Trying to wrap my head around how Fibre Channel Frames are actually populated and sent through a switched fabric. I Understand WWNN WWPN, WWNN is a WWN of the actual HBA, and WWPN are the WWN of the actually ports on the card. So if a HBA has 4 ports, they all share the same WWNN but have different WWPN. Still not sure where WWNN comes into play with the communication in a fabric though. Secondly, the FLOGI Process by which a new N_port node tries to login to the fabric and get assigned a dynmic FCID. There after a PLOGI is done so the N-port node can submit it's WWPN. This maintains a WWPN to FCID relationship....
Lastly, FC addressing is a combination of a domain ID, area ID, and port ID. All 8bits. My understanding is it is used to locate where in a fabric a interface is? So if i have two switches domain 1 and domain 2, 0100000 would mean first switch area 00 and port 00?
Furthermore I am still unsure of how a host sends to another host. Looking at a FC frame there are fields for Destination ID and Source ID which are 24-bit FC addresses or FCIDs. My question is do these DestID and SourceID get populated by the host HBA or by the FC switch?? I thought a host only knew it's own WWNN and WWPN from the HBA?
Secondly I don't see anywhere in the Fibre Channel frame where WWNN or WWPN come in to play. Unless they are only used in the FLOGI and PLOGI process to obtain a dynamic FCID.
Thanks for your help. Appreciate it.
PS I am using a Cisco MDS and on our hosts fcinfo to gather information, I cannot see a way to get the FCID using fcinfo on each host? That is why i am confused if the host maintains a list of destination FCIDs or not.
Also, for directly connected hosts, no switch involvment, do the hosts FLOGI into each other?