peters@cc.msstate.edu (Frank W. Peters) (02/23/89)
Hello, We have a large, unsubnetted, class B network (130.18) on our campus. Though this network is unsubnetted addresses are assigned in a subnetted fashion (that is, each building has its own 'subnet number' although no subnet mask is actually in use). In one of the buildings we are currently attempting to attach we have several Sun 4 servers running 4.0 (one is running 4.0.1). To isolate NFS traffic each of these servers has two ethernet cards. One card attaches to the campus network while the other attaches to the server's diskless clients. Each of the client networks has its own 'subnet number' of the class B network. In order to allow the servers to have portions of the same network on two different interfaces it seems that some degree of subnetting is necessary. Now we come to the question of how, exactly, to configure these servers. Our first pass was to subnet the test server (in a class C manner). We set the broadcast address to 130.18.255.255 so that the unsubnetted hosts would be able to converse with the servers. When we attempt to boot under this configuration we get the error: Unable to send Broadcast: Network is unreachable and ypbind hangs because it cannot reach a ypserv (this all ocurring on the ypserver machine itself). When we set the broadcast to the subnetted address (ie 130.18.64.255) the machine boots. So, in short, why does: ifconfig ie1 $hostname up -trailers netmask 255.255.255.0 broadcast \ 130.18.64.255 allow the machine to boot (and yp to start) when ifconfig ie1 $hostname up -trailers netmask 255.255.255.0 broadcast \ 130.18.255.255 doesn't? ========== Assuming that we can solve the above problem then the following question becomes relevant. The above solution still leaves some problems. Since the servers are subnetted they still refuse to communicate directly to hosts that are not on the same subnet. That is, machine 130.18.64.11 refuses to speak to 130.18.96.64 because that machine is not on the same subnet (even though it is directly reachable). What would actually be the ideal solution is for the servers to be subnetted on the client side and unsubnetted on the server side (this is perfectly legal under the RFCs, its just a matter of logistics). I note in the documentation that a subnet mask is assigned on each interface. I have been given to believe that, under 4.0{.1} it is possible to subnet one interface and leave the other unsubnetted. What I envision is the following ifconfig for the interface on the unsubnetted backbone: ifconfig ie1 $hostname netmask 255.255.0.0 up -trailers and the following on the client side: ifconfig ie1 $hostname netmask 255.255.255.0 up -trailers Will the above entries accomplish the desired goal (allowing the backbone side to be unsubnetted while subnetting the client side)? If not, do you have any pointers to the correct method to accomplish this? Frank Peters Systems Programmer | Mississippi State University Phone: (601) 325-2942 | Computing Center and Services Internet: peters@CC.MsState.Edu | Post Office Drawer CC BITNET: PETERS@MSSTATE.BITNET | Mississippi State, MS. 39759