VSS Link on port-channel err-disabled

[v.matiakis]

Hello there,

One of the 4  VSS link has changed to err-disabled :

Port      Name               Status       Reason
Te2/3/5       *VSL* Link         err-disabled link-flap

My concern is why something like might have happened and which steps should i follow in order to fix this problem? If i re-enable the link via shut-no shut will i have any strange behaviour? Unfortunatelly no log is beeing kept.

[Yogesh Ramdoss]

Hello,

Whenever you experience physical layer issue with VSL, I would recommend doing following commands and analyze the results.

(1) show switch virtual link

(2) show switch virtual link port

(3) show vslp lmp counters

(2) command gives you general health of the VSL links, and (3) command provides statistics for LMP traffic (both Rx and Tx) on all VSL ports.

Say, SW1 see LMP from SW2 without its info in the packet, then it indicates unidirectional failure and may shutdown the port (same as UDLD)

I am not sure if you have the setup still in the broken condition, If so, please do send us the logs.

Regards,

Yogesh

[v.matiakis]

Hi there and thank you for the reply. The configuration output you have requested :

************ show switch virtual link ***************

VSL Status : UP

VSL Uptime : 4 weeks, 2 days, 3 hours, 38 minutes

VSL SCP Ping : Pass

VSL ICC Ping : Pass

VSL Control Link : Te1/5/4 

************* show switch virtual link port *******************

  LMP summary

    Link info:        Configured: 2        Operational: 1

                            Peer Peer          Peer   Peer      Timer(s)running

Interface Flag State        Flag MAC           Switch Interface (Time remaining)

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

Te1/5/4   vfs  operational  vfs  ec30.91e1.c8c0 2      Te2/5/4   T4(228ms)

                                                                 T5(59.97s)

Te1/2/6   v    link_down    -    -               -     -         

Flags:  v - Valid flag set        f - Bi-directional flag set

         s - Negotiation flag set

Timers: T4 - Hello Tx Timer   T5 - Hello Rx Timer

  LMP Status

          Last operational        Current packet          Last Diag   Time since

Interface Failure state           State                   Result      Last Diag

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

Te1/5/4   Link down               Hello bidir             Never ran   --

Te1/2/6   Probe myinfo absent     Probe myinfo absent     Passed      142d:15h:46m:26s

  LMP hello timer

                         Hello Tx (T4) ms          Hello Rx (T5*) ms

Interface   State        Cfg     Cur     Rem       Cfg     Cur     Rem

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

Te1/5/4     operational  -       500     228       -       60000   59760

Te1/2/6     link_down    -       -       -         -       -       -    

*T5 = min_rx * multiplier

Cfg : Configured Time

Cur : Current Time

Rem : Remaining Time

******************* show vslp lmp counters **********************

Instance #1:

  LMP counters

                  Tx                              Rx

Interface    OK      Fail            Bidir   Uni     Fail    Bad

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

Te1/5/4      64905956 0               64911298 1       0       0     

Te1/2/6      40420899 0               40423699 29      0       0     

                        Rx error details

Interface  My info     My info     Bad MAC     Bad switch  Domain id   Peer info

           mismatch    absent      Address     id          mismatch    mismatch

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

Te1/5/4    0           1           0           0           0           0    

Te1/2/6    0           29          0           0           0           0  

[Yogesh Ramdoss]

Hello,

I assume the VSL links are setup as follows:

SW1 (1/5/4) ---- (2/5/4) SW2

          (1/2/6) ---- (2/3/5)

As you notice, SW1 Te1/2/6 port has received LMP packets from SW2 Te2/3/5, but without its info in the packet. This indicate that SW2 do not see SW1 on Te2/3/5.

LMP Status

          Last operational        Current packet          Last Diag   Time since

Interface Failure state           State                   Result      Last Diag

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

Te1/5/4   Link down               Hello bidir             Never ran   --

Te1/2/6   Probe myinfo absent     Probe myinfo absent     Passed      142d:15h:46m:26s  <<<===

******************* show vslp lmp counters **********************

Instance #1:

LMP counters

                        Rx error details

Interface  My info     My info     Bad MAC     Bad switch  Domain id   Peer info

           mismatch    absent      Address     id          mismatch    mismatch

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

Te1/5/4    0           1           0           0           0           0

Te1/2/6    0           29          0           0           0           0   <<<===

Te1/2/6 has received 29 LMP packets from peer, without its info.

Looks like unidirectional link issue ..... from SW1 to SW2 on (1/2/6)---(2/3/5) link.

Check fiber and transceivers on both sides. Hope this helps.

Regards,

Yogesh

[v.matiakis]

Hi there,

TenGigabitEthernet2/3/5 is down, line protocol is down (err-disabled)

If i shut-no shut the port could this be a solution tothe problem? Any ideas on how this issue could have happened?

[Yogesh Ramdoss · Accepted solution]

Hello,

Ten2/3/5 indicates "link-flap" error-disabled the port, and Te1/2/6 received LMP with "MyInfoAbsent".

It is a physical layer issue. Someone need to check the fiber/transceiver and/or check the dB levels on the fiber.

If dB level is not in the "acceptable" range, link will go down.

Yogesh