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

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

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.

How to Get into the Top N%

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

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

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.

Data Center Design Case Studies on Amazon – Take 2

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:

We Need Consistency more than Controllers

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.

LAG versus ECMP

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.

Interop New York: It Was Great Fun

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)!

Network Automation Tools with Jason Edelman on Sofware Gone Wild

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:

Bufferbloat Killed my HTTP Session… or not?

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.

Tech Talks: MPLS Traffic Engineering Basics

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.

Replacing a Central Firewall

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.

Building a Small Cloud with UCS Mini

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.

It’s the Application Development, Stupid

I love reading blog posts on Plexxi blog (you SHOULD add them to your RSS reader) and the “It’s the Application, Stupid” series from Mat Matthews is no exception. What pleasantly surprised me was that a large enterprise came to the same conclusions I’m preaching for the last few years.

TCP Is a Stream Protocol

I hope you know TCP provides a reliable stream service not reliable packet delivery, but you might not have realized all the implications – I found an old post by Robert Graham explaining how things really work and how you can use them to bypass quick-and-dirty IDS that rely on signatures instead of doing proper protocol decodes.

Schprokits with Jeremy Schulman on Software Gone Wild

Jeremy Schulman was the driving force behind the Puppet agent that Juniper implemented on some Junos switches (one of the first fully supported Puppet-on-a-switch implementations). In the meantime, he quit Juniper and started his own company focused on a network automation product – more than enough reasons to chat with him on Software Gone Wild.

Quick Guide to my Interop New York Sessions

I’m running or participating in five workshops or sessions during next week’s Interop New York. Three of them build on each other, so you might want to attend all of them in sequence:

Designing Infrastructure for Private Clouds starts with requirements gathering phase and focuses on physical infrastructure design decisions covering compute, storage, physical and virtual networking, and network services. If you plan to build a private (or a reasonable small public) cloud, start here.

Network Programmability 101: The Problem

In the first part of the Network Programmability webinar Matt Oswalt described some of the major challenges most networks are facing today:

• Why is everyone claiming that the network is so slow to change?
• Is that really the case? Why?
• Why is the manual configuration culture so widespread in networking?
• How does the holistic thinking in the design phase dissolve into the box mentality of CLI commands?
• How does the box mentality limit the scalability of network deployments?

Connecting Virtual Routers to the Outside World

Stefan de Kooter (@sdktr) sent me a follow-up question to my Going All Virtual with Virtual WAN Edge Routers blog post:

How would one interface with external Internet in this scenario? I totally get the virtual network assets mantra, but even a virtual BGP router would need to get a physical interconnect one way or another.

As always, there are plenty of solutions depending on your security needs.