[lvs-users] The effect of wlc, lblc, and persistent

[Robinson, Eric]

Need some help understanding the effect of wlc, lblc, and persistent.

In our environment, the following realserver configuration in ldirectord results in pretty even load balancing.

# Virtual Server for tomcat(site103), Outside to Inside
virtual=192.168.5.100:3103
        real=192.168.10.64:3103 masq
        real=192.168.10.63:3103 masq
        service=http
        request="/mobiledoc/jsp/catalog/xml/CheckDBConnection.jsp"
        receive="success"
        scheduler=wlc
        protocol=tcp
        checktype=3
        persistent=15
Here's the output of ipvsadm -Ln


TCP 192.168.5.100:3103 wlc persistent 15
-> 192.168.10.64:3103 Masq 1 24 15
-> 192.168.10.63:3103 Masq 1 23 22

Whereas the following config results in very uneven load balancing.

# Virtual Server for tomcat(site077), Outside to Inside
virtual=192.168.5.100:3077
        real=192.168.10.64:3077 masq
        real=192.168.10.63:3077 masq
        service=http
        request="/mobiledoc/jsp/catalog/xml/CheckDBConnection.jsp"
        receive="success"
        scheduler=lblc
        protocol=tcp
        checktype=3
        persistent=360
Here's the outpuut of ipvsadm -Ln
TCP 192.168.5.100:3077 lblc persistent 360
-> 192.168.10.63:3077 Masq 1 16 9
-> 192.168.10.64:3077 Masq 1 1 0
Why is the second one so imbalanced? There are probably 20 computers using the second one, so about half of them should be going to each realserver. Once they connect to a realserver, the connection should persist for at least 360 seconds. But that should not result in such a disparity in the number of connections going to each RS should it?

Wait... if the customer is behind NAT, and all of their workstations appear to be the same source IP, I guess it would cause this behavior?

--
Eric Robinson
















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