connection problems

[je5tyu 0]

hello!

i have a problem with the connection:

i'm in one student campus,and the only connections possible is the passive mode n i was trying to make a hub for more students campus n we confront a problem!

if u take a look on the picture from the next link:

http://img823.imageshack.us/img823/5012/58912928.jpg

CASE 1: we realize than the green line,represent the passive connection with NAT traversal,beetween 2 campus wat it's working is the way passive-passive,

n then we can see the red line what it's represent the same connection passive-passive with NAT traversal,wat is not working because the access on router is limited,n port forward is not possible!

CASE 2: i was trying than 1 client to be in active mode n the other client to be in passive mode,n i realize than the red line working,n the green line is not working!

i want a explanation how is working the CASE 2,n if there is any possibility than in the mode passive-passive with NAT traversal ,to work also the red line?