Network Emulation

Network Emulation Settings

Whenever a client and a server need to communicate, a connection between the two is established through one or more networks. This network connection is used to send and receive data, which typically is split into data packets.

The connection between client and server can comprise various networks with vastly diverse characteristics. This can result in a delayed transfer of data packets (latency), in a loss of data packets (packet drop rate), or in a reduced transfer rate of one of the networks (bandwidth).

Silk Performer allows you to emulate complex network connections by configuring a range of settings and parameters:

• The Latency is the time that is required for a data packet to travel from one endpoint of the network connection to the other. It depends on various factors, such as the physical speed limit of the network medium (fiber, wire, over-the-air), the bandwidth restrictions and the distance between the two endpoints. The latency of a network connection can vary over time. This variation is called jitter. For typical web load testing scenarios jitter is of less importance as network emulation parameter. Emulating jitter is not supported by Silk Performer.
• The Bandwidth is defined as the data transfer rate, bit rate or throughput. It is measured in bits per second (bit/s or bps), kbps, Mbps, or Gbps.
• The Packet drop rate: Occasionally data packets can get lost on the way from the sender to the receiver. The main reason for dropped packets is an overloaded network or network device. The TCP/IP (Transmission Control Protocol/Internet Protocol) has a built-in detection of dropped packets and guarantees that sent packets are delivered even if some get lost and need to be retransmitted. A high packet drop rate involves high administration effort on the TCP/IP level and thus has a significant effect on the data throughput.

Silk Performer offers presets (preconfigured settings) for a variety of wired and wireless network technology standards. You can adjust all settings to your needs to simulate specific network conditions.

The Network Emulation Driver

Silk Performer can emulate bandwidth limitation out of the box. For latency and packet drop emulation a dedicated network emulation driver is required. By default, the driver is not installed with Silk Performer. To use the full network emulation functionality, make sure to install the driver during Silk Performer setup on your agents.

Note the following specifics:

• The network emulation driver is not compatible with all network adapters. In such a case, machines or network interfaces might no longer be accessible and the network might slow down.
• The network emulation driver is currently not supported for Windows 10.
• Network emulation is not supported for CloudBurst.