Avaya 8600 Configuration Manual page 27

Figure 5: SMLT aggregation switches and operations
Aggregation switches use the interswitch trunk to:
• Confirm that they are alive and exchange MAC address forwarding tables.
• Send traffic between single switches attached to the aggregation switches.
• Serve as a backup if one SMLT link fails.
Because SMLT requires the interswitch trunk, Avaya recommends that you use multiple links
on the interswitch trunk to ensure reliability and high availability. Avaya also recommends that
you use Gigabit Ethernet links for interswitch trunk connectivity to provide enough bandwidth
for potential cross traffic.
Avaya recommends that an interswitch MultiLink trunk contain at least two physical ports.
Avaya also recommends that you disable CP-Limit on all physical ports that are members of
an interswitch trunk MultiLink trunk, so as not to compromise the stability of SMLT.
Important:
Avaya recommends that you do not configure CP-Limit or Extended CP-Limit on the IST
MLT.
Disabling the CP-Limit on interswitch trunk MultiLink trunk ports forces another, less-critical
port to be disabled if the defined CP Limits are exceeded. This preserves network stability if a
protection condition (CP Limit) arises. It is likely that one of the MultiLink trunk ports (risers)
can be disabled in such a condition; traffic continues to flow uninterrupted through the
remaining SMLT ports.
For more information about CP-Limit and Extended CP-Limit, see Avaya Ethernet Routing
Switch 8800/8600 Administration, NN46205-605 .
Configuration — Link Aggregation, MLT, and SMLT
Split MultiLink Trunking
January 2012 27