FSPF = Fabric Shortest Path First

FSPF is a path selection protocol. IT is enabled by default on all storage switches and doesn't have to be configured.

1. Fibre Channel routing is based only on Domain ID (first byte in the 3-byte FCID address assigned by and MDS switch to an end device)
2. FSPF runs only on E and TE ports and it provides a loop free topology
3. FSPF runs on a per VSAN basis
4. FSPF routes are unidirectional. It is possible to have different paths in each direction of the fibre channel traffic
5. uses the Dijkstra's algorithm.
6. FSPF treats a port channel as a single logical link. If one of the members fails in a port channel FSPF is not aware of this change

Default FSPF cost:

1 Gig link is 1000

2 Gig link is 500

4 Gig link is 250

8 Gig link is 125

10 Gig link is 100

We could change this value:

(config)# interface fc 1/2

(config-if)# fspf const 20 vsan 2

mds9506# show fspf internal route vsan 1
FSPF Unicast Routes
---------------------------
 VSAN Number  Dest Domain   Route Cost    Next hops
-----------------------------------------------
           1    0xc9(201)          250        fc1/8
                                             fc1/12


bdc-mds9506-2# show fspf interface
FSPF interface fc1/8 in VSAN 1
FSPF routing administrative state is active
Interface cost is 250
Timer intervals configured, Hello 20 s, Dead 80 s, Retransmit 5 s
FSPF State is FULL
Neighbor Domain Id is 0xc9(201)
Neighbor Interface is fc1/7 (0x00010006)


bdc-mds9506-2# show fspf database vsan 1
FSPF Link State Database for VSAN 1 Domain 0x1f(31)
LSR Type                = 1
Advertising domain ID   = 0x1f(31)
LSR Age                 = 1695
LSR Incarnation number  = 0x8000023e
LSR Checksum            = 0xa174
Number of links         = 2
 NbrDomainId      IfIndex   NbrIfIndex    Link Type         Cost
-----------------------------------------------------------------------------
   0xc9(201) 0x00010007     0x00010006               1          250
   0xc9(201) 0x0001000b     0x00010004               1          250


To see actual routing table for unicast:

mds9506# show fcroute unicast

D:direct  R:remote  P:permanent  V:volatile  A:active  N:non-active
                                                          # Next
Protocol  VSAN       FC ID/Mask        RCtl/Mask    Flags  Hops  Cost
--------  ----    -------- --------    ---- ----    -----  ----  ----
local     1       0x1f0000 0xffffff    0x00 0x00    D P A  1     1
fspf      1       0xc90000 0xff0000    0x00 0x00    D P A  2     250
fspf      100     0x8c0000 0xff0000    0x00 0x00    D P A  2     250

? show system internal rib unicast