Traffic Flow - Cisco catalyst 6500 series Configuration Note

Traffic Flow

Traffic Flow
This section describes how the traffic flows between the client and server in a CSM environment.
(See
Figure 1-3 Traffic Flow Between Client and Server
1
www.example.com
Note The numbers in
When you enter a request for information by entering a URL, the traffic flows as follows:
1.
2.
3.
4.
5.
6.
Catalyst 6500 Series Content Switching Module Configuration Note
1-8
Figure 1-3.)
www.example.com
IP address
4
client
2
DNS
3
IP address
Figure 1-3 correspond to the steps in the following procedure.
You enter a URL. (Figure 1-3
The client contacts a DNS server to locate the IP address associated with the URL.
The DNS server sends the IP address of the virtual IP (VIP) to the client.
The client uses the IP address (CSM VIP) to send the HTTP request to the CSM.
The CSM receives the request with the URL, makes a load-balancing decision, and selects a server.
For example, in Figure 1-3, the CSM selects a server (X server) from the www.example.com server
pool, replacing its own VIP address with the address of the X server (directed mode), and forwards
the traffic to the X server. If the NAT server option is disabled, the VIP address remains unchanged
(dispatch mode).
The CSM performs Network Address Translation (NAT) and eventually TCP sequence numbers
translation.
www.example.com
IP address
www.example.com
5
IP address
Content
Switching
Module
shows www.example.com as an example.)
Chapter 1
W
Server
6
X
Server
Y
Server
Z
Server
www.example.com
Server pool
Product Overview
OL-4612-01