[c-nsp] how to get ICMP host unreachables?

[Gert Doering]

Hi,

On Fri, Apr 08, 2005 at 02:40:39PM +0200, Oliver Boehmer (oboehmer) wrote:
> Can we ascertain that there is no path if we don't receive an ARP reply?

Very much so - there is no way you can deliver the packet, so there is
no path (for you).  The interesting question is "how long do you need to
wait for the ARP reply"...

You might also want to discuss this with the Cisco IPv6 team - for IPv6,
IOS *does* send back an ICMP unreachable if a neighbour cannot be 
reached...

20:16:35.571611 2001:608:0:11::113 > 2001:608:4::3: icmp6: 2001:608:0:1::ffff unreachable address (len 68, hlim 62)
20:16:38.955944 2001:608:0:11::113 > 2001:608:4::3: icmp6: 2001:608:0:1::ffff unreachable address (len 68, hlim 62)
20:16:42.959655 2001:608:0:11::113 > 2001:608:4::3: icmp6: 2001:608:0:1::ffff unreachable address (len 68, hlim 62)

(2001:608:0:1::/64 is connected to 2001:608:0:11::113, but there is no
::ffff in the segment)

gert

-- 
USENET is *not* the non-clickable part of WWW!
                                                           //www.muc.de/~gert/
Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de