Le 2018-11-28 21:33, Martin Pieuchot a écrit :
> On 28/11/18(Wed) 17:48, Stuart Henderson wrote:
>> On 2018-11-27, Arnaud BRAND <arnaud.brand--obsd@tib.cc> wrote:
>> > Good evening everyone,
>> >
>> > I am stuck with a IPv6 traceroute problem in an OSPFv3 environment.
>> >
>> > Long story short :
>> > - IPv6 routes are propagated using OSPFv3
>> > - so they are installed with link-local gateways in the fib
>> > - ICMPv6 "time exceeded" packets are generated with link-local source
>> > address
>> > - these packets are not to be routed so they do not get past the next
>> > hop
>> > - the endpoint never receives the "time exceeded packets"
>> >
>> > This of course is only true if the router generating the icmp packet is
>> > not the endpoint, but only a hop in the path.
>> >
>> > I checked the code (or at least tried to).
>> > It seems like it's in function icmp6_reflect in file icmp6.c at lines
>> > 1144/1147.
>> >
>> > This code (if I understood it correctly) :
>> > - fetches the route to the destination
>> > - gets the interface source address for this route
>> > - uses it as the source for the generated IP packet
>> >
>> > As my routes are installed with link-local addresses by OSPFv3, I get a
>> > generated packet with a link local source-address.
>> > The problem is when the destination is not on the local subnet : the
>> > generated packet is unroutable and never makes it to its destination
>> >
>> > Would it be better to try to find another address on the interface that
>> > is not link local if the destination address isn't on the interface
>> > subnets ?
>
> That could be a solution. But if you do that, why don't you attach the
> routes to a routable address in the first place?
>
> Why is ospfd(8) not doing that?
I'm not 100% sure, but afaik that's standard behavior for ospf6d.
At least that's what I have seen on the few different brands I've worked
with so far.
The old thread contains more information imho, so I'm gonna revive it.
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