Alteon Application Switch Operating System Application Guide
WAN Link Load Balancing
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Document
ID:
RDWR-ALOS-V2900_AG1302
Figure 101: WAN Link Load Balancing for Outbound Traffic
The outbound traffic resolution in
Figure 101 - WAN Link Load Balancing for Outbound Traffic, page
1. Client 1 makes a data request for content on the Internet.
2. When the request reaches port 5, the redirection filter is triggered and Alteon selects the
optimal WAN link.
3. Before the packets leave the WAN link ports, the client IP address is substituted with the
configured proxy IP address on port 2 or 7. Proxy IP address maintains persistency for the
returning request.
4. Alteon sends the request to the destination IP address.
5. The returning request from the Internet uses the same WAN link because the destination IP
address responds to the proxy IP address, thereby maintaining persistency. The selected ISP
processes the packet.
6. Alteon converts the proxy IP address to the client IP address and the request is returned to the
client.
Inbound Traffic
Inbound traffic is data from an external client on the Internet that enters Alteon to access an
internal service, such as corporate Web servers or FTP servers.
Alteon lets you load balance the inbound traffic by providing access to the external client with the
best available WAN link.
Note:
For load balancing inbound traffic, you must have the Inbound Link Load Balancing license
installed. For more information on installing licenses see the section on the /
oper/swkey
command
in the Alteon Application Switch Operating System Command Reference, and the Radware Alteon
Installation and Maintenance Guide.
This is implemented by configuring Alteon as an authoritative name server. Alteon dynamically
determines the best ISP link to use at the time the request is generated. The best link is determined
by the configured metric, the load on the ISP, and periodic health checks on the upstream routers.
For more information on load-balancing metrics, see
Metrics for Real Server Groups, page 180
. Real
server weighting can also be used to determine the best link when using the hash metric for load
balancing inbound WAN links. For more information on real server weighting, see
When the external client makes a DNS request, Alteon responds with the IP address of the best
available WAN link (ISP).