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Re: How to deploy OpenStack on thousands of nodes?



I think there is some confusion as to the term broadcast.  Many of the
Rabbit docs describe the delivery of a message from one publisher to
multiple subscribers as a 'broadcast'.  This is not to be confused with a
network broadcast where traffic is sent over the network broadcast address.
 Rabbit uses tcp and a publisher/subscriber model - even in more complex
configurations where there are multiple publishers (think cluster).

I have personally implemented large openstack compute clouds that had many
hypervisors, each on individual subnets and a rabbit server on yet another
subnet and all message traffic worked as expected.  There were no actual
network broadcasts to worry about.

In my previous message I had assumed that you were actually in the process
of implementation and were running into problems.  It now seems that is not
the case - you are in a review or planning period.  However - as I noted
above the openstack queues on rabbit will work in a distributed network
configuration as long as all of the subscribers can reach the rabbit server
on tcp/5672.  I've personally done it and not had an issue.


On Tue, Jun 25, 2013 at 9:40 PM, Sg Kylin <kylin7.sg@xxxxxxxxx> wrote:

> Hi Brent,
> Thanks for your reply! But we are afraid that Rabbitmq needs broadcast to
> work correctly and usually broadcast is not available in cross-subnets
> deployments. That is what we are worrying about...
> Best,
> Kylin CG
> 2013/6/26 Brent Roskos <brent.roskos@xxxxxxxxxxx>
>> By default rabbit uses tcp port 5672 for communication.. tcp can
>> certainly cross subnet boundaries and be routed without issue.
>>   I suggest you do some network troubleshooting; ping your rabbit server
>> then telnet to port 5672 on the rabbit server from hosts on the other
>> subnets.
>> Check your router acls and local host firewalls.  Check to make sure that
>> your rabbit server has a route to get back to the other subnets with the
>> reply.
>> Dual homed hosts with one local connection and one Internet connection
>> will need specific routes added to allow them to reach other local subnets
>> since you wouldn't want that traffic to try to traverse the default route
>> which points out to the Internet.  This is true even if you are using
>> virtual interfaces with vlans instead of separate physical interfaces.
>> Regards,
>> Brent
>> On Tue, Jun 25, 2013 at 6:10 AM, Sg Kylin <kylin7.sg@xxxxxxxxx> wrote:
>>> Hi All,
>>> We are currently trying to deploy OpenStack on thousands of nodes. We
>>> are using Grizzly stable version and Ubuntu 12.04.2. However, the big
>>> problem we meet now is the network topology. If we want to use HA
>>> (haproxy + keepalived) for the controller nodes on which *-apis are
>>> running as well as network nodes which are deployed across different
>>> VLANs (VLANs can reach each other by setting gateways), e.g
>>> and, HA would not work correctly. Also we
>>> found that rabbitmq could not work when nova-* services were deployed
>>> across different subnets.
>>> Thus, we want to know whether HA and rabbitmq can be used across
>>> subnets? If it not true, we can only deploy them in a single flat
>>> layer 2 net, which seems unfeasible in real-world because of
>>> broadcast storms...
>>> Best,
>>> Kylin CG
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