S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m
The host is configured with a VRRP address as the portal address. When the VRRP master port receives
the first iSCSI session from an initiator, it assigns a backup port to serve that particular host. This
information is synchronized to all switches through CFS if recovery is needed when a master port fails.
The initiator gets a temporary redirect iSCSI login response. The host then logs in to the backup port at
its physical IP address. If the backup port goes down, the host will revert to the master port. The master
port knows through CFS that the backup port has gone down and redirects the host to another backup
If an Ethernet PortChannel is configured between the IPS module and an Ethernet switch, the load
balancing policy on the Ethernet switch must be based on source/destination IP address only, not port
numbers, for load balancing with VRRP to operate correctly.
An initiator can also be redirected to the physical IP address of the master interface.
iSLB VRRP load balancing is based on the number of iSLB initiators and not number of sessions. Any
iSLB initiator that has more targets configured than the other iSLB initiators (resulting in more sessions)
should be configured with a higher load metric. For example, you can increase the load metric of the
iSLB initiator with more targets to 3000 from the default value of 1000.
Cisco MDS 9000 Family CLI Configuration Guide
iSLB Initiator Load Balancing Example
to T2, T3
to T3, T4
OL-16184-01, Cisco MDS SAN-OS Release 3.x