Blog Posts in June 2015

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.

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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.

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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.

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Webinars in 1H2015, and a Look Forward

The first half of 2015 was extremely productive – seven brand new webinars (or 22 hours of new content) were added to the webinar library.

Most of the development focus was on SDN and network automation: OpenFlow, NETCONF and YANG, Ansible, Jinja and YAML, and Monitoring SDN networks. There was also the traditional Data Center Fabrics Update session in May, IPv6 Microsegmentation webinar in March, and (finally!) vSphere 6 Networking Deep Dive in April.

Do I have to mention that you get all of them (and dozens of other webinars) with the subscription?

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Just Out: Metro- and Carrier Ethernet Encryptors Market Overview

Christoph Jaggi has just published the third part of his Metro- and Carrier Ethernet Encryptor trilogy: the 2015 market overview. Public versions of all three documents are available for download on his web site:

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SDN/OpenFlow/NFV Workshop: Frequent Questions

One of the potential attendees of my SDN workshop sent me a long list of questions. Almost every networking engineer, team leader or CIO asks the first one:

What will happen, if we don´t follow the SDN hype (in the short term, in the medium term and in the long term)?

Answering this question is the whole idea of the workshop.

The up-to-date list of scheduled SDN workshops is available on my web site.

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Industry Thoughts in 30 seconds

A while ago someone working for an IT-focused media site approached me with a short list of high-level questions. Not sure when they’ll publish the answers, so here they are in case you might find them interesting:

What can enterprises do to ensure that their infrastructure is ready for next-gen networking technology implementations emerging in the next decade?

Next-generation networks will probably rely on existing architectures and forwarding mechanisms, while being significantly more uniform and heavily automated.

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NAPALM: Integrating Ansible with Network Devices on Software Gone Wild

What happens when network engineers with strong programming background and focus on open source tools have to implement network automation in a multi-vendor network? Instead of complaining or ranting about the stupidities of traditional networking vendors and CLI they write an abstraction layer that allows them to treat all their devices in the same way and immediately open-source it.

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So You Need ISSU on Your ToR switch? Really?

During the Cumulus Linux presentation Dinesh Dutt had at Data Center Fabrics webinar, someone asked an unexpected question: “Do you have In-Service Software Upgrade (ISSU) on Cumulus Linux” and we both went like “What? Why?

Dinesh is an honest engineer and answered: “No, we don’t do it” with absolutely no hesitation, but we both kept wondering, “Why exactly would you want to do that?

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Video: Scale-Out NAT

Network Address Translation (NAT) is one of those stateful services that’s almost impossible to scale out, because you have to distribute the state of the service (NAT mappings) across all potential ingress and egress points.

Midokura implemented distributed stateful services architecture in their Midonet product, but faced severe scalability challenges, which they claim to have solved with more intelligent state distribution.

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Video: Implementing VLAN-aware Bridge with OpenFlow

Reinventing the wheels makes little sense. Implementing old solutions with new tools might be in the same category, but at least it shows you the power and shortcomings of the new tools.

Building a VLAN-aware bridge in OpenFlow is thus a mandatory case study, and as you’ll see in the video from the OpenFlow Deep Dive webinar, it’s not as easy as it looks. For more details, watch the whole OpenFlow webinar (6 hours of in-depth videos), which you also get by buying Advanced SDN Training or subscription.

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Case Study: Scale-Out Cloud Infrastructure

I helped several customers design scale-out private or public cloud infrastructure. In every case, I tried to start with a reasonably small pod (based on what they’d consider acceptable loss unit – another great term I inherited from Chris Young), connected them to a shared L3 backbone (either within a data center or across multiple data centers), and then tried to address the inevitable desire for stretched layer-2 connectivity.

You’ll find a summary of these designs in my next ExpressExpress case study: Scale-Out Private Cloud Infrastructure, and if you need more details, I’m usually available for online consulting.

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