[lvs-users] UDP load balancing (Virtual server)

Simon Bernard contact at simonbernard.eu
Mon Nov 19 13:59:54 GMT 2018


I would like to understand if it's possible to hide a cluster of servers 
behind 1 public IP address.

Communication between my clients and my server is done over UDP.
Communication can be initiated by clients or by one cluster-node.

For client initiated use-case, if a client C1 with C1IP ip address send 
an udp packet to the public VIP address. The loadbalancer receives the 
packet, examines it and searches if there is a "rule" for it. If there 
is one, it rewrites destination IP choosing a server (let's say R1 with 
R1IP address) depending of loadbalancing algorithm and it adds in kind 
of association table that C1IP is attached to R1IP. In UDP, this 
association has a configurable lifetime.

Does it works for Server initiated use-case ?
If I send an udp packet from server-node R2 (R2IP) to C2 (there is no 
association entry for this IP), does it create a new entry (C2IP<=>R2IP) 
in the association table.
What happened when I send an udp packet from R3 (R3IP) to C1 although 
C1IP is already associated to  R1IP ? does it replace the previous 


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