pmtud + ipnat RELENG_6_2 appears to be broken

[Alexey Karagodov]

is there any progress?
just one "me too"

this problem appeared for me when i try to use vlan over lagg ( to em NICs
)

thanx
kernel: vlan301: discard oversize frame (ether type 800 flags 3 len 1514 >
max 1510)



2007/7/13, Chuck Swiger <cswiger at mac.com>:
>
> On Jul 12, 2007, at 1:38 PM, Stephen Clark wrote:
> >> The MTU is actually defined in reference to a network segment such
> >> as  an "ethernet collision domain", and applies to all machines
> >> sending  traffic to that segment.  If the MTU is really 1280,
> >> nobody else  should be sending larger packets, and the drivers
> >> will drop any  larger packets they receive and generate the
> >> appropriate ICMP error....
> >
> > First thanks for responding but thats the problem,
> > this did't generate an icmp when the packet was dropped.
> >
> > kernel: rl0: discard oversize frame (ether type 800 flags 3 len
> > 1514 > max
> > 1294)
> >
> > This message did not result in any icmp packet.
> >
> > I was running tcpdump looking for them.
>
> Taking a quick look at ether_input() in src/sys/net/if_ethersubr.c
> suggests that you are right-- if the incoming packet exceeds the MTU
> being set, the input errors count for that interface is incremented,
> but no ICMP_UNREACH_NEEDFRAG is generated even if DF flag is set.
>
> You might file a PR and see whether you can get Andre or one of the
> other networking gurus interested in fixing this.  Or maybe I'll give
> it a try myself if I can get some free time....  :-)
>
> --
> -Chuck
>
>
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