ZyXEL Communications GS-2750, User Manual

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GS-2750 User’s Guide
293
C
H A P T E R
37
IP Table
This chapter introduces the IP table.
37.1 IP Table Overview
The IP Table screen shows how packets are forwarded or filtered across the Switch’s ports.
When a device (which may belong to a VLAN group) sends a packet which is forwarded to a
port on the Switch, the IP address of the device is shown on the Switch’s
IP Table . The IP
Table also shows whether the IP address is dynamic (learned by the Switch) or static
(belonging to the Switch).
The Switch uses the
IP Table to determine how to forward packets. See the following figure.
1
The Switch examines a received packet and learns the port from which this source IP
address came.
2
The Switch checks to see if the packet's destination IP address matches a source IP
address already learned in the
IP Table .
• If the Switch has already learned the port for this IP address, then it forwards the
packet to that port.
• If the Switch has not already learned the port for this IP address, then the packet is
flooded to all ports. Too much port flooding leads to network congestion.
• If the Switch has already learned the port for this IP address, but the destination port is
the same as the port it came in on, then it filters the packet.
Figure 175 IP Table Flowchart