Published: New SDN and NFV Materials

Last week I published slide decks for Network Function Virtualization, BGP-Based SDN Solutions and SDN Use Cases webinars – they’re available to subscribers and attendees registered for individual webinars.

Content from all three webinars is part of my SDN workshop – if you’d like to hear a live explanation, register for one of them.

Video: What Is IPv6?

One of the topics I’m addressing in the Enterprise IPv6 101 webinar (after all, it’s an introductory-level webinar) is the question of “what exactly is IPv6”. After all the promises, myths, in the end it turns out all we got were bigger addresses (and ton of additional complexity).

Fat Fingers and Other Campfire Stories

A recent well-publicized network outage prompted someone to start collecting fat-finger horror stories, and dozens of networking engineers were quick to chime in. Enjoy!

Reliability of SD-WAN and Hybrid WAN Solutions

My Business Case for SD-WAN blog post received numerous comments pointing out the potential pitfalls of hybrid WAN, including reduced security, unreliable Internet services and denial-of-service attacks.

While all those comments are perfectly valid, I still think hybrid WAN (whether implemented with traditional technologies or SD-WAN products) makes perfect sense.

Explaining the Pervasive Kludgeitis

I found a great explanation for hodgepodge of kludges found in "organically grown" solutions (legacy precursors to SD-WAN come to mind):

In a long-lived project, components are being replaced. Nice reusable components are easy to replace and so they are. Ugly non-reusable components are pain to replace and each replacement means both a considerable risk and considerable cost. Thus, more often then not, they are not replaced. As the years go by, reusable components pass away and only the hairy ones remain. In the end the project turns into a monolithic cluster of ugly components melted one into another.

Note: You really should read the whole blog post.

Must read: Big Flowering Thing

It's so nice to see someone saying eloquently what you've been trying to say for a while – you (RFC 2119) MUST read what my friend Matt Oswalt wrote about Big Flowering Things.

Explaining the Mysteries of WiFi and Internet ;)

“Daddy, why is Internet not working even though I have good signal?”
“You really want to know?”
“Sure”
“OK, let me draw a diagram or two ;)”

… and now my 8-year old knows how DHCP and DNS works (root cause was a broken DNS proxy running on upstream $0.99 WAN router).

Can You Avoid Networking Software Bugs?

One of my readers sent me an interesting reliability design question. It all started with a catastrophic WAN failure:

Once a particular volume of encrypted traffic was reached the data center WAN edge router crashed, and then the backup router took over, which also crashed. The traffic then failed over to the second DC, and you can guess what happened then...

Obviously they’re now trying to redesign the network to avoid such failures.

Interested in Mesh Wireless Networks?

Engineers developing open-source wireless mesh network protocols and solutions get together every now and then to test the performance of competing mesh network ideas.

The next conference is organized in August 2015 in Maribor, Slovenia, so if you ever needed a good excuse to drop by Slovenia, now you have one ;)

Why Should I Care About Networking?

A month ago I was asked to deliver a short presentation on “something interesting about networking” at my local university. The temptation to talk about network automation and SDN was huge, but I quickly figured out that would make no sense (the audience were students in their freshman year) and decided to talk about a fundamental question: why should a programmer care about networking.

Unfortunately the presentation wasn’t recorded, but you can browse the slide deck on the ipSpace.net public content web site.

Some Ridiculous SD-WAN Claims

SDx Central is usually a pretty good web site that I love to read, but even they occasionally manage to publish a gem like this one:

The problem with MPLS and similar technologies is that they weren’t designed with today’s business challenges in mind. Today, a company may need to launch an overseas R&D office overnight, or it may acquire a startup and want to immediately network with offices in distant regions and countries. Older technologies just don’t have the flexibility to do this on the fly.

Not surprisingly, the above paragraph triggered a severe case of Deja-Moo.

Must Read: IPv6 at Swisscom

While some people lament the lack of IPv6 business case, others are busy rolling it out – you (RFC 2119) SHOULD check out the Status of Swisscom’s IPv6 Activities presentation from recent Swiss IPv6 summit.

Is Linux TCP/IP Stack Really That Slow?

Most people casually involved with virtual appliances and network function virtualization (NFV) believe that replacing Linux TCP/IP stack with user-mode packet forwarding (example: Intel’s DPDK) boosts performance from meager 1 Gbps to tens of gigabits (and thus makes hardware forwarding obsolete).

Having data points is always better than having opinions; today let’s look at Receiving 1 Mpps with Linux TCP/IP Stack blog post.

2015-07-18: The blog post was updated based on feedback by Kristian Larsson.

Routing Protocols and SD-WAN: Apples and Furbies

Ethan Banks recently wrote a nice blog post detailing the benefits and drawbacks of traditional routing protocols and comparing them with their SD-WAN counterparts.

While I agree with everything he wrote, the comparison between the two isn’t exactly fair – it’s a bit like trying to cut the cheese with a chainsaw and complaining about the resulting waste.

Video: ISP IPv6 Transition Strategies

The responses of Internet Service Providers (ISPs) to lack of IPv4 address space range from outright denial (sometimes coupled with reassuringly-expensive large-scale carrier-grade NAT) to all-in IPv6-only designs using 464XLAT for residual IPv4 connectivity.

To understand the implications of these extremes and a few data points between them, watch the ISP IPv6 Transition Strategies video from Enterprise IPv6 – the First Steps webinar.

Business Case for SD-WAN

An anonymous commenter wrote this comment to my initial SD-WAN post:

I can still hardly imagine the business case behind SD-WAN. Any thoughts?

This question is really easy to answer. There’s a huge business case that SD-WAN products are aiming to solve: replacing traditional MPLS/VPN networks with encrypted transport over public Internet. However…

Save the Date: Designing Infrastructure for Private Clouds Workshop in Switzerland

Gabi Gerber (the wonderful mastermind behind the Data Center Day event) is helping me bring my Designing Infrastructure for Private Clouds workshop (one of the best Interop 2015 workshops) to Switzerland.

This is the only cloud design workshop I’m running in Europe in 2015. If you’d like to attend it, this is your only chance – register NOW.

Project Calico: Is It Any Good?

At least a dozen engineers sent me emails or tweets mentioning Project Calico in the last few weeks – obviously the project is getting some real traction, so it was high time to look at what it’s all about.

TL&DR: Project Calico is yet another virtual networking implementation that’s a perfect fit for a particular use case, but falters when encountering the morass of edge cases.

LDP Label Allocation Revisited

One of my readers was having an LDP argument with his colleague:

Yesterday I was arguing with someone who works for a large MPLS provider about LDP label allocation. He kept saying that LDP assigns a label to each next-hop, not to each prefix. Reading your blog, I believe this is the default behavior on Juniper but on Cisco LDP assigns a unique label for each IGP (non-BGP) prefix.

He’s absolutely right; Cisco and Juniper use different rules when allocating MPLS labels.

Software-Defined Hardware Forwarding Pipeline on HP Switches

Writing OpenFlow controllers that interact with physical hardware is harder than most people think. Apart from developing a distributed system (which is hard in itself), you have to deal with limitations of hardware forwarding pipelines, differences in forwarding hardware, imprecise abstractions (most vendors still support single OpenFlow table per switch), and resulting bloated flow tables.