利用netns做自环Iperf测试

netns可以让一台机器上模拟多个网络设备，是网络虚拟化的重要组成，将不同类型的网络应用隔离。一个net namespace有自己独立的路由表，iptables策略，设备管理。

本文利用netns模拟网络来实现单机上网卡自环上的iperf测试或其他网络测试。

用法

1. 先打开内核的网络转发功能

echo 1 > /proc/sys/net/ipv4/ip_forward   //临时方法
sysctl -w net.ipv4.ip_forward=1         //临时方法2

永久方法：修改/etc/sysctl.conf文件
将 net.ipv4.ip_forward=0改为net.ipv4.ip_forward=1

2. 添加2个namespace 

[root@localhost ~]# ip netns add ns1
[root@localhost ~]# ip netns add ns2
[root@localhost ~]# ip netns show
ns2
ns1

3. 将enp5s0添加到ns1并查看

[root@localhost ~]# ip link set enp5s0 netns ns1
[root@localhost ~]# ip netns exec ns1 ip a
1: lo:  mtu 65536 qdisc noop state DOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
8: enp5s0:  mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 8c:1c:da:45:4c:d9 brd ff:ff:ff:ff:ff:ff
[root@localhost ~]# 

 4. 将enp6s0添加到ns2并查看

[root@localhost ~]# ip link set enp6s0 netns ns2
[root@localhost ~]# ip netns exec ns2 ip a
1: lo:  mtu 65536 qdisc noop state DOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
9: enp6s0:  mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 8c:1c:da:45:4c:da brd ff:ff:ff:ff:ff:ff
[root@localhost ~]# 

5. 给ns1，ns2的2个接口分别配置IP

[root@localhost ~]# ip netns exec ns1 ifconfig enp5s0 7.7.7.7/24
[root@localhost ~]# ip netns exec ns2 ifconfig enp6s0 7.7.7.8/24

6. ping测试

[root@localhost ~]# ip netns exec ns2 ping 7.7.7.7
PING 7.7.7.7 (7.7.7.7) 56(84) bytes of data.
64 bytes from 7.7.7.7: icmp_seq=1 ttl=64 time=0.419 ms
64 bytes from 7.7.7.7: icmp_seq=2 ttl=64 time=0.328 ms
64 bytes from 7.7.7.7: icmp_seq=3 ttl=64 time=0.308 ms
^C
--- 7.7.7.7 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2000ms
rtt min/avg/max/mdev = 0.308/0.351/0.419/0.052 ms

7. 在ns1上运行iperf服务端

[root@localhost ~]# ip netns exec ns1 iperf -s -D -p 1111
Running Iperf Server as a daemon
The Iperf daemon process ID : 2174

8. 在ns2上运行iperf客户端

[root@localhost ~]# ip netns exec ns2 iperf -c 7.7.7.7 -p 1111 -i 1  -R
------------------------------------------------------------
Client connecting to 7.7.7.7, TCP port 1111
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[  3] local 7.7.7.8 port 41814 connected with 7.7.7.7 port 1111
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 1.0 sec   280 MBytes  2.35 Gbits/sec
[  3]  1.0- 2.0 sec   280 MBytes  2.35 Gbits/sec
[  3]  2.0- 3.0 sec   281 MBytes  2.36 Gbits/sec
[  3]  3.0- 4.0 sec   280 MBytes  2.35 Gbits/sec
[  3]  4.0- 5.0 sec   281 MBytes  2.36 Gbits/sec
[  3]  5.0- 6.0 sec   281 MBytes  2.36 Gbits/sec
[  3]  6.0- 7.0 sec   281 MBytes  2.35 Gbits/sec
[  3]  7.0- 8.0 sec   280 MBytes  2.35 Gbits/sec
[  3]  8.0- 9.0 sec   280 MBytes  2.35 Gbits/sec
[  3]  9.0-10.0 sec   281 MBytes  2.36 Gbits/sec
[  3]  0.0-10.0 sec  2.74 GBytes  2.35 Gbits/sec
[root@localhost ~]# 

9. 在ns2上ping大包测试

[root@localhost ~]# ip netns exec ns2 ping 7.7.7.7 -c 100000 -s 65500 -f
PING 7.7.7.7 (7.7.7.7) 65500(65528) bytes of data.
 
--- 7.7.7.7 ping statistics ---
100000 packets transmitted, 100000 received, 0% packet loss, time 125759ms
rtt min/avg/max/mdev = 0.718/0.963/2.789/0.088 ms, ipg/ewma 1.257/0.980 ms