[openstack-dev] [Openstack] [qa] How to troubleshoot why a VM at Compute node won't response to ARP request from Neutron router
Salvatore Orlando
sorlando at nicira.com
Sun Oct 12 18:49:34 UTC 2014
If the ARP request reaches the compute node, then you do already know
tunnelling (or whatever transport type you're using) is not your problem.
The security group is also configured properly, so it does not seem
something you need to worry about.
This leaves us with two possible problems:
1) did the dhcp agent give our VM an IP address?
To this aim, check if there is any error in the dhcp agent log. Check if
your VM's MAC address is in the hosts file for the VM's network dnsmasq
instance.
In case you should not be able to find the dnsmasq instance, then this
would be the root cause of your problem.
2) did the ovs agent wire the port for your VM?
Find the ovs port associated with the VM's interface. If you are using ML2
with hybrid plugging the interface name should something like qvo-<port_id>.
Ensure a local vlan tag is attached to that port. If the vlan tag is 4095
then your port is on the "dead vlan" because the ovs agent recognized it as
"alien". Check for errors in the ovs agent log.
However, the first thing you should do in my opinion is to check the VM
log. It won't be the first time I blame the network and then find out that
the VM image I was using was broken.
You don't need to have connectivity to access the VM console. nova
console-proxy does that for you. Also, if you just want to see the vm
console rather than interact with it, just use the command nova console-log
<vm_id>
Hope this helps,
Salvatore
On 12 October 2014 19:26, Shashank Hegde <hegde.shashank at gmail.com> wrote:
> Hi Danny,
>
> You can ssh into your compute node with X forwarding:
> ssh -X user at compute
>
> You can then attach to the VM's console using the command:
> vncviewer :<display-number>
>
> You can find the display number using the command:
> ps aux | grep kvm
> Look for vnc there. Its of the form 127.0.0.1:<display-number>
>
> ~ Shashank
>
> On Sun, Oct 12, 2014 at 10:17 AM, Danny Choi (dannchoi) <
> dannchoi at cisco.com> wrote:
>
>> I do have security rule configured to allow ICMP.
>>
>> localadmin at qa4:~/devstack$ nova secgroup-list-rules default
>>
>> +-------------+-----------+---------+-----------+--------------+
>>
>> | IP Protocol | From Port | To Port | IP Range | Source Group |
>>
>> +-------------+-----------+---------+-----------+--------------+
>>
>> | tcp | 22 | 22 | 0.0.0.0/0 | |
>>
>> | | | | | default |
>>
>> | | | | | default |
>>
>> | icmp | -1 | -1 | 0.0.0.0/0 | |
>>
>> +-------------+-----------+---------+-----------+———————+
>>
>>
>> Danny
>>
>> From: Remo Mattei <remo at italy1.com>
>> Date: Sunday, October 12, 2014 at 1:00 PM
>> To: Danny Choi <dannchoi at cisco.com>
>> Cc: "openstack at lists.openstack.org" <openstack at lists.openstack.org>, "
>> openstack-dev at lists.openstack.org" <openstack-dev at lists.openstack.org>
>> Subject: Re: [Openstack] [qa] How to troubleshoot why a VM at Compute
>> node won't response to ARP request from Neutron router
>>
>> By default icmp is not allowed
>>
>> Inviato da iPhone ()
>>
>> Il giorno 12/ott/2014, alle ore 09:25, Danny Choi (dannchoi) <
>> dannchoi at cisco.com> ha scritto:
>>
>> Hi,
>>
>> Using devstack to deploy OpenStack, I have Controller + Network running
>> at one physical node and Compute at a separate node.
>>
>> I launched a VM at the Compute node with a private address 10.0.0.2
>> (Neutron router interface is 10.0.0.1).
>>
>> At the Controller node, in the qrouter namespace, I could not ping the
>> VM private address 10.0.0.2.
>>
>> At the Compute node, tcpdump of the tap interface indicated ARP
>> requests were received.
>>
>> However, it did not show any ARP response.
>>
>> My understanding is that the VM’s virtual interface is directly
>> connected to this tap interface. Since the VM is unreachable, I cannot
>> launch its console to see if the ARP requests are received at the virtual
>> interface.
>>
>> Any suggestions on how to troubleshoot this?
>>
>> localadmin at qa4:~/devstack$ nova show vm1
>>
>>
>> +--------------------------------------+----------------------------------------------------------------+
>>
>> | Property | Value
>> |
>>
>>
>> +--------------------------------------+----------------------------------------------------------------+
>>
>> | OS-DCF:diskConfig | MANUAL
>> |
>>
>> | OS-EXT-AZ:availability_zone | nova
>> |
>>
>> | OS-EXT-STS:power_state | 1
>> |
>>
>> | OS-EXT-STS:task_state | -
>> |
>>
>> | OS-EXT-STS:vm_state | active
>> |
>>
>> | OS-SRV-USG:launched_at | 2014-10-12T14:25:15.000000
>> |
>>
>> | OS-SRV-USG:terminated_at | -
>> |
>>
>> | accessIPv4 |
>> |
>>
>> | accessIPv6 |
>> |
>>
>> | config_drive |
>> |
>>
>> | created | 2014-10-12T14:23:30Z
>> |
>>
>> | flavor | m1.tiny (1)
>> |
>>
>> | hostId |
>> 00ac69883737ebd290ad4f38cae979a6e268902333261ba6bfbade44 |
>>
>> | id |
>> 04b5a345-cadf-4dee-9209-5bcf589b6a3c |
>>
>> | image | cirros-0.3.2-x86_64-uec
>> (14a55982-a093-4850-80c8-7b2ae3a7eaba) |
>>
>> | key_name | -
>> |
>>
>> | metadata | {}
>> |
>>
>> | name | vm1
>> |
>>
>> | os-extended-volumes:volumes_attached | []
>> |
>>
>> | private network | 10.0.0.2, 172.29.173.5
>> |
>>
>> | progress | 0
>> |
>>
>> | security_groups | default
>> |
>>
>> | status | ACTIVE
>> |
>>
>> | tenant_id | 90058797dddc49efae4d1f45aa5ab982
>> |
>>
>> | updated | 2014-10-12T14:23:39Z
>> |
>>
>> | user_id | 5ab6344540974a1fbda5b539778ebe35
>> |
>>
>>
>> +--------------------------------------+----------------------------------------------------------------+
>>
>> localadmin at qa4:~/devstack$
>>
>> localadmin at qa4:~/devstack$ ip netns
>>
>> qdhcp-f55f0683-830f-4523-82cb-46d638f91d47
>>
>> qrouter-62aecbdd-d58d-4b33-a743-b16ca38544c5
>>
>> localadmin at qa4:~/devstack$
>>
>> localadmin at qa4:~/devstack$
>>
>> localadmin at qa4:~/devstack$ sudo ip netns exec
>> qrouter-62aecbdd-d58d-4b33-a743-b16ca38544c5 ping 10.0.0.2
>>
>> PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
>>
>> From 10.0.0.1 icmp_seq=1 Destination Host Unreachable
>>
>> From 10.0.0.1 icmp_seq=2 Destination Host Unreachable
>>
>> From 10.0.0.1 icmp_seq=3 Destination Host Unreachable
>>
>> From 10.0.0.1 icmp_seq=4 Destination Host Unreachable
>>
>> From 10.0.0.1 icmp_seq=5 Destination Host Unreachable
>>
>> From 10.0.0.1 icmp_seq=6 Destination Host Unreachable
>>
>>
>>
>> localadmin at qa5:~/devstack$ sudo tcpdump -i tapade47169-57
>>
>> tcpdump: WARNING: tapade47169-57: no IPv4 address assigned
>>
>> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
>>
>> listening on tapade47169-57, link-type EN10MB (Ethernet), capture size
>> 65535 bytes
>>
>> 11:58:30.042379 ARP, Request who-has 10.0.0.2 tell 10.0.0.1, length 42
>>
>> 11:58:31.041840 ARP, Request who-has 10.0.0.2 tell 10.0.0.1, length 42
>>
>> 11:58:32.041848 ARP, Request who-has 10.0.0.2 tell 10.0.0.1, length 42
>>
>> 11:58:33.044212 ARP, Request who-has 10.0.0.2 tell 10.0.0.1, length 42
>>
>> 11:58:34.041866 ARP, Request who-has 10.0.0.2 tell 10.0.0.1, length 42
>>
>>
>> Thanks,
>> Danny
>> !DSPAM:1,543aaefc201211675819574!
>>
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