Open Stack

Wuhongning,

 The code for forwarding traffic from a DVR serviced node to the default snat gw node is now included in the latest L-3 agent patch posted at (https://review.openstack.org/89413). It utilizes a combination of ip rules and ip routes to implement policy based routing for snat traffic. Carl's description is a very good representation of what it implements. Additional information is also available at (https://docs.google.com/document/d/1jCmraZGirmXq5V1MtRqhjdZCbUfiwBhRkUjDXGt5QUQ/edit)

thanks,
-Rajeev.

> -----Original Message-----
> From: Narasimhan, Vivekanandan
> Sent: Thursday, May 22, 2014 10:04 PM
> To: OpenStack Development Mailing List (not for usage questions)
> Cc: Grover, Rajeev; Smith, Michael (HPN R&D)
> Subject: RE: [openstack-dev] [Neutron] Default routes to SNAT gateway
> in DVR
> 
> 
> Thanks Carl, for pitching in for us.
> 
> As Carl said, this is the last detail that is being worked out.
> 
> Wuhogning,
> 
> I am requesting Rajeev and Mike(CC'ed) who are working in DVR SNAT to
> post the document into to the blueprint link here, so that you can take
> a look.
> 
> https://blueprints.launchpad.net/neutron/+spec/neutron-ovs-dvr
> 
> -
> Thanks,
> 
> Vivek
> 
> 
> 
> -----Original Message-----
> From: Carl Baldwin [mailto:carl at ecbaldwin.net]
> Sent: Friday, May 23, 2014 3:57 AM
> To: OpenStack Development Mailing List (not for usage questions)
> Subject: Re: [openstack-dev] [Neutron] Default routes to SNAT gateway
> in DVR
> 
> Hi,
> 
> I found this message in my backlog from when I was at the summit.
> Sorry for the delay in responding.
> 
> The "default SNAT" or "dynamic SNAT" use case is one of the last
> details being worked in the DVR subteam.  That may be why you do not
> see any code around this in the patches that have been submitted.
> Outbound traffic that will use this SNAT address will first enter the
> IR on the compute host.  In the IR, it will not match against any of
> the static SNAT addresses for floating IPs.  At that point the packet
> will be redirected to another port belonging to the central component
> of the DVR.  This port has an IP address  different from the default
> gateway address (e.g. 192.168.1.2 instead of 192.168.1.1).  At this
> point, the packet will go back out to br-int and but tunneled over to
> the network node just like any other intra-network traffic.
> 
> Once the packet hits the central component of the DVR on the network
> node it will be processed very much like default SNAT traffic is
> processed in the current Neutron implementation.  Another "interconnect
> subnet" should not be needed here and would be overkill.
> 
> I hope this helps.  Let me know if you have any questions.
> 
> Carl
> 
> On Fri, May 16, 2014 at 1:57 AM, Wuhongning <wuhongning at huawei.com>
> wrote:
> > Hi DVRers,
> >
> > I didn't see any detail documents or source code on how to deal with
> > routing packet from DVR node to SNAT gw node. If the routing table
> see
> > a outside ip, it should be matched with a default route, so for the
> > next hop, which interface will it select?
> >
> > Maybe another standalone "interconnect subnet" per DVR is needed,
> > which connect each DVR node and optionally, the SNAT gw node. For
> > packets from dvr
> > node->snat node, the interconnect subnet act as the "default route"
> > node->for this
> > host, and the next hop will be the snat node.
> >
> > _______________________________________________
> > OpenStack-dev mailing list
> > OpenStack-dev at lists.openstack.org
> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> >
> 
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