Number of IP Alias that can be configured
Q: With the IP Alias feature, is WAN IP Alias automatically set to the primary public IP address assigned by the ISP, and what is the maximum number of auxiliary IP Alias addresses that can be entered?
A: WAN IP Alias is automatically set to whatever the primary public IP address assigned by the ISP. The 2820 allows a total of 8 IP Alias entries, thus giving you 7 additional IPs that can be configured.
Restrictions on the Range of IP Address Used for IP Alias
Q: With the IP Alias feature, are there any restrictions on the range of additional public IP addresses – e.g. do they have to be contiguous, or within the same subnet, and can they be completely independent of the primary WAN 1 IP address?
A: There are no restrictions on the range of additional public IP addresses and they do not need to be contiguous
Join NAT IP Pool option in IP Alias setting
Q: When setting up IP Aliases can you explain what the “Join NAT IP Pool” option does, and in what circumstance it would be used?
A: If this box is ticked, any outgoing request from a client on the LAN will randomly appear as from any of the WAN IP Alias addresses. This may be beneficial for some activities but can also sometimes cause problems with some websites like Internet Banking. If it is not ticked, the outgoing request will always appear as coming from the router’s primary WAN IP address unless it is a response to an incoming request via one of the IP Alias addresses.
Note: The “Join NAT IP Pool” check box is no longer available in more recent products and firmware versions.
Email and IP Alias
Q: How to configure the router so that outgoing SMTP mail source address will be seen coming from the IP alias address configured in the router, e.g. public IP Alias of 22.214.171.124
A: To use the public IP Alias address (126.96.36.199) as the source address, you will need to configure the “Open Port” rule to implement the scenario.