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Internetworking perspectives by Ivan Pepelnjak
Updated: 9 hours 56 min ago

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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LAG versus ECMP

October 5, 2014 - 10:20pm

Bryan sent me an interesting question:

When you have the opportunity to use LAG or ECMP, what are some things you should consider?

He already gathered some ideas (thank you!) and I expanded his list and added a few comments.

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Interop New York: It Was Great Fun

October 5, 2014 - 8:42am

Last week’s Interop New York was hard work (three workshops in two days), but also lots of nerdy fun. I love doing workshops with smart participants who bring their real-life problems to the room and challenge my assumptions and conclusions, and I had plenty of these interactions during the week. Thank you all (you know who you are)!

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Network Automation Tools with Jason Edelman on Sofware Gone Wild

October 3, 2014 - 3:17am

The stars have finally aligned, and after months of scheduling Jason and myself found time to chat about network automation tools and all the other exciting things Jason is doing (and blogging about).

We started with easy topics:

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Bufferbloat Killed my HTTP Session… or not?

October 1, 2014 - 10:25pm

Every now and then I get an email from a subscriber having video download problems. Most of the time the problem auto-magically disappears (and there’s no indication of packet loss or ridiculous latency in traceroute printout), but a few days ago Henry Moats managed to consistently reproduce the problem and sent me exactly what I needed: a pcap file.

TL&DR summary: you have to know a lot about application-level protocols, application servers and operating systems to troubleshoot networking problems.

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Tech Talks: MPLS Traffic Engineering Basics

October 1, 2014 - 3:49am

After covering the basics of MPLS, the discussion I had with Seamus Gilchrist turned to the basics of MPLS Traffic Engineering.

The video of that discussion is available online on the ipSpace.net Tech Talks web page.

Watch the video

Replacing a Central Firewall

September 30, 2014 - 3:39am

During one of my ExpertExpress engagements I got an interesting question: “could we replace a pair of central firewalls with iptables on the Linux server?

Short answer: Maybe (depending on your security policy), but I’d still love to see some baseline scrubbing before the traffic hits the server – after all, if someone pwns your server, he’ll quickly turn off iptables.

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Building a Small Cloud with UCS Mini

September 29, 2014 - 3:26am

During the last round of polishing of my Designing Infrastructure for Private Clouds Interop New York session (also available in webinar format) I wondered whether one could use the recently-launched UCS Mini to build my sample private cloud.

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