General Lvs Networking Tips; Multi-Port Services And Lvs - Red Hat ENTERPRISE LINUX 5 - VIRTUAL SERVER ADMINISTRATION Manual

system-config-network, see the chapter titled Network Configuration in the Red Hat Enterprise Linux
Deployment Guide. For the remainder of the chapter, example alterations to network interfaces are
made either manually or through the Piranha Configuration Tool.

3.3.1. General LVS Networking Tips

Configure the real IP addresses for both the public and private networks on the LVS routers before
attempting to configure LVS using the Piranha Configuration Tool. The sections on each topology
give example network addresses, but the actual network addresses are needed. Below are some
useful commands for bringing up network interfaces or checking their status.
Bringing Up Real Network Interfaces
To bring up a real network interface, use the following command as root, replacing N with the
number corresponding to the interface (eth0 and eth1).
/sbin/ifup ethN
Warning
Do not use the ifup scripts to bring up any floating IP addresses you may configure
using Piranha Configuration Tool (eth0:1 or eth1:1). Use the service
command to start pulse instead (see
Bringing Down Real Network Interfaces
To bring down a real network interface, use the following command as root, replacing N with the
number corresponding to the interface (eth0 and eth1).
/sbin/ifdown ethN
Checking the Status of Network Interfaces
If you need to check which network interfaces are up at any given time, type the following:
/sbin/ifconfig
To view the routing table for a machine, issue the following command:
/sbin/route

3.4. Multi-port Services and LVS

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 with 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
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
General LVS Networking Tips
Section 4.8, "Starting LVS"
for details).
Section 4.6.1, "The
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