netdev - Re: [PATCH] bonding: L2L3 xmit doesn't support IPv6

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Date:	Tue, 11 Oct 2011 20:30:02 -0700
From:	Yinglin Sun <yinglin.s@...il.com>
To:	Jay Vosburgh <fubar@...ibm.com>
Cc:	Andy Gospodarek <andy@...yhouse.net>, netdev@...r.kernel.org
Subject: Re: [PATCH] bonding: L2L3 xmit doesn't support IPv6

On Tue, Oct 11, 2011 at 8:58 AM, Jay Vosburgh <fubar@...ibm.com> wrote:
> Andy Gospodarek <andy@...yhouse.net> wrote:
>
>>On Fri, Oct 07, 2011 at 10:36:45PM -0700, Yinglin Sun wrote:
>>> Add IPv6 support in L2L3 xmit policy.
>>> L3L4 doesn't support IPv6 either, and I'll try to fix that later.
>>>
>>> Signed-off-by: Yinglin Sun <Yinglin.Sun@....com>
>>> ---
>>>  drivers/net/bonding/bond_main.c |    7 +++++++
>>>  1 files changed, 7 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>>> index 6d79b78..d6fd282 100644
>>> --- a/drivers/net/bonding/bond_main.c
>>> +++ b/drivers/net/bonding/bond_main.c
>>> @@ -41,8 +41,10 @@
>>>  #include <linux/ptrace.h>
>>>  #include <linux/ioport.h>
>>>  #include <linux/in.h>
>>> +#include <linux/in6.h>
>>>  #include <net/ip.h>
>>>  #include <linux/ip.h>
>>> +#include <linux/ipv6.h>
>>>  #include <linux/tcp.h>
>>>  #include <linux/udp.h>
>>>  #include <linux/slab.h>
>>> @@ -3372,10 +3374,15 @@ static int bond_xmit_hash_policy_l23(struct sk_buff *skb, int count)
>>>  {
>>>      struct ethhdr *data = (struct ethhdr *)skb->data;
>>>      struct iphdr *iph = ip_hdr(skb);
>>> +    struct ipv6hdr *ipv6h = ipv6_hdr(skb);
>>>
>>>      if (skb->protocol == htons(ETH_P_IP)) {
>>>              return ((ntohl(iph->saddr ^ iph->daddr) & 0xffff) ^
>>>                      (data->h_dest[5] ^ data->h_source[5])) % count;
>>> +    } else if (skb->protocol == htons(ETH_P_IPV6)) {
>>> +            return ((ntohl(ipv6h->saddr.s6_addr32[3] ^
>>> +                           ipv6h->daddr.s6_addr32[3]) & 0xffff) ^
>>> +                    (data->h_dest[5] ^ data->h_source[5])) % count;
>>>      }
>>>
>>
>>There have been some attempts to add support for ipv6 hashing this in
>>the past, but none have been committed.  The best one I had seen was one
>>that did some extensive testing one a wide variety of ipv6 traffic and
>>it showed nice traffic distribution.  I'm not sure if it was ever posted
>>upstream, so I will see if I can dig it up.
>>
>>Can you quantify how traffic was distributed with this algorithm?
>
>        As I recall, the IPv6 issues had to do with the "layer3+4" hash,
> because the IPv6 TCP or UDP port numbers can be harder to get at than in
> IPv4 (which typically has a fixed size header).  The above is just for
> layer 2, so it only hits the IPv6 addresses, which don't move around.
>
>        That said, I believe that many IPv6 addresses are derived from
> the MAC address, the autoconf addresses in particular, so s6_addr32[3]
> may not show a lot more variation than just the MAC address.  I don't
> know for sure though, since I haven't tested it.
>

This is a good point. The last 32bit portion is not enough for some cases.

Yinglin
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