Re: same link-local address on multiple interface and OSPFv3
A short wrap-up: On 29. jun. 2013, at 22:31, Brian E Carpenter brian.e.carpen...@gmail.com wrote: On 29/06/2013 22:18, Benedikt Stockebrand wrote: Hi Phil and list, [Using the same link-local address on multiple (VLAN) interfaces] Many routers wouldn't let you do that in IPv4. Cisco IOS doesn't, for example: IPv4 doesn't have link-local addresses or anything similar (unless you want to consider 192.169/16 similar in this context). Of course not, but I was trying to see how deep in the product design the issue might go. It sounds like dumb copying of the IPv4 logic (where as Gert says there is no implied scope and therefore a real ambiguity). In this particular case the logic that signals that the local OSPF-interface is not ready was copied from IPv4 OSPF to OSPFv3. I've run with a simple test. - Configured two IRB (or BVI or Vlan X, you name it) interfaces or router R1, bot with the same IPv6 link-local address (fe80::10:1:1:1) and no global addresses. - I run OSPFv3 on one of them, the other is just sitting there, like this: tcpdump here | v ++*fe80::10:1:1:1---OSPF--*++ | R1 | | R2 | ++*fe80::10:1:1:1---no-OSPF---*++ ^ | shutdown this interface - OSPFv3 adjacency come up and everything is fine. - Then I drop the non-OSPF link by shutting down the interface on the neighboring side R2. - From the tcpdump at R1 I can see that R1 stops sending OSPF hello messages. R1 says: ipv6 src Address fe80::10:1:1:1 is not ready ...and stops sending OSPF helloes. - OSPF at R1 gets stuck in the Init state. Brian Thank you all for all your comments and feedback. Kind regards, Matjaž
Re: same link-local address on multiple interface and OSPFv3
On 06/29/2013 09:31 PM, Brian E Carpenter wrote: Of course not, but I was trying to see how deep in the product design the issue might go. It sounds like dumb copying of the IPv4 logic That seems like a pretty reasonable guess. OTOH, OSPFv3 is different enough that I expect the code was all or largely original, so it might be a layer 8 logic error ;o)
Re: same link-local address on multiple interface and OSPFv3
On 06/29/2013 03:18 AM, Benedikt Stockebrand wrote: IPv4 doesn't have link-local addresses or anything similar (unless you want to consider 192.169/16 similar in this context). https://tools.ietf.org/html/rfc3927
Re: same link-local address on multiple interface and OSPFv3
Hi, On Sat, Jun 29, 2013 at 08:07:57AM +1200, Brian E Carpenter wrote: Dumb question: would the same product fail if you configured 10.1.1.1 on two different IPv4 interfaces? (If yes, it tells you there is some sloppy basic design.) Uh, for IPv4, this is not exactly clearly defined what the outcome of two IPv4 interfaces having the same IP address is supposed to be - where will a packet for 10.1.1.2 be sent to, given that IPv4 has no concept of a scoped ID? For IPv6, fe80:: is fairly well defined... Gert Doering -- NetMaster -- have you enabled IPv6 on something today...? SpaceNet AGVorstand: Sebastian v. Bomhard Joseph-Dollinger-Bogen 14 Aufsichtsratsvors.: A. Grundner-Culemann D-80807 Muenchen HRB: 136055 (AG Muenchen) Tel: +49 (89) 32356-444USt-IdNr.: DE813185279
Re: same link-local address on multiple interface and OSPFv3
On 29/06/2013 22:18, Benedikt Stockebrand wrote: Hi Phil and list, [Using the same link-local address on multiple (VLAN) interfaces] Many routers wouldn't let you do that in IPv4. Cisco IOS doesn't, for example: IPv4 doesn't have link-local addresses or anything similar (unless you want to consider 192.169/16 similar in this context). Of course not, but I was trying to see how deep in the product design the issue might go. It sounds like dumb copying of the IPv4 logic (where as Gert says there is no implied scope and therefore a real ambiguity). Brian
Re: same link-local address on multiple interface and OSPFv3
On Fri, 28 Jun 2013, Matjaž Straus Istenič wrote: Workaround is rather simple: use different link-local addresses on IPv6-enabled interfaces and you are safe. But, nevertheless, I think using same link-local pairs on links should not get you into any trouble, right? Correct, the same way that configuring fe80::1 on one interface and fe80::2 on a second interface, and on this second interface the other end should be able to have fe80::1 as its address, and everything should work fine. Everything else is buggy, as you already have concluded. -- Mikael Abrahamssonemail: swm...@swm.pp.se
