Comment 7 for bug 1376325

Reviewed: https://review.openstack.org/134676
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=7eb23f662cd62f29700ae51ee16dc535d251fc27
Submitter: Jenkins
Branch: master

commit 7eb23f662cd62f29700ae51ee16dc535d251fc27
Author: rajeev <email address hidden>
Date: Wed Nov 12 11:25:55 2014 -0500

    Add index generation for IPv6 rules for DVR

    For IPv6 support with DVR the index used for rule priority and
    route table needs to be generated such that the index is 32 bits
    or less but greater than the system generated rule entries.

    For IPv4 the numeric value of the network is used as the index.
    For IPv6 the 30 bit xor-folded crc32 of the cidr is used.
    Values smaller than system generated entries are extended into
    the range freed up because of xor-folding.
    For code modularity, index generation is wrapped into a helper
    method.

    Partial-bug: #1376325

    Change-Id: I4bcde80257ef5fe7c744086019841cdef5e3c60c