ZyXEL Communications GS-4012F, User Manual

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GS-4012F User’s Guide
Chapter 36 IP Table 213
C
H A P T E R
36
IP Table
This chapter introduces the IP table.
36.1 Overview
The IP Table screen shows how packets are forwarded or filtered across the switch’s ports. It
shows what device IP address, belonging to what VLAN group (if any) is forwarded to which
port(s) and 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 on 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 133 IP Table Flowchart