CIDR question

Mark Knopper mak
Thu Jul 29 03:52:14 UTC 1993

  Since you raised the point about the Fuzzballs, I would also
like to point out that the Merit PDP-11 operating system has
had CIDR routing capabilities since 1985 or so. Obviously
the wave of the future.
  On a more substantial note, one issue that was raised at
the IETF concerned the idea of subnetting with CIDR (as opposed
to supernetting). When do you think that the NIC(s) will be able
to hand out pieces of what we now think of as class A nets,
for example? My thought is that not only will a very large portion
of the Internet need to be CIDR-ized before this happens, but
several routers will need to have significant changes to the way
forwarding works. Does anyone agree with this?

> From:    "Milo S. Medin" (NASA ARC NSI Office) <medin at>
> To:      Vince Fuller <vaf at Valinor.Stanford.EDU>
> CC:      Erik Sherk <sherk at>, regional-techs at

> I strongly agree.  The issue of an "all-nets" broadcast is inconsistent with 
> classless network routing.  We should be taking steps to eliminate 
> knowledge of class in all router and host implementations, as flexibility
> here will certainly be helpful in increasing the lifetime of the IPv4
> protocol suite, and transitions from that suite.  I always thought the "all
> nets" broadcast was a broken idea for many reasons, this being one of them.
> OSPF was designed to be classless internally, but have defaults that are
> somewhat based on class boundaries.  In general, it should be possible
> emulate "class" for human factors reasons if you implement everything
> in a truly classless way.  Other routing protocols are making this 
> transition as well.  It's sort of back to the future, since I believe
> the original NSF backbone (56 Kbps fuzzballs which did a pure mask and
> match forwarding decision) had this capability!
> 						Thanks,
> 						   Milo

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