D-Link DSR-150N DSR-150 User Manual - Page 56

Unified Services Router User Manual  NA T is a t ech n iq u e wh ich allo ws s ev eral co mp u t ers o n a LA N t o s h are an In t ern et co n n ect io n . Th e co mp u t ers o n t h e LA N u s e a " p riv at e" IP ad d res s range while the W A N port on the router is configured with a s ingle " public" IP addres s. Along with connection s haring, NAT als o hides internal IP addres s es fro m t h e co mp u t ers o n t h e In t ern et . NA T is req u ired if y o u r ISP h as as s ig n ed o n ly o n e IP ad d res s t o y o u. Th e co mp u te rs t hat co n nect t h ro u g h t h e ro u t er will need to be as s igned IP addres s es from a private s ubnet .  Tran s p aren t ro u t in g b et ween t h e LA N an d W A N d o es n o t p erfo rm NA T. Bro ad cas t an d mu lt icast p ackets t h at arriv e o n t h e LA N in t erface are s wit ch ed t o t h e W A N an d v ice v ers a, if t h ey d o n o t g et filt ered b y firewall o r VPN p o licies . To main t ain t h e LA N an d W A N in t h e s ame b ro ad cas t d o main s elect Tran s p aren t mo d e , wh ich allo ws b rid g ing o f t raffic fro m LA N t o W A N an d v ice v ers a, excep t fo r ro u t er-t ermin at ed t raffic an d o t h er man ag emen t t raffic . A ll DSR feat u res (su ch as 3G mo d em s u p p o rt ) are s u p p o rt ed in t ran s p aren t mo d e as s u min g t h e LA N an d W A N are co n fig u red t o b e in t h e s ame b ro ad cas t d o main .  NA T routing has a feature called "NA T Hair-pinning" that allows internal ne twork u s ers o n t h e LA N an d DM Z t o access in t ern al s erv ers (eg . an in t ern al FTP s erv er) u s in g t h eir ext ern ally -kn o wn d o main n ame. Th is is als o referred t o as "NA T lo o p b ack" s ince LA N g en erat ed t raffic is red irect ed t h ro u g h t h e firewall t o reach LA N s erv ers b y t h eir ext ern al n ame. 54