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fc2/y is down (Link failure: NOS received)

Please Help

UCSM : 1.4 (3l)

Storage FC Ports : fc2/1, fc2/3, fc2/5

error : fc2/5

B(nxos)# sh interface fc 2/5

fc2/5 is down (Link failure: NOS received)

----------------------------------------------------------------------------------------------------------------------

from UCSM

fc port 5 on fabric interconnect B oper state:failed, reason:Link failure: NOS received

-----------------------------------------------------------------------------------------------------------------------

disable and enable port

error : fc2/5

B(nxos)# sh interface fc 2/5

fc2/5 is down (Link failure or not-connected)

wahtis the root cause problem?

Best regards

1 Accepted Solution

Accepted Solutions

Pragna Yeraballi
Cisco Employee
Cisco Employee

Hello,

NOS refers to "No operatioal sequence". Fibre channel has primitive seqences which are used to establish and maintain a link among the devices.

During the initial login phase,

1.Fiber channel switch sends a NOS signal

2.HBA connected to it sends an "OLS (offline sequence) signal.

3.Switch would send  a "Link reset"(LR)

4.HBA responds with a "LRR (link reset response)"

When a NOS received condition is met,

A signal loss or sync loss condition is detected.

The port is administratively shut down.

The port is operationally down.

When the port status is in "link failure or not-connected" state, it means that the physical path is not completely active or no active signals has been sent. Check the cables/SFP's if pluged in properly and check the configuration (port type, speed and vsan settings) for further troubleshooting.

View solution in original post

2 Replies 2

Pragna Yeraballi
Cisco Employee
Cisco Employee

Hello,

NOS refers to "No operatioal sequence". Fibre channel has primitive seqences which are used to establish and maintain a link among the devices.

During the initial login phase,

1.Fiber channel switch sends a NOS signal

2.HBA connected to it sends an "OLS (offline sequence) signal.

3.Switch would send  a "Link reset"(LR)

4.HBA responds with a "LRR (link reset response)"

When a NOS received condition is met,

A signal loss or sync loss condition is detected.

The port is administratively shut down.

The port is operationally down.

When the port status is in "link failure or not-connected" state, it means that the physical path is not completely active or no active signals has been sent. Check the cables/SFP's if pluged in properly and check the configuration (port type, speed and vsan settings) for further troubleshooting.

Hello Pragna,

Thank u so much,

  change the cable : solved

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