Switch Operation; Address Table; Learning; Forwarding & Filtering - Planet SGS-5220-24P2X User Manual

User's Manual of SGS-5220 Series

5. SWITCH OPERATION

5.1 Address Table

The Managed 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 in-formation comes from
the learning process of Managed Switch.

5.2 Learning

When one packet comes in from any port, the 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 Managed Switch, it will also check the destination address besides the source
address learning. The Managed Switch 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 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 Managed Switch 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 Managed Switch scans the destination address from the packet-header, searches the routing table pro-vided 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. How-ever, the switch is most commonly used to segment
existence hubs, which nearly always improves overall performance. An Ethernet Switching can be easily configured in any
Ethernet network environment to signifi-cantly boost bandwidth using conventional cabling and adapters.
Due to the learning function of the 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 on the same segment as the source address. This confines network traffic to its respective domain and reduce the overall
load on the network.
The Managed Switch performs "Store and Fforward" therefore, no error packets occur. More reliably, it reduces the
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