Planet FSD-804P [13/21] Switch operation

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3. SWITCH OPERATION

3.1 Address Table

The Switch is implemented with an address table. This address table composed of many entries. Each entry is used to

store the address information of some node in network, including MAC address, port no, etc. This information comes

from the learning process of Ethernet Switch.

3.2 Learning

When one packet comes in from any port. The Switch will record the source address, port no. And the other related

information in address table. This information will be used to decide either forwarding or filtering for future packets.

3.3 Forwarding & Filtering

When one packet comes from some port of the Ethernet Switching, it will also check the destination address besides

the source address learning. The Ethernet Switching will lookup the address-table for the destination address. If not

found, this packet will be forwarded to all the other ports except the port which this packet comes in. And these ports

will transmit this packet to the network it connected. If found, and the destination address is located at different port

from this packet comes in, the Ethernet Switching will forward this packet to the port where this destination address is

located according to the information from address table. But, if the destination address is located at the same port with

this packet comes in, then this packet will be filtered. Thereby increasing the network throughput and availability.

3.4 Store-and-Forward

Store-and-Forward is one type of packet-forwarding techniques. A Store-and Forward Ethernet Switching stores the

incoming frame in an internal buffer, do the complete error checking before transmission. Therefore, no error packets

occurrence, it is the best choice when a network needs efficiency and stability.

The Ethernet Switch scans the destination address from the packet-header, searches the routing table provided for

the incoming port and forwards the packet, only if required. The fast forwarding makes the switch attractive for

connecting servers directly to the network, thereby increasing throughput and availability. However, the switch is most

commonly used to segment existing hubs, which nearly always improves overall performance. An Ethernet Switching

can be easily configured in any Ethernet network environment to significantly boost bandwidth using conventional

cabling and adapters.

Due to the learning function of the Ethernet switching, the source address and corresponding port number of each

incoming and outgoing packet are stored in a routing table. This information is subsequently used to filter packets

whose destination address is on the same segment as the source address. This confines network traffic to its re-

spective domain, reducing the overall load on the network.

The Switch performs "Store and forward" therefore, no error packets occur. More reliably, it reduces the

re-transmission rate. No packet loss will occur.

3.5 Auto-Negotiation

The STP ports on the FSD-804P switch have built-in "Auto-negotiation". This technology automatically sets the best

possible bandwidth when a connection is established with another network device (usually at Power On or Reset).

Detecting the modes does this and speeds at the second of both devices are connected and capable of, both

10Base-T and 100Base-TX devices can connect with the port in either Half- or Full-duplex mode.