Re: Bridge interface and IP address

[Michael Richardson <mcr%sandelman.ca@localhost>]

>>>>> "der" == der Mouse <mouse%Rodents-Montreal.ORG@localhost> writes:
    >> I would argue that it's not interfaces/bridges that is the
    >> problem, it's the fact that "struct ifnet" is associated with an
    >> "interface", rather than with a network (broadcast/ppp) domain
    >> (for which, we do not have any names).

    der> Perhaps I've just succumbed to the downside of Sapir-Whorf
    der> here, but I'm not sure what this is talking about.

    der> Could you give a concrete example?

There are two kinds of things, which we call "interface", which are
connected together by history more than planning:

a) the connector on the computer (the "port")
b) the set of protocol things like the list of addresses, and the like.

I know that FreeBSD changed some of this with their netgraph stuff, and
this is related, but perhaps not exactly the same.

Here are three examples.
   1) the desire to tcpdump on an interface without having any
      addresses/protocols configured.
      (related is IPv4 or IPv6, but not both)
      
      Here you want a port, but no "ifnet" goo.

   2) the desire to configure a bridge between two ports without
      having IP connected.

      Here you want two ports, and a special "ifnet" goo that implements
      a learning bridge (or maybe, not).  The resulting "thing" could
      itself be a port (or you could include a virtual port in the
      bridge), on which you can attach more things, such as "ifnet" goo.
      
   3) the desire to bond two interfaces together, for 802 trunking
      purposes, for instance.

      In this case, you might want to associate "ifnet" goo with *TWO*
      ports, with some rules as to how you load balance.

   4) the desire to create new ports based upon vlan tags, some of
      which you might want to attach "ifnet" goo, while others you
      might want to "bridge" to something else (domU, another, untagged
      port). 

      In this case, you want to associate "vlan" goo with the port,
      and the vlan goo creates a bunch of new network domains (ports),
      on which you can do things.

-- 
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