[Click] Building a packet reflector in click

[Cliff Frey]

I suspect the problem is that IPMirror does not set the dst_ip_anno
annotation, which is what ARPQuerier uses.

If you add a GetIPAddress(IP dst) after the IPMirror, you might have better
luck.... but I'm not positive if that'll be enough.  It is hard to know as I
don't know what your exact device configuration (ip, subnet, gateway, etc)
is.

I'd add ARPPrint elements after c[1] and arpq[1] to see what ARP traffic you
are generating/receiving.

Cliff;

On Tue, Aug 25, 2009 at 12:57 PM, david johnson <
david.lloyd.johnson at gmail.com> wrote:

> Hi
>
> I presented a course on click today - used a lot of material from
> University of Antwerp - thanks Bart and Michael. I thought up some
> tutorials for them to practice their concepts and I thought building a
> packet reflector would be easy - until I tried to solve it
>
> I tried something like this:
>
> define($DEV ath0)
>
> FromDevice($DEV)
>  -> c :: Classifier(12/0800, 12/0806 20/0002)
>  -> CheckIPHeader(14)
>  -> IPMirror
>  -> StripToNetworkHeader
>  -> Print ("Before ARP",200)
>  -> arpq :: ARPQuerier($DEV)
>  -> Print ("After ARP",200)
>  -> IPPrint
>  -> q :: Queue
>  -> ToDevice($DEV)
>
>
> arpq[1] -> q;
> c[1] -> [1] arpq;
>
> But it doesn't work - the IP address swapping is working - but it never
> gets to the Print("After ARP",200) statement.
>
> Is this a hard problem or is their a simple solution that I'm missing
>
> I'm trying to think out a set of click exercises that get progressively
> harder for the students to  do. Firstly without writing their own
> elements and then with including writing their own elements - any ideas
> will be most welcome. This would probably be a nice addition to the
> documentation - exercises like these and their solutions.
>
> Regards
> David
>
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