Storage Network
The Storage Network domain covers Cisco MDS and Nexus FCoE: Fibre Channel services, VSAN design, zoning, NPV/NPIV, SAN port channels, and FCIP.
Fibre Channel basics
FC uses WWPNs for ports and WWNNs for nodes. An N port logs in with FLOGI to an F port and receives a fabric address (domain, area, port). The principal switch assigns domain IDs; FSPF routes between E ports; FCNS distributes name-server entries. VSANs partition one physical SAN into isolated fabrics, each with its own domain IDs, zoning, and services.
Zoning
Zoning is the access control mechanism and is enforced in the fabric. Best practice is single-initiator, single-target zones, built from device aliases rather than raw pWWNs, grouped into a zone set that must be activated. Enhanced zoning distributes the full database and locks changes; the default zone is the fallback for devices that are in no zone.
NPV and NPIV
NPIV lets one N port present many WWPNs. NPV makes an edge switch behave as a host to the core: its uplinks are NP ports, it does not take a domain ID, and it passes logins through. Use NPV when the edge should not participate in fabric services.
FCoE and FCIP
FCoE carries FC frames over lossless Ethernet. It needs jumbo MTU, PFC, and DCBX on the LAN, a vFC interface bound to a physical port, and FIP snooping on the bridge. FCIP tunnels FC over IP between sites with VE ports, which lets you merge fabrics without dark fibre.
Worked example
A new host HBA must see exactly one storage array port. Create device alias host_hba for the HBA pWWN and array_port for the array pWWN, create zone host_hba_to_array_port containing both, add it to the zone set, activate the zone set, then verify with show zoneset active and show flogi database. The single-initiator zone stops the host from discovering other initiators.
Traps
- Believing NPV switches consume a domain ID.
- Leaving devices in the default zone and assuming they are blocked.
- Building zones without activating the zone set.
- Mixing VSAN IDs on the two ends of an ISL or SAN port channel.