User's Manual Part 1

Chapter 6 WAN Setup
AMG1202-T10A User’s Guide
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IP Assignment with PPPoA or PPPoE Encapsulation
If you have a dynamic IP, then the IP Address and Gateway IP Address fields are not applicable
(N/A). If you have a static IP, then you only need to fill in the IP Address field and not the
Gateway IP Address field.
IP Assignment with RFC 1483 Encapsulation
In this case the IP address assignment must be static.
IP Assignment with ENET ENCAP Encapsulation
In this case you can have either a static or dynamic IP. For a static IP you must fill in all the IP
Address and Gateway IP Address fields as supplied by your ISP. However for a dynamic IP, the
ZyXEL Device acts as a DHCP client on the WAN port and so the IP Address and Gateway IP
Address fields are not applicable (N/A) as the DHCP server assigns them to the ZyXEL Device.
6.4.5 Nailed-Up Connection (PPP)
A nailed-up connection is a dial-up line where the connection is always up regardless of traffic
demand. The ZyXEL Device does two things when you specify a nailed-up connection. The first is
that idle timeout is disabled. The second is that the ZyXEL Device will try to bring up the connection
when turned on and whenever the connection is down. A nailed-up connection can be very
expensive for obvious reasons.
Do not specify a nailed-up connection unless your telephone company offers flat-rate service or you
need a constant connection and the cost is of no concern.
6.4.6 NAT
NAT (Network Address Translation - NAT, RFC 1631) is the translation of the IP address of a host in
a packet, for example, the source address of an outgoing packet, used within one network to a
different IP address known within another network.
6.5 Traffic Shaping
Traffic Shaping is an agreement between the carrier and the subscriber to regulate the average rate
and fluctuations of data transmission over an ATM network. This agreement helps eliminate
congestion, which is important for transmission of real time data such as audio and video
connections.
Peak Cell Rate (PCR) is the maximum rate at which the sender can send cells. This parameter may
be lower (but not higher) than the maximum line speed. 1 ATM cell is 53 bytes (424 bits), so a
maximum speed of 832Kbps gives a maximum PCR of 1962 cells/sec. This rate is not guaranteed
because it is dependent on the line speed.
Sustained Cell Rate (SCR) is the mean cell rate of each bursty traffic source. It specifies the
maximum average rate at which cells can be sent over the virtual connection. SCR may not be
greater than the PCR.