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>> People keep talking about sessions, but I don't know what
>> they're doing. I assume the client has a cookie which the
>> servers recognise (via mysql replication). Presumably the
>> clients keep hitting different realservers as part of their
>> session (which I guess has state - eg a shopping cart) and
>> you have to pass the state info around too. Is this what
>> you're doing?
>>
Yes that is exactly right. We have state info stored server side in a
PHP session. Client side there is a cookie that holds a session id only
(no state). We are working on ways to replicate the server side session
info across N real servers. I think relying on mysql will work in the
short term. Just have to test it under load to see how it behaves. I can
see an issue if mysql replication gets behind on a server, but that is
not an LVS issue...
>
> The machines behind the NAT router call from high ports in
> order. So say you're websurfing and you've just fired up the
> homecomputer, The first call to VIP:80 will come from
> CIP:1025. When that tcpip connection is closed down, the
> next call to VIP:80 will come from CIP:1026 etc. These calls
> get nat'ed into a similar monotonic series of ports from the
> NAT router (with 2.2 linux starting somewhere up near
> 40,000, but now starting with port 1025). Originally there
> was a separate range reserved for each client (I think),
> allowing the ISP to watch for multiple clients behind the
> nat router. Now I think theirs only one range (to stop this
> pattern being observed).
>
>
So Graeme's solutions looks like our best bet. The good news for us is
that we have 100% control of the client routers and are not trying to
hide our activity from an isp. So I should be able to tweak the router
in such a way that it behaves in a consistent manner with regard to port
usage, and that should allow me to implement Graeme's solution with a
reasonable level of assurance that clients will stay within the
designated port ranges... I hope :)
Thanks for the info,
Matthew Smart
President
Smart Software Solutions Inc.
108 S Pierre St.
Pierre, SD 57501
Phone: (605) 280-0383
Skype: msmart13
Email: msmart@xxxxxxxxxxxxxxxxxxxx
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