IPv6 Address Allocation Is Operating System-Specific

The breadth of address allocation options available in IPv6 world confuses many engineers thoroughly fluent in IPv4, but it also gives operating system developers way too many options… and it turns out that different operating systems behave way differently when faced with the same environment.

2016-01-21: In the meantime, Luka got further details on Windows behavior, and Enno Rey provided a few additional links.

Spanning Tree (STP) on Virtual Switches

One of my readers sent me this question:

I'm researching NFV/SDN and wonder if the software L2 switches support spanning tree.

TL&DR: Some do, some don’t.

Upcoming Events: Data Center Fabrics Workshop in Zurich

Online webinars are great, but many engineers still prefer live workshops – they’re an excellent opportunity for unrestricted 2-way communication and exchange of ideas – so I decided to turn a few of my best webinars (or webinar tracks) into workshops, and Gabi Gerber, the wonderful organizer of Data Center days in Switzerland took over the logistics, resulting in the first-ever Data Center Fabrics workshop in Zurich in late March.

Network Node Shutdown Is a Process, not an Event

In theory, you should shut down a network device with a well-defined procedure:

• Drain the traffic from the device;
• Verify the device is no longer forwarding traffic;
• Turn off the device.

In practice, network devices don’t have a shutdown command, and reload typically just restarts the network OS.

OpenSwitch Deep Dive on Software Gone Wild

A while ago I watched a Networking Field Day Extra video in which Chris Young and Michael Zayats talked about HP’s open source initiative – they decided to build yet another open networking operating system.

Obviously I wanted to know more, reached out to Chris, and we quickly managed to set up an online chat resulting in Episode 48 of Software Gone Wild podcast.

Upcoming Events: Troopers 2016

Last autumn’s SDN roadtrip left me totally exhausted – at the moment it’s so bad that I can’t push myself to work on non-urgent things – but there are some conferences are that so awesome that I wouldn’t skip them no matter what.

Troopers 16 (March 14th – 18th in Heidelberg, Germany) is a must-go-to security conference. Past events were fantastic, and when Enno Rey asked me what I’d like to talk about this year it wasn’t hard to come up with three interesting topics:

Are Unnumbered Interfaces Harmful?

A few weeks ago I got into an interesting discussion about the potential harm caused by unnumbered IPv4/IPv6 interfaces.

Ignoring for the moment the vendor-specific or media-specific implementation details, these two arguments usually pop up in the first 100 milliseconds (assuming engineers involved in the discussion have some hands-on operational experience):

The Sad State of Enterprise Networking

John wrote an optimistic comment to my fashionable designs rant:

Nobody in their right mind does "fashionable" things when dealing with infrastructures that are required to be solid, dependable and robust.

Unfortunately many enterprises aren’t that prudent – the last Expert Express engagement I had in 2015 was yet another customer who lost two major data centers due to a bridging loop spilling over a stretched VLAN infrastructure.

A Quick Look Back: Webinars in 2015

As you know I always promise my loyal subscribers at least 6 new webinars per year. Well, 2015 was a bit more fruitful. Let’s start with the easy ones:

• There was the regular Data Center Fabrics update webinar in May with guest speaker Dinesh Dutt from Cumulus Networks;
• IPv6 microsegmentation webinar in March extended the IPv6 curriculum;
• Michele Chubirka had a great webinar on open-source security tools in September;
• The Designing Active-Active and Disaster Recovery Data Centers completed the first phase of the cloud building curriculum (more to come in 2016);

However, I spent most of my time developing the SDN and network automation curriculum:

New Webinar: BGP-LS and PCEP

I was often asked about two emerging technologies that enable standard controller-based WAN traffic engineering: BGP-LS to extract the network topology and PCEP to establish end-to-end tunnels from a controller.

Unfortunately, I never found time to explore these emerging technologies and develop a webinar. However, after Julian Lucek from Juniper did such a great job on the NorthStar podcast, I asked him whether he would be willing to do a deep dive technology webinar on the two technologies and he graciously agreed to do it.

All the Best in 2016!

The number of visits to my web site is slowly going down – you’re giving me a very clear signal that it’s time to stop blogging.

I hope you’ll manage to catch at least a few quiet days with your loved ones and I wish you all the best in 2016!

More in 3 weeks or so ;)

Broadcom Tomahawk 101

Juniper recently launched their Tomahawk-based switch (QFX5200) and included a lot of information on the switching hardware in one of their public presentations (similar to what Cisco did with Nexus 9300), so I got a non-NDA glimpse into the latest Broadcom chipset.

You’ll get more information on QFX5200 as well as other Tomahawk-based switches in the Data Center Fabrics Update webinar in spring 2016.

Here’s what I understood the presentation said:

Leftover Training Budget? Let Me Help You

If you have some leftover training budget for 2015, there’s no better way to spend it than to invest it in a workgroup ipSpace.net subscription ;)

You can choose between two standard packages (6 or 21 users) which include online consulting sessions, or create your own customized package.

Finally, if you plan to buy one of the standard packages, hurry up – the Dec15 promotional code gives you 10% discount till the end of the year.

Running Open Daylight in Production Network on Software Gone Wild

Nick Buraglio used OpenDaylight and OpenFlow-enabled switches to build a part of the exhibition network of a large international supercomputing conference and was kind enough to talk about his real-life experience in Episode 47 of Software Gone Wild.

We covered:

CPLANE Networks on Software Gone Wild

When I wrote a blog post explaining the difference between centralized control and centralized control plane, John Casey, CEO of CPLANE Networks wrote a comment saying “yeah, that’s exactly what we’re doing.”

It took us a while to get the stars aligned, but finally we managed to sit down and chat about what they’re doing, resulting in Episode 46 of Software Gone Wild.

The Grumpy Old Network Architects and Facebook

Nuno wrote an interesting comment to my Stretched Firewalls across L3 DCI blog post:

You're an old school, disciplined networking leader that architects networks based on rock-solid, time-tested designs. But it seems that the prevailing fashion in network design and availability go against your traditional design principles: inter-site firewall clustering, inter-site vMotion, DCI, etc.

Not so fast, my young padawan.

Let’s define prevailing fashion first. You might define it as Kool-Aid id peddled by snake oil salesmen or cool network designs by people who know what they’re doing. If we stick with the first definition, you’re absolutely right.

Now let’s look at the second camp: how people who know what they’re doing build their network (Amazon VPC, Microsoft Azure or Bing, Google, Facebook, a number of other large-scale networks). You’ll find L3 down to ToR switch (or even virtual switch), and absolutely no inter-site vMotion or clustering – because they don’t want to bet their service, ads or likes on the whims of technology that was designed to emulate thick yellow cable.

Want to know how to design an application to work over a stable network? Watch my Designing Active-Active and Disaster Recovery Data Centers webinar.

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Featured Webinar: vSphere 6 Networking Deep Dive

The featured webinar of December 2015 is vSphere 6 Networking, a 6-hour deep dive into vSphere 6 networking features covering almost every single vSphere network-related feature.

What does this mean?

Trial subscribers get free access to select videos from this webinar (those marked with a yellow star in this listing) and can purchase it at significant discount.

Should We Use OpenFlow for Load Balancing?

Yesterday I described the theoretical limitations of using OpenFlow for load balancing purposes. Today let’s focus on the practical part and answer another question:

@colin_dixon @ioshints and for a fair comparison: Would a $100k OF switch be able to act as proper LB?

— Kristian Larsson (@plajjan) December 3, 2015

I wrote about the same topic years ago here and here. I know it’s hard to dig through old blog posts, so I collected them in a book.

Could We Use OpenFlow for Load Balancing?

It all started with a tweet Kristian Larsson sent me after I published my flow-based forwarding blog post:

@ioshints sure but can't OpenFlow be used to implement an LB? It feels like a mix of terms here

— Kristian Larsson (@plajjan) December 3, 2015

Why Do We Need VXLAN (and What Is It)?

Do you need VXLAN in your data center or could you continue using traditional bridging? Do layer-2 fabrics make sense or are they a dead end in the evolution of virtual networking?

I tried to provide a few high-level answers in the Introduction to VXLAN video which starts the VXLAN Technical Deep Dive webinar. The public version of the video is now available on ipSpace.net Free Content web site.