In a mesh topology,each switch is directly connected to other switches by using ISC.This topology promotes enhanced connectivity within SAN.When the number of ports on a network increases,the number of nodes that can participate & communicate also increases.

There are two types of Mesh Topology-

a)Full Mesh

b)Partial Mesh

In Full Mesh every switch is connected to every other switch in topology.

Full Mesh topology may be appropriate when the number of switches involved in are small.

A typical deployment would involve upto four switches or directors with each of them servicing highly localized host to storage traffic.

In a full mesh topology , a maximum of one ISL or hop is required for host to storage traffic.

In a partial mesh topology,several hops or ISL may be required for the traffic to reach its destination.

Hosts and storage can be located anywhere in the fabric ,& storage can be localized to a director or a switch in both mesh topologies.

Thus for high availability solution ,full mesh topology is used.

In mesh one ISL for each host to storage

i.e.17*16=272 ports

Total ports available = 17*16=272

So ISL required are 136 i.e.272/2

Each ISL requires / consume two ports available ports 272 ports

Thus 'zero'/'0' number of ports available for hosts.

free ports = total port -(total switch - ISL)

           = 16-(17-1)

           =0