On Wed 2016-Jun-01 14:03:41 -0700, Octavio Alvarez <octalnanog@alvarezp.org> wrote:
On 05/31/2016 11:22 AM, William Herrin wrote:
I'm not sure if you mean that, if sent through C it should have the source addres of A, or that it should actually be sent through A regardless of the routing table (which sounds better to me).
That doesn't make sense. There may be multiple next hops out A. If the next hop in the FIB is out C, how would the router pick the next hop to send to out A?
Back to the physical address that sent the TTL-offending packet.
Which comes back to my question: What guarantees do you have that the device at that physical address (so, adjacent off of R's interface A) has a valid route for S, and that the route does not simply point back to R?
Anyway, Randy's comment was about source address selection, not routing. With the packet coming from S into interface A, he'd prefer that the ICMP error message be sourced from the IP address assigned to A, not the IP address assigned to C or R.
Thanks.
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