Pr od uct io n Ne tw ork Ar ch it ect ur es an d Web Lo gic SI P S er ver Con f igu ra t ion
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Populating OSI Layer 3 information with the correct source IP address.
For example, in the configuration shown in Figure 2-3, WebLogic SIP Server must add the
correct subnet address to SIP system headers and transport datagrams in order for each UA to
continue processing SIP transactions. If the wrong subnet is used, replies cannot be delivered
because neither UA can directly access the other UA’s subnet.
The route resolver works by determining which NIC the operating system will use to send a
datagram to a given destination, and then examining the network channel that is associated with
that NIC. It them uses the address configured in the selected network channel to populate SIP
headers and Layer 3 address information.
For example, in the configuration shown in Figure 2-3, an INVITE message sent from WebLogic
SIP Server to UAC B would have a destination address of 10.2.1.16. The operating system would
transmit this message using NIC B, which is configured for the corresponding subnet. The route
resolver associates NIC B with the configured sipchannelB and embeds the channel’s IP
address (10.2.1.10) in the VIA header of the SIP message. UAC B then uses the VIA header to
direct subsequent messages to the server using the correct IP address. A similar process is used
for UAC A, to ensure that messages are delivered only on the correct subnet.
IP Aliasing with Multihomed Hardware
IP aliasing assigns multiple logical IP addresses to a single NIC, and is configured in the
underlying server operating system. If you configure IP aliasing and all logical IP addresses are
within the same subnet, you can simply configure WebLogic SIP Server to listen on all addresses
as described in “Multihomed Servers Listening On All Addresses (IP_ANY)” on page 2-6.
If you configure IP aliasing to create multiple logical IP addresses on different subnets, you must
configure a separate network channel for each logical IP address. In this configuration, WebLogic
SIP Server treats all logical addresses as separate physical interfaces (NICs) and uses the route
resolver to populate OSI Layer 4 and Layer 7 information based on the configured channel.
Load Balancer Configurations
In addition to providing failover capabilities and distributing the client load across multiple
servers, a load balancer is also an important tool for configuring the network information
transmitted between clients and servers. The sections that follow describe common load balancer
configurations used with WebLogic SIP Server.
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Configuring Network Resources