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Server Port - Trunk Mode

Level 4
Level 4


One of the Server ports (pointing towards a UCS Chassis) on my fabric interconnect is currently showing as down as it is Trunk mode not Fabric Mode as per all the other server ports.

For some reason when I look under the LAN tab this one interface is showing under "internal LAN". I have tried disabling and/or deleting the interface from under "internal LAN" however every time I re-configure the port as a Server Port it is showing back under and the mode remains in Trunk.

Does anyone have some advice how I can get this port out of Trunk Mode and into Fabric Mode?

Many Thanks, Paul

7 Replies 7

Zaira Vega
Cisco Employee
Cisco Employee

The port will be on Trunk when it is not getting proper connectivity between the IOM and the FI.

Check the physical connection and make sure the cable is properly seated at both ends.

If possible, try a different cable.

You can also try:

- Unconfigure the port

- Configure it as uplink

- Disable it

- Reconfigure as server.

What is the chassis discovery policy?

How many links are connected between IOMs and FI?

Thanks Zaira for getting back to me.

I have tried your suggested steps to resolve this and unfortunately this has not resolved the problem.

However to confirm when we moved the "faulty" optic/cable to new ports to a new location and it worked so would indicate this is not an issue with the optics or cables.

The chassis discovery policy is 1 link and there are 2 links between the IOMs/FIs.

Hi Paul,

Does the interface report any fault?

Is the interface able to confirm the presence of the optic cable?

What happens if you try setting up the interface as a uplink port?

Did the issue perists?

Please provide us with the following details:

UCS-A(nxos)# show run interface eth x/y

UCS-A(nxos)# show interface fex-fabric

UCS-A(nxos)# show fex detail

UCS-A(nxos)# show interface ethernet x/x transceiver details


Hi Cristian,

As requested please see outputs below:

UCS1-A(nxos)# sh run int e1/22

interface Ethernet1/22

  description S: Server

  no pinning server sticky

  switchport mode trunk

  switchport trunk native vlan xxx4

  switchport trunk allowed vlan xxx4,xxx7

  no shutdown

UCS1-A(nxos)# show int fex-fabric

     Fabric      Fabric       Fex                FEX

Fex  Port      Port State    Uplink    Model         Serial


  1    Eth1/1        Active     1         N20-C6508  xx

  1    Eth1/2        Active     2         N20-C6508  xx

  2    Eth1/3        Active     1         N20-C6508  xx

  2    Eth1/4        Active     2         N20-C6508  xx

  3    Eth1/5        Active     1         N20-C6508  xx

  3    Eth1/6        Active     2         N20-C6508  xx

  4    Eth1/7        Active     1         N20-C6508  xx

  4    Eth1/8        Active     2         N20-C6508  xx

  5    Eth1/9        Active     1         N20-C6508  xx

  5   Eth1/10        Active     2         N20-C6508  xx

  6   Eth1/11        Active     1         N20-C6508  xx

  6   Eth1/12        Active     2         N20-C6508  xx

  7   Eth1/13        Active     1         N20-C6508  xx

  7   Eth1/14        Active     2         N20-C6508  xx

  8   Eth1/15        Active     1         N20-C6508  xx

  8   Eth1/16        Active     2         N20-C6508  xx

  9   Eth1/17        Active     1         N20-C6508  xx

  9   Eth1/18        Active     2         N20-C6508  xx

10   Eth1/19        Active     1         N20-C6508  xx

10   Eth1/20        Active     2         N20-C6508  xx

11   Eth1/21        Active     1         N20-C6508  xx

12   Eth1/23        Active     1         N20-C6508  xx

12   Eth1/24        Active     2         N20-C6508  xx

13   Eth1/25        Active     1         N20-C6508  xx

13   Eth1/26        Active     2         N20-C6508  xx

14   Eth1/27        Active     1         N20-C6508  xx

14   Eth1/28        Active     2         N20-C6508  xx

UCS1-A(nxos)# show fex 1 detail

FEX: 1 Description: FEX0001   state: Online

  FEX version: 5.0(3)N2(2.11.3a) [Switch version: 5.0(3)N2(2.11.3a)]

  FEX Interim version: 5.0(3)N2(2.11.3a)

  Switch Interim version: 5.0(3)N2(2.11.3a)

  Chassis Model: N20-C6508,  Chassis Serial: XXX

  Extender Model: UCS-IOM-2204XP,  Extender Serial: XXX

  Part No: 73-14488-03

  Card Id: 184, Mac Addr: c0:67:af:84:a6:5a, Num Macs: 38

  Module Sw Gen: 21  [Switch Sw Gen: 21]

  post level: complete

pinning-mode: static    Max-links: 1

  Fabric port for control traffic: Eth1/1

  Fabric interface state:

    Po1025 - Interface Up. State: Active

    Eth1/1 - Interface Up. State: Active

    Eth1/2 - Interface Up. State: Active

  Fex Port        State  Fabric Port

         Eth1/1/1  Down      Po1025

         Eth1/1/2  Down      Po1025

         Eth1/1/3  Down        None

         Eth1/1/4  Down        None

         Eth1/1/5  Down        None

                Eth1/1/6  Down        None

         Eth1/1/7  Down        None

         Eth1/1/8  Down        None

         Eth1/1/9  Down      Po1025

        Eth1/1/10  Down      Po1025

        Eth1/1/11  Down        None

        Eth1/1/12  Down        None

        Eth1/1/13  Down        None

        Eth1/1/14  Down        None

        Eth1/1/15  Down        None

        Eth1/1/16  Down        None

        Eth1/1/17    Up      Po1025


01/03/2014 11:23:14.295257: Module register received

01/03/2014 11:23:14.296133: Registration response sent

01/03/2014 11:23:14.580311: Module Online Sequence

01/03/2014 11:23:17.47105: Module Online

If possible would you be free to discuss this on a WebEx?

Kind Regards, Paul

Please feel free to reach me Paul.

Did you get this resolved? I have a similar issue with 3 ports.



FYI - My issue was caused by the wrong type of SFP being inserted into the IOM.



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