[Neutron] The first glance of L3HA mode in OpenStack Neutron ( Liberty version )

I just quickly take the first glance of L3HA mode in OpenStack Neutron ( Liberty version ) and is based on my tenant environment as follows:

My tenant environment

# neutron router-list

# neutron net-list

# neutron subnet-list

The Topology view looks like this:

Here I have 2 instances in my tenant:

So, if I use the instance: daanny_vm1 to ping danny_vm2, due to the different subnets, this action will trigger L3 vrouter function.

# ping ( danny_vm2 )

# ip netns exec qrouter-f1e03fef-cccf-43de-9d35-56d11d636765 tcpdump -eln -i qr-4433f31f-5d icmp

The interface qr-4433f31f-5d is my subnet's gateway port as follows:
# neutron --os-tenant-name danny port-list | grep 4433f31f-5d
| 4433f31f-5d93-4fe4-868a-04ddcc38be20 |                                                 | fa:16:3e:25:22:b3 | {"subnet_id": "d169f180-4304-42f0-b11f-e094287bcd00", "ip_address": ""}  |

Keepalived related

L3HA mode is havily relied on the daemon: Keepalived and this daemon is existed in qrouter namespace.

# vi /var/lib/neutron/ha_confs/f1e03fef-cccf-43de-9d35-56d11d636765/keepalived.conf
vrrp_instance VR_1 {
    state BACKUP
    interface ha-857640ad-a6
    virtual_router_id 1
    priority 50
    garp_master_delay 60
    advert_int 2
    track_interface {
    virtual_ipaddress { dev ha-857640ad-a6
    virtual_ipaddress_excluded { dev qg-f02984c6-dc dev qg-f02984c6-dc dev qr-4433f31f-5d dev qr-16e20a36-fc dev qr-35235c4f-64
        fe80::f816:3eff:fe0d:2702/64 dev qr-16e20a36-fc scope link
        fe80::f816:3eff:fe25:22b3/64 dev qr-4433f31f-5d scope link
        fe80::f816:3eff:fe51:30a1/64 dev qg-f02984c6-dc scope link
        fe80::f816:3eff:fe8f:a85b/64 dev qr-35235c4f-64 scope link
    virtual_routes { via dev qg-f02984c6-dc

There are other two files under /var/lib/neutron/ha_confs/<< qrouter uuid >>/
neutron-keepalived-state-change.log ==> log file
state ==> HA status

# find -L /proc/[1-9]*/task/*/ns/net -samefile /run/netns/qrouter-f1e03fef-cccf-43de-9d35-56d11d636765 | cut -d/ -f5

# ps aux | grep -e "2276895|2276896|2277216|2277217|3284547"
neutron  2276895  0.0  0.0 126160 41364 ?        S    Jul22   0:00 /usr/bin/python2.7 /usr/bin/neutron-keepalived-state-change --router_id=f1e03fef-cccf-43de-9d35-56d11d636765 --namespace=qrouter-f1e03fef-cccf-43de-9d35-56d11d636765 --conf_dir=/var/lib/neutron/ha_confs/f1e03fef-cccf-43de-9d35-56d11d636765 --monitor_interface=ha-857640ad-a6 --monitor_cidr= --pid_file=/var/lib/neutron/external/pids/f1e03fef-cccf-43de-9d35-56d11d636765.monitor.pid --state_path=/var/lib/neutron --user=119 --group=125
root     2276896  0.0  0.0   6696   756 ?        S    Jul22   0:00 ip -o monitor address
root     2277216  0.0  0.0  44752   856 ?        Ss   Jul22   0:13 keepalived -P -f /var/lib/neutron/ha_confs/f1e03fef-cccf-43de-9d35-56d11d636765/keepalived.conf -p /var/lib/neutron/ha_confs/f1e03fef-cccf-43de-9d35-56d11d636765.pid -r /var/lib/neutron/ha_confs/f1e03fef-cccf-43de-9d35-56d11d636765.pid-vrrp
root     2277217  0.0  0.0  51148  1712 ?        S    Jul22   0:24 keepalived -P -f /var/lib/neutron/ha_confs/f1e03fef-cccf-43de-9d35-56d11d636765/keepalived.conf -p /var/lib/neutron/ha_confs/f1e03fef-cccf-43de-9d35-56d11d636765.pid -r /var/lib/neutron/ha_confs/f1e03fef-cccf-43de-9d35-56d11d636765.pid-vrrp
neutron  3284547  0.0  0.0 172176 36032 ?        S    Jul22   0:00 /usr/bin/python2.7 /usr/bin/neutron-ns-metadata-proxy --pid_file=/var/lib/neutron/external/pids/f1e03fef-cccf-43de-9d35-56d11d636765.pid --metadata_proxy_socket=/var/lib/neutron/metadata_proxy --router_id=f1e03fef-cccf-43de-9d35-56d11d636765 --state_path=/var/lib/neutron --metadata_port=8775 --metadata_proxy_user=119 --metadata_proxy_group=125 --verbose --log-file=neutron-ns-metadata-proxy-f1e03fef-cccf-43de-9d35-56d11d636765.log --log-dir=/var/log/neutron

# neutron l3-agent-list-hosting-router f1e03fef-cccf-43de-9d35-56d11d636765

Then, we learn that the master vrouter is in node-8. 
There are other ways to know which node is master:
1. use the command to see if the interface qr-xxxxx and qg-xxxxx have ip address or not. If yes, this node is master.
  • ip netns exec qrouter-f1e03fef-cccf-43de-9d35-56d11d636765 ip a
2. Check the following file that contains "master" or not.
  • vim /var/lib/neutron/ha_confs/<< qrouter uuid >>/state
For more details:

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