User Manual

3-3. Flow Control

Flow control is a mechanism to tell the source device stopping sending frame for a specified period of time designated by target device until the PAUSE time expires. This is accomplished by sending a PAUSE frame from target device to source device. When the target is not busy and the PAUSE time is expired, it will send another PAUSE frame with zero time-to-wait to source device. After the source device receives the PAUSE frame, it will again transmit frames immediately. PAUSE frame is identical in the form of the MAC frame with a pause-time value and with a special destination MAC address 01-80-C2-00-00-01. As per the specification, PAUSE operation can not be used to inhibit the transmission of MAC control frame.

Normally, in 10Mbps and 100Mbps Ethernet, only symmetric flow control is supported. However, some switches (e.g. 16 Gigabit Web Smart Switch) support not only symmetric but asymmetric flow controls for the special application. In Gigabit Ethernet, both symmetric flow control and asymmetric flow control are supported. Asymmetric flow control only allows transmitting PAUSE frame in one way from one side, the other side is not but receipt-and-discard the flow control information. Symmetric flow control allows both two ports to transmit PASUE frames each other simultaneously.

Inter-frame Gap time

After the end of a transmission, if a network node is ready to transmit data out and if there is no carrier signal on the medium at that time, the device will wait for a period of time known as an inter-frame gap time to have the medium clear and stabilized as well as to have the jobs ready, such as adjusting buffer counter, updating counter and so on, in the receiver site. Once the inter-frame gap time expires after the de-assertion of carrier sense, the MAC transmits data. In IEEE802.3 specification, this is 96-bit time or more.

Collision

Collision happens only in half-duplex operation. When two or more network nodes transmit frames at approximately the same time, a collision always occurs and interferes with each other. This results the carrier signal distorted and un- discriminated. MAC can afford detecting, through the physical layer, the distortion of the carrier signal. When a collision is detected during a frame transmission, the transmission will not stop immediately but, instead, continues transmitting until the rest bits specified by jamSize are completely transmitted. This guarantees the duration of collision is enough to have all involved devices able to detect the collision. This is referred to as Jamming. After jamming pattern is sent, MAC stops transmitting the rest data queued in the buffer and waits for a random period of time, known as backoff time with the following formula. When backoff time expires, the device goes back to the state of attempting to transmit frame. The backoff time is determined by the formula below. When the times of collision is increased, the backoff time is getting long until the collision times excess 16. If this happens, the frame will be discarded and backoff time will also be reset.

where

k = min (n, 10)

Publication date: January, 2005

Revision A1

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Edimax Technology ES-516G+ user manual Flow Control
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ES-516G+ specifications

Edimax Technology has carved a niche for itself in the realm of networking devices, and one of its standout products is the Edimax ES-516G+. This 16-port Ethernet switch is designed to meet the demanding needs of small to medium-sized businesses and network enthusiasts.

At the core of the ES-516G+ is its capacity to support 10/100/1000 Mbps speeds across its 16 ports, enabling efficient data transmission and minimal latency for connected devices. This switch is a Layer 2 unmanaged switch, which simplifies the user experience by eliminating the need for complex configurations. Users can plug in their devices and start functioning immediately, making it an ideal option for those who may not have extensive networking knowledge.

One of the key features of the Edimax ES-516G+ is its support for Auto-MDI/MDI-X, which automatically detects the type of connection required for each port, whether it’s connecting to another switch or end devices like computers and printers. This eliminates the hassle of crossover cables and ensures seamless connectivity.

Moreover, the ES-516G+ incorporates advanced energy-saving technologies that are designed to minimize power consumption without compromising performance. This feature is particularly appealing for environmentally-conscious businesses looking to reduce their carbon footprint. It includes capabilities such as energy-efficient Ethernet (EEE), which adjusts power usage based on the link status and length of connected cables.

The switch features a compact metal housing, providing durability and a professional look suitable for any office environment. It also supports a fanless design for quiet operation, making it an excellent addition to workplaces where noise levels need to be kept to a minimum.

In terms of performance, the Edimax ES-516G+ employs store-and-forward switching technology, which helps to minimize errors by ensuring that only error-free packets are forwarded. This significantly enhances network performance and reliability.

Overall, the Edimax Technology ES-516G+ stands out as a robust, efficient, and user-friendly solution for enhancing network performance in small to medium-sized businesses. Its combination of speed, plug-and-play convenience, energy-saving features, and reliability makes it a compelling choice for users seeking to expand their network capabilities. Whether for a bustling office or a home network, the ES-516G+ is engineered to deliver a seamless, high-performance networking experience.
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