SG550XG-8F8T LAG allways change to Active/Standby instead of ACT/ACT

[harold.polet]

Hi,

I have a LAG with port 8 (copper) and port 16 (fiber) between two SG550XG-8F8T

One leg of the LAG sometimes change from active to standby and I couldn't find a way to go back to Active.

Latest firmware 2.4.5.71 on both switches. No issue on port 16.

Cable between switch is 30cm long 10G Eth and already checked/swapped

Config is the same on both switches :

!

interface TengigabitEthernet1/0/8
 no negotiation
 channel-group 1 mode auto

!

interface TengigabitEthernet1/0/16
 channel-group 1 mode auto

!
interface Port-Channel1
 speed 10000
 no negotiation
 description BkpLink
 switchport mode trunk

SW550XG#sh int po1
Load balancing: src-dst-mac-ip.
Channel  Ports
-------  -----
Po1      Active: te1/0/16 Non-candidate: te1/0/8

I don't understand why to port 8 goes to non-candidate after a variable time and how to go back to normal.

[Georg Pauwen]

Hello,

what if you disable LACP and configure static LAG (page 150 of the attached admin guide) ?

https://www.cisco.com/c/dam/en/us/td/docs/switches/lan/csbms/350xg/admin_guide/AG_Tesla_350_550.pdf

[harold.polet]

Changed mode to static.

Same issue, TE1/0/8 is now inactive instead of non-candidate. If I disconnect manually TE1/0/16, TE1/0/8 stay inactive and I loose the PO1 connection.

!
interface TengigabitEthernet1/0/8
 no negotiation
 channel-group 1 mode on

!
interface TengigabitEthernet1/0/16
 channel-group 1 mode on

!
interface Port-Channel1
 speed 10000
 no negotiation
 description BkpLink
 switchport mode trunk

SW#sh int po1
Load balancing: src-dst-mac-ip.
Channel  Ports
-------  -----
Po1      Active: te1/0/16 Inactive: te1/0/8

If I disconnect TE1/0/16 :

Po1      Inactive: te1/0/8,te1/0/16 

Thanks

[Georg Pauwen · Accepted solution]

Hello,

--> I have a LAG with port 8 (copper) and port 16 (fiber) between two SG550XG-8F8T

This might be the problem, copper and fiber. As per the guidelines, all ports in a LAG must be of the same media type. Can you, for the sake of testing, connect two copper or two fiber ports ?

[harold.polet]

Missed that guideline page 149 of the admin guide

1. Every LAG has the following characteristics:

• All ports in a LAG must be of the same media type.

I made a LAG with port 15 & 16, both fiber, no issue.

Surprised that there is no validation during the configuration.

I have two others pairs of SG550XG where the mixed LAG is working, the 3 pairs had the same configuration.

THANKS @Georg Pauwen

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