rpomm...@sfgmembers.com (Pommier, Rex) writes: > Sorry if these are silly questions, but my brain is really foggy this > morning. My questions are for validation of what I think would happen > with various iterations of IPCONFIG DATAGRAMFWD. > > Scenario 1, I have a single IP address on my z/OS system running to a > single network segment out an OSA port. In this scenario, DATAGRAMFWD > would have no effect, correct? > > Scenario 2, I have 2 IP addresses, connected via 2 different OSA > adapters to 2 different networks. If I have DATAGRAMFWD, when TCPIP > sees a packet coming in on OSA 1 but it has a destination address of a > device on network 2, TCP/IP will forward the packet out the other OSA, > effectively acting like a router or gateway. If I set it to > NODATAGRAMFWD, if TCP/IP sees the same packet on OSA1, it will ignore > the packet rather than forwarding it. Is this how it actually works? > > What I'm looking at is we have a new machine being installed that I > need to be able to access from 2 different networks at different > times. These two networks need to be isolated from each other and I > don't want the mainframe to start acting as a router, passing packets > from one to the other. Is there some other configuration setting I > need to be aware of, or would the NODATAGRAMFWD be sufficient to > keeping them isolated? > > Yes, the safest solution would be to unplug one of the network cables, > and just have 1 plugged in at a time, but the machine is about 300 > miles from me.
modulo bugs in the code. the weekend before 1988 Interop, the floor nets were crashing well into early Monday morning ... before problem was identified. As a result, new requirements were mandated in RFC1122 (RFC1122 & RFC1123 combined are official internet STD3). regarding automagically forwarding packets. ... Any host that forwards datagrams generated by another host is acting as a gateway and MUST also meet the specifications laid out in the gateway requirements RFC [INTRO:2]. An Internet host that includes embedded gateway code MUST have a configuration switch to disable the gateway function, and this switch MUST default to the non-gateway mode. In this mode, a datagram arriving through one interface will not be forwarded to another host or gateway (unless it is source-routed), regardless of whether the host is single- homed or multihomed. The host software MUST NOT automatically move into gateway mode if the host has more than one interface, as the operator of the machine may neither want to provide that service nor be competent to do so. ... snip ... trivia: i had hardware&demo in booth at Interop 88 ... but not in the IBM booth ... which was on the other side of the floor. -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
