Very Computer

I have mounted a "net" between a DX4100 and a DX266 with
a serial cable. The transmision protocol that I'm using is ppp.
        My problem is that when the dx2 make a telnet to the dx4
al works fine but when i try to make a telnet to dx2 from dx4 that
machine get lost its kernel routing table. After that operation when i
try to make an network operation linux says network is unreachable
(on both machines).

what's wrong???

P.D.
excuseme but my english is poor ;-)