Posted on May 14, 2021 4:51 am
 |  Asked by Niranjan Murali
 |  47 views
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Hi, I have a pair of Arista-7050TX2 switches in mlag and the servers are connected to the mlag pair. I recently found the below given logs in the switches. I don’t know how to interpret the logs. Can any one please help me why the mentioned logs are being captured and what could be the issue? At server end i could not find any logs related to the interface up/down.

I did shut and no shut the Ethernet11-port of switch-2 and the logs were stopped.

Logs from Switch-1:

Mlag: %MLAG-6-INTF_ACTIVE: Local interface Port-Channel11 and peer interface Port-Channel11 are link up. MLAG 11 is active.
Mlag: %MLAG-4-INTF_INACTIVE_PEER: Interface Port-Channel11 is link down on the MLAG peer. MLAG 11 is inactive.
Mlag: %MLAG-6-INTF_ACTIVE: Local interface Port-Channel11 and peer interface Port-Channel11 are link up. MLAG 11 is active.
Mlag: %MLAG-4-INTF_INACTIVE_PEER: Interface Port-Channel11 is link down on the MLAG peer. MLAG 11 is inactive.
Mlag: %MLAG-6-INTF_ACTIVE: Local interface Port-Channel11 and peer interface Port-Channel11 are link up. MLAG 11 is active.
Mlag: %MLAG-4-INTF_INACTIVE_PEER: Interface Port-Channel11 is link down on the MLAG peer. MLAG 11 is inactive.
Mlag: %MLAG-6-INTF_ACTIVE: Local interface Port-Channel11 and peer interface Port-Channel11 are link up. MLAG 11 is active

 

Logs from Switch-2:

Ebra: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet11, changed state to down
Mlag: %MLAG-4-INTF_INACTIVE_LOCAL: Local interface Port-Channel11 is link down. MLAG 11 is inactive.
Ebra: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-Channel11, changed state to down
Lag: %LAG-5-MEMBER_REMOVED: Interface Ethernet11 has left Port-Channel11 due to: not full duplex
Lag: %LACP-5-FALLBACK_STATIC: Entering static fallback mode on interface Port-Channel11.
Ebra: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet11, changed state to up
%LACP-5-FALLBACK_INACTIVE: Reverting to normal LACP negotiation on interface Port-Channel11.
Lag: %LAG-5-MEMBER_ADDED: Interface Ethernet11 has joined Port-Channel11
Mlag: %MLAG-6-INTF_ACTIVE: Local interface Port-Channel11 and peer interface Port-Channel11 are link up. MLAG 11 is active.
Ebra: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-Channel11, changed state to up

Port Configurations:

Switch1:

interface Ethernet11
channel-group 11 mode active
lacp port-priority 15000

interface Port-Channel11
switchport access vlan 100
port-channel lacp fallback static
port-channel lacp fallback timeout 5
mlag 11

Switch2:
========
interface Ethernet11
channel-group 11 mode active
lacp port-priority 16000

interface Port-Channel11
switchport access vlan 100
port-channel lacp fallback static
port-channel lacp fallback timeout 5
mlag 11

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Posted by Kishore Sukumaran
Answered on May 14, 2021 8:55 am

Hello Niranjan,

Thank you for your question. From the logs it indeed looks like interface Ethernet11 on Switch 2 had flapped which caused the port-channel to flap and mlag to be inactive -

...

Ebra: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet11, changed state to down

Lag: %LAG-5-MEMBER_REMOVED: Interface Ethernet11 has left Port-Channel11 due to: not full duplex

...

To understand the root cause about why the itnerface went down and why the interface left the port-channel with the reason "not full duplex", we would want to take a closer look at the system logs and show tech. More importantly we will be eager to look at other system logs that are seen around the same time and the interface speed/duplex configuration at the time of the issue and few more outputs. We would also be interested to understand what the other end device is and about it's speed and duplex configurations.

Hence to check this further, I would request you to open up a case with support@arista.com and provide us the system logs and the show tech outputs for analysis.

Thanks!

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