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Re: Cisco - ip verify unicast reverse-path
- From: Mark Prior
- Date: Sun Feb 13 08:28:49 2000
And then there is http://www.cisco.com/warp/public/707/newsflash.html. It
says that the RPF check is based on CEF. I'm not familiar with CEF and
want to clarify something about unicast RPF. If the source address of a
packet arrived on an interface that would not be the preferred route for
that address but is one of the less-preferred routes would the packet get
Nope it has to be the preferred route.
If, as I hope, it would not, I don't understand the argument that it
doesn't work for multi-homed connections. Such systems should be
advertising their routes over all connections - thus the routes should
appear on all paths outbound from the multi-homed systems (less any long
prefix filtering being done by the upstreams).
I agree it would be more helpful if the test was "a route exists"
instead of "the best route" as I have seen it cause havoc with
customers who have multiple links to us and get the MEDs wrong.