Re: BUG: IPv6 stops working after a while, needs ip ne del commandto reset

[Thomas Habets]

On Mon, 16 Aug 2010, Eric Dumazet wrote:
> > $ ip -6 r sh
> > 2a00:800:752:1::5c:0/112 dev eth0  proto kernel  metric 256  mtu 1500
> > advmss 14 hoplimit 4294967295 unreachable
>
> advmss 14 ? or is it a copy/paste error ?
> unreachable ?

Copy/paste error, sorry.

advmss 1440, and no "unreachable"

Complete (correct) line:

2a00:800:752:1::5c:0/112 dev eth0 proto kernel metric 256 mtu 1500 advmss 
1440 hoplimit 4294967295

> This route seems wrong.

Did you mean the below?

> > 2a00:800:1000:64::1 dev lo proto kernel  metric 256  error -101 mtu 
> > 16436 advmss 16376 hoplimit 4294967295

Yes, that's where the "unreachable" belonged.

unreachable 2a00:800:1000:64::1 dev lo proto kernel  metric 256  error 
-101 mtu 1500 advmss 1440 hoplimit 4294967295

That's an additional address on the lo interface, seen here again:

> > 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436
> >      inet6 2a00:800:1000:64::1/128 scope global
> >         valid_lft forever preferred_lft forever
> >      inet6 ::1/128 scope host
> >         valid_lft forever preferred_lft forever

Am I not allowed to add addresses to lo? That I've deconfigured this 
address and rebooted the box to check if this matters.

> I am wondering if you have some lowlevel problem, say lost frames in an
> otherwise idle link, maybe a full/half duplex mismatch ?

But at first it works perfectly, and then it doesn't work at all. The link 
is ~idle both before and after, and IPv4 is unaffected. When I run "ip ne 
del ..." it *immediately* starts working again. From 100% packet loss to 
0%.

Duplex is full according to dmesg and ethtool (mii-tool says 1000BaseT-HD, 
but I suppose mii-tool is not as reliable?).

Cisco router also says "Full-duplex, 1000Mb/s", so there doesn't seem to 
be a mismatch. No errors in "show int giX/Y" either.

ethtool info right after reboot (when ipv6 is still working):
$ sudo ethtool eth0
Settings for eth0:
        Supported ports: [ TP ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Half 1000baseT/Full
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Half 1000baseT/Full
        Advertised auto-negotiation: Yes
        Speed: 1000Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 1
        Transceiver: internal
        Auto-negotiation: on
        Supports Wake-on: g
        Wake-on: g
        Current message level: 0x000000ff (255)
        Link detected: yes


No errors show in "ethtool -S eth0 | grep -v ': 0$'" now that it's 
working.

I will re-check ethtool and Cisco router output for mismatches when it 
breaks again to make sure that there's no change or errors counting up.


---------
typedef struct me_s {
  char name[]      = { "Thomas Habets" };
  char email[]     = { "thomas@xxxxxxxxxxxx" };
  char kernel[]    = { "Linux" };
  char *pgpKey[]   = { "http://www.habets.pp.se/pubkey.txt"; };
  char pgp[] = { "A8A3 D1DD 4AE0 8467 7FDE  0945 286A E90A AD48 E854" };
  char coolcmd[]   = { "echo '. ./_&. ./_'>_;. ./_" };
} me_t;
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/