Neutron的Floating ip实现原理

http://www.cnblogs.com/sammyliu/p/4636091.html

本机实验

查看虚拟路由所在的namespace中的ip地址。

[root@network01 home]# ip netns exec qrouter-ddc9e259-57d6-4965-b0aa-89b139a64c04 ip addr
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
10: qr-2666afbd-02:  mtu 1450 qdisc noqueue state UNKNOWN qlen 1000
    link/ether fa:16:3e:6a:65:69 brd ff:ff:ff:ff:ff:ff
    inet 10.0.0.1/24 brd 10.0.0.255 scope global qr-2666afbd-02
       valid_lft forever preferred_lft forever
    inet6 fe80::f816:3eff:fe6a:6569/64 scope link 
       valid_lft forever preferred_lft forever
11: qg-d761e544-c7:  mtu 1500 qdisc noqueue state UNKNOWN qlen 1000
    link/ether fa:16:3e:85:4a:fb brd ff:ff:ff:ff:ff:ff
    inet 202.95.237.56/24 brd 202.95.237.255 scope global qg-d761e544-c7
       valid_lft forever preferred_lft forever
    inet 202.95.237.53/32 brd 202.95.237.53 scope global qg-d761e544-c7
       valid_lft forever preferred_lft forever
    inet6 fe80::f816:3eff:fe85:4afb/64 scope link 
       valid_lft forever preferred_lft forever

查看查看虚拟路由所在的namespace中的nat表。

[root@network01 home]# ip netns exec qrouter-ddc9e259-57d6-4965-b0aa-89b139a64c04 iptables -S -t nat
-P PREROUTING ACCEPT
-P INPUT ACCEPT
-P OUTPUT ACCEPT
-P POSTROUTING ACCEPT
-N neutron-l3-agent-OUTPUT
-N neutron-l3-agent-POSTROUTING
-N neutron-l3-agent-PREROUTING
-N neutron-l3-agent-float-snat
-N neutron-l3-agent-snat
-N neutron-postrouting-bottom
-A PREROUTING -j neutron-l3-agent-PREROUTING
-A OUTPUT -j neutron-l3-agent-OUTPUT
-A POSTROUTING -j neutron-l3-agent-POSTROUTING
-A POSTROUTING -j neutron-postrouting-bottom
-A neutron-l3-agent-OUTPUT -d 202.95.237.53/32 -j DNAT --to-destination 10.0.0.11
-A neutron-l3-agent-POSTROUTING ! -i qg-d761e544-c7 ! -o qg-d761e544-c7 -m conntrack ! --ctstate DNAT -j ACCEPT
-A neutron-l3-agent-PREROUTING -d 169.254.169.254/32 -i qr-+ -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 9697
-A neutron-l3-agent-PREROUTING -d 202.95.237.53/32 -j DNAT --to-destination 10.0.0.11
-A neutron-l3-agent-float-snat -s 10.0.0.11/32 -j SNAT --to-source 202.95.237.53
-A neutron-l3-agent-snat -j neutron-l3-agent-float-snat
-A neutron-l3-agent-snat -o qg-d761e544-c7 -j SNAT --to-source 202.95.237.56
-A neutron-l3-agent-snat -m mark ! --mark 0x2/0xffff -m conntrack --ctstate DNAT -j SNAT --to-source 202.95.237.56
-A neutron-postrouting-bottom -m comment --comment "Perform source NAT on outgoing traffic." -j neutron-l3-agent-snat

此类问题处理：1，通过api的接口查信息。2，查看制定route所在的namespace和iptables。