Health Checks; Fdb Flush; Configuration Guidelines - IBM RackSwitch G8000 Application Manual

Health Checks

FDB Flush

Configuration Guidelines

© Copyright IBM Corp. 2011
When the AMP loop is broken, the STP port states are set to forwarding or blocking,
depending on the switch priority and port/trunk precedence, as follows:
• An aggregator's port/trunk has higher precedence over an access switch's
port/trunk.
• Static trunks have highest precedence, followed by LACP trunks, then physical
ports.
• Between two static trunks, the trunk with the lower trunk ID has higher prece-
dence.
• Between two LACP trunks, the trunk with the lower admin key has higher prece-
dence.
• Between two ports, the port with the lowest port number has higher precedence.
An AMP keep-alive message is passed periodically from each switch to its
neighbors in the AMP group. The keep-alive message is a BPDU-like packet that
passes on an AMP link even when the link is blocked by Spanning Tree. The
keep-alive message carries status information about AMP ports/trunks, and is used
to verify that a physical loop exists.
An AMP link is considered healthy if the switch has received an AMP keep-alive
message on that link. An AMP link is considered unhealthy if a number of
consecutive AMP keep-alive messages have not been received recently on that
link.
When an AMP port/trunk is the blocking state, FDB flush is performed on that
port/trunk. Any time there is a change in the data path for an AMP group, the FDB
entries associated with the ports in the AMP group are flushed. This ensures that
communication is not blocked while obsolete FDB entries are aged out.
FDB flush is performed when an AMP link goes down, and when an AMP link comes
up.
The following configuration guidelines apply to Active MultiPath Protocol:
• The G8000 can be used as an AMP access switch or AMP aggregator switch.
• 802.1x access control must be disabled before AMP is enabled.
• Enable AMP on all switches in the AMP group before connecting the switch
ports.
• Access switches must be configured with a higher priority value (lower prece-
dence) than the aggregators. Otherwise, unexpected AMP keep-alive packets
may be sent from one aggregator switches to another, even when its AMP group
is disabled.
• Only one active connection (port or trunk) is allowed between switches in an
AMP group.
• Spanning Tree must be disabled on AMP trunks/ports.
• Hot Links must be disabled on AMP trunk/ports.
• Private VLANs must be disabled before AMP is enabled.
• AMP ports cannot be used as monitoring ports in a port-mirroring configuration.
• Do not configure AMP ports as Layer 2 Failover control ports.
• Layer 3 routing protocols are not supported on AMP-configured switches.
Chapter 23. Basic Redundancy
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