Design Reference

Scenario 1: VSP 4000 as an edge router
Scenario 1 demonstrates a triangular setup with ERS 8800 switches as IST peers, and VSP 4000
on the edge. From VSP 4000, there are four links that are part of the same MLT, with SLPP enabled
on the VSP 4000 ports. Because the MLT ports are misconfigured, loops can occur. For example,
port 1/1 on VSP 4000 can be part of the MLT, but on the ERS port, 2/1 is not part of the MLT,
although they are on the same VLAN.
Figure 9: VSP 4000 as an edge router
SLPP PDUs are generated by VSP 4000. If there is a loop, the SLPP PDUs return to port 1/1. After
the threshold value is reached, SLPP shuts the ports down.
Scenario 2: VSP 4000 as an edge router but with an additional link to the ERS 8800
Scenario 2 is similar to scenario 1 except that there is an additional link from ERS 8800 to VSP
4000 that is not part of MLT 1. The additional link is a member of the SLPP-enabled VLAN, and
does not have to be directly connected from ERS 8800 to VSP 4000, but can be connected from
other devices interconnected to the ERS 8800 and VSP 4000.
Layer 2 loop prevention
48 Network Design Reference for Avaya VSP 4000 Series January 2015
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