[openstack-dev] [neutron][nova]Can not ping VM after setup devstack with neutron enabled

Wang, Peter (Xu) Peter.Wang13 at dell.com
Thu Dec 29 10:19:16 UTC 2016


Hi all

I was trying to setup a Devstack environment within an OpenStack VM(it's host also neutron enabled), saying nested VM


My OpenStack VM is configure with IP (192.168.77.37 and floating IP 192.168.1.121) on eth0 , I can ping it from HOST namespace, or ping the floating IP, it has internet connectivity as well.

After I tried to setup the devstack(with neutron enabled) on the OpenStack VM, the devstack failed due to network unreachable, and could not ping the 192.168.77.37 or 192.168.1.121

Here is the OpenStack VM(not host's) config:

sudo ovs-vsctl show
....
Bridge br-ex
     Port "eth0"
                  Interface "eth0"
     Port br-ex
                 Interface br-ex
                               Type: internal
....

And ip of eth0 is set to br-ex as expected.

# I can arping the IP from HOST namespace

ip netns exec qdhcp-89caf1b4-27f9-4744-a4db-176453fac80e arping 192.168.77.37
ARPING 192.168.77.37 from 192.168.77.2 tap676cac8b-02
Unicast reply from 192.168.77.37 [5E:A8:F3:A3:68:46]  2.227ms
Unicast reply from 192.168.77.37 [5E:A8:F3:A3:68:46]  1.112ms

# But ping will fail
ip netns exec qdhcp-89caf1b4-27f9-4744-a4db-176453fac80e ping 192.168.77.37
PING 192.168.77.37 (192.168.77.37) 56(84) bytes of data.
^C
--- 192.168.77.37 ping statistics ---
337 packets transmitted, 0 received, 100% packet loss, time 338680ms

I tcpdump a lot of interfaces, found the OpenStack VM did reply the outter ./st request, but the reply package stopped at  veth pair(qvod2a60161-b3 )of the OpenStack VM, while package could be dumped from the Linux bridge(qbrd2a60161-b3 )
See following tcpdump output:

tcpdump -i qbrd2a60161-b3  -ne
tcpdump: WARNING: qbrd2a60161-b3: no IPv4 address assigned
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on qbrd2a60161-b3, link-type EN10MB (Ethernet), capture size 65535 bytes
00:20:30.256200 fa:16:3e:2c:37:cc > 5e:a8:f3:a3:68:46, ethertype IPv4 (0x0800), length 98: 192.168.77.2 > 192.168.77.37: ICMP echo request, id 1369, seq 1, length 64
00:20:30.257176 5e:a8:f3:a3:68:46 > fa:16:3e:2c:37:cc, ethertype IPv4 (0x0800), length 98: 192.168.77.37 > 192.168.77.2: ICMP echo reply, id 1369, seq 1, length 64
00:20:31.264591 fa:16:3e:2c:37:cc > 5e:a8:f3:a3:68:46, ethertype IPv4 (0x0800), length 98: 192.168.77.2 > 192.168.77.37: ICMP echo request, id 1369, seq 2, length 64
00:20:31.264836 5e:a8:f3:a3:68:46 > fa:16:3e:2c:37:cc, ethertype IPv4 (0x0800), length 98: 192.168.77.37 > 192.168.77.2: ICMP echo reply, id 1369, seq 2, length 64

tcpdump -i qvod2a60161-b3  -ne
00:21:34.264419 fa:16:3e:2c:37:cc > 5e:a8:f3:a3:68:46, ethertype IPv4 (0x0800), length 98: 192.168.77.2 > 192.168.77.37: ICMP echo request, id 1369, seq 65, length 64
00:21:35.264450 fa:16:3e:2c:37:cc > 5e:a8:f3:a3:68:46, ethertype IPv4 (0x0800), length 98: 192.168.77.2 > 192.168.77.37: ICMP echo request, id 1369, seq 66, length 64

I wonder who can lead me out of the trap, or it's just a OpenStack limitation?

Thanks
Peter
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