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.

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.

After I wrote a comment on a LinkedIn discussion in the Carrier Ethernet group (more details here), Vishal Sharma wrote an interesting response, going into more details of distinction between centralized control and centralized control plane.

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

One of the Software Defined Evangelists has declared 2015 as the Year of SD-WAN, and my podcast feeds are full of startups explaining how wonderful their product is compared to the mess made by legacy routers, so one has to wonder: is SD-WAN really something fundamentally new, or is it just another old idea in new clothes?

Geoff Huston published an interesting number-crunching exercise in his latest IPv6-focused blog post: 8% of the value of the global Internet (GDP-adjusted number of eyeballs) is already on IPv6, and a third of the top-30 providers (which control 43% of the Internet value) have deployed large-scale IPv6.

The message is clear: The big players have moved on. Who cares about the long tail?

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:

• Introduction to Metro- and Carrier Ethernet Encryption
• Evaluation Guide for Metro- and Carrier Ethernet Encryptors
• Metro- and Carrier Ethernet Encryptors: 2015 Market Overview

Elisa Jasinska, Bob McCouch and I were scheduled to record a NetOps podcast with a major vendor, but unfortunately their technical director cancelled at the last minute. Like good network engineers, we immediately found plan B and focused on Elisa’s specialty: open-source tools.

Matjaž Straus started the SINOG 2 meeting I attended last week with a great story: during the RIPE70 meeting (just as I was flying home), Amsterdam Internet Exchange (AMS-IX) crashed.

Here’s how the AMS-IX failure impacted ATLAS probes (world-wide monitoring system run by RIPE) – no wonder, as RIPE uses AMS-IX for their connectivity.

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.