Netscaler at times uses a different SNIP IP Address rather than the one bound in NetProfile on LB VIP.

If you have high rate of client side connections you can add another SNIP IP Address on the NetProfile attached to LB VIP, so that you provide more ports to NS to use and not fallback to general SNIP.

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Problem Cause

If the client concurrent connection rate is higher than the ports available to SNIP IP Address for port allocations, then we may run into a problem, where NS cannot allocate further ports with this SNIP.

We can look for presence of such message in nsconmsg
ip_err_portalloc_failed NetScaler_SNIP_X.X.X.X (where X.X,X.X) is the SNIP IP Addressed bound to NetProfile.

Then the reason why 2nd General SNIP is used is because "Current code falls back to default method of IP and Port selection, when ports are exhausted on IPs bound in netprofile."
We should return an error when port alloc fails on netprofile, falling back to default ip and port selection should happen only in case of no IPs bound on netprofile



 

Run the following command from NetScaler shell to view the number of free ports:
nsapimgr -d freeports

Below is the sample output of above command for the reference:

Displaying all free ports of all MIPs...
Index IP              FreePorts
    0 0.0.0.1         16513536
    1 127.0.0.2       1031679
    2 241.0.0.2       1032096
    3 241.0.0.4       1032096
    4 241.0.0.5       16513536
    5 10.107.98.19   1032096
    6 10.107.98.20   1032071