Roland Dreier wrote: > OK, fair enough. I was really replying to the first sentence of: > > Caitlin> From the perspective of any given host, IP addresses are > Caitlin> unique across all interface devices. A given connection > Caitlin> can therefore be identified by just the 4-tuple, with no > Caitlin> need to explicitly state "via this device". > > IP addresses are not unique. However, I do agree that a > 4-tuple uniquely identifies a TCP connection. > > - R.
>From RFC 1918: An enterprise that decides to use IP addresses out of the address space defined in this document can do so without any coordination with IANA or an Internet registry. The address space can thus be used by many enterprises. Addresses within this private address space will only be unique within the enterprise, or the set of enterprises which choose to cooperate over this space so they may communicate with each other in their own private internet. So the unique scope of the IP address is limited to the enterprise, rather than being global. But that scope still encompasses any one single host. It is incorrect to have two "private" networks with the same network prefix attached to the same host. If both eth0 and eth1 claim to be 192.168.1.1, how will a request to connect to 192.168.1.2 be processed? Are they redundant interfaces to the same subnet (leaving the only problem being the determination of which MAC address should be in the ARP reply), or are they two different networks where the 192.168.1.2 they will reach could be different hosts entirely? A given IP address reaches *one* remote host (or a cluster pretending to be a single remote host). There is no ambiguity allowed. And if the local IP address belongs to the same subnet then there can be no ambiguity about the local IP address either. The semantics of an IP address should not be affected by the underlying transport. _______________________________________________ openib-general mailing list [email protected] http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
