Design Reference

Chapter 10: Layer 3 switch clustering and
RSMLT
This section describes designs for achieving network redundancy. Network redundancy minimizes
failure and ensures a faulty switch does not interrupt service.
Related Links
Routed SMLT on page 54
Switch clustering topologies and interoperability with other products on page 61
Routed SMLT
Core network convergence time usually depends on the length of time a routing protocol requires to
successfully converge. This convergence time can cause network interruptions that range from
seconds to minutes depending on the specific routing protocol. Routed Split Multilink Trunking
(RSMLT) allows rapid failover for core topologies by providing an active-active router concept to
core SMLT networks. Virtual Services Platform 4000 supports RSMLT on SMLT triangles, squares,
and SMLT full-mesh topologies that have routing enabled on the core VLANs. RSMLT provides
redundancy as well. If a core router fails, RSMLT provides packet forwarding. This eliminates
dropped packets during convergence.
Virtual Services Platform 4000 can use one of the following routing protocols to provide
convergence:
• IP or IPv6 unicast static routes
• Routing Information Protocol version 1 (RIPv1) or version 2 (RIPv2) (IPv4)
• Open Shortest Path First (OSPF) and OSPFv3
• Border Gateway Protocol (BGP) (IPv4) and BGP+
SMLT and RSMLT operation
SMLT and RSMLT in Layer 2 and 3 environments on page 55 shows a typical redundant network
with user aggregation, core, and server access layers. To minimize the creation of many IP subnets,
one VLAN (VLAN 1, IP subnet A) spans all wiring closets. SMLT provides loop prevention and
enables all links to forward to VLAN 1, IP Subnet A. RSMLT runs on the core.
54 Network Design Reference for Avaya VSP 4000 Series June 2015
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