SAMBA authentication on multiple subnets

[Luciano Klein]

Dear list,

I have a SAMBA server sharing files and authenticating users in one of
my University Labs - LAB A. Now I have two other labs, on two different
subnets LAB B and LAB C. If I configure a client computer on LAB B or C,
using a valid LAB A address, everything works fine - this seems to mean
physical connections are allright (the labs are connected through
optical fiber). If I configure a client computer on LAB A (the original
LAB) using a valid LAB B or C address, everything works - this seems to
mean addressing is Ok. However, neither LAB B or C are able to
authenticate within SAMBA with their own subnet addresses. I am able to
ping any lab machine form any other lab machine, so routing must be Ok.
Any hint? Any timeout I should worry about?

Regards,

Luciano