ZyXEL Communications XS3800-28, User Manual, Page: 114 / 789

Chapter 10 IP Table
XS3800-28 User’s Guide
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HAPTER
10
IP Table
This chapter introduces the IP table screen.
10.1 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 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 70 IP Table Flowchart