Re: ICMP handling in Linux
On Tue, 2012-04-10 at 21:10 -0300, Henrique de Moraes Holschuh wrote:
> On Tue, 10 Apr 2012, Martin T wrote:
> > It's a well known fact that even most(with exceptions like ASR1K) of
> > the high-end Cisco or Juniper routers handle ICMP traffic in routing
> > engines not in ASIC's which means that they share the CPU time with
> > other processes. How prioritized is ICMP handling in modern Linux 2.6
> > and newer kernels? Is it possible to prioritize ICMP handling in
> > kernel?
>
> AFAIK, it has the same priority of every other packet that makes it to the
> IP stack.
>
> Easy depriorizing is possible by outright dropping incoming ICMP packets
> in the iptables layer, before it is processed by the IP stack.
>
> I suppose advanced NICs might be able to use receiver-side flow-steering to
> priorize or depriorize ICMP packets before delivering them to the driver, or
> you could steer them all to a particular core.
>
> I fear you will probably need to ask this question in the netdev ML if
> you want a better answer.
>
Setting up a qdisc via the tc utility would be a more controlled way
than simply drop or not drop. Alas, it is not one of the simpler things
to do in Linux - John
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