithm to
obtain the ID.
NOTE
Each MCT cluster device has a unique cluster ID and one MCT client ID. The LACP key is predefined
from the client ID and cluster ID. The user cannot change the key.
MCT does not involve stacking, and control protocol synchronization is minimal. The LACP runs
independently on the cluster devices.
Port loop detection
Loop detection can be used in an MCT topology to detect Layer 2 loops that occur due to
misconfigurations, for example, on the client side when MCT links are not configured as trunk links on
the MCT-unaware client.
In MCT, ICL links should be up at all times to prevent the cluster from going down. These links should
not be shut down when a loop is detected in a network. Instead, other available ports (CCEPs) should
be shut down. If loop detection BDPUs are received on the ICL port, instead of shutting down the ICL
links, all CCEPs are error-disabled, and the user is notified with the following log message.
Loop-detection: Packet received on ICL port for vlan .
Errdisable CCEPs.
Strict mode loop detection can be enabled on ICL ports. In strict mode, a port is disabled only if a
packet is looped back to that same port. Strict mode overcomes specific hardware issues where
packets are echoed back to the input port. This process assists in detecting hardware faults on ICL
ports.
Loop-detection can be enabled on MCT and non-MCT VLANs simultaneously. There is no change in
loop detection behavior when it is enabled on non-MCT VLANs.
The following example shows how to configure loop detection on MCT and non-MCT VLANS.
device(config)# vlan 1905
device(config-vlan-1905)# loop-detection
device(config-vlan-1905)# end
MCT Layer 2 protocols
Keep the following information in mind when configuring Layer 2 protocols with MCT.
MRP
• An ICL interface cannot be configured as an MRP secondary interface or vice versa because the ICL
cannot be BLOCKING.
• MRP cannot be enabled on MCT CCEP port or vice versa.
Port loop detection
FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide 177
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