Smlt And Lacp Support - Avaya 8600 Configuration Manual

SMLT and LACP support

The Ethernet Routing Switch 8800/8600 fully supports the IEEE 802.3ad LACP on MLTs and
on a pair of SMLT switches.
With LACP the Ethernet Routing Switch 8800/8600 provides a standardized external link
aggregation interface to third-party vendor IEEE 802.3ad implementations. This protocol
extension provides dynamic link aggregation mechanisms. Only dual-home devices benefit
from this enhancement.
Advantages of this protocol extension include:
• MLT peers and SMLT client devices can be both network switches and any type of server/
workstation that supports link bundling through IEEE 802.3ad.
• Single-link and MultiLink trunk solutions support dual-home connectivity for more than
350 attached devices, so that you can build dual-home server farm solutions.
Supported SMLT/LACP scenarios
SMLT/IEEE link aggregation interaction supports all known SMLT scenarios in which an IEEE
802.3ad SMLT pair connects to SMLT clients, or in which two IEEE 802.3ad SMLT pairs
connect to each other in a square or full-mesh topology.
Unsupported SMLT/LACP scenarios
Some of the unsupported SMLT/LACP scenarios include the following factors, which lead to
failure:
• Incorrect port connections.
• Mismatched SMLT IDs assigned to SMLT client. SMLT switches can detect if SMLT IDs
are not consistent. The SMLT aggregation switch, which has the lower IP address, does
not allow the SMLT port to become a member of the aggregation thereby avoiding
misconfigurations.
• SMLT client switch does not have automatic aggregation enabled (LACP disabled). SMLT
aggregation switches can detect that aggregation is not enabled on the SMLT client, thus
no automatic link aggregation is established until the configuration is resolved.
• Single CPU failures. In the case of a CPU failure in a system with only one switch fabric,
the LACP on the other switch (or switches) detects the remote failure and triggers removal
of links connected to the failed system from the LAG. This process allows failure recovery
for the network along a different network path.
• LACP is not supported on SMLT NNIs because it can cause traffic to be silently
dropped.
Configuration — Link Aggregation, MLT, and SMLT
Split MultiLink Trunking
January 2012 37