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How to resolve fabric related connectivity issues

Last Updated:

Applies to

SAN Protocol


In a SAN environment, a fabric is the transport layer and is essential for reliable communications. When the transport layer is unreliable, hosts may experience issues ranging from high or increased latency to LUN resets to IO timeouts.

In a NETAPP SAN, either Ethernet or Fibre Channel can be used for data transport.  This workflow will cover common Fibre Channel issues.

If the issue is a NETAPP LIF (not a port) that is down, then see this KB: FCP/FCoE LIF reports operationally down

Link is flapping

A link flapping event is defined as a link that goes down and comes back up (usually immediately) with no user intervention.  Usually, but not always, the link will go down again either immediately or shortly thereafter, and the process will repeat.

Port is down or offline on the switch  

The switch reports a port status as down for a port.

The switch may log an error stating the reason for the port being offline in the errdump output for Brocade or show logging log for Cisco:

Mon Jun 26 2017 09:45:41 GMT+03:00ErrorS0,P12(Bp8) user_idx:12 [PID 0x3e0c00] faulted due to SFP validation failure.

Additionally, the Switchshow output shows the port offline:

Index  Port    Address      Media      Speed      State       Proto
2          2       3e0200          id            N16      No_Light     FC
11       11      3e0b00          id            N16      No_Light     FC
12       12     3e0c00           id             16G     Laser_Flt    FC
19       19     3e1300           id            N16      Laser_Flt    FC

Port is down or offline on the filer

The NETAPP controller will report the port as simply offline or link disconnected in sysconfig -a:

slot 1: Fibre Channel Target Host Adapter 1b (Emulex LPe32000 (LPe32002) rev. 12, <LINK DISCONNECTED>)


slot 0: FC Host Adapter 0c (QLogic 8324 rev. 2, L-port, <OFFLINE (hard)>)


slot 0: FC Host Adapter 0a (QLogic 8324 rev. 2, L-port, <OFFLINE>)

Port may not negotiate speed corectly

Ports negotiate speeds different than what is expected.  For example, a 16 gb port may negotiate to 8 gb.


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