Each Media stream terminated in CommuniGate Pro (a stream relayed with a media proxy or a stream processed with a media server channel) is bound to a particular Cluster Member. The Load Balancer must ensure that all incoming Media packets are delivered to the proper Cluster Member.
The "single-IP" method is useful for a small and medium-size installations. The Cluster Members have internal addresses L1, L1, L3, etc. The Load Balancer has an external address G0. The Network Settings of each Cluster Member are modified, so the Media Ports used on each Member are different: ports 10000-19999 on the L1 Member, ports 20000-29999 on the L2 Member, ports 30000-39999 on the L3 Member, etc. All packets coming to the G0 address to the standard ports (5060 for SIP) are distributed to the L1, L2, L3 addresses, to the same ports. All packets coming to the G0 address to the media ports are distributed according to the port range:
The Server-wide WAN IP Address setting should be left empty on all Cluster Members. The Cluster-wide WAN IP Address setting should specify the G0 address.
This method should not be used for large installations (unless there is little or no media termination): it allows you to allocate only 64000 ports for all Cluster media streams (each AVP stream takes 2 ports, so the total number of audio streams is limited to 32000, and if video is used (together with audio), such a Cluster cannot support more than 16,000 concurrent A/V sessions.
The "multi-IP" method is useful for large installations. Each frontend has its own IP address, and when a Media Channel or a Media Proxy is created on that frontend Server, this unique IP address is used for direct communication between the Server and the client device or remote server.
The Network Settings of each Cluster Member can specify the same Media Port ranges, and the number of concurrent RTP streams is not limited by 64000 ports.
In the simplest case, all frontend Servers have "real" IP Addresses, i.e. they are directly connected to the Internet.
If the Load Balancer uses a DSR method (see above), then it should not care about the packets originating on the frontend Servers from non-VIP addresses: these packets either bypass the Load Balancer, or it should deliver them without any modification.
If the Load Balancer uses a "normal" method, it should be instructed to process "load balanced ports" only, while packets to and from "other ports" (such as the ports in the Media Ports range) should be redirected without any modification.
You can use the Multi-IP method even if your frontend Servers do not have "real" IP Addresses, but they use "LAN"-type addresses L1, L1, L3, etc. Configure the Load Balancer to host real IP Addresses G1, G2, G3,... - in addition to the VIP IP Address used to access CommuniGate Pro services.
Configure the Load Balancer to "map" its external IP address G1 to the frontend Server address L1, so all packets coming to the IP Address G1, port g (G1:g) are redirected to the frontend Server address L1, same port g (L1:g). The L