To: lvs-users@xxxxxxxxxxxxxxxxxxxxxx
Subject: LVS-DR
From: Torsten Buslei <mail@xxxxxxxxx>
Date: Sat, 27 Apr 2002 11:06:02 +0200
Hello all!

Did I understand LVS-DR correct?

The VIP on the director is the only one who answers to a arp-request.
So, if a client want's to connect to the LVS, a arp-request to the VIP
is send, which the director answers.
Then, the director looks up the ipvsadm-rules and directs the
tcp-request to a realserver. (again over MAC's, I think it's not
importent here.)
When the request arrives at a specific realserver, an answer is
generated and send back to the client directly. The source-address of
the tcp-packets is the VIP (non-arping address on the realserver), but
the source-address of the IP-packets (MAC-layer) is the MAC-address of
the sending device (ethernet-adapter of the realserver).

That would mean, that the client has two different
IP-MAC-addresses-pairs in its arp-table for the VIP. But it is only
allowed to save one. Which one is it, the first (which means the
MAC-address of the director) or the last (which means  the MAC-address
of a realserver)?

I think this question is importent for a nicely balenced cluster,
because if the last possibility is true (MAC-address of the realserver
in arp-table of the client), the next request will be directly send to
the realserver without a scheduling of the director.

In my tests with Linux-Boxes and solving the arp-problem with a second
NIC, I had the described problems. (connection to realserver without
scheduling by director), if you can realy speak of a problem ...

Thanks for comments,


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