At the beginning was just the “SAN”, today that word has been often replaced with “Solution”, and the SAN is just part of it, but sometimes we forgot that SAN is not just connectivity. That is what recently happened to me, has already posted in my Blog about SAN zero buffer-to-buffer credit, in another situation I had to go back to SAN principle to understand if a Storage Virtualization solution with SVC in split cluster could use ISL with different link speed. I started the time machine and I got back to remove the dust from the SAN theory to refresh the FSPF concept.
FSPF (Fabric Shortest Path First) is a Link State path selection protocol, similar to OSPF, which is an Interior Gateway Protocol (IGP) widely used in IP networks.This protocol keeps track of the state of the links on all switches in the Fabric. It also associates a cost with each link. The protocol computes paths from a switch to all the other switches in the fabric, by adding the cost of all the links traversed by the path, and choosing the path that minimizes the cost. In order for the protocol to work,the cost must be a positive integer number. The collection of link states (including cost) of all the switches in a fabric constitutes the topology database.
Very helpful has been the following tip: