on 03-30-201307:10 AM - last edited on 10-28-201309:31 PM by bcm1
I recently returned from IETF 86 and would like to provide a short update on the SDN related activities. While the ONF continues to drive standards around OpenFlow and continues to promote SDN use cases and solutions, the IETF is now becoming more involved in SDN related technologies, protocols and standards.
Here is a link to a previous blog where I talked about some standards activity related to SDN. That blog will also provide some background information on various IETF WGs.
MPLS Working Group’s
The various MPLS WG activities focus on many things specific to service provider networks; and interesting enough, there is now becoming a more evident relationship between the various MPLS WGs and the SDN solution space.
For example, in the L2VPN WG there was a discussion of a VXLAN over L2VPN Internet Draft (ID). This would provide layer-2 MPLS connectivity between data center VXLAN or NVGRE logical overlay networks. This is a pretty cool use case and it appears to be a needed solution if VXLAN/NVGRE solutions become more widely deployed in data centers. A somewhat related topic was discussed on how Ethernet VPNs (E-VPNs) could be leveraged to provide a data center overlay solution. In this context, E-VPNs are based on MPLS technologies. While this solution revolves around Network Virtualization Overlays, it was discussed in the L2VPN WG due to it leveraging MPLS technologies. This same Internet Draft was also discussed in the NVO3 WG.
In the L3VPN WG, there were also quite a few IDs that overlap with the NVO3 WG and data center overlay technologies. The general support for MPLS-based solutions for data center overlay architectures appears to be gathering momentum. This is only my personal observation after attending these meetings. But it is interesting to notice that the various MPLS WGs are becoming more involved in data center overlay solutions; often including SDN-like solutions. This makes one wonder where this might be heading ...
Specific to the L3VPN WG, drafts that could be considered related to SDN are VXLAN/NVGRE encapsulation for L3VPNs and the activity around the virtual PE and CE.
While activities in other WGs, such as PCE and ALTO, could also be considered related to the SDN solution space as well, I will discuss those in my SP community blog so please go there for additional details.
The Newer IETF Working Group’s
Now on to the more interesting (and controversial?) WG activities! Of all the WG meetings at this IETF, NVO3 was the most heavily attended. It was practically standing-room only.
As you may recall, NVO3 is focused on the data center overlay problem space and architecture. This is not to be confused with DC “underlay” architectures, such as TRILL. Ethernet fabrics, whether based on TRILL or some other protocols, are considered an underlay technology; while an overlay technology is a logical network construct that leverages the many benefits of Ethernet fabrics.
In earlier NVO3 meetings, overlay technologies such as VXLAN and NVGRE were often discussed; while more recently, a lot of the discussions now include MPLS based overlays. This particular meeting was heavily focused on the charter and framework of the NVO3 WG, rather than what an architecture or solution might look like. I believe what happened here is that there were too many solutions being offered as part of this WG; while a clear definition of the charter and the requirements of the problem space weren’t fully specified and agreed upon. So, this WG has some re-chartering to accomplish with the intent of having an architectural framework and clear requirements defined by the next IETF in Berlin. Lots of work to do here!
Also discussed in the NVO3 and L3VPN WGs was the need for “inter-subnet routing”; in other words, layer-3 routing between IP subnets and/or between logical network overlays. I kept thinking of Vyatta during these discussions.
Another WG that should also be followed by the SDN community is I2RS. Like NVO3, this WG is fairly new. The primary goal of this WG is to provide a real-time interface into the IP routing system. While some could say this activity is not SDN related, I think it’s close enough to warrant a mention here. There is also more on this topic in my SP community blog.
I’ll close this blog out with an update on the SDNRG. Brocade’s SP CTO, Dave Meyer, kicked off the meeting with a high-level architectural discussion of what SDN is really all about. This thought provoking talk is aimed at helping to “bound” the SDN problem space. SDN means many different things to many different people, so this talk is intended to get the audience on the same page.
A presentation was made on a Software Defined Internet Exchange (SDX) proof of concept. It uses a Brocade switch as the cross-connect fabric! The idea behind a SDX is to use a controller to peer (ie. BGP) in the control plane, and use OpenFlow to instantiate the connectivity (ie. flows) in the SDX data plane. What a cool use case! This reminds me of the early days of MPLS (circa 2000’ish), when an MPLS-based Internet Exchange switch was being talked about and a similar proof of concept was tested. Although that concept did not take hold (all Internet Exchange Points or IXPs are Ethernet based), it helped promote and eventually validate MPLS as a deployable networking technology. Could this SDX proof of concept hold the same premonition for OpenFlow? Here is the diagram from the presentation.
[Diagram from IETF 86, SDNRG WG, SDX: A Software Defined Internet Exchange, by Nick Feamster]
A very interesting talk was given on Network Functions Virtualization (NFV). This work is not coming out of the SDNRG, but a fairly new organization called the Industry Specifications Group (ISG) is focusing on NFV. The ISG members are all large service provider carriers. This particular talk was about virtualizing Broadband Remote Access Server (BRAS) and Content Distribution Network (CDN) functions onto an x86 platform. It was basically an “acid test” to validate this can be done and the performance was shown to be pretty good! It didn’t have all the features and functions typically found in a BRAS, but it had enough functionality to validate the network functions virtualization capability.
A mention of the FORCES WG is worth bringing up as it relates to SDN and more importantly, OpenFlow. A presentation was made explaining how some of the problems the OpenFlow movement are experiencing and working to solve have already been solved in various FORCES activities and implementations. So it was recommended that those folks who are developing OpenFlow solutions leverage the work and experience from the FORCES community.
So, that wraps up this short update on IETF 86 activities that are related to the SDN solution space. I hope you found it useful. And don’t forget that the ONS event is coming in April!