Matt Stone sent me a great set of questions about the emerging Data Center technologies (the headline is also his, not mine) together with an interesting observation “it seems as though there is a lot of reinventing the wheel going on”. Sure is – read Doug Gourlay’s OpenFlow article for a skeptical insider view. Here's a lovely tidbit:

So every few years the networking industry invents some new term whose primary purpose is to galvanize the thinking of IT purchasers, give them a new rallying cry to generate budget, hopefully drive some refresh of the installed base so us vendor folks can make our quarter bookings targets.

But I’m digressing, let’s focus on Matt’s questions. Here are the first few.

A while ago I wrote that the hypervisor vendors should consider turning the virtual switches into PE-routers. We all know that’s never going to happen due to religious objections from everyone who thinks VLANs are the greatest thing ever invented and MP-BGP is pure evil, but there are at least two good technical reasons why putting MPLS/VPN (as we know it today) in the hypervisors might not be the best idea in very large data centers.

The first question everyone asked after Nicira had published yet another MAC-over-IP tunneling draft was probably “do we really need yet another encapsulation scheme? Aren’t VXLAN or NVGRE enough?” Bruce Davie tried to answer that question in his blog post (and provided more details in another one), and I’ll try to make the answer a bit more graphical.

Wim (@fracske) De Smet sent me a whole set of very good VXLAN- and EVB-related questions that might be relevant to a wider audience.

If I understand you correctly, you think that VXLAN will win over EVB?

I wouldn’t say they are competing directly from the technology perspective. There are two ways you can design your virtual networks: (a) smart core with simple edge (see also: voice and Frame Relay switches) or (b) smart edge with simple core (see also: Internet). EVB makes option (a) more viable, VXLAN is an early attempt at implementing option (b).

In almost every field of IT lots of people try to do their job relying on uncle Google and his friends (bloggers, forum wizards and other content producers) and cut-and-paste solutions found on the web into their programs, server- or device configurations. Here’s my theory why that might be the case; please feel free to shoot it down in flames.

My regular readers probably know that I’m running a 4-month course in scalable web application design at University of Ljubljana (everyone else will find more details here). I was extremely surprised when we started – I’d expected to see about a dozen students, and suddenly realized I was standing in front of a totally crowded classroom. The next amazing surprise was the students’ level of motivation, commitment, knowledge, and the quality of their questions. It’s definitely fun to have an audience like that.

HP has recently released OpenFlow support on a few more switches and some people think it’s a big deal. It just might be if you’re a researcher with limited grant budget (which seems to be one of the major OpenFlow use cases today); for everyone else, it’s a meh. Lacking a commercial-grade OpenFlow controller supported by HP (or at least tested with HP switches), OpenFlow on HP switches remains a shiny new toy.

When I was writing about the NEC+IBM OpenFlow trials, I figured out a perfect use case for OpenFlow-controlled network forwarding: SMB data centers that need less than a few hundred physical servers – be it bare-metal servers or hypervisor hosts (hat tip to Brad Hedlund for nudging me in the right direction a while ago)

Instead of drinking beer and lab-testing vodka during the PLNOG party I enjoyed DHCPv6 discussions with Tomasz Mrugalski, the “master-of-last-resort” for the ISC’s DHCPv6 server. I mentioned my favorite DHCPv6 relay problem (relay redundancy) and while we immediately agreed I’m right (from the academic perspective), he brought up an interesting question – is this really an operational problem?

One of the few presentations I could understand @ PLNOG meeting yesterday (most of them were in Polish) was the fantastic “Guide To Building Secure Network Infrastructures” by Merike Kaeo, during which she revealed an obvious but oft forgotten fact: by deploying IPv6 in your router, you’ve actually created a parallel entry into the management plane that has to be secured using the same (or similar) mechanisms as its IPv4 counterpart.