User’s Guide
Version 1.0
Chapter 3 – Universal Address Translation
What is UAT
Universal Address Translation
(UAT) allows Hotspot operators to offer true IP Plug&Play access for
their subscribers.
With
UAT
enabled, the Access Controller will automatically and transparently translate fixed IP
settings (IP address, gateway, DNS, proxy server) on a user’s PC enabling him to connect to the
broadband Internet service, even if the client’s IP overlaps the IP subnet of the WAN port.
Without
UAT
public access, subscribers are forced to switch their TCP/IP settings to
DHCP
(automatic IP address assignment), potentially losing any fixed IP address settings they previously
entered.
UAT Principle
BW1330 acts as an ARP proxy to each client who has a fixed IP which not belong to the subnet of
LAN interface. As below figure descript, BW1330 will automatic reply a client’s ARP Request if its IP
doesn’t belong to its LAN subnet to pretend as if BW1330 is its Gateway; then inside BW1330, a
unicast router will be added for UAT client.
Figure 18 – UAT Principle
UAT Limitation
When using
UAT
operators have to be aware of some principal limitations:
If UAT mode is enabled on BW1330, BW1330 will act as an ARP Proxy under its LAN interface. If
there has a sub-net behind a router which under the LAN of BW1330 and there has a PC whose IP
belong to the sub-net as the figure show, the communication between PC2 and PC1 will be failed for
the reason of BW1330’s ARP proxy packet.
But if the router is working under NAT mode, the communication from PC2 to PC1 will be OK.
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