veth pair

http://heychenbin.github.io/post/veth-pair/

Virtual Ethernet Pair简称veth pair,是一个成对的端口,所有从这对端口一 端进入的数据包都将从另一端出来,反之也是一样.

下面用例子说明veth pair的创建和使用:

现在有这样一个环境,两个网桥,一个是Linux内核网桥br1,另一个是ovs网桥 br-eth1,现在想把两个网桥连接起来,就可以用veth pair.

+------------------+              +------------------+
|                  |              |                  |
|   ovs bridge     |              |   Linux bridge   |
|   br-eth1        |              |   br1            |
|                  |              |                  |
+------------------+              +------------------+

首先创建一对veth pair:

[root@compute-195 ~]# ip link add eth1-br1 type veth peer name phy-br1
[root@compute-195 ~]# ip link list

...

25: phy-br1:  mtu 1500 qdisc noop state DOWN mode DEFAULT qlen 1000
    link/ether 22:83:01:db:37:b4 brd ff:ff:ff:ff:ff:ff
26: eth1-br1:  mtu 1500 qdisc noop state DOWN mode DEFAULT qlen 1000
    link/ether 32:b2:aa:1a:8a:13 brd ff:ff:ff:ff:ff:ff

创建成功后,可以通过ip link看到一对端口,可以通过ethtool查看他们是否成 对:

[root@compute-195 ~]# ethtool -S phy-br1
NIC statistics:
     peer_ifindex: 26

创建成功后,就可以分别将两个端口添加到不同的网桥上:

Linux网桥

[root@compute-195 ~]# brctl addif br1 phy-br1
[root@compute-195 ~]# brctl show
bridge name     bridge id               STP enabled     interfaces
br0             8000.e41f136dc9f0       no              enp11s0f0
                                                        vnet0
                                                        vnet2
                                                        vnet3
br1             8000.deef26d9c76a       no              phy-br1
                                                        vnet1
                                                        vnet4

可以看到phy-br1添加到了br1网桥上.

ovs网桥

[root@compute-195 ~]# ovs-vsctl add-port br-eth1 eth1-br1
[root@compute-195 ~]# ovs-vsctl show
e61b93e6-a701-4b6e-86c2-05f883885ab8
    Bridge br-int
        fail_mode: secure
        Port "qvof01b51bf-71"
            tag: 1
            Interface "qvof01b51bf-71"
        Port "int-br-eth1"
            Interface "int-br-eth1"
        Port br-int
            Interface br-int
                type: internal
    Bridge "br-eth1"
        Port "eth1-br1"
            Interface "eth1-br1"
        Port "eth1"
            Interface "eth1"
        Port "phy-br-eth1"
            Interface "phy-br-eth1"
        Port "br-eth1"
            Interface "br-eth1"
                type: internal
    ovs_version: "2.3.0"

可以看到eth1-br1也添加到了br-eth1网桥上了.这样整个网络就完成了网桥的 连接:

+------------------+              +------------------+
|  ovs bridge      |              |   Linux bridge   |
|  br-eth1         |              |   br1            |
|       +----------+              +----------+       |
|       | eth1-br1 +--------------+ phy-br1  |       |
+-------+----------+              +----------+-------+