CentOS VM（由 Openstack 管理）添加辅助 IP 但辅助 IP 无法 ping 其他主机的 IP

Question

I'd like add a secondary IP address for 'eth0' from CentOS VM managed by Openstack. The result is: cannot ping another VM's IP from secondary IP. Could you help?

Steps to reproduce:

1. ip -f inet addr list 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 inet 172.22.42.220/24 brd 172.22.42.255 scope global noprefixroute dynamic eth0 valid_lft 83609sec preferred_lft 83609sec
2. ping -I 172.22.42.220 172.22.42.1 is OK
3. add a secondary IP by: ip -f inet addr add 172.22.42.222/32 brd 172.22.42.255 dev eth0 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 inet 172.22.42.220/24 brd 172.22.42.255 scope global noprefixroute dynamic eth0 valid_lft 83368sec preferred_lft 83368sec inet 172.22.42.222/32 brd 172.22.42.255 scope global eth0 valid_lft forever preferred_lft forever
4. ping -I 172.22.42.220 172.22.42.222 and ping -I 172.22.42.222 172.22.42.220 are OK (-I means source IP)
5. ping -I 172.22.42.220 172.22.42.1 is OK but ping -I 172.22.42.222 172.22.42.1 fails

Answer 1

you have to set the additional (multiple) ip address to the same port-id in openstack first.

Here is an example:

neutron port-update a5e93de7-927a-5402-b545-17f79538d3a6 --allowed_address_pairs list=true type=dict mac_address=ce:9e:5d:ad:6d:80,ip_address=10.101.11.5 ip_address=10.101.11.6

then you can check with:

neutron port-show a5e93de7-927a-5402-b545-17f79538d3a6

Answer 2

so, if you are aware of your openstack server instance name, then you can find the port id with:

openstack port list --server testserver01

+--------------------------------------+------+-------------------+------------------------------------------------------------------------------+--------+
| ID                                   | Name | MAC Address       | Fixed IP Addresses                                                           | Status |
+--------------------------------------+------+-------------------+------------------------------------------------------------------------------+--------+
|  a5e93de7-927a-5402-b545-17f79538d3a6|      | fa:16:3e:5d:73:24 | ip_address='10.10.0.1', subnet_id='89387a48-5c5e-4dd0-8e0a-2181c97ec19a' | ACTIVE |
+--------------------------------------+------+-------------------+------------------------------------------------------------------------------+--------+