[j-nsp] ARP resolution algorithm? Storage of MX transit packets?

Robert Raszuk robert at raszuk.net
Thu Jan 31 03:56:15 EST 2019

We are talking about transit - right ?

So regardless of subnet mask you know your next hop IP from control plane.

Then you creating adj in FIB/CEF without waiting for any packet to arrive.

End hosts on directly connected LANs are different but my impression was
that we are discussing case of transit.


On Thu, Jan 31, 2019, 09:51 Saku Ytti <saku at ytti.fi wrote:

> On Thu, 31 Jan 2019 at 10:34, Robert Raszuk <robert at raszuk.net> wrote:
> > As mentioned on the other thread decent routers should resolve peer's IP
> to mac when creating FIB adj and building rewrite entries.
> > There is no "first packet" notion nor any ARPing driven by packet
> reception. This should apply to p2p adj as well as p2mp - classic LANs.
> > Are you guys saying that say MXes don't do that ?
> I'm not sure what you are saying. I must misunderstand, but are you
> saying once I configure /8 LAN, router ARPs all of them periodically
> until the end of time, retaining unresolved, resolved cache for each
> of /8? Which router does this?
> At least routers I've worked with punt traffic destined to unresolved
> addresses and then build HW adjacency. No traffic to given /32, not
> adjacency, no knowledge of DMAC.
> --
>   ++ytti

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