Connection Errors || onConnectTimeout MP unable to connect to backend

[Roaa]

Hi all ,,, 

We have a service callout policy. It calls an authorized and whitelisted source, most of the time it calls the source successfully but sometimes not ! it gives timeout error.

I tested the host and IP by using telnet it gives me connected so it not port issue

Error from MP logs:

2022-01-23 10:37:18,194 org:xxx env:staging api:xxxxxxx rev:76 messageid:apg-cv-s-nd03-16252-5752377-8  NIOThread@1 ERROR HTTP.CLIENT - HTTPClient$Context.onTimeout() :  ClientChannel[Connected:]@2066403 useCount=1 bytesRead=0 bytesWritten=0 age=3003ms  lastIO=3003ms  isOpen=true.onConnectTimeout host=accounts.accesscontrol.windows.net resolvedAddress=accounts.accesscontrol.windows.net/xx.xxx.xxx.xxx

What I see is: The MP is trying to connect to the source but it failed. Connection timeout period (Default: 3 seconds).

I am wondering why sometime it's failed to connect the source ! 

Any help and support ? 

Thanks 

[API-Evangelist]

An onConnectTimeout error indicates that the Message Processor was unable to connect to the backend server within the preset connection timeout period..Could be due to issues with DNS resolution or backend.

Refer below informative article & you can learn very detail as why & how to avoid.

https://docs.apigee.com/api-platform/troubleshoot/runtime/503-service-unavailable#connectionerrorsdn...

https://docs.apigee.com/api-platform/troubleshoot/runtime/503-service-unavailable#connectionerrors

Good Luck.

[Roaa]

Thank you for your response .. great article !! 

but why sometime it is connect to backend successfully but sometime failed.

Is it because network issue or backend !?