On Tue, 16 May 2000, Ed Carp wrote:
> Michael H. Warfield (mhw@wittsend.com) writes:
> >
> > > > No, sir, those addresses are not valid addresses, since most if not all hosts
> > > > may respond to them. Witness what happens when you ping an address ending in
> > > > either .0 or .255 - they are usually interpreted as broadcast addresses, NOT
> > > > to be assigned to hosts.
> >
> >
> > > This is only true in classful routing, not classless. In any
> > > case (old or new), the last hop router is the one that should be
> > > dropping or not dropping the packet, *never* a router somewhere in the
> > > middle.
> >
> > It's not even true then. It's only true in the case of classful
> > routing on a class C network (255.255 and 0.0 on a class B and 255.255.255
> > and 0.0.0 on a Class A) or in a /24 in classless routing (as defined by
> > the end router - intermediate routers can NOT make that determination).
> > In the case of /25 or smaller (larger number), 255 and 0 are bad but
> > so are 128 and 127 as well as others (depending on netmask number).
>
> Did you deliberately overlook the point? It's not the routers that were my
> point, it was the hosts that respond to such broadcasts.
There is not a point here. The addresses *would* have been a
network or broadcast address under old classful systems, and they
might be now, or they might not be.
*IF* you have a network, that *uses* these addresses and
network and broadcast, then your *last* hop router should
respond/block this traffic, if you network *DOES NOT* use them this
way then they are valid addresses.
---
As folks might have suspected, not much survives except roaches,
and they don't carry large enough packets fast enough...
--About the Internet and nuclear war.
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This archive was generated by hypermail 2b29 : Tue May 23 2000 - 21:00:11 EST