some info for DH and SH schedulers (fwd)

[Wensong Zhang <wensong@xxxxxxxxxxxx>]

---------- Forwarded message ----------
Date: Fri, 16 Feb 2001 00:14:33 +0800 (CST)
From: Wensong Zhang <wensong@xxxxxxxxxxxx>
To: lvs-users@xxxxxxxxxxxxxxxxxxxxxx
Subject: some info for DH and SH schedulers



Hi,

Please see "man ipvsadm" for short description of DH and SH
schedulers. I think some examples to use those two schedulers.

Example1:  cache cluster shared by several load balancers.

                Internet
                |
                |------cache array
                |
                |-----------------------------
                   |                |
                   DH               DH
                   |                |
                 Access            Access
                 Network1          Network2

The DH scheduler can keep the two load balancer redirect requests
destined for the same IP address to the same cache server. If the server
is dead or overloaded, the load balancer can use cache_bypass feature to
send requests to the original server directly. (Make sure that the cache
servers are added in the two load balancers in the same order)

Note that the DH development is inspired by the consistent hashing
scheduler patch from Thomas Proell <proellt@xxxxxx>


Example2: Firewall Load Balancing

                      |-- FW1 --|
  Internet ----- SH --|         |-- DH -- Protected Network
                      |-- FW2 --|

Make sure that the firewall boxes are added in the load balancers in the
same order. Then, request packets of a session are sent to a firewall,
e.g. FW1, the DH can forward the response packets from protected network
to the FW1 too. However, I don't have enough hardware to test this setup
myself. Please let me know if any of you make it work for you. :)

Cheers,

Wensong