Re: IPv6 forwarding fail = mbuf leak?

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> What is the interface type on the upstream link?

As seen by the host, Ethernet.  The physical layer is DSL (MVL, to be
specific), but as far as I've been able to tell it's operationally just
a really slow Ethernet.  (In case it matters, the DSL CPE is behind a
switch which vlan-trunks that, among other things, to the router host.)

The other end is not a mass-market big-ISP head; the DSL is being run
over dry copper to a DSLAM at my upstream/employer.

> Are you sending v6 natively on the link, or is there some
> encapsulation?

Native, or at least as native as IPv6-over-Ethernet ever is.  (Not
counting comments, there's nothing in the network config that says
vlan4 is a DSL line instead of a normal Ethernet.)

> Static route, or some IGP, or BGP, or ?

Entirely manually-configured statics.

> When you said "isn't answering", do you mean that you have an ndp
> cache entry, but when the unicast packet is sent, there is no
> link-level receiver?  Or do you mean that there is no ndp entry,
> because it doesn't answer the ndp request packets?

The latter.  (It might have been the former initially, but certainly
after the reboot to clear the first wedge it will have been the latter
until I fixed things.  The upstream host and my router disagreed over
what /127 to use on the DSL; I must have changed one end but not the
other and not rebooted since, or some such.)

> I'm reading code in -current, but look in
> src/sys/net/if_ethersubr.c:ether_output() and audit the memory
> handling.  I haven't found anything yet, but that's what I would
> first suspect.

Possibly.  But I would be inclined to suspect there's something
IPv6-specific going on; if this happened for v4 as well I would surely
have run into it long since.  This is relevant because, AIUI,
ether_output() is not protocol-aware...though it's been a while since I
read it, so even if that memory is correct it could be out of date.

Of course, I still haven't ruled out that it's something idiosyncratic
about my setup, but I'm considering that unlikely enough to be not
worth looking into unless, for example, I find I can't reproduce it in
a test-bench setup.

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