Avaya 8800 Planning And Engineering, Network Design page 85

Network redundancy
A triangle design is an SMLT configuration in which you connect edge switches or SMLT clients to
two aggregation switches. You connect the aggregation switches together with an interswitch trunk
that carries all the SMLTs configured on the switches. Each switch pair can have up to 127 SMLT
client switch connections, and up to 512 SLT connections. When you use the square design (Figure
22: SMLT square configuration on page 85), keep in mind that all links facing each other (denoted
by the MLT ring on an aggregation pair) must use the same SMLT IDs.
Figure 22: SMLT square configuration
You can configure an SMLT full-mesh configuration as shown in Figure 23: SMLT full-mesh
configuration on page 85. In this configuration, all SMLT ports use the same SmltId (denoted by
the MLT ring). The SMLT ID is of local significance only and must be the same on a cluster. For
example, the top cluster could use SMLT ID 1 while the bottom cluster can use SMLT ID 2.
Because the full-mesh configuration requires MLT-based SMLT, you cannot configure SLT in a full-
mesh. In the following figure, the vertical and diagonal links emanating from any switch are part of
an MLT.
Figure 23: SMLT full-mesh configuration
R series modules, in Release 4.1 and later, and RS modules, in Release 5.0 and later, support up to
128 MLT groups of 8 ports. Within the network core, you can configure SMLT groups as shown in
the following figure. Both sides of the links are configured for SMLT. No state information passes
across the MLT link; both ends believe that the other is a single switch. The result is that no loop is
introduced into the network. Any of the core switches or any of the connecting links between them
may fail, but the network recovers rapidly.
You can scale SMLT groups to achieve hierarchical network designs by connecting SMLT groups
together. This allows redundant loop-free Layer 2 domains that fully use all network links without
using an additional protocol.
June 2016 Planning and Engineering — Network Design 85
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