Nortel Networks WEB OS 212777 - Manual (Page 310)

Web OS 10.0 Application Guide
310 n Chapter 12: Global Server Load Balancing
212777-A, February 2002
Client A, with a source IP address of 205.178.13.10, initiates a request that is sent to the local
DNS server. The local DNS server is configured to forward requests to the DNS server at Site
4. The Web switch at Site 4 looks up its proximity table and finds Client A prefers to connect
to Sites 1 or 3. Similarly, Client B’s requests are always forwarded to Sites 2 or 4.
Figure 12-6 Configuring Client Proximity Table
You can add static entries in the proximity table for up to 128 client networks.
N OTE – Web OS allows you to configure a single domain only and for each client subnet you
can configure up to two preferred sites.
The Web switch forwards the client request based on the minimum available sessions and
response time between the two preferred sites.
Internet
Client Site B
DNS
Request
Client Site A
DNS
Request
205.178.13.0 204.165.0.0
IF: 1.1.1.1 / 24
VIP: 1.1.1.100
IF: 2.2.2.2 / 24
VIP: 2.2.2.100
IF: 3.3.3.3 / 16
VIP: 3.3.3.100
IF: 4.4.4.4 / 24
VIP: 4.4.4.100
Web
Servers
Web
Servers
DNS DNS
DNS DNS
Web Switch
Web Switch Web Switch
Web Switch
Site 3 Site 2
Site 4 Site 1
Web
Servers
Web
Servers
Master switch returns
Client's request with the
VIP of the preferred site
2. The master switch looks through its
proximity table and responds to the
DNS request by providing the virtual
IP address of the preferred site.
3. The client sends out a new request
and connects to the preferred site.
Prefers
Sites 1 and 3
Prefers
Sites 2 and 4
1. Client sites A and B send requests to
their DNS servers which are forwarded
to the master switch at Site 4.