On Sun, 2012-08-26 at 23:20 +0200, Patrick McHardy wrote:

On Wed, 22 Aug 2012, Jesper Dangaard Brouer wrote:

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On Sun, 2012-08-19 at 21:44 +0200, Patrick McHardy wrote:

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On Sun, 19 Aug 2012, Jesper Dangaard Brouer wrote:

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On Sat, 2012-08-18 at 14:26 +0200, Patrick McHardy wrote:

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Don't I need to load some of the helper modules, or just the
nf_conntrack_ipv6 module, or perhaps only nf_defrag_ipv6 ?

Not with the entire patchset, just IPv6 conntrack is enough. Aith IPv6 NAT
the first packet of a connection must always be defragemented, independant
of an assigned helper.

When loading "nf_conntrack_ipv6" I run into issues.

When sending a fragmented UDP packet.  With these patches, the IPVS
stack will no longer see the fragmented packets, but instead see one
large SKB.  This will trigger a MTU path check in e.g.
ip_vs_dr_xmit_v6() and an ICMPv6 too big packet is send back.

 IPVS: ip_vs_dr_xmit_v6(): frag needed

Perhaps we could change/fix the MTU check in IPVS?
(This would also solve issues I've seen with TSO/GSO frames, hitting
this code path).

I guess this should use the same check as in IPv6 output, check
whether IP6CB(skb)->max_frag_size is != 0 and > MTU and only send
an ICMPv6 error in that case.

Hans have (already) proposed this solution:

  if ((!skb->local_df && skb->len > mtu && !skb_is_gso(skb)) ||
      (IP6CB(skb)->frag_max_size && IP6CB(skb)->frag_max_size > mtu)) {

And I have tested it works.
But I'm not sure about, if we really need the "!skb->local_df" check ?


Thus, we should extend you patchset with a patch, that also address the
MTU checks in IPVS.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Sr. Network Kernel Developer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer