Re: some trouble when using vrf

[linmiaohe <linmiaohe@huawei.com>]

On 2019/4/16 23:20, David Ahern wrote:
> On 4/16/19 5:26 AM, linmiaohe wrote:
>>     ...
>>     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.
> 
> Applications must bind to the device first and then bind to the local
> address. As I recall this applies regardless of whether it is a VRF or
> other.
> 
> 
It should be, but unfortunately some applications break this.

>>
>>     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.
> 
> UDP applications can use cmsg with IP_PKTINFO to send the reply out the
> same device as the request was received. An app can also track the
> relationship of the enslaved device to a VRF to use a VRF based lookup
> to send a response. Choices.
> 
> 

UDP applications using cmsg with IP_PKTINFO is really a good idea.

>>
>> Thanks a lot if you can help me fix these. Have a nice day.
>>
> .
> 

Thanks a lot for your advice.