I have a 3550 as core switch for my network
I have 2 subnets: 192.168.42.0/24 & 192.168.43.0/24
my 3550 is configured as D\G for both subnets
from 42.x machines I can pign any 42.x or 43.x IP
from 43.x I can ping any server on the 42.x subnet BUT not any of the 42.x routers that connect directly to the 3550 switch...
I have no idea why and how can it happen
Thank you for posting the additional information that I asked for. I believe that it is very hellpful.
From this information I notice that the router has a static route for the 192.168.43.0 subnet. I am going to guess that the static route is of the form:
ip route 192.168.43.0 255.255.255.0 fastethernet0/0
rather than of the form which specifies the next hop address. Can you verify whether this is true?
If this is true then the router knows that it must go through interface Fastethernet0/0 to get to the 43 subnet. And the router must ARP for the destination address in the 43 subnet. And I believe that the switch is receiving the ARP request and not responding. If you change the static route on the router so that it specifies the next hop address (is it 192.168.42.254?) then I believe that the problem will be solved.