[TriLUG] LVS persistence and NAT

[John Turner]

I don't have an answer to your problem, but I did run into the same 
issue where everyone at a site was using a proxy server to access the 
web. So one doesn't have to be behind a NAT firewall to see this 
problem.  We ended up setting up all the PCs to bypass the proxy for 
local addresses.

John

On Jan 20, 2004, at 11:17 AM, Ryan Leathers wrote:

> I want my cake and eat it too.  The more I use and read about LVS the
> less optimistic I am about cake eating.  Don't get me wrong - I think
> LVS is great.  I just want it to handle persistence and distribute load
> at the same time.  Let me explain...
>
> I have set up an LVS-NAT instance in my lab with three real servers
> fielding http requests.  The real servers run an application server
> where state is important.
>
> Prior to turning on persistence I observed that the load was being
> distributed accross all three servers, but the application was 
> unusable.
> With persistence turned on, the application state is kept but the load
> is no longer distributed.  That is to say, all connections made from 
> all
> hosts behind a NAT router wind up going to the same real server due to
> the persistence rule.
>
> I understand that persistence is dependant solely upon the source IP
> address and the protocol in use.  I also see that a mask may be
> specified to account for multiple / changing source addresses.  This
> seems fine if there are not too many requests from the same host /
> network.
>
> Suppose I have a number of hosts connecting to my application servers.
> Is there a way to maintain state while also distributing the load?  Can
> I have my cake and eat it too?  I originally thought firewall marks 
> were
> the ticket but I am coming to understand that marking will only
> associate multiple protocols which will do nothing to distribute the
> load when persistence is required.
>
> I suppose I could move to a more complex clustering model on the back
> end, but it would be the bees knees if LVS could be configured to
> acheive both goals.
> -- 
> Ryan Leathers <ryan.leathers at globalknowledge.com>
> Global Knowledge
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