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Internetworking perspectives by Ivan Pepelnjak
Updated: 13 hours 26 min ago

Overlay-to-Underlay Network Interactions: Document Your Hidden Assumptions

20 hours 30 min ago

If you listen to the marketing departments of overlay virtual networking vendors, it looks like the world is a simple place: you deploy their solution on top of any IP fabric, and it all works.

You’ll hear a totally different story from the physical hardware vendors: they’ll happily serve you a healthy portion of FUD, hoping you swallow it whole, and describe in gory details all the mishaps you might encounter on your virtualization quest.

The funny thing is they’re all right (not to mention the really fun part when FUDders change sides ;).

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Bad Ideas and Abominations

October 29, 2014 - 2:28am

This post SHOULD have been published on April 1st, but I need to define the terminology for another upcoming post, so here it is ;)

RFC 2119 defines polite words to use when something really shouldn’t be done. Some network designs I see deserve more colorful terminology.

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New Webinar: Scaling Overlay Virtual Networks

October 27, 2014 - 11:20pm

You can get an overlay virtual networking solution from almost every major hypervisor- and data center networking vendor. Do you ever wonder which one to choose for your large-scale environment? I’m positive you’d get all of them up and running in a one-rack environment, but what if you happen to be larger than that?

We’ll try to address scalability hiccups and roadblocks you might encounter on your growth path in Scaling Overlay Virtual Networks webinar (get your free ticket here).

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Cumulus Linux in Real Life on Software Gone Wild

October 27, 2014 - 2:25am

A year ago Matthew Stone first heard about Cumulus Linux when I ranted about it on a Packet Pushers podcast (which only proves that any publicity is good publicity even though some people thought otherwise at that time), and when his cloud service provider company started selecting ToR switches he considered Cumulus together with Cisco and Arista… and chose Cumulus.

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Tech Talks: Introduction to Label Distribution Protocol (LDP)

October 23, 2014 - 10:40pm

In the third part of MPLS Tech Talks we focused on the role of label distribution protocol (LDP) and its operation in frame-mode MPLS. You can watch the video on the Tech Talks web page.

Watch the video

IPv6 in a Global Company – a Real-World Example

October 22, 2014 - 10:34pm

More than a year ago I wrote a response to a comment Pascal wrote on my Predicting the IPv6 BGP table size blog post. I recently rediscovered it and figured out that it’s (unfortunately) as relevant as it was almost 18 months ago.

Other people have realized we have this problem in the meantime, and are still being told to stop yammering because the problem is not real. Let’s see what happens in a few years.

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All You Need Are Two Top-of-Rack Switches

October 22, 2014 - 8:44pm

Every time I’m running a classroom version of my Designing the Cloud Infrastructure workshop, I start with a simple question: “Who has more than 2000 VMs or bare-metal servers in the data center?

I might see three hands on a good day; 90-95% of the audience have smaller data centers… and some of them get disappointed when I tell them they don’t need more than two ToR switches in their data center.

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Network Programmability Phase 1: the Configured Network

October 21, 2014 - 2:20am

During his Network Programmability 101 webinar Matt Oswalt described three phases of network programmability. The first level in the pyramid of programmable awesomeness (his words, not mine) is described in today’s video.

Watch the video

Micro-BFD: BFD over LAG (Port Channel)

October 19, 2014 - 10:15pm

The discussion in the comments to my LAG versus ECMP post took a totally unexpected turn when someone mentioned BFD failure detection over port channels (link aggregation groups – LAGs).

What’s the big deal?

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Just Published: Juniper Data Center Switches

October 19, 2014 - 9:01am

Want to know what the difference between Virtual Chassis and Virtual Chassis Fabric is? How Local Link Bias works? How ISSU on QFX 5100 works even though the box doesn’t have two supervisor boards? You’ll find answers to all these questions in new videos describing Juniper data center switches.

Workload Mobility and Reality: Bandwidth Constraints

October 17, 2014 - 2:43am

People talking about long-distance workload mobility and cloudbursting often forget the physical reality documented in the fallacies of distributed computing. Today we’ll focus on bandwidth, in a follow-up blog post we’ll deal with its ugly cousin latency.

TL&DR summary: If you plan to spread application components across the network without understanding their network requirements, you’ll get the results you deserve.

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Networking Is Not as Special as We Think It Is

October 14, 2014 - 10:14pm

I was listening to the Packet Pushers show #203 – an interesting high-level discussion of policies (if you happen to be interested in those things) – and unavoidably someone had to mention how the networking is all broken because different devices implement the same functionality in different ways and use different CLI/API syntax.

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Last Call: Free Version of SDN and OpenFlow – The Hype and the Harsh Reality

October 13, 2014 - 10:09pm

If you want to get a free copy of my SDN and OpenFlow – The Hype and the Harsh Reality book, download it now. The offer will expire by October 20th.

Packet Reordering and Service Providers

October 12, 2014 - 10:59pm

My “Was it bufferbloat?” blog post generated an unexpected amount of responses, most of them focusing on a side note saying “it looks like there really are service providers out there that are clueless enough to reorder packets within a TCP session”. Let’s walk through them.

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How to Get into the Top N%

October 12, 2014 - 8:57am

Michael Church wrote an interesting answer on Quora, describing a logarithmic scale of programming skills and (even more importantly) hints to follow to get from n00b into the top N% (for some small value of N):

  • Budget 7–14 years;
  • Study voraciously;
  • Build things when you don’t know that you’ll succeed;
  • Network to get new ideas;
  • Job hop when you stop learning.

Replace “programmer” with “networking engineer” and read the whole answer ;)

IPv6 High Availability Strategies on NIL TV

October 9, 2014 - 11:59pm

I had a shorter version of my IPv6 High Availability talk @ Slovenian IPv6 summit this spring. The video is online, but wouldn’t be of much use to anyone but both Slovenian readers of this blog.

The English version of that same talk is now available on NIL TV (or you could decide to go for the full webinar or whole IPv6 track).

VXLAN and OTV: The Saga Continues

October 8, 2014 - 10:31pm

Randall Greer left a comment on my Revisited: Layer-2 DCI over VXLAN post saying:

Could you please elaborate on how VXLAN is a better option than OTV? As far as I can see, OTV doesn't suffer from the traffic tromboning you get from VXLAN. Sure you have to stretch your VLANs, but you're protected from bridging failures going over your DCI. OTV is also able to have multiple edge devices per site, so there's no single failure domain. It's even integrated with LISP to mitigate any sub-optimal traffic flows.

Before going through the individual points, let’s focus on the big picture: the failure domains.

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Data Center Design Case Studies on Amazon – Take 2

October 7, 2014 - 10:37pm

In July I wrote about an Amazon Kindle version of my Data Center Design Case Studies book and complained about their royalties model. Someone quickly pointed out how to adapt to their system: split the book into multiple volumes and charge $9.99 for each.

It took me months to get there, but the first two volumes are finally on Amazon:

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We Need Consistency more than Controllers

October 6, 2014 - 10:25pm

I was listening to the I2RS Packet Pushers podcast a while ago and was more than glad that when Greg Ferro yet again mentioned the complexity of OSPF, someone simply pointed out that controllers would not reduce the complexity; if anything they would increase it.

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