ZyXEL Communications P-870HW-51a v2 User Manual page 63

ENET ENCAP
The MAC Encapsulated Routing Link Protocol (ENET ENCAP) is only implemented with the
IP network protocol. IP packets are routed between the Ethernet interface and the WAN
interface and then formatted so that they can be understood in a bridged environment. For
instance, it encapsulates routed Ethernet frames into bridged ATM cells.
PPP over Ethernet
Point-to-Point Protocol over Ethernet (PPPoE) provides access control and billing
functionality in a manner similar to dial-up services using PPP. PPPoE is an IETF standard
(RFC 2516) specifying how a personal computer (PC) interacts with a broadband modem
(DSL, cable, wireless, etc.) connection.
For the service provider, PPPoE offers an access and authentication method that works with
existing access control systems (for example RADIUS).
One of the benefits of PPPoE is the ability to let you access one of multiple network services,
a function known as dynamic service selection. This enables the service provider to easily
create and offer new IP services for individuals.
Operationally, PPPoE saves significant effort for both you and the ISP or carrier, as it requires
no specific configuration of the broadband modem at the customer site.
By implementing PPPoE directly on the ZyXEL Device (rather than individual computers),
the computers on the LAN do not need PPPoE software installed, since the ZyXEL Device
does that part of the task. Furthermore, with NAT, all of the LANs' computers will have
access.
IP Address Assignment
A static IP is a fixed IP that your ISP gives you. A dynamic IP is not fixed; the ISP assigns you
a different one each time. The Single User Account feature can be enabled or disabled if you
have either a dynamic or static IP. However the encapsulation method assigned influences
your choices for IP address and default gateway.
Full Cone NAT
In full cone NAT, the NAT router maps all outgoing packets from an internal IP address and
port to a single IP address and port on the external network. The NAT router also maps packets
coming to that external IP address and port to the internal IP address and port.
In the following example, the ZyXEL Device maps the source address of all packets sent from
the internal IP address 1 and port A to IP address 2 and port B on the external network. The
ZyXEL Device also performs NAT on all incoming packets sent to IP address 2 and port B and
forwards them to IP address 1, port A.
P-870HW-51a v2 User's Guide
Chapter 5 WAN Setup
63