ZyXEL Communications XS1920 Series, User Manual

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XS1920 Series User’s Guide
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H A P T E R
4 6
IP Table
This chapter introduces the IP table.
46.1 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 Switch sends an
ARP to request the MAC address. The Switch then learns the port that replies with the MAC
address.
• 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 268
IP Table Flowchart