On Sun, 29 Jun 2008 16:31:50 +0530, आशीष शुक्ल Ashish Shukla wrote:

> So this is what one should expect from a top-level internet host, right
> ?

Packets with "unroutable" addresses should be dropped at border routers
whether those are source or destination addresses. I can see the
motivation for choosing to let packets with unroutable source addresses
through: they can be usefully informative w/o wasting public address
space on internal infrastructure.

But those packets also become untraceable back to their source after a
few hops, which can be a bad thing.

I'd worry more, though, about a failure to filter out routable but
impossible addresses. A network shouldn't let a packet out if that
packet has a source address not correct for that network. Or, for that
matter, routers shouldn't accept incorrect route announcements. That's
how some ISP in Pakistan was able to shut down youtube for a while, for
example.

- Andrew