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Five Years

By stretch | Saturday, March 23, 2013 at 7:53 p.m. UTC

Today marks the five-year anniversary of my first post on Packet Life. (Funny, it doesn't feel like it's been that long.) Those of you who follow the blog regularly no doubt have noticed that I don't post as often as I used to. Several factors contribute to this, probably the largest of which has been the increasing burden and tedium of my day job. My wife and I also relocated here to the Raleigh-Durham area of North Carolina last year, so getting settled has eaten up a good amount of time over the past months.

Rather than rehashing the past year, I thought it would be interesting to discuss what's coming up in the near future. We've seen quite a number of new technologies and ideas pop up recently, so many in fact that I've been having a difficult time keeping sense of it all. Here's my take on what will be big in our world over the next few years.

Software-Defined Networking (SDN)

The functions of any network device can be assigned among three planes of operation: control, forwarding, and management. Traditionally, routers and switches (or switch stacks) have been deployed as autonomous units which operate independently on all three planes. A router, for example, might be configured via SSH (management plane) to learn routes via OSPF (control plane) which are then installed in its forwarding table (forwarding plane). Software-defined networking (SDN) is a broad term which refers to offloading the functions of the control and management planes from individual devices to a centralized controller.

Why does this matter? Offloading control plane functions to one or more central controllers theoretically allows for much more flexible, granular handling of data flows transiting a network. Forwarding decisions can be made within the context of an entire network rather than on a hop-by-hop basis. This flexibility also permits centralized configuration and provisioning of resources, which saves on operational costs. Although emerging SDN products are heavily focused on the data center, I suspect we will see SDN expand to the enterprise in the coming years as well. Google has been of particular interest lately with its SDN WAN deployment (PDF).

It's worth pointing out that there's a very good reason that routers and switches have remained largely autonomous devices for so many years: In most environments, a network device needs to remain manageable and operational in the event connectivity to remote resources (such as a controller) is lost. The larger you try to grow an SDN domain, the more susceptible it becomes to failure, and the more resiliency must be built into the infrastructure to ensure that controller availability is assured. This is relatively easy to do within the contained, highly reliable environment of a data center, but it will be interesting to see how the SDN approach fairs in the wild.


Whereas SDN is an abstract concept, OpenFlow is a defined protocol which runs between a centralized controller and the routers and switches (deemed OpenFlow agents) which comprise a network. OpenFlow is used by a controller to "program" an agent device; that is, to install or manipulate forwarding information. An agent device needs to possess only enough logic to facilitate communication with the OpenFlow controller and to manipulate its local forwarding table. Forwarding instructions are defined as flow tables which match transit traffic based on any combination of header fields (source IP address, destination TCP port, etc.) similar to a firewall policy.

The OpenFlow white paper provides a brief introduction to the protocol. The complete OpenFlow v1.1.0 standard is also freely available for an in-depth look at how flows can be defined.

Whereas OpenFlow is an open standard, some vendors are developing their own proprietary implementations of the SDN paradigm. Cisco's One Platform Kit (OnePK), for example, seeks to provide an alternative to OpenFlow by providing API access directly into router and switch firmware.

VMware NSX

Just earlier this month, VMware announced its new network virtualization product, VMware NSX. VMware has combined its proven albeit limited vSwitch technology with the fruits of its Nicira acquisition last year to produce a much more featureful virtual routing and switching product. From what I can tell, NSX seems similar to Cisco's Nexus 1000V drop-in hypervisor switch but more tightly integrated with the rest of VMware's software suite.

IaaS Integration

We're going to see (or continue seeing) a large push to bring the provisioning of virtual network resources in line with other resources. Network as a Service (NaaS), it's called, because everything needs an acronym (ENAA). The goal is to allow for the automated provisioning of VLANs, firewall policies, and so forth to be completed in parallel with the creation of new virtual machines and storage. "Cloud" software suites like OpenStack and CloudStack seek to optimize the process of virtual network deployments. It's an intriguing idea, no doubt, but the possibility of arbitrarily turning up and tearing down vital network resources like people do today with VMs makes me a little uneasy.

IEEE 802.11ac

Gigabit wireless LAN is on the horizon in the form of IEEE 802.11ac. I haven't had much reason to keep up with wireless developments lately, but Andrew von Nagy (@revolutionwifi) has written up an excellent, practical introduction to the emerging standard.

(Food for thought: IEEE 802.11n was officially ratified only three and a half years ago in September of 2009.)

Everything Else I Haven't Caught Onto Yet

What have I overlooked (or mentioned above but missed the point entirely)?

Posted in News


Calin C.
March 23, 2013 at 9:14 p.m. UTC

Happy Birthday!

March 23, 2013 at 11:36 p.m. UTC

I just wanted to let you know what an inspiration you have been to me over the past few years as I have begun to develop my career as a network engineer. I have kept your cheat sheets as my rotating background screen on all my computers for over a year (which help tremendously as I study for my CCNP), and you even inspired me to start a blog of my own.

Thanks for all of the excellent knowledge and inspiration you provide, it really means a lot to people like myself :-)

March 24, 2013 at 1:17 a.m. UTC

Great blog! I love your cheat sheet posters! Very nicely done and big time savers!

March 24, 2013 at 1:46 p.m. UTC

Thanks for all the knowledge that you have shared with us, every network admin should have your website bookmarked.

March 24, 2013 at 3:44 p.m. UTC

Happy birthday Packet Life! I've used both the cheat sheets and the Routing IP notes.
March 24, 2013 at 7:28 p.m. UTC

By far the best description of SDN out on the net to date. Great work....

March 24, 2013 at 11:51 p.m. UTC

Congratulations Jeremy on the Five Years blogging.

Your style of writing is very easy to read and understand.
Keep it going! Thanks!

March 24, 2013 at 11:53 p.m. UTC

P.S. Is there a way to subscribe to your blog updates (email)?

March 25, 2013 at 9:12 a.m. UTC

Thank you so much Jeremy for the great and unvaluable work you did in your first 5 years of Now i demand at least five more years! :)

March 25, 2013 at 12:14 p.m. UTC

That was probably the best definition of SDN and OpenFlow I've heard so far

Dan Jones
March 25, 2013 at 10:47 p.m. UTC

Congrats on 5 years.

VM-FEX versus NSX will be a fun fight to watch.

March 28, 2013 at 3:34 p.m. UTC

Thanks for the work to keep a free functioning Cisco lab online for a very long time.Many of us have passed Cisco exams because of that and we are very grateful.

April 1, 2013 at 7:00 p.m. UTC

Burden and tedium of your day job? Are you a manager now?

Your lab inspired me to create my own online lab.

April 9, 2013 at 5:05 a.m. UTC


Try RSS to subscribe this blog. Google reader or feedly are both good RSS tools

April 28, 2013 at 6:10 a.m. UTC

Five years? It sure seems longer than that to me. I continue to see your cheat sheets taped up around random government offices in DC metro man. It's crazy to see that you have had such a great impression on the network community.

I'll let you know when I come down to see Dave in RTP for my next lab attempt and we will get that dinner we never got around to. Hit me up on irc or whatev.


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