Cannot ping gateway for external Openstack network

Question

I installed Openstack Ansible, Pike version. There is a separate network controller and on it one physical network interface. We created VLAN 139 that leads the traffic to gateway. Config file for that part looks like:

/etc/network/interfaces
...
auto eno1.139
iface eno1.139 inet manual
    vlan-raw-device eno1
# OpenStack Networking VLAN bridge
auto br-vlan
iface br-vlan inet manual
    bridge_stp off
    bridge_waitport 0
    bridge_fd 0
    bridge_ports eno1.139

We created an external Openstack network using:

openstack network create --external --share --provider-physical-network vlan --provider-network-type vlan --provider-segment 139 provider1

and all the other steps (subnet, router, etc)

As per documentation, first test should be pinging default gateway from router namespace. When I try that it is not working:

root@infra1-neutron-agents-container-e800e983:/# ip netns exec qrouter-eb842b12-9a35-4a93-baa9-38cc73531d9f ping 139.25.25.193

When I do TCP dump on physical network interface of controller node I can see packets going out without any problem:

openstackadmin@clcontroller:~$ sudo tcpdump -i eno1 --immediate-mode -e -n | grep 139.25.25.193
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eno1, link-type EN10MB (Ethernet), capture size 262144 bytes
16:30:09.182894 fa:16:3e:d4:b6:a1 > ff:ff:ff:ff:ff:ff, ethertype 802.1Q (0x8100), length 50: vlan 139, p 0, ethertype 802.1Q, vlan 139, p 0, ethertype ARP, Request who-has 139.25.25.193 tell 139.25.25.200, length 28

I see ARP request getting to gateway that has 139.25.25.193 and I am trying to ping:

hpadmin@hos-gw01:~$ sudo tcpdump -i any --immediate-mode -e -n | grep 139.25.25.193
[sudo] password for hpadmin:
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on any, link-type LINUX_SLL (Linux cooked), capture size 262144 bytes
15:53:29.857281   B fa:16:3e:d4:b6:a1 ethertype 802.1Q (0x8100), length 62: vlan 139, p 0, ethertype 802.1Q, vlan 139, p 0, ethertype ARP, Request who-has 139.25.25.193 tell 139.25.25.200, length 38
15:53:29.857281   B fa:16:3e:d4:b6:a1 ethertype 802.1Q (0x8100), length 58: vlan 139, p 0, ethertype ARP, Request who-has 139.25.25.193 tell 139.25.25.200, length 38

but what is confusing is my gateway is not responding to those ARP requests.

If I try to do same thing from stand alone Linux machine connected to same network segment and same VLAN everything works perfect.

Any idea what the problem might be? Thanks in advance.

Dusan Dordevic Dusan Dordevic · Accepted Answer · 2018-03-29T19:14:42

It seems that problem was that external OpenStack network was set up to be on VLAN 139. Once we changed it to be flat everything started working without any problems. I am still confused, though, why gateway did not sent ARP responses.

Cannot ping gateway for external Openstack network

1 Answers