James Carlson wrote: > I think there's a confusion of terminology here. > > IP interfaces for routing purposes (e.g., with OSPF) may be one of > these types: > > Point-to-Point > Broadcast > Non-broadcast Multi-access > > It has almost nothing to do with physical hardware design; it's an IP > issue, and it depends on the design of the datalink itself, not the > physical layer. > > "Point-to-Point" links don't have netmasks, don't run L2 address > resolution issues (e.g., ARP), and don't have broadcast addresses. > All that they have is a peer IP address. (And, really, that might be > optional in some implementations.) > > "Broadcast" links have all of those things except the peer IP > address. > > Ethernet is a broadcast-type medium, even when run on physically > point-to-point links. Even with your hypothetical point-to-point > connection, it would be necessary to send out ARP messages in order to > get the peer L2 address, as long as we're still speaking standard IP > over Ethernet. > > (Yes, I suppose you could just reduce everything to being broadcasts > at L2. At that point, I think you're defining a brand new > non-Ethernet protocol where the former destination address is just > filled in with 1s.) > > And, yes, point-to-point links sometimes appear on physical layers > that are anything but point-to-point (such as SONET rings), but where > the physical layer provides a service that directly connections two > datalinks together. > > The key issues for identifying the interfaces are: > > - Does the datalink layer provide for the possibility of separate > addressable nodes? > > - Does the datalink layer provide for the possibility of sending to > all addressable nodes at once? > > If Y/Y, then broadcast. If Y/N, then NBMA. If N/N, then > point-to-point. (If N/Y, then someone's lying. ;-}) > >> I think what needs fixing, in the first instance, is to allow >> ifconfig to reset IFF_POINTTOPOINT if it is setting the >> broadcast address or netmask. > > I don't think that's the right fix, either. That just hacks around > the original stumble: point-to-pointedness isn't something determined > by the administrator. Ever. It's something that's a property of the > medium itself.
Agreed. So what is the right approach? It doesn't seem that any are in favor of hacking around the issue in ifconfig or in ip. Adding support for DL_PPP has a gob of issues all on its own as well. I imagine there is going to be more than a little politicking done before all is said and done (especially if DL_PPP is the solution). This is beginning to feel a bit like a rabbit hole - I would certainly be curious to see where it goes, but if no one cares it is a moot point. Bad analogies aside, I suppose what I am really asking, is this even worth pursuing? I have a good bit of time I can dedicate toward this (and other issues) and I would like the opportunity to do something more substantive within Solaris networking. Steve -- Yet magic and hierarchy arise from the same source, and this source has a null pointer. Reference the NULL within NULL, it is the gateway to all wizardry. _______________________________________________ networking-discuss mailing list [email protected]
