Red Hat ENTERPRISE LINUX AS 2.1 -, Руководство по установке

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126 Chapter 8:Setting Up a Red Hat Enterprise Linux AS LVS Cluster
Once forwarding is enabled on the LVS routers and the real servers are set up and have the clustered
services running, use the
Piranha Configuration Tool
to configure the cluster as shown in Chapter
9, Configuring the LVS Routers with Piranha Configuration Tool .
WARNING
Do not configure the floating IP for
eth0:1
or
eth1:1
by manually
editing network scripts or using a network configuration tool. Instead,
use the
Piranha Configuration Tool
as shown in Section 9.4, GLOBAL
SETTINGS and Section 9.6.1, The VIRTUAL SERVER Subsection to con-
figure any cluster-related virtual interfaces.
When finished, start the
pulse
service as shown in Section 9.8, Starting the Cluster. Once
pulse
is up and running, the active LVS router will begin routing requests to the pool of real servers.
8.3 Multi-port Services and LVS Clustering
LVS routers under any topology require extra configuration when creating multi-port LVS services.
Multi-port services can be created artificially by using firewall marks to bundle together different, but
related protocols, such as HTTP (port 80) and HTTPS (port 443), or when LVS is used to cluster true
multi-port protocols, such as FTP. In either case, the LVS router uses firewall marks to recognize that
packets destined for different ports, but bearing the same firewall mark, should be handled identically.
Also, when combined with persistence, firewall marks ensure connections from the client machine are
routed to the same host, as long as the connections occur within the length of time specified by the
persistence parameter. For more on assigning persistence to a virtual server, see Section 9.6.1, The
VIRTUAL SERVER
Subsection.
Unfortunately, the mechanism used to balance the loads on the real servers — IPVS — can recognize
the firewall marks assigned to a packet, but cannot itself assign firewall marks. The job of assigning
firewall marks must be performed by a network packet filter, such as
iptables
or
ipchains
out-
side of Piranha Configuration Tool .
8.3.1 Assigning Firewall Marks
To assign firewall marks to a packet destined for a particular port, the administrator must use
ipta-
bles
or
ipchains
.