IP Alias

Using IP Alias

- What is IP Alias ?

In a typical environment, a LAN router is required to connect two local networks. The Prestige can connect three local networks to the ISP or a remote node, we call this function as 'IP Alias'. In this case, an internal router is not required. For example, the network manager can divide the local network into three networks and connect them to the Internet using Prestige's single user account. See the figure below.

The Prestige supports three virtual LAN interfaces via its single physical Ethernet interface. The first network can be configured in menu 3.2 as usual. The second and third networks that we call 'IP Alias 1' and 'IP Alias 2' can be configured in menu 3.2.1-IP Alias Setup.

There are three internal virtual LAN interfaces for the Prestige to route the packets from/to the three networks correctly. They are enif0 for the major network, enif0:0 for the IP alias 1 and enif0:1 for the IP alias 2. Therefore, three routes are created in the Prestige as shown below when the three networks are configured. If the Prestige's DHCP is also enabled, the IP pool for the clients can be any of the three networks.

`Copyright (c) 1994 - 1999 ZyXEL Communications Corp.`
`ras> ip ro st`
`Dest FF Len Interface Gateway Metric stat Timer Use`
`192.168.3.0 00 24 enif0:1 192.168.3.1 1 041b 0 0`
`192.168.2.0 00 24 enif0:0 192.168.2.1 1 041b 0 0`
`192.168.1.0 00 24 enif0 192.168.1.1 1 041b 0 0`
`ras>`

Two new protocol filter interfaces in menu 3.2.1 allow you to accept or deny LAN packets from/to the IP alias 1 and IP alias 2 go through the Prestige. The filter set in menu 3.1 is used for main network configured in menu 3.2.

- IP Alias Setup

1. Edit the first network in menu 3.2 by configuring the Prestige's first LAN IP address.

> > > > Menu 3.2 - TCP/IP and DHCP Setup
> > > > DHCP Setup
> > > > DHCP= Server
> > > > Client IP Pool Starting Address= 192.168.1.33
> > > > Size of Client IP Pool= 6
> > > > Primary DNS Server= 168.95.1.1
> > > > Secondary DNS Server= 168.95.192.1
> > > > Remote DHCP Server= N/A
> > > > TCP/IP Setup:
> > > > IP Address= 192.168.1.1
> > > > IP Subnet Mask= 255.255.255.0
> > > > RIP Direction= Both
> > > > Version= RIP-1
> > > > Multicast= None
> > > > IP Policies=
> > > > Edit IP Alias= Yes

> > > > Press ENTER to Confirm or ESC to Cancel:

Key Settings:

DHCP Setup | If the Prestige's DHCP server is enabled, the IP pool for the clients can be any of the three networks.
TCP/IP Setup | Enter the first LAN IP address for the Prestige. This will create the first route in the enif0 interface.
Edit IP Alias | Toggle to 'Yes' to enter menu 3.2.1 for setting up the second and third networks.

2. Edit the second and third networks in menu 3.2.1 by configuring the Prestige's second and third LAN IP addresses.

`Menu 3.2.1 - IP Alias Setup`

`IP Alias 1= Yes`
`IP Address= 192.168.2.1`
`IP Subnet Mask= 255.255.255.0`
`RIP Direction= None`
`Version= RIP-1`
`Incoming protocol filters=`
`Outgoing protocol filters=`
`IP Alias 2= Yes`
`IP Address= 192.168.3.1`
`IP Subnet Mask= 255.255.255.0`
`RIP Direction= None`
`Version= RIP-1`
`Incoming protocol filters=`
`Outgoing protocol filters=`

`Enter here to CONFIRM or ESC to CANCEL:`

Key Settings:

IP Alias 1 | Toggle to 'Yes' and enter the second LAN IP address for the Prestige. This will create the second route in the enif0:0 interface.
IP Alias 2 | Toggle to 'Yes' and enter the third LAN IP address for the Prestige. This will create the third route in the enif0:1 interface.

All contents copyright © 2003 ZyXEL Communications Corporation.