Planet IGS-5225 Series, Руководство пользователя

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User’s Manual of IGS-5225 series
441
5. SWITCH OPERATION
5.1 Address Table
The Industrial Managed Switch is implemented with an address table. This address table is composed of many entries. Each
entry is used to store the address information of some nodes in the network, including MAC address, port no, etc. This
information comes from the learning process of
Industrial Managed Switch .
5.2 Learning
When one packet comes in from any port, the Industrial Managed 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.
5.3 Forwarding & Filtering
When one packet comes from some port of the Industrial Managed Switch , it will also check the destination address besides
the source address learning. The Industrial Managed Switch will look up 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 a different port from this
packet comes in, the
Industrial Managed Switch 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.
5.4 Store-and-Forward
Store-and-Forward is one type of packet-forwarding techniques. A Store-and-Forward Industrial Managed Switch stores the
incoming frame in an internal buffer and do the complete error checking before transmission. Therefore, no error packets occur;
it is the best choice when a network needs efficiency and stability.
The
Industrial Managed 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 existence hubs, which nearly always improves the overall performance. An Ethernet switching can be easily
configured in any Ethernet network environment to significantly boost bandwidth using the conventional cabling and adapters.
Due to the learning function of the
Industrial Managed Switch , 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 in the same segment as the source address. This confines network traffic to its respective domain and
reduce the overall load on the network.
The
Industrial Managed Switch performs "Store and Fforward" ; therefore, no error packets occur. More reliably, it reduces
the re-transmission rate. No packet loss will occur.