What causes a port to be No_Sync in Fabric OS?

Applies to

• Brocade FC Switch
• Fabric OS (FOS)

Answer

• FC port cannot complete the synchronization phase when establishing a link with the remote device and is in state No_Sync
• Port showing No_Sync indicates that the port is receiving the light but frames received are 'out of sync'.
• Faulty cable or remote SFP can be narrowed down further with porterrshow delta or after statsclear  after port was enabled:

• Port down and enabled in No_Sync

Example:

switchshow:
Index Port Address  Media Speed   State       Proto
==================================================
   5   5   080500   id    16G     No_Sync     FC

portshow 5
portDisableReason: None
portCFlags: 0x1
portFlags: 0x4041        PRESENT U_PORT LED
LocalSwcFlags: 0x0
portType:  27.0
POD Port: Port is licensed
portState: 2    Offline
Protocol: FC
portPhys:  5    No_Sync        portScn:   2    Offline

sfpshow:
RX Power:    -7.0    dBm (199.8uW) 
TX Power:    -40.0   dBm (0.1   uW)

Note: As the port is offline, the SFP's laser is turned off (TX -40)

• Port down and disabled in No_Sync

Example:

switchshow:
Index Slot Port Address Media  Speed        State    Proto
============================================================
 213   10   21   67d540   id    N32   No_Sync     FC  Disabled

portshow 213
portDisableReason: None
portCFlags: 0x0
portFlags: 0x4021     PRESENT U_PORT DISABLED LED
LocalSwcFlags: 0x0
portType:  26.0
portState: 2    Offline  
Protocol: FC
portPhys:  5    No_Sync      portScn:   2    Offline   

sfpshow:
RX Power:    -9.0    dBm (125.7uW)
TX Power:    -40.0   dBm (0.1   uW) 

• Faulty switch-side SFP
• Brocade FC port offline with No_Sync state and -inf TX power - NetApp Knowledge Base
• Brocade FC port offline with No_Sync state due to faulty switch SFP
• Brocade FC port offline with No_Sync state due to faulty cable

• Port down, disabled, throttled and in No_Sync

Example:

switchshow:
Index Slot Port Address Media  Speed        State    Proto
============================================================
 383   12   47   67f7c0   id    N32   No_Sync     FC  Disabled (Port Throttled)

portshow 383
portDisableReason: None
portCFlags: 0x1
portFlags: 0x41     PRESENT U_PORT
LocalSwcFlags: 0x0
portType:  26.0
portState: 2    Offline  
Protocol: FC
portPhys:  5    No_Sync      portScn:   2    Offline   

sfpshow:
RX Power:    -3.1    dBm (494.9uW) 
TX Power:    -40.0   dBm (0.1   uW) 

• This may require further analysis (supportshow / supportsave)

Additional Information

• FOS 9.1: switchShow (broadcom.com)
• FOS 8.2: Brocade® Fabric OS® Command Reference Manual, 8.2.x (broadcom.com)
• To see statistics within a known timeframe:
  1. Enable port (port enable or portCfgPersistentEnable)
  2. Run statsclear or portstatsclear
  3. Wait 15 min (or longer (hours) as it increases accuracy)
  4. Analyse porterrshow output