ovs实践--openFlow跨网段组网

fearlessxjdx 2019-06-29

sdn (software defines network)

看了些相关的资料,这里记录一下自己对sdn的理解,能力有限,如有错误欢迎指正。

sdn软件定义网络,目的是想要利用软件来模拟网络设备,如交换机,路由器之类的。

为什么需要这么做? 一个主要原因是云计算的高速发展,给传统的数据中心带来了更加灵活和复杂的组网需求。

传统网络设备完成数据中心服务器的组网,在此之上,通过sdn来完成虚机和容器之间的连通

ovs (openvSwitch)

官方的说法:Open vSwitch是一款高质量的多层虚拟交换机,以开源Apache 2许可证授权,非常适合在虚拟机环境中充当2层交换机。支持多种基于Linux的虚拟化技术,包括Xen / XenServer、KVM和VirtualBox。
支持Open Flow协议,所以可以很方便的通过编程实现大规模网络的自动化,被大量运用于SDN网络中。

架构和原理之类的文章很多,这里就不在一一阐述,本文以实践为主。

安装

# 安装docker
yum install -y docker-1.13.1

# 预安装
yum -y install wget openssl-devel gcc make python-devel openssl-devel kernel-devel graphviz kernel-debug-devel autoconf automake rpm-build redhat-rpm-config libtool python-twisted-core python-zope-interface PyQt4 desktop-file-utils libcap-ng-devel groff checkpolicy selinux-policy-devel

# 安装open vswitch:
yum install -y  openvswitch-2.8.2-1.el7.x86_64  # 此版本包含ovs-docker
systemctl start openvswitch.service
systemctl is-active openvswitch
systemctl enable openvswitch

ovs单机连通性

创建容器, 设置net=none可以防止docker0默认网桥影响连通性测试

docker run -itd --name con6 --net=none ubuntu:14.04 /bin/bash
docker run -itd --name con7 --net=none ubuntu:14.04 /bin/bash
docker run -itd --name con8 --net=none ubuntu:14.04 /bin/bash

创建网桥

ovs-vsctl add-br ovs0

使用ovs-docker给容器添加网卡,并挂到ovs0网桥上

ovs-docker add-port ovs0 eth0 con6 --ipaddress=192.168.1.2/24
ovs-docker add-port ovs0 eth0 con7 --ipaddress=192.168.1.3/24
ovs-docker add-port ovs0 eth0 con8 --ipaddress=192.168.1.4/24

查看网桥

[root@controller /]# ovs-vsctl show
21e4d4c5-cadd-4dac-b025-c20b8108ad09
    Bridge "ovs0"
        Port "b167e3dcf8db4_l"
            Interface "b167e3dcf8db4_l"
        Port "f1c0a9d0994d4_l"
            Interface "f1c0a9d0994d4_l"
        Port "121c6b2f221c4_l"
            Interface "121c6b2f221c4_l"
        Port "ovs0"
            Interface "ovs0"
                type: internal
    ovs_version: "2.8.2"

测试连通性

[root@controller /]# docker exec -it con8 sh
# ping 192.168.1.2      
PING 192.168.1.2 (192.168.1.2) 56(84) bytes of data.
64 bytes from 192.168.1.2: icmp_seq=1 ttl=64 time=0.886 ms
^C
--- 192.168.1.2 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.886/0.886/0.886/0.000 ms
# 
# ping 192.168.1.3  
PING 192.168.1.3 (192.168.1.3) 56(84) bytes of data.
64 bytes from 192.168.1.3: icmp_seq=1 ttl=64 time=0.712 ms
^C
--- 192.168.1.3 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.712/0.712/0.712/0.000 ms
#

设置VLAN tag

查看网桥

[root@controller /]# ovs-vsctl show
21e4d4c5-cadd-4dac-b025-c20b8108ad09
    Bridge "ovs0"
        Port "b167e3dcf8db4_l"
            Interface "b167e3dcf8db4_l"
        Port "f1c0a9d0994d4_l"
            Interface "f1c0a9d0994d4_l"
        Port "121c6b2f221c4_l"
            Interface "121c6b2f221c4_l"
        Port "ovs0"
            Interface "ovs0"
                type: internal
    ovs_version: "2.8.2"

查看interface

[root@controller /]# ovs-vsctl list interface f1c0a9d0994d4_l
_uuid               : cf400e7c-d2d6-4e0a-ad02-663dd63d1751
admin_state         : up
duplex              : full
error               : []
external_ids        : {container_id="con6", container_iface="eth0"}
ifindex             : 239
ingress_policing_burst: 0
ingress_policing_rate: 0
lacp_current        : []
link_resets         : 1
link_speed          : 10000000000
link_state          : up
mac_in_use          : "96:91:0a:c9:02:d6"
mtu                 : 1500
mtu_request         : []
name                : "f1c0a9d0994d4_l"
ofport              : 3
other_config        : {}
statistics          : {collisions=0, rx_bytes=1328, rx_crc_err=0, rx_dropped=0, rx_errors=0, rx_frame_err=0, rx_over_err=0, rx_packets=18, tx_bytes=3032, tx_dropped=0, tx_errors=0, tx_packets=40}
status              : {driver_name=veth, driver_version="1.0", firmware_version=""}
type                : ""

设置vlan tag

ovs-vsctl set port   f1c0a9d0994d4_l tag=100  //con6
ovs-vsctl set port   b167e3dcf8db4_l tag=100  //con8
ovs-vsctl set port   121c6b2f221c4_l tag=200  //con7

测试连通性

[root@controller /]# docker exec -it con8 sh
# 
# ping 192.168.1.2 -c 3
PING 192.168.1.2 (192.168.1.2) 56(84) bytes of data.
64 bytes from 192.168.1.2: icmp_seq=1 ttl=64 time=0.413 ms
64 bytes from 192.168.1.2: icmp_seq=2 ttl=64 time=0.061 ms
64 bytes from 192.168.1.2: icmp_seq=3 ttl=64 time=0.057 ms
--- 192.168.1.2 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2044ms
rtt min/avg/max/mdev = 0.057/0.177/0.413/0.166 ms
# 
# ping 192.168.1.3 -c 3
PING 192.168.1.3 (192.168.1.3) 56(84) bytes of data.
From 192.168.1.4 icmp_seq=1 Destination Host Unreachable
From 192.168.1.4 icmp_seq=2 Destination Host Unreachable
--- 192.168.1.3 ping statistics ---
3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2068ms
pipe 3
#

跨主机连通性

环境

host1 172.29.101.123
网桥:  ovs0      

容器:    
con6  192.168.1.2   
con7  192.168.1.3   
con8  192.168.1.4

创建方式依上

host2 172.29.101.82
网桥: ovs1

容器: con11

准备环境

创建网桥
ovs-vsctl add-br ovs1

创建容器
docker run -itd --name con11 --net=none ubuntu:14.04 /bin/bash

挂到ovs0网桥
ovs-docker add-port ovs1 eth0 con11 --ipaddress=192.168.1.6/24

查看网桥ovs1

[root@compute82 /]# ovs-vsctl show
380ce027-8edf-4844-8e89-a6b9c1adaff3
    Bridge "ovs1"
        Port "0384251973e64_l"
            Interface "0384251973e64_l"
        Port "ovs1"
            Interface "ovs1"
                type: internal
    ovs_version: "2.8.2"

设置vxlan

在host1上

[root@controller /]# ovs-vsctl add-port ovs0 vxlan1 -- set interface vxlan1 type=vxlan options:remote_ip=172.29.101.82 options:key=flow
[root@controller /]# 
[root@controller /]# ovs-vsctl show
21e4d4c5-cadd-4dac-b025-c20b8108ad09
    Bridge "ovs0"
        Port "b167e3dcf8db4_l"
            tag: 100
            Interface "b167e3dcf8db4_l"
        Port "f1c0a9d0994d4_l"
            tag: 100
            Interface "f1c0a9d0994d4_l"
        Port "121c6b2f221c4_l"
            tag: 200
            Interface "121c6b2f221c4_l"
        Port "ovs0"
            Interface "ovs0"
                type: internal
        Port "vxlan1"
            Interface "vxlan1"
                type: vxlan
                options: {key=flow, remote_ip="172.29.101.82"}
    ovs_version: "2.8.2"

在host2上

[root@compute82 /]# ovs-vsctl add-port ovs1 vxlan1 -- set interface vxlan1 type=vxlan options:remote_ip=172.29.101.123 options:key=flow
[root@compute82 /]# 
[root@compute82 /]# ovs-vsctl show
380ce027-8edf-4844-8e89-a6b9c1adaff3
    Bridge "ovs1"
        Port "0384251973e64_l"
            Interface "0384251973e64_l"
        Port "vxlan1"
            Interface "vxlan1"
                type: vxlan
                options: {key=flow, remote_ip="172.29.101.123"}
        Port "ovs1"
            Interface "ovs1"
                type: internal
    ovs_version: "2.8.2"

设置vlan tag

ovs-vsctl set port 0384251973e64_l tag=100

连通性测试

[root@compute82 /]# docker exec -ti con11 bash
root@c82da61bf925:/# ping 192.168.1.2
PING 192.168.1.2 (192.168.1.2) 56(84) bytes of data.
64 bytes from 192.168.1.2: icmp_seq=1 ttl=64 time=0.161 ms
64 bytes from 192.168.1.2: icmp_seq=2 ttl=64 time=0.206 ms
^C
--- 192.168.1.2 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
root@c82da61bf925:/# 
root@c82da61bf925:/# ping 192.168.1.3
PING 192.168.1.3 (192.168.1.3) 56(84) bytes of data.
^C
--- 192.168.1.3 ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 2027ms
root@c82da61bf925:/# 
root@c82da61bf925:/# exit

结论

vxlan只能连通两台机器的ovs上同一个网段的容器,无法连通ovs上不同网段的容器。如果需要连通不同网段的容器,接下来我们尝试通过ovs的流表来解决这个问题。

OpenFlow

flow table

支持openflow的交换机中可能包含多个flow table。每个flow table包含多条规则,每条规则包含匹配条件和执行动作。flow table中的每条规则有优先级,优先级高的优先匹配,匹配到规则以后,执行action,如果匹配失败,按优先级高低,继续匹配下一条。如果都不匹配,每张表会有默认的动作,一般为drop或者转给下一张流表。

实践

环境

host1 172.29.101.123

网桥:  ovs0      

容器:    
con6  192.168.1.2     tag=100
con7  192.168.1.3     tag=100

host2 172.29.101.82

网桥: ovs1

容器:  
con9:  192.168.2.2    tag=100
con10:192.168.2.3    tag=100
con11: 192.168.1.5    tag=100

查看默认流表

在host1上查看默认流表

[root@controller msxu]# ovs-ofctl dump-flows ovs0
 cookie=0x0, duration=27858.050s, table=0, n_packets=5253660876, n_bytes=371729202788, priority=0 actions=NORMAL

在容器con6中ping con7,网络连通

[root@controller /]# docker exec -ti con6 bash
root@9ccc5c5664f9:/# 
root@9ccc5c5664f9:/# ping 192.168.1.3
PING 192.168.1.3 (192.168.1.3) 56(84) bytes of data.
64 bytes from 192.168.1.3: icmp_seq=1 ttl=64 time=0.613 ms
64 bytes from 192.168.1.3: icmp_seq=2 ttl=64 time=0.066 ms
--- 192.168.1.3 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1058ms
rtt min/avg/max/mdev = 0.066/0.339/0.613/0.274 ms
root@9ccc5c5664f9:/#

删除默认流表

[root@controller /]# ovs-ofctl del-flows ovs0
[root@controller /]# 
[root@controller /]# ovs-ofctl dump-flows ovs0
[root@controller /]#

测试网络连通性,发现网络已经不通

[root@controller /]# docker exec -ti con6 bash
root@9ccc5c5664f9:/# 
root@9ccc5c5664f9:/# ping 192.168.1.3
PING 192.168.1.3 (192.168.1.3) 56(84) bytes of data.
^C
--- 192.168.1.3 ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 1025ms
root@9ccc5c5664f9:/#

添加流表

如果要con6和con7能够通信,需要建立规则,让ovs转发对应的数据

查看con6和con7在ovs上的网络端口

[root@controller /]# ovs-vsctl show
21e4d4c5-cadd-4dac-b025-c20b8108ad09
    Bridge "ovs0"
        Port "f1c0a9d0994d4_l"
            tag: 100
            Interface "f1c0a9d0994d4_l"
        Port "121c6b2f221c4_l"
            tag: 100
            Interface "121c6b2f221c4_l"
        Port "ovs0"
            Interface "ovs0"
                type: internal
        Port "vxlan1"
            Interface "vxlan1"
                type: vxlan
                options: {key=flow, remote_ip="172.29.101.82"}
    ovs_version: "2.8.2"
[root@controller /]# ovs-vsctl list interface f1c0a9d0994d4_l |grep ofport
ofport              : 3
ofport_request      : []
[root@controller /]# 
[root@controller /]# ovs-vsctl list interface 121c6b2f221c4_l |grep ofport
ofport              : 4
ofport_request      : []

添加规则:

[root@controller /]#ovs-ofctl add-flow ovs0 "priority=1,in_port=3,actions=output:4"
[root@controller /]#ovs-ofctl add-flow ovs0 "priority=2,in_port=4,actions=output:3"
[root@controller /]# ovs-ofctl dump-flows ovs0
 cookie=0x0, duration=60.440s, table=0, n_packets=0, n_bytes=0, priority=1,in_port="f1c0a9d0994d4_l" actions=output:"121c6b2f221c4_l"
 cookie=0x0, duration=50.791s, table=0, n_packets=0, n_bytes=0, priority=1,in_port="121c6b2f221c4_l" actions=output:"f1c0a9d0994d4_l"
[root@controller /]#

测试连通性:con6和con7已通

[root@controller msxu]# docker exec -ti con6 bash
root@9ccc5c5664f9:/# ping 192.168.1.3
PING 192.168.1.3 (192.168.1.3) 56(84) bytes of data.
64 bytes from 192.168.1.3: icmp_seq=1 ttl=64 time=0.924 ms
64 bytes from 192.168.1.3: icmp_seq=2 ttl=64 time=0.058 ms
^C
--- 192.168.1.3 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1057ms
rtt min/avg/max/mdev = 0.058/0.491/0.924/0.433 ms
root@9ccc5c5664f9:/#

设置一条优先级高的规则:

[root@controller /]# ovs-ofctl add-flow ovs0 "priority=2,in_port=4,actions=drop"
[root@controller /]# 
[root@controller /]# docker exec -ti con6 bash
root@9ccc5c5664f9:/# 
root@9ccc5c5664f9:/# ping  192.168.1.3
PING 192.168.1.3 (192.168.1.3) 56(84) bytes of data.
^C
--- 192.168.1.3 ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 2087ms
root@9ccc5c5664f9:/# 
root@9ccc5c5664f9:/#

流表中的规则是有优先级的,priority数值越大,优先级越高。流表中,优先级高的优先匹配,并执行匹配规则的actions。如果不匹配,继续匹配优先级低的下一条。

跨网段连通

在上一个vxlan的实践中,通过设置vxlan可以打通两个机器上的ovs,但我们提到两个机器ovs上的容器得在同一个网段上才能通信。

在ip为192.168.2.2的con9上ping另一台机上的con6 192.168.1.2

[root@compute82 /]# docker exec -ti con9 bash
root@b55602aad0ac:/# 
root@b55602aad0ac:/# ping 192.168.1.2
connect: Network is unreachable
root@b55602aad0ac:/#

添加流表规则:

在host1上:

[root@controller /]# ovs-ofctl add-flow ovs0 "priority=4,in_port=6,actions=output:3"
[root@controller /]# 
[root@controller /]# ovs-ofctl add-flow ovs0 "priority=4,in_port=3,actions=output:6"
[root@controller /]# ovs-ofctl dump-flows ovs0
 cookie=0x0, duration=3228.737s, table=0, n_packets=7, n_bytes=490, priority=1,in_port="f1c0a9d0994d4_l" actions=output:"121c6b2f221c4_l"
 cookie=0x0, duration=3215.544s, table=0, n_packets=0, n_bytes=0, priority=1,in_port="121c6b2f221c4_l" actions=output:"f1c0a9d0994d4_l"
 cookie=0x0, duration=3168.297s, table=0, n_packets=9, n_bytes=546, priority=2,in_port="121c6b2f221c4_l" actions=drop
 cookie=0x0, duration=12.024s, table=0, n_packets=0, n_bytes=0, priority=4,in_port=vxlan1 actions=output:"f1c0a9d0994d4_l"
 cookie=0x0, duration=3.168s, table=0, n_packets=0, n_bytes=0, priority=4,in_port="f1c0a9d0994d4_l" actions=output:vxlan1

在host2上

[root@compute82 /]# ovs-ofctl add-flow ovs1 "priority=1,in_port=1,actions=output:6"
[root@compute82 /]# 
[root@compute82 /]# ovs-ofctl add-flow ovs1 "priority=1,in_port=6,actions=output:1"
[root@compute82 /]# ovs-ofctl dump-flows ovs1
 cookie=0x0, duration=1076.522s, table=0, n_packets=27, n_bytes=1134, priority=1,in_port="0384251973e64_l" actions=output:vxlan1
 cookie=0x0, duration=936.403s, table=0, n_packets=0, n_bytes=0, priority=1,in_port=vxlan1 actions=output:"0384251973e64_l"
 cookie=0x0, duration=70205.443s, table=0, n_packets=7325, n_bytes=740137, priority=0 actions=NORMAL

测试连通性

在host2 con9上ping 192.168.1.2

[root@compute82 /]# docker exec -ti con9 bash
root@b55602aad0ac:/# 
root@b55602aad0ac:/# ping 192.168.1.2
connect: Network is unreachable
root@b55602aad0ac:/#

发现网络并不通,查看发现路由规则有问题,添加默认路由规则,注意这里需要已privileged权限进入容器

[root@compute82 /]# docker exec --privileged -ti con9 bash
root@b55602aad0ac:/# 
root@b55602aad0ac:/# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.2.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
root@b55602aad0ac:/# route add default dev eth0
root@b55602aad0ac:/# 
root@b55602aad0ac:/# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         0.0.0.0         0.0.0.0         U     0      0        0 eth0
192.168.2.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
root@b55602aad0ac:/#

在host1和host2的容器中都添加好路由规则后,测试连通性

[root@compute82 /]# docker exec --privileged -ti con9 bash
root@b55602aad0ac:/# 
root@b55602aad0ac:/# ping 192.168.1.2
PING 192.168.1.2 (192.168.1.2) 56(84) bytes of data.
64 bytes from 192.168.1.2: icmp_seq=1 ttl=64 time=1.16 ms
64 bytes from 192.168.1.2: icmp_seq=2 ttl=64 time=0.314 ms
^C
--- 192.168.1.2 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1002ms
rtt min/avg/max/mdev = 0.314/0.739/1.165/0.426 ms

已成功通过ovs,vxlan打通两台机器上不同网段容器

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