[openstack-dev] DVR and FWaaS integration
beyounn at gmail.com
Wed Jun 25 20:00:51 UTC 2014
During last summit, we were talking about the integration issues between
DVR and FWaaS. After the summit, I had one IRC meeting with DVR team. But
after that meeting I was tight up with my work and did not get time to
continue to follow up the issue. To not slow down the discussion, I'm
forwarding out the email that I sent out as the follow up to the IRC
meeting here, so that whoever may be interested on the topic can continue
to discuss about it.
First some background about the issue:
In the normal case, FW and router are running together inside the same box
so that FW can get route and NAT information from the router component. And
in order to have FW to function correctly, FW needs to see the both
directions of the traffic.
DVR is designed in an asymmetric way that each DVR only sees one leg of the
traffic. If we build FW on top of DVR, then FW functionality will be
broken. We need to find a good method to have FW to work with DVR.
During the IRC meeting, we think that we could force the traffic to the FW
before DVR. Vivek had more detail; He thinks that since the br-int knowns
whether a packet is routed or switched, it is possible for the br-int to
forward traffic to FW before it forwards to DVR. The whole forwarding
process can be operated as part of service-chain operation. And there could
be a FWaaS driver that understands the DVR configuration to setup OVS flows
on the br-int.
The concern is that normally firewall and router are integrated together so
that firewall can make right decision based on the routing result. But what
we are suggesting is to split the firewall and router into two separated
components, hence there could be issues. For example, FW will not be able
to get enough information to setup zone. Normally Zone contains a group of
interfaces that can be used in the firewall policy to enforce the direction
of the policy. If we forward traffic to firewall before DVR, then we can
only create policy based on subnets not the interface.
Also, I’m not sure if we have ever planed to support SNAT on the DVR, but
if we do, then it depends on at which point we forward traffic to the FW,
the subnet may not even work for us anymore (even DNAT could have problem
Another thing that I may have to get detail is that how we handle the
overlap subnet, it seems that the new namespaces are required.
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