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BelAir100SN User Guide
Network Address Translation
May 31, 2010
Confidential
Document Number BDTM11001-A01 Released
Network Address Translation
Network Address Translation (NAT) allows the BelAir100SN to modify
network address information in packet headers to remap a given address space
into another. This technique can hide several private network IP addresses
behind a single IP address in another public address space.
The BelAir100SN implements NAT IP masquerading, where the BelAir100SN
acts as a DHCP server to assign IP addresses in the private network starting
from a specified base IP address. NAT applies only to traffic entering and leaving
the BelAir100SN through its Ethernet interface.
The BelAir100SN lets you configure up to eight NAT address scopes. For each
scope, you can associate different VLAN traffic, a different base IP address and
different DHCP lease settings.
For each scope, you can also configure and enable a portal to provide client
authentication. Authentication is done using a Web browser redirect to an
external HTTP server that displays a splash page where the client must provide
credentials. The external HTTP server uses an external RADIUS server to
authenticate the client and UAM to collect billing information. Once
authenticated, the client Web session is redirected back to its original
destination, usually an Internet connection.
The BelAir100SN can provide both NAT and Layer 2 tunnels. User traffic
separation is based on VLANs. If you use both NAT and Layer 2 tunnels, make
sure that your VLANs are mapped to either an NAT scope or a Layer 2 tunnel,
but not both. Refer to
“Using Layer 2 Tunnels” on page 150
for a description of
Layer 2 tunnels.
The following tasks can be done:
•
“Displaying the Operational Status” on page 146
•
“Displaying the Current DHCP Lease Status” on page 146
•
“Displaying the DHCP Lease History” on page 147
•
“Configuring Network Address Translation” on page 147
•
“Choosing an Egress Interface” on page 148
•
“Preventing Node Management from within the Scope” on page 148
•