Linux network - virtual network

Linux network - Virtual Ethernet

什么是Virtual Ethernet？

我们知道Linux可以通过物理网卡，可以实现两台机器的连通，Linux同样提供了一种机制，可以使两个端口连通，不通过物理接口，Linux称之为virtual ethernet。这种技术需要定义两端，可以分配IP，走指定的路由进行通信。

怎么创建L2层的Virtual Ethernet？

• 创建用于通信的bridge

[root@localhost ~]# ip link add edge_bridge1 type bridge
#创建bridge设备
[root@localhost ~]# ip link set dev ens9 master edge_bridge1
#绑定物理网卡到bridge设备

• 创建virtual Ethernet 

[root@localhost ~]# ip link add host_veth1 type veth peer name edge_veth1
[root@localhost ~]# ip link show
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: ens9:  mtu 1500 qdisc pfifo_fast master edge_bridge1 state UP mode DEFAULT qlen 1000
link/ether 52:54:00:6b:cc:77 brd ff:ff:ff:ff:ff:ff
3: eth0:  mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
link/ether 52:54:00:97:1d:2e brd ff:ff:ff:ff:ff:ff
4: br-87a2e3ee5e64:  mtu 1500 qdisc noqueue state DOWN mode DEFAULT
link/ether 02:42:78:1e:0c:7e brd ff:ff:ff:ff:ff:ff
5: docker0:  mtu 1500 qdisc noqueue state DOWN mode DEFAULT
link/ether 02:42:bd:f5:bc:a8 brd ff:ff:ff:ff:ff:ff
6: edge_bridge1:  mtu 1500 qdisc noop state DOWN mode DEFAULT qlen 1000
link/ether 52:54:00:6b:cc:77 brd ff:ff:ff:ff:ff:ff
7: edge_veth1@host_veth1:  mtu 1500 qdisc noop state DOWN mode DEFAULT qlen 1000
link/ether 62:b9:b5:5b:4e:90 brd ff:ff:ff:ff:ff:ff
8: host_veth1@edge_veth1:  mtu 1500 qdisc noop state DOWN mode DEFAULT qlen 1000
link/ether a2:6c:46:37:3f:1f brd ff:ff:ff:ff:ff:ff

• 为virtual ethernet 绑定到设备  

[root@localhost ~]# ip link set host_veth1 master host_bridge1
[root@localhost ~]# ip link set edge_veth1 master edge_bridge1
[root@localhost ~]# ip link show
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: ens9:  mtu 1500 qdisc pfifo_fast master host_bridge1 state UP mode DEFAULT qlen 1000
link/ether 52:54:00:6b:cc:77 brd ff:ff:ff:ff:ff:ff
3: eth0:  mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
link/ether 52:54:00:97:1d:2e brd ff:ff:ff:ff:ff:ff
4: br-87a2e3ee5e64:  mtu 1500 qdisc noqueue state DOWN mode DEFAULT
link/ether 02:42:78:1e:0c:7e brd ff:ff:ff:ff:ff:ff
5: docker0:  mtu 1500 qdisc noqueue state DOWN mode DEFAULT
link/ether 02:42:bd:f5:bc:a8 brd ff:ff:ff:ff:ff:ff
6: edge_bridge1:  mtu 1500 qdisc noop state DOWN mode DEFAULT qlen 1000
link/ether 62:b9:b5:5b:4e:90 brd ff:ff:ff:ff:ff:ff
7: edge_veth1@host_veth1:  mtu 1500 qdisc noop master edge_bridge1 state DOWN mode DEFAULT qlen 1000
link/ether 62:b9:b5:5b:4e:90 brd ff:ff:ff:ff:ff:ff
8: host_veth1@edge_veth1:  mtu 1500 qdisc noop master host_bridge1 state DOWN mode DEFAULT qlen 1000
link/ether a2:6c:46:37:3f:1f brd ff:ff:ff:ff:ff:ff
9: host_bridge1:  mtu 1500 qdisc noop state DOWN mode DEFAULT qlen 1000
link/ether 52:54:00:6b:cc:77 brd ff:ff:ff:ff:ff:ff

• 设置这几个设备的状态为up

[root@localhost ~]# ip link set host_bridge1 up
[root@localhost ~]# ip link set edge_bridge1 up
[root@localhost ~]# ip link set host_veth1 up
[root@localhost ~]# ip link set edge_veth1 up

创建L3层的virtual Ethernet

• 创建一个bridge  

[root@localhost ~]# ip link add edge_bridge2 type bridge
[root@localhost ~]# ip link set dev ens9 master edge_bridge2

• 创建virtual ethernet

[root@localhost ~]# ip link add host_veth2 type veth peer name edge_veth2
[root@localhost ~]# ip addr add 10.90.241.201/24 dev host_veth2
[root@localhost ~]# ip addr show dev host_veth2
8: host_veth2@veth0:  mtu 1500 qdisc noop state DOWN qlen 1000
link/ether 62:92:e6:31:5b:1e brd ff:ff:ff:ff:ff:ff
inet 10.90.241.201/24 scope global host_veth2
valid_lft forever preferred_lft forever

此时network还是不通的

[root@localhost ~]# ping 10.90.241.200
PING 10.90.241.200 (10.90.241.200) 56(84) bytes of data.
From 10.90.241.94 icmp_seq=1 Destination Host Unreachable
From 10.90.241.94 icmp_seq=2 Destination Host Unreachable
From 10.90.241.94 icmp_seq=3 Destination Host Unreachable

• 设置host的对端为bridge的master

[root@localhost ~]# ip link set edge_veth2 master edge_bridge2

• 设置端口的状态为up

    

[root@localhost ~]# ip link set host_veth2 up
[root@localhost ~]# ip link set edge_veth2 up
[root@localhost ~]# ip link set edge_bridge2 up