Open Stack

 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




 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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