From Yahoo Answers.
Well, After downloading the manual
ftp://files.dlink.com.au/products/DIR-30…
It appears that with these units what you want to do is not possible with the Dlink Firmware. The function does not exist in the current firmware.
Linksys, Netgear, and others have builtin to them a system called WDS (wireless distribution) which will do what you want. Allow router to router wireless. The DIR300s do not have that feature.
1. you have to use a wire between them.
2 you can buy a wireless repeater unit which would also do the job.