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SubjectRe: some trouble when using vrf
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On 2019/4/16 20:11, Mike Manning wrote:
> On 16/04/2019 12:26, linmiaohe wrote:
>> Hi all:
>> I meet some trouble when using vrf, it's very nice of you if you
>> can help me fix it.
>>
>> 1.If I bind a vrf address before I set SO_BINDTODEVICE opts to bind an
>> enslaved device, "Cannot assign requested address" will occurs. It's
>> because only after we set SO_BINDTODEVICE opts to bind an enslaved device,
>> then we can lookup the route in the specified l3mdev domain.
>> I think we couldn't limit the order of bind ip addr and SO_BINDTODEVICE opts
>> otherwise many vrf unaware apps many need to change their code.
>> I can't find a convenient way to fix it.Here is an example:
>>
>> ...
>> bind(sock_fd, (struct sockaddr *)&addr_serv, sizeof(addr_serv));
>> ...
>> ret = setsockopt(sock_fd, SOL_SOCKET, SO_BINDTODEVICE, bind_dev, strlen(bind_dev)+1);
>> ...
>> This code snipet doesn't work if the ip address of addr_serv is not in default vrf. And
>> "Cannot assign requested address" will occurs.
> Or you can run instances of vrf-unaware applications per VRF with 'sudo
> ip vrf exec <vrf> <cmd>', with the 3 sysctl you indicate below set to 0.
>> 2.When I run a udp server in default vrf and set net.ipv4.udp_l3mdev_accept=1,
>> it's supposed to work accorss VRFs.
>> But it occurs when udp server received a packet, it sends back with the source
>> ip address from default vrf which is supposed to from the specified l3mdev domain.
>> And the connection between server and client is broken. It's because udp server
>> run in default vrf and doesn't bind the enslaved device, so only the route table in
>> default vrf is avaliable.
>>
>> For example,I run a udp server in default vrf and set net.ipv4.udp_l3mdev_accept=1:
>> [root@localhost vrf]# sysctl -a | grep l3mdev
>> net.ipv4.raw_l3mdev_accept = 1
>> net.ipv4.tcp_l3mdev_accept = 1
>> net.ipv4.udp_l3mdev_accept = 1
>>
>> Then connect the server and send a udp packet to the specified vrf. Here is tcpdump output:
>> 17:28:54.925417 IP 10.0.0.2.43003 > 10.0.0.1.irdmi: UDP, length 17
>> 17:28:54.925953 IP 9.85.153.236.irdmi > 10.0.0.2.43003: UDP, length 17
>> ps. 10.0.0.2 is client ip, 10.0.0.1 is specified vrf ip, and 9.85.153.236 is default vrf ip.
>> 10.0.0.1 and 9.85.153.236 are in the same host.
>>
>> Thanks a lot if you can help me fix these. Have a nice day.
>>
>>
>>
>
>
> .
>
Thanks for your reply. Run instances of vrf-unaware applications per VRF is an optional solution for problem 1.
But maybe it will limits the applications supposed to accross VRFS can't coexist with per VRF applications as
udp_l3mdev_accept is globally effective.
And what about problem 2?
Thanks again.

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