The Internet, private wide area networks, and cloud services represent some of the aspects that connect the user to their application. As users demand faster response and more complex data from their applications, the networks carrying this data are under greater pressure to meet these expectations. To truly test out applications before rolling it out to the users, network emulation must be used. Network emulation is also referred to as wan emulation
Network emulation is used by manufacturers, service providers, and applications developers to verify the robustness of their network product or application. A wan emulator recreates the real world effects seen in the network. Standard features of network emulators include filtering, impairments, modifiers, and routing.
A WAN Emulator or WAN emulation allows one to study the real world effects on an application or device in the lab by emulating every wide area network condition.
Filtering allows the wan emulator to separate traffic into different groups to represent different networks. Therefore, a network emulator emulates multiple network scenarios between two emulator ports. Even though end devices are only feet apart and connected to the same server through the emulator, device “A” and device “B” could be viewed to be on different sides of the world by the server.
Impairments are a core component of a network emulator. Standard impairments include: delay, jitter, packet loss, fragment, and bandwidth restriction. However, with the vast majority of traffic becoming video, video specific impairments such as FEC, Active Video, or Over-The-Top dynamic impairments have become essential.
Network emulators use modifiers to serve two purposes: corrupt certain field values and change packet delivery information. A good method to stress an application is to corrupt certain fields in the IP header or the payload to see if the application can overcome it without getting stuck or crashing. Also, modifers of wan emulators can change the packet delivery information such as MAC addresses, IP addresses, or port numbers to either divert the traffic away from the target or steer it to the target.
Routing is the network emulator way to forward packets out of the emulator. Routing can be conducted by using the following techniques: Ethernet bridging, interface mapping, and IP routing. Ethernet bridging uses bridging broadcasts to determine the exit port. The wan emulator uses interface mapping to make the emulator to be truly transparent to the adjacent network devices. IP routing uses an internal network emulator routing table to determine destination ports for each packet. IP routing makes each port of the wan emulator to be viewed as a network device by the other network devices.
Using network emulators to recreate network conditions has become a testing staple before application deployment. A wan emulator can provide “what-if” testing in a laboratory environment and the ability to create reliable, repeatable and standard test configurations in a manufacturing or development environment.
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