关于ECS 无法使用VIP的问题 - SDN , openflow

背景

给ECS虚拟机配置VIP，无法通讯，原因？

HOST A

[root@pg11 ~]# ip addr show eth0  
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000  
    link/ether 00:16:3e:0a:5c:f1 brd ff:ff:ff:ff:ff:ff  
    inet 172.17.20.29/20 brd 172.17.31.255 scope global dynamic eth0  
       valid_lft 313883835sec preferred_lft 313883835sec  

HOST B

postgres@pg11-> ip addr show eth0  
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000  
    link/ether 00:16:3e:12:2f:48 brd ff:ff:ff:ff:ff:ff  
    inet 172.17.20.30/20 brd 172.17.31.255 scope global dynamic eth0  
       valid_lft 313883847sec preferred_lft 313883847sec  

互相在同一个VPC（vswitch , hub）

相互可以访问

a ping b  
ping 172.17.20.29  
PING 172.17.20.29 (172.17.20.29) 56(84) bytes of data.  
64 bytes from 172.17.20.29: icmp_seq=1 ttl=64 time=0.156 ms  
64 bytes from 172.17.20.29: icmp_seq=2 ttl=64 time=0.102 ms  
  
b ping a  
ping 172.17.20.30  
PING 172.17.20.30 (172.17.20.30) 56(84) bytes of data.  
64 bytes from 172.17.20.30: icmp_seq=1 ttl=64 time=0.166 ms  
64 bytes from 172.17.20.30: icmp_seq=2 ttl=64 time=0.112 ms  

配置VIP，无法跨机访问

host a

[root@pg11 ~]# ip addr add 172.17.20.39/20 brd + dev eth0 label eth0:1  
[root@pg11 ~]# ifconfig  
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500  
        inet 172.17.20.29  netmask 255.255.240.0  broadcast 172.17.31.255  
        ether 00:16:3e:0a:5c:f1  txqueuelen 1000  (Ethernet)  
        RX packets 22221492822  bytes 33552649055304 (30.5 TiB)  
        RX errors 0  dropped 0  overruns 0  frame 0  
        TX packets 631860042  bytes 42907936724 (39.9 GiB)  
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0  
  
eth0:1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500  
        inet 172.17.20.39  netmask 255.255.240.0  broadcast 172.17.31.255  
        ether 00:16:3e:0a:5c:f1  txqueuelen 1000  (Ethernet)  
  
lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536  
        inet 127.0.0.1  netmask 255.0.0.0  
        loop  txqueuelen 1  (Local Loopback)  
        RX packets 959417  bytes 111291935 (106.1 MiB)  
        RX errors 0  dropped 0  overruns 0  frame 0  
        TX packets 959417  bytes 111291935 (106.1 MiB)  
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0  
  
  
[root@pg11 ~]# ping 172.17.20.39  
PING 172.17.20.39 (172.17.20.39) 56(84) bytes of data.  
64 bytes from 172.17.20.39: icmp_seq=1 ttl=64 time=0.012 ms  
64 bytes from 172.17.20.39: icmp_seq=2 ttl=64 time=0.008 ms  

host b

[root@pg11 ~]# ping 172.17.20.39  
PING 172.17.20.39 (172.17.20.39) 56(84) bytes of data.  

无防火墙

[root@pg11 ~]# iptables -L -v -n  
Chain INPUT (policy ACCEPT 8 packets, 528 bytes)  
 pkts bytes target     prot opt in     out     source               destination           
  
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)  
 pkts bytes target     prot opt in     out     source               destination           
  
Chain OUTPUT (policy ACCEPT 6 packets, 1000 bytes)  
 pkts bytes target     prot opt in     out     source               destination  

原因

宿主机通过openflow进行流控，未注册的vm+ip可以被拒绝。具体可参考SDN文档。

删除VIP

[root@pg11 ~]# ip addr del 172.17.20.39/20 brd + dev eth0 label eth0:1  
[root@pg11 ~]# ifconfig  
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500  
        inet 172.17.20.29  netmask 255.255.240.0  broadcast 172.17.31.255  
        ether 00:16:3e:0a:5c:f1  txqueuelen 1000  (Ethernet)  
        RX packets 22221492889  bytes 33552649060975 (30.5 TiB)  
        RX errors 0  dropped 0  overruns 0  frame 0  
        TX packets 631860095  bytes 42907943783 (39.9 GiB)  
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0  
  
lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536  
        inet 127.0.0.1  netmask 255.0.0.0  
        loop  txqueuelen 1  (Local Loopback)  
        RX packets 959424  bytes 111292619 (106.1 MiB)  
        RX errors 0  dropped 0  overruns 0  frame 0  
        TX packets 959424  bytes 111292619 (106.1 MiB)  
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0  

参考

《linux IP 命令使用举例》

A Virtual Switch Platform for Host SDN in the Public Cloud

https://www.microsoft.com/en-us/research/wp-content/uploads/2017/09/login_fall17_02_firestone.pdf

https://www.opennetworking.org/

https://www.cisco.com/c/en/us/about/press/internet-protocol-journal/back-issues/table-contents-59/161-sdn.html

https://en.wikipedia.org/wiki/OpenFlow

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