address spoofing

> > Furthermore, whether the RFC [1918] says so or not, I'm going to block
> > these packets at *my* border routers, because:
> Curious as to the cost (added latency) in doing RFC 1918 source address
> filtering on all packets in the context of cost-benfit analysis.

The cost is dependent on the quality of the filtering implementation of
your routers. It's quite possible to implement source address filtering
as a part of ASIC-assisted routing, resulting in wire-speed filtering.
Whether any given vendor has or has not implemented their equipment to
allow wire speed filtering is something you might want to ask salesmen.

As it's something which network providers should be doing, its a
capability that should be demanded of the hardware vendors.

Daniel Senie
Amaranth Networks Inc.

Well, that will eventually get somebody into trouble. Long ago & far
away, Dave Mills greated a list of "forbidden" network prefixes in the
fuzzball routers. The Martian list consisted of the "zero & all-ones"
/24 networks at the edges of the old classfull boundaries. Many router
vendors hardcoded those as well. Ate my lunch a few years ago w/
ciscos. It seems to be fixed (again) in the latest 12.0 codebase.

Tossing six /24s is one thing. Tossing twohundred seventy /16s is
something else again...