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Why does etherchannel log messages ECH_CHAIN_FAIL and ECH_PING_FAIL_BCKP in the errpt every day?

Question & Answer


Question

Why does etherchannel log messages ECH_CHAIN_FAIL and ECH_PING_FAIL_BCKP in the errpt every day?
Setup:
AIX: 7300-02-01-2346
ent0 - Virtual I/O Ethernet Adapter - PVID: 1, VLAN Tag IDs: None, Switch ID: ETHERNET0, poll_uplink: no
ent1 - Virtual I/O Ethernet Adapter - PVID: 2, VLAN Tag IDs: None, Switch ID: ETHERNET0, poll_uplink: no
ent2 - Etherchannel
     Primary adapter: ent0
     Backup Adapter: ent1
     hash_mode: default
     hcn_id: 0
     mac_swap: no
     mode: standard
     netaddr: 10.0.0.1
     num_retries: 3
     retry_time: 1
errpt:
Feb 17 09:43:59 - ent2 - ECH_PING_FAIL_BCKP - Unable to reach remote host through backup adapter: switching over to primary adapter
Feb 17 04:00:02 - ent2 - ECH_CHAN_FAIL - All primary EtherChannel adapters failed: switching over to backup adapter
Feb 16 11:19:16 - ent2 - ECH_PING_FAIL_BCKP - Unable to reach remote host through backup adapter: switching over to primary adapter
Feb 16 04:00:01 - ent2 - ECH_CHAN_FAIL - All primary EtherChannel adapters failed: switching over to backup adapter
Feb 15 12:31:30 - ent2 - ECH_PING_FAIL_BCKP - Unable to reach remote host through backup adapter: switching over to primary adapter
Feb 15 04:00:02 - ent2 - ECH_CHAN_FAIL - All primary EtherChannel adapters failed: switching over to backup adapter
Feb 14 10:29:45 - ent2 - ECH_PING_FAIL_BCKP - Unable to reach remote host through backup adapter: switching over to primary adapter
Feb 14 04:00:02 - ent2 - ECH_CHAN_FAIL - All primary EtherChannel adapters failed: switching over to backup adapter
errpt -a:
LABEL: ECH_PING_FAIL_BCKP
IDENTIFIER: 6169289D
...
...
Resource Name:   ent2
Resource Class:  adapter
Resource Type:   ibm_ech
Location:
Description
PING TO REMOTE HOST FAILED
...
...
Detail Data
Unable to reach remote host through backup adapter: switching over to primary adapter
LABEL: ECH_CHAN_FAIL
IDENTIFIER: 59224136
...
...
Resource Name:   ent2
Resource Class:  adapter
Resource Type:   ibm_ech
Location:
Description
ETHERCHANNEL FAILOVER
...
...
Detail Data
All primary EtherChannel adapters failed: switching over to backup adapter

Answer

There were two different events that occurred every day. First, the failover from the primary adapter to the backup adapter at 4:00 AM, followed by a failback from the backup adapter to the primary adapter due to a ping failure a few hours later. This cycle continued for few days.
The "ECH_CHAN_FAIL:All primary EtherChannel adapters failed: switching over to backup adapter" is logged when etherchannel failover from the primary adapter to the backup adapter occurs due to link failure or manual failover. In this particular case, it was logged because a script was running the following command at 4:00 AM every day without the administrator's knowledge. The ethchan_config forces a failover of the etherchannel.
/usr/lib/methods/ethchan_config -f ent2
Once the script was corrected, ECH_CHAN_FAIL stopped logging and stopped the failover.
The "ECH_PING_FAIL_BCKP:Unable to reach remote host through backup adapter: switching over to primary adapter" is logged when Etherchannel is unable to ping the netaddr (10.0.0.1) using backup adapter ent1 for the number of times specified by the num_retries attribute (3) and within the time interval in seconds that is specified by the retry_time attribute (1 sec), etherchannel fails over to the primary adapter ent0. On the VIO server, the SEA, physical adapter and link were up and stable at the time when the ping failed. The further debugging by the network team revealed that ping was failing because of a problem (i.e., switch, firewall, gateway etc.) in the physical network outside of the power frame.

Author: Darshan Patel
Platform: AIX on Power
Feedback: aix_feedback@wwpdl.vnet.ibm.com

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Document Information

Modified date:
22 April 2025

UID

ibm17230381

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