Hi Joakim,
On 17/12/2018 09:37, Joakim Nohlgård wrote:
Thank you for your answer. OK I think I understand what you mean, but
is this really the correct behavior?
It was certainly unexpected to me to have the packets go out the
default route instead of on the interface with the configured prefix.
I will try to elaborate:
I have a prefix 2001:db8::/64 configured for the wireless interface.
When I run ping6 2001:db8::1234 from the shell on the RIOT node, I
expect the system to first attempt to find 2001:db8::1234 on the
interface which has been configured for that prefix, instead of
immediately falling back and taking the default route when the
destination does not already exist in the NIB neighbor table.
I would expect so, too: This should be the correct routing decision and
default routing is wrong. Sorry, I didn't see that in your previous mail.
I'm not sure such fallback makes sense at all, if a specific, globally
routable prefix is configured. If 2001:db8::1234 is not reachable via
2001:db8::/64, a 'destination unreachable' should be triggered.
Cheers,
thomas
On Mon, Dec 17, 2018 at 9:11 AM Thomas C. Schmidt
<t.schm...@haw-hamburg.de> wrote:
Hi Joakim,
it appears that you are experimenting with a special case.
Normally, a sending node decides on the outgoing interface based on the
destination IP prefix. If you don't have a more specific routing entry,
the default IF is correctly chosen in your case.
After the interface is selected, the source needs to decide on the
Layer2 framing. Most link-layer technologies use an addressing
(802.3/11, 15.4 ...) and the MAC address is acquired via ND. In your
case, you mention SLIP. A serial line interface does not use L2
addresses and does not need ND.
Best,
Thomas
On 17/12/2018 08:59, Joakim Nohlgård wrote:
Hi developers,
When using the shell on the gnrc_border_router application trying to
send to an unknown address with its designated prefix, the application
does not send any neighbor solicitations on the wireless network.
When I type ping6 2001:db8::1234 I expected that a neighbor
solicitation query to go out on the interface that has been configured
with the routing destination for 2001:db8::/64, but wireshark shows
that nothing is sent on the wireless, but instead the ICMPv6 packet is
sent immediately over the slip/ethos interface, which is configured as
the default route.
Is this behavior correct or is this a routing bug?
Configurations:
ifconfig
Iface 6 HWaddr: 02:DA:F1:03:BC:48
MTU:1500 HL:64 RTR
RTR_ADV Source address length: 6
Link type: wired
inet6 addr: fe80::da:f1ff:fe03:bc48 scope: local TNT[1]
inet6 addr: fe80::2 scope: local VAL
inet6 group: ff02::2
inet6 group: ff02::1
inet6 group: ff02::1:ff03:bc48
inet6 group: ff02::1:ff00:2
Iface 7 Channel: 26 Page: 0 NID: 0x23
Long HWaddr: 23:31:53:29:36:B7:6E:5A
TX-Power: 0dBm State: IDLE max. Retrans.: 3 CSMA Retries: 4
ACK_REQ CSMA MTU:1280 HL:64 RTR
RTR_ADV IPHC
Source address length: 8
Link type: wireless
inet6 addr: fe80::2131:5329:36b7:6e5a scope: local VAL
inet6 addr: 2001:db8::2131:5329:36b7:6e5a scope: global VAL
inet6 group: ff02::2
inet6 group: ff02::1
inet6 group: ff02::1:ffb7:6e5a
routing:
nib route
2001:db8::/64 dev #7
default* via fe80::1 dev #6
Best regards,
Joakim
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--
Prof. Dr. Thomas C. Schmidt
° Hamburg University of Applied Sciences Berliner Tor 7 °
° Dept. Informatik, Internet Technologies Group 20099 Hamburg, Germany °
° http://inet.haw-hamburg.de/members/schmidt Fon: +49-40-42875-8452 °
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_______________________________________________
devel mailing list
devel@riot-os.org
https://lists.riot-os.org/mailman/listinfo/devel
--
Prof. Dr. Thomas C. Schmidt
° Hamburg University of Applied Sciences Berliner Tor 7 °
° Dept. Informatik, Internet Technologies Group 20099 Hamburg, Germany °
° http://inet.haw-hamburg.de/members/schmidt Fon: +49-40-42875-8452 °
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