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LB_FAILED causing by "out of ports"


We have a "LB_FAILED" issue in a VS causinf a 503 error.

When activating "event info", the error code is "ERR_PORT" which means "out of ports"

Is it possible to have more information about this error code

is it "out of port" between what ?

Thank you



F5 Employee
F5 Employee

This is mostly due to either (1) not enough ports on the SNAT IP or (2) your virtual server is configured to 'preserve strict' for it's source port preservation option.


To resolve the first issue you would either (1) switch from SNAT automap to SNAT pool with mulitiple SNAT IPs or (2) add more SNAT IPs if you're already using a SNAT pool on the virtual server.


To resolve the first issue you could switch the source port preservation from 'preserve strict' to 'preserve' in the virtual server advanced configuration.


K8246: How the BIG-IP system handles SNAT port exhaustion

K33355231: Error Message: 01010201:2: Inet port exhaustion on <ip_address> to <ip_address:port> (pro...

K13433: Configuring source port preservation for SNATs