> # About iSLB

> The iSCSI server load balancing (iSLB) feature provides a means to easily configure large scale iSCSI deployments containing hundreds or even thousands of initiators. iSLB provides the following features:

> - The iSLB initiator configuration is simplified with support for initiator targets and auto-zones.
> - Cisco Fabric Services (CFS) eliminates the need for manual configuration by distributing the iSLB initiator configuration among all MDS switches in the fabric.
> - Dynamic load balancing of iSLB initiators is available using iSCSI login redirect and VRRP.

> When not using iSLB, configuring iSCSI requires the following:

> - You need to perform multiple configuration steps on the MDS switch, including the following:
> - Initiator configuration using static pWWN and VSAN.
> - Zoning configuration for initiators and targets.
> - Optional create virtual target and give access to the initiator.
> - Configuration of target LUN mapping and masking on the storage system for the initiator based on the static pWWN created for the initiator on the MDS switch.
> - You need to duplicate the configuration manually on multiple MDS switches.
> - There is no load balancing for IPS ports. For example:
> - The Virtual Router Redundancy Protocol (VRRP) only supports active and backup, not load balancing.
> - You must use multiple VRRP groups and configure hosts in different groups.

> iSLB provides the following features:

> - The iSLB initiator configuration is simplified with support for initiator targets and auto-zones.
> - Cisco Fabric Services (CFS) eliminates the need for manual configuration by distributing the iSLB initiator configuration among all MDS switches in the fabric.

> Note Only statically mapped iSLB initiator configuration is distributed throughout the fabric using CFS. Dynamically and statically mapped iSCSI initiator configurations are not distributed.

> - Dynamic load balancing of iSLB initiators is available using iSCSI login redirect and VRRP.

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