Mlt With Lacp And Spanning Tree Configuration Considerations - Avaya 8600 Configuration Manual

causes all edge switches that run LACP to think that their links are connected to a different
switch. The edge switches stop forwarding traffic on their remaining uplinks until the
aggregation can reform (which can take several seconds). Additionally, when the rebooted
switch comes back on line, the same actions occur, thus disrupting traffic twice.
The solution to this problem is to statically configure the same SMLT System ID MAC address
on both aggregation switches.
When you install an RS or 8800 module and have SMLT and LACP configured, LACP goes
down and the switch shows the message: swA:6# CPU6 [01/09/0814:39:28] LACP
INFO lacpOperDisablePort: LACP operationally disabled on port x/y
because the port's capability doesn't match key z's capability.
The solution to this problem is to globally disable and enable LACP to bring the ports back to
the MLT. For reliable LACP operation, use CANA. If CANA is not supported, enforce a speed
and duplex mode on all 10/100/1000 Mbps and 10/100 Mbps ports.
MLT designated ports show as null after toggling the SMLT/IST ports. This is purely a display
difference. There is no impact on functionality.

MLT with LACP and Spanning Tree configuration considerations

Only the physical link state or its LACP peer status affects LACP module operation. When a
link is enabled or disabled, an LACP module is notified. STP forwarding state does not affect
LACP module operation. LACPDUs can be sent if the port is in an STP blocking state.
Unlike legacy MultiLink trunks, configuration changes (such as speed and duplex mode) to a
LAG member port are not applied to all member ports in the MultiLink trunks. The changed
port is removed from the LAG and the corresponding aggregator and the user is alerted when
the configuration is created.
In contrast to MLT, MLT with LACP does not expect BPDUs to be replicated over all ports in
the trunk group. Therefore, you must enter the ntstg disable command to disable the
parameter on the Spanning Tree Group (STG) for LACP-based link aggregation. For more
information about this command, see Avaya Ethernet Routing Switch 8800/8600 Configuration
— VLANs and Spanning Tree, NN46205-517.
ntstg disable parameter is applicable to all trunk groups that are members of the STG.
This is applicable when internetworking with devices only send BPDUs out of one port of the
LAG.
Important:
LACP, as defined by IEEE, is a protocol that exists between two bridge endpoints; therefore,
the LACP PDUs are terminated at the next SP interface.
Configuration — Link Aggregation, MLT, and SMLT
Link aggregation configuration considerations
January 2012 53