Posted on April 2, 2019 4:09 pm
 |  Asked by Grant Eastridge
 |  1296 views
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What type of physical layer events could potentially lead to an interface going to an errdisabled state…within the context of ‘show interface phy details’ counters? We are seeing three of these messages within the switch logs : 3981: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet4 followed by this: Ebra: 3984: %ETH-4-ERRDISABLE: link-interrupt-storm error detected on Ethernet4

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Posted by Runxin Wang
Answered on April 4, 2019 4:32 pm

Hi Grant,

Thanks for posting the questions.

For checking the reason of errdisable, you can use the following CLI:
# show interfaces status errdisabled

Link flapping is one possible reason interfaces are disabled. You can use “show mac detail” CLI to get a summary of the states of the interface, phy, “local fault” and “remote fault”. “show phy detail” gives more details but relatively more difficult to interpret.

show mac detail
# show interfaces mac detail

show phy detail
# show interfaces phy details

If you have more questions, you can provide the output of the above CLI, we can have a look.

-1
Posted by Niklas Hoglund
Answered on August 7, 2019 5:13 pm

hi,
if an interface is ErrDisabled (phy), it doesnt seem that it always reports why.
Is there another command than “sh int eth status errd” ?

Example:
SWITCH-SSL1#sh int eth 57/1 mac detail
Current System Time: Wed Aug 7 18:54:30 2019

Ethernet57/1
Current State Changes Last Change
PHY State errDisabled 3 5 days, 8:03:09 ago
Interface State linkDown 3 5 days, 8:03:18 ago
MAC Rx Local Fault True 1 5 days, 8:03:15 ago
MAC Rx Remote Fault False 0 never
SWITCH-SSL1#show interface status errd
SWITCH-SSL1#

2
Posted by Shreyas Ruwala
Answered on August 7, 2019 10:00 pm

Hello,

There can be couple of reasons for interface to go into errdisable state

1.For example if the number of flaps are more because of low light level/inconsistency in incoming Rx optical signal arista default behavior is to put the interface state in errdisable state as this alleviates the port going into Bad state because of excessive heating.
As far as I know, if we receive more than 5 flaps within 180 sec interval the port is put into errdisable state.

2.The same can be verified by
2a.Switch#sh interface status errdisable
This will give the reason
2b.From The mac details command
Switch#sh int etx/1-4 mac detail there are two fields
Mac Rx Local Fault=True, meaning problem with incoming signal from neighboring port/device
Mac Rx Remote Fault=True, meaning Arista switch port is sending faulty signal

3. Coming to Phy details, when you do
Switch#show int etx phy details
3a.The Rx_LOS signal row should be seen that indicates when was the last time the interface received proper light from neighboring port/device
3b.If we are sending bad signal then there is a row named TX_Fault that should be true

4.Now to recover from errdisable state, it depends on what is the reason you obtained 2a.
4a.Sometime bouncing (shut/no shut) a port resolve the issue
4b.Otherwise we have CLI command that can be configured across interface
Switch(conf-if)#errdisable recovery cause ?
? will list options to keep the port ij UP state until it is stabilized thereby avoiding active production impact.

5.Before concluding if its a optic,cable or port issue there are a series of L1 T-shooting steps I can share it with you

I would be more than happy to discuss this over a call if you would like to.
I am based out in East Coast Arista TAC team.

Otherwise, Feel free to send a email to support@arista.com and my colleagues are more than happy to dive deep into the issue if required

Hope this helps!

Sincerely,
Shreyas Ruwala
Technical Solutions Engineer – Arista Networks
Direct Support line: +1 919 312 9613 [10:00 AM to 16:00 EST] (GMT-4)
International Support line: +1 408 547 5502 or +44 207 023 9352
Toll-free Support line: +1 866 476 0000 (US), +44 808 234 0722 (UK)
Please call support if immediate assistance is required.
If you have feedback or concerns at any point during the course of this case, please contact tac-feedback@arista.com

2
Posted by Shreyas Ruwala
Answered on August 7, 2019 10:13 pm

Missed one more point in your case the reason is

Ethernet4 followed by this: Ebra: 3984: %ETH-4-ERRDISABLE: link-interrupt-storm error detected on Ethernet4

Can you share eth4 configurations? and show version from the switch

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