Open Stack

On 03/16/2015 01:13 PM, Georgios Dimitrakakis wrote:
>
> Hi again! I 've used tcpdump to capture the ARP requests.
>
> This is what I get for ARP requests coming from "send_arp_for_ha" by
> OpenStack:
>
> 04:56:25.995860 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.34 tell 15.12.11.226, length 46
> 04:56:25.995894 ARP, Ethernet (len 6), IPv4 (len 4), Reply 15.12.11.34
> is-at 70:e2:84:0b:59:a0 (oui Unknown), length 28
> 04:56:31.889363 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.228 tell 15.12.11.227, length 46
> 04:56:32.581746 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.228 tell 15.12.11.227, length 46
> 04:56:33.482519 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.228 tell 15.12.11.227, length 46
> 04:56:34.382775 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.228 tell 15.12.11.227, length 46
> 04:56:35.082594 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.228 tell 15.12.11.227, length 46
> 04:56:47.121268 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.240 tell 15.12.11.226, length 46
> 04:56:47.699135 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.34 tell 15.12.11.227, length 46
> 04:56:47.699162 ARP, Ethernet (len 6), IPv4 (len 4), Reply 15.12.11.34
> is-at 70:e2:84:0b:59:a0 (oui Unknown), length 28

I'm guessing none of that was broadcast.  Which could be a large 
difference between that and what you did manually.

You didn't by any chance happen to capture the packets to a binary file 
so you can re-read the .pcap with the -e option (show ethernet info) and 
perhaps -v ?


rick jones

> If I manually try with the
>
>
> "arping -c 10 -U -I eth0 15.12.11.34" command, tcpdump logs the following:
>
>
> 04:57:15.907743 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.34 (Broadcast) tell 15.12.11.34, length 28
> 04:57:16.907843 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.34 (Broadcast) tell 15.12.11.34, length 28
> 04:57:17.907943 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.34 (Broadcast) tell 15.12.11.34, length 28
> 04:57:18.908068 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.34 (Broadcast) tell 15.12.11.34, length 28
> 04:57:19.908165 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.34 (Broadcast) tell 15.12.11.34, length 28
> 04:57:20.908288 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.34 (Broadcast) tell 15.12.11.34, length 28
> 04:57:21.908375 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.34 (Broadcast) tell 15.12.11.34, length 28
> 04:57:22.908551 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.34 (Broadcast) tell 15.12.11.34, length 28
> 04:57:23.908652 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.34 (Broadcast) tell 15.12.11.34, length 28
> 04:57:24.908846 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has
> 15.12.11.34 (Broadcast) tell 15.12.11.34, length 28
>
>
>
>
> The IP addresses ending at *.226 and *.227 are according to the
> datacenter spare gateway addresses.
>
>
> Is it possible that OpenStack ARP requests is just to verify if the IP
> address is known and by which machine
> rather than sending update requests???
>
>
>
> Kind regards,
>
>
> George
>
>
>
>
>> I will try to see if I can get anything from the logs.
>> If someone else can come to a better suggestion I am all ears.
>>
>> Not having full access to the DataCenter and the underlying equipment
>> has caused me enough headaches so far :-(
>>
>>
>> Best,
>>
>>
>> George
>>
>>
>>> On 03/14/2015 03:32 PM, Georgios Dimitrakakis wrote:
>>>> Hello again Rick!
>>>>
>>>>
>>>>> On 03/13/2015 06:25 PM, Georgios Dimitrakakis wrote:
>>>>>> If I do an :
>>>>>>
>>>>>> arping -U -I etho x.x.x.x
>>>>>>
>>>>>> where x.x.x.x is the IP address.
>>>>>>
>>>>>> I can almost immediately access them outside of the subnet!
>>>>>
>>>>> I had forgotten that,  Still is that the very same set of options the
>>>>> OpenStack code uses?
>>>>
>>>>
>>>> I am not aware about that and I would like to know!
>>>> What does Openstack does and how ofted does it send the gratuitous ARP
>>>> request?
>>>
>>> I don't recall off the top of my head (perhaps someone else does) -
>>> and my corner of the world is Neutron rather than Nova networking. If
>>> there is much logging enabled I suspect you could see the commands in
>>> the logs.  Certainly Neutron is very "chatty" when it comes to logging
>>> things.
>>>
>>>>
>>>>
>>>>
>>>>>
>>>>>> Do you mean that OpenStack is sending a gratuitous ARP for all
>>>>>> and the router is ignoring them unless it is for a specific IP
>>>>>> address?
>>>>>>
>>>>>> If this is the case is there anything I can do?
>>>>>
>>>>> I will second the suggestion of getting a packet trace to see just
>>>>> what sort of ARP traffic the compute node(s) send and then compare
>>>>> that with the documentation for your router.
>>>>>
>>>>> rick
>>>>>
>>>>
>>>>
>>>> I will try to see if I can get anything but the problem is that the
>>>> datacenter hosting the facility is in Japan and there is a huge gap
>>>> communicating with them (actually there is no communication).
>>>>
>>>> If I could only find out what does the router accept would be very
>>>> nice :-)
>>>
>>> Nothing beats being able to see the blinking lights :)
>>>
>>> rick
>>
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