• John Eaglesham's avatar
    bonding: support for IPv6 transmit hashing · 6b923cb7
    John Eaglesham authored
    Currently the "bonding" driver does not support load balancing outgoing
    traffic in LACP mode for IPv6 traffic. IPv4 (and TCP or UDP over IPv4)
    are currently supported; this patch adds transmit hashing for IPv6 (and
    TCP or UDP over IPv6), bringing IPv6 up to par with IPv4 support in the
    bonding driver. In addition, bounds checking has been added to all
    transmit hashing functions.
    
    The algorithm chosen (xor'ing the bottom three quads of the source and
    destination addresses together, then xor'ing each byte of that result into
    the bottom byte, finally xor'ing with the last bytes of the MAC addresses)
    was selected after testing almost 400,000 unique IPv6 addresses harvested
    from server logs. This algorithm had the most even distribution for both
    big- and little-endian architectures while still using few instructions. Its
    behavior also attempts to closely match that of the IPv4 algorithm.
    
    The IPv6 flow label was intentionally not included in the hash as it appears
    to be unset in the vast majority of IPv6 traffic sampled, and the current
    algorithm not using the flow label already offers a very even distribution.
    
    Fragmented IPv6 packets are handled the same way as fragmented IPv4 packets,
    ie, they are not balanced based on layer 4 information. Additionally,
    IPv6 packets with intermediate headers are not balanced based on layer
    4 information. In practice these intermediate headers are not common and
    this should not cause any problems, and the alternative (a packet-parsing
    loop and look-up table) seemed slow and complicated for little gain.
    Tested-by: default avatarJohn Eaglesham <linux@8192.net>
    Signed-off-by: default avatarJohn Eaglesham <linux@8192.net>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    6b923cb7
bond_main.c 132 KB