Messages in this thread |  | | Subject | Re: some trouble when using vrf | From | David Ahern <> | Date | Tue, 16 Apr 2019 09:20:51 -0600 |
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On 4/16/19 5:26 AM, 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.
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.
> > 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.
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.
> > 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. > > >
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