[ovs-dev] [PATCH] ofproto-dpif-xlate: makes OVS native tunneling honor tunnel-specified source addresses

wenxu wenxu at ucloud.cn
Tue Apr 17 02:54:29 UTC 2018

At 2018-04-17 04:40:26, "Ben Pfaff" <blp at ovn.org> wrote:
>On Mon, Apr 16, 2018 at 03:35:57PM +0800, wenxu at ucloud.cn wrote:
>> From: wenxu <wenxu at ucloud.cn>
>> It makes OVS native tunneling honor tunnel-specified source addresses,
>> in the same way that Linux kernel tunneling honors them.
>> This patch made valid tun_src specified by flow-action can be used for
>> tunnel_src of packet. add a "local" property for a route entry.
>> Like the kernel space when lookup the route, if there are tun_src specified
>> by flow-action or port options. Check the tun_src wheather is a local
>> address, then lookup the route.
>> Signed-off-by: wenxu <wenxu at ucloud.cn>
>Thanks for v2.  It resolves the portability issue.  I hope I may ask
>some more questions, because there are some pieces that I do not
>understand yet.
>I think that there is a redundant assignment to change->rd.rtm_dst_len
>in route_table_parse().  I think that the first assignment here may be
>        change->rd.rtm_dst_len = rtm->rtm_dst_len + (ipv4 ? 96 : 0);
>        if (rtm->rtm_type == RTN_LOCAL) {
>            dst_len_off += 64;
>            change->rd.local = true;
>        } else {
>            change->rd.local = false;
>        }
>        change->rd.rtm_dst_len = rtm->rtm_dst_len + (ipv4 ? dst_len_off : 0);
>I do not understand dst_len_off yet.  It is normally 96, but for local
>addresses it increases by 64, to 160.  Then, only for IPv4, it gets
>added to the prefix length.  I don't understand how a prefix length
>greater than 128 is to be interpreted, since an IPv6 address is only 128
>bits long.  (Without the addition of 64, I understand: it is because
>32-bit IPv4 addresses are mapped into 128-bit IPv6 addresses and 96 =
>128 - 32.)  rd.rtm_dst_len eventually gets passed to ovs_router_insert()
>as plen, then to rt_init_match() as plen, and then that is used to
>create a IPv6 address mask, so it seems like the value should be 128 or
>less, not 160 or more.

I want to improve the priority of the local route higher than userdef route
in the ovs_router_add : the priority of userdef route  is alway higheer than cached route
ovs_router_insert__(mark, plen + 32, &ip6, plen, argv[2], &gw6);

I think I should only enhance the priority of the local route is fine, but not dst_len


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