Intermittent connection between Agent and Scalability Server when using TCP
Article ID: 423310
Updated On:
Products
Issue/Introduction
CAM can be set to use TCP 4105 port instead of default 4104 UDP, procedure explained here:
How do I configure CAM to use TCP from the command line?
When this change is done, Port Multiplexer Service (CSAM PMUX) is used to connect both endpoints.
If there is a connection problem between these 2 endpoints, it’s possible that CSAM port is having a problem.
Environment
Client Automation 14.5 and above
Cause
CSAM PMUX service uses port 7163 and if there is any block/filter of it between the 2 involved machines, a connection problem may happen.
A simple way to check this is to run ‘camstat -a’ command on any of the involved machines, and check the state of the connection of the target machine:
Host proto state port Qlen m/sent m/recv retry disc RTO
--------------------- ----- ----- ----- ----- ------- ------- ------ ----- ----
11.22.33.44 tcp CWT 4105 1 421 431 39 19 60
In this case, the state “CWT” corresponds to “Connection Wait”, which means the local machine sent a connection request but the ACK has not yet received, this may mean an actual blocking/filtering of port 7163.
Resolution
There are several ways to check ports availability between 2 endpoint, but the following Powershell command can be used:
Test-NetConnection -ComputerName 11.22.33.44 -Port 7163
The result will show the local and remote address, the port being tested, the interface used and the result.
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