D-Link DSR-150 User Manual page 56

Unified Services Router
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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
ran g e wh ile t h e W A N p o rt o n t h e ro u ter is co n figu red wit h a s in g le " p u b lic" IP
ad d res s. A lo ng wit h co n nectio n s harin g, NA T als o h id es in t ern al IP ad d res 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
n eed t o b e as s ig n ed IP ad d res s es fro m a p riv at e s u b n et .
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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 .
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NA T ro u t in g h as a feat u re called "NA T Hair -p in nin g" t h at allo ws in t ern al n e t wo rk
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.
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User Manual