Switch Operation; Address Table; Learning; Forwarding & Filtering - Interlogix IFS NS3601-24P User Manual

SWITCH OPERATION

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 in-formation comes from the learning
process of Ethernet Switch.

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.
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
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 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 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 respective domain and reduce 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.

Auto-Negotiation

The STP ports on the 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). This is done by detect the modes
and speeds at the second of both device is connected and capable of, both 10Base-T and 100Base-TX devices can connect
with the port in either Half- or Full-Duplex mode.
If attached device is:
10Mbps, no auto-negotiation
10Mbps, with auto-negotiation
100Mbps, no auto-negotiation
100Mbps, with auto-negotiation
User's Manual of NS3601-24P/4S Series
100Base-TX port will set to:
10Mbps.
10/20Mbps (10Base-T/Full-Duplex)
100Mbps
100/200Mbps (100Base-TX/Full-Duplex)
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