Design Reference

holddown timer to a minimum of 1.5 times the IGP convergence time is sufficient. For OSPF,
Avaya recommends that you use a value of 90 seconds if you use the default OSPF timers.
• Implement VRRP BackupMaster for an active-active configuration (BackupMaster works
across multiple switches that participate in the same VRRP domain).
• Configure VRRP priority as 200 to configure VRRP Master.
• Stagger VRRP Masters between switches in the core to balance the load between switches.
• If you implement VRRP Fast, you create additional control traffic on the network and also
create a greater load on the CPU. To reduce the convergence time of VRRP, the VRRP Fast
feature allows the modification of VRRP timers to achieve subsecond failover of VRRP.
Without VRRP Fast, normal convergence time is approximately 3 seconds.
• Do not use VRRP BackupMaster and critical IP at the same time. Use one or the other.
• When you implement VRRP on multiple VLANs between the same switches, Avaya
recommends that you configure a unique Virtual Router ID (VRID) on each VLAN.
VRRP and spanning tree
VSP 4000 can use one of two spanning tree protocols: Rapid Spanning Tree Protocol (RSTP) and
Multiple Spanning Tree Protocol (MSTP).
VRRP protects clients and servers from link or aggregation switch failures. Configure the network to
limit the amount of time a link is out of service during VRRP convergence. The following figure
shows two possible configurations of VRRP and spanning tree; configuration A is optimal and
configuration B is not.
Figure 30: VRRP and STG configurations
Virtual Router Redundancy Protocol
June 2015 Network Design Reference for Avaya VSP 4000 Series 79
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