ZyXEL Communications NBG420N - Manual (Page 129)

Chapter 9 LAN
NBG420N User’s Guide
129
Figure 82 Any IP Example
The Any IP feature does not apply to a computer using either a dynamic IP address or a static
IP address that is in the same subnet as the NBG420N’s IP address.
"
You must enable NAT to use the Any IP feature on the NBG420N.
Address Resolution Protocol (ARP) is a protocol for mapping an Internet Protocol address (IP
address) to a physical machine address, also known as a Media Access Control or MAC
address, on the local area network. IP routing table is defined on IP Ethernet devices (the
NBG420N) to decide which hop to use,
to help forward data along to its specified destination.
The following lists out the steps taken, when a computer tries to access the Internet for the first
time through the NBG420N.
1 When a computer (which is in a different subnet) first attempts to access the Internet, it
sends packets to its default gateway (which is not the NBG420N) by looking at the MAC
address in its ARP table.
2 When the computer cannot locate the default gateway, an ARP request is broadcast on
the LAN.
3 The NBG420N receives the ARP request and replies to the computer with its own MAC
address.
4 The computer updates the MAC address for the default gateway to the ARP table. Once
the ARP table is updated, the computer is able to access the Internet through the
NBG420N.
5 When the NBG420N receives packets from the computer, it creates an entry in the IP
routing table so it can properly forward packets intended for the computer.
After all the routing information is updated, the computer can access the NBG420N and the
Internet as if it is in the same subnet as the NBG420N.