Reinventing CLNS with L3-only Forwarding

Hank left a lovely comment on my Rearchitecting L3-Only Networks blog post:

What you describe is literally intra-area routing in CLNS.

He’s absolutely right (and I admitted as much during my IPv6 Microsegmentation presentations @ Troopers 15).

Presentation & Video: Quo Vadis, SDN?

From the automation perspective, the RIPE conference is a dream come true – 30 seconds after you upload your presentation, it appears on the RIPE web site, it’s automatically updated on the podium computer, and the video recording of your talk is published before you even manage to get off the podium – so you can already watch my “SDN - 4 years later (aka Quo Vadis, SDN?)” presentation if you missed it yesterday.

Do We Need Network Programmability?

Jsicuran left this comment on my You Must Understand the Fundamentals to Be Successful blog post:

I just went through some Cisco webinar where they were showcasing the use of NX-OS API and Python to add a VLAN. I do some Python myself and have used that API for some simple DevOps-like uses, but for the most part if you are an enterprise and use Prime DCIM to add VLANs, why should you go through the coding process?

It obviously depends on where you are in your IT automation journey.

OpenStack Got Full IPv6 Support

Great news for everyone trying to deploy IPv6 in OpenStack: the Kilo release has full support for IPv6 in the tenant networks, including SLAAC, stateless and stateful DHCPv6. For more details, read an extensive blog post by Shannon McFarland.

OpenFlow in HP Campus Solutions on Software Gone Wild

When I finished my SDN workshop @ Interop Las Vegas (including a chapter on OpenFlow limitations), some attendees started wondering whether they should even consider OpenFlow in their SDN deployments. My answer: don’t blame the tool if people use it incorrectly.

Two days later, I discovered HP is one of those companies that knows how to use that tool.

ARP Processing in Layer-3-Only Networks

John Jackson wrote an interesting comment on my Rearchitecting L3-Only Networks blog post:

What the host has configured for its default gateway doesn't really matter, correct? Because the default gateway in traditional L2 access networks really isn't about the gateway's IP address, but the gateway's MAC address. The destination IP address in the packet header is always the end destination IP address, never the default gateway.

He totally got the idea, however there are a few minor details to consider.

Video: End-to-End High Availability in Dual Stack Networks

One of the topics I discussed in the IPv6 High Availability webinar is the problem of dual-stack deployments – what do you do when the end-to-end path for one of the protocol stacks breaks down. Happy eyeballs is one of the solutions, as is IPv6-only data center (Facebook is moving in that direction really fast). For more details, watch the short End-to-End High Availability in Dual Stack Networks demo video.

Dinesh Dutt from Cumulus Networks on Data Center Fabrics Webinar

Occasionally I’d invite a vendor speaker (usually working for an interesting startup) to present in my Data Center Fabrics webinar series. Dan Backman from Plexxi was talking about affinity networking in 2013, and in the May 2015 update session we’ll have Dinesh Dutt from Cumulus Networks talking about their software platform, architectures you can build with whitebox (or britebox) switches running Cumulus Linux, exciting network automation options, and cool new features they’re constantly adding to their software.

Replacing Central Router with a Next-Generation Firewall?

One of my readers sent me this question:

After reading this blog post and a lot of blog posts about zero trust mode versus security zones, what do you think about replacing L3 Data Center core switches by High Speed Next Generation Firewalls?

Long story short: just because someone writes about an idea doesn’t mean it makes sense. Some things are better left in PowerPoint.

On Theory and Practice

I recently read a must-read blog post by Russ White in which he argued that you need to understand both theory and practice (see also Knowledge or Recipes and my other certification rants) and got a painful flashback of a discussion I had with a corner-cutting SE (fortunately he was an exception) almost two decades ago when I was teaching my Advanced OSPF course at Cisco.

ALF: Application Layer Fixup

I was talking about “application-layer gateways” on firewalls and NAT boxes with a fellow engineer, and we came to an interesting conclusion: in most cases they are not gateways; they don’t add any significant functionality apart for payload fixups for those broken applications that think carrying network endpoint information in application packets is a good idea (I’m looking at you, SIP and FTP). These things should thus be called Application Layer Fixups or ALFs ;)

PF_RING Deep Dive with Luca Deri on Software Gone Wild

Whenever software switching nerds get together and start discussing the challenges of high-speed x86-based switching, someone inevitably mentions PF_RING, an open-source library that gives you blazingly fast packet processing performance on a Linux server.

I started recording a podcast with Luca Deri, the author of PF_RING, but we diverted into discussing ntopng, Luca’s network monitoring software. We quickly fixed that and recorded another podcast – this time, it’s all about PF_RING, and we discussed these topics:

Going Back to the Mainframes?

25 years ago when I started my networking career, mainframes were all the rage, and we were doing some crazy stuff with small distributed systems that quickly adapted to topology changes, and survived link, port, and node failures. We called them routers.

Yes, we were crazy and weird, but our stuff worked. We won and we built the Internet, proving that we can build networks bigger than any mainframe-based solution could ever hope to be.

How Do I Start My IPv6 Addressing Plan?

One of my readers was reading the Preparing an IPv6 Addressing Plan document on RIPE web site, and found that the document proposes two approaches to IPv6 addressing: encode location in high-order bits and subnet type in low-order bits (the traditional approach) or encode subnet type in high-order bits and location in low-order bits (totally counter intuitive to most networking engineers). His obvious question was: “Is anyone using type-first addressing in production network?”

Terastream project seems to be using service-first format; if you’re doing something similar, please leave a comment!

On SDN Controllers, Interconnectedness and Failure Domains

A long long time ago Colin Dixon wrote the following tweet in response to my Controller Cluster Is a Single Failure Domain blog post:

He’s obviously right, but I wasn’t talking about interconnected domains, but failure domains (yeah, I know, you could argue they are the same, but do read on).

OMG, VXLAN Encapsulation Has No Security!

Every now and then someone actually looks at the VXLAN packet format and eventually figures out that VXLAN encapsulation doesn’t provide any intrinsic security.

TL&DR Summary: That’s old news, the sky is not falling, and deploying VXLAN won’t make your network less secure than traditional VLAN- or MPLS-based networks.

Hardware Gateways in Overlay Virtual Networks

Whenever I’m running an SDDC workshop or doing on-site SDN/SDDC-related consulting, the question of hardware gateways between overlay virtual networks and physical world inevitably pops up.

My usual answer: You have to understand (A) what type of gateway you need, (B) what performance you need and (C) what form factor will give you that performance. For more details, watch the Hardware Gateways video from Scaling Overlay Virtual Networks webinar

Great News: My Workshops Are Available from NIL Data Communications

In the last few months I ran into a sweet problem: dozens of organizations would like to have on-site SDN, SDDC or IPv6 workshop. Obviously I had to turn many of them down, and my calendar is almost full till early November.

A week ago I also found a solution: my friends at NIL Data Communications will start offering the same workshops with their instructors.

Rearchitecting L3-Only Networks

One of the responses I got on my “What is Layer-2” post was

Ivan, are you saying to use L3 switches everywhere with /31 on the switch ports and the servers/workstation?

While that solution would work (and I know a few people who are using it with reasonable success), it’s nothing more than creative use of existing routing paradigms; we need something better.

Update 2015-04-22 14:30Z - Added a link to Cumulus Linux Redistribute Neighbor feature.

When Did SDN Really Start?

You might remember my blog post claiming we had a system with SDN-like properties more than 20 years ago.

It turns out SDN is older than that – Rob Faulds found an old ComputerWorld ad from 1989 promoting AT&T SDN service, and it seems SDN was in operation as early as 1985.