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Keith Hellman wrote:
>
> I do have one nagging lack-of-understanding:
>
> I have attached a diagram as plain text.
got it. we're reaching new heights of ascii art.
My understanding is that the following happens:
> 1 A client connects to the VIP on the Director
> 2 The Director (using DR) mods the MAC to an appropriate value for a
> real server, and retransmits on the LAN A
> 3 The RS picks this packet up, and when it transmits back to the
> client, it will go out the default interface (LAN B) - avoiding the LAN A
I'm not sure where LAN A is, but basically yes.
> Here are my questions/impressions:
> A I'm under the impression that under VS-DR, the Director does not
> finish the TCP session setup - it passes the first packet (SYN?) directly to
> the RS and the RS finishes the session setup with the client - is this
> correct? Note that I'm only interested in DR.
yes
> B Packets sent from the real server for TCP/IP session initiation, as
> well as application layer transmission, will always be sent across LAN B -
> is this correct?
it depends. packets with src_addr=VIP get sent via B to the internet.
Connections
initiated on the realserver have nothing to do with the function of the LVS
and can will have src_addr=DIP. They can be sent anywhere. For an example see
http://www.linuxvirtualserver.org/Joseph.Mack/HOWTO/LVS-HOWTO-13.html#ss13.10
> C Packets from the Client will ALWAYS go through the Director, and be
> re-routed to the appropriate real server (through LAN A) - is this correct?
yes
> Or will the IP address of the real-server's default interface actually be
> 'noticed' by the client (perhaps not at the application layer, but inside
> the networking stack...) and 100% of client<->RS communications will happen
> across LAN B?
the client only knows about the VIP and sees the LVS as one machine.
Joe
--
Joseph Mack PhD, Senior Systems Engineer, Lockheed Martin
contractor to the National Environmental Supercomputer Center,
mailto:mack.joseph@xxxxxxx ph# 919-541-0007, RTP, NC, USA
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