Installation guide

94 Chapter 7. Linux Virtual Server Overview
7.5.2. Firewall Marks
Firewall marks are an easy and efficient way to a group ports used for a protocol or group
of related protocols. For instance, if an LVS cluster is deployed to run an e-commerce site,
firewall marks can be used to bundle HTTP connections on port 80 and secure, HTTPS
connections on port 443. By assigning the same firewall mark to the virtual server for each
protocol, state information for the transaction can be preserved because the LVS router
forwards all requests to the same real server after a connection is opened.
Because of its efficiency and ease-of-use, administrators of LVS clusters should use fire-
wall marks instead of persistence whenever possible for grouping connections. However,
administrators should still add persistence to the virtual servers in conjunction with firewall
marks to ensure the clients are reconnected to the same server for an adequate period of
time.
7.6. LVS Cluster — A Block Diagram
LVS routers use a collection of programs to monitor cluster members and cluster ser-
vices. Figure 7-4 illustrates how these various programs on both the active and backup
LVS routers work together to manage the cluster.
Figure 7-4. Components of a Running LVS Cluster