If you’re attending Interop Las Vegas next week, do drop by my Network Infrastructure for Cloud Computing workshop on Monday or one of the networking track sessions on Wednesday: Overlay Networking Explained in late morning and IPv6 – It’s High Time to Get Started in the afternoon. I’ve reserved plenty of time after each one for follow-up questions and discussions.

Other fine sessions you shouldn’t miss: Beware the Firewall, My Son! by Network Security Princess, Chopping Down the Fat Tree by venerable Ethan Banks, Death to Spanning Tree by Data Center Overlord Tony Bourke and How to Keep Video from Blowing Up Your Network by the very first CCIE Terry Slattery.

Hatem Naguib claimed that “the NSX controller cluster is completely out-of-band, and never handles a data packet” when describing VMware NSX Network Virtualization architecture, preemptively avoiding the “flow-based forwarding doesn’t scale” arguments usually triggered by stupidities like this one.

Does that mean there’s no packet punting in the NSX/Open vSwitch world? Not so fast.

I was talking about virtual firewalls for almost an hour at the Troopers13 conference, and the first question I got after the presentation was “who is going to manage the virtual firewalls? The networking team, the security team or the virtualization team?”

There’s the obvious “silos don’t work” answer and “DevOps/NetOps” buzzword bingo, but the real solution requires everyone involved to shift their perspective.

The 45 minute virtual firewalls presentation I had at Troopers 13 is now available online. The virtual firewalls webinar is an in-depth 2,5 hour version that includes numerous product architectures.

You can get all my recent public presentations and a list of upcoming events on my web site.

More than four years ago one of my friends wrote about uselessness of UMTS connections (the page has decayed into digital wasteland in the meantime) for inter-router backup links and although I got numerous comments trying to explain the issues I never found a good explanation that a simplistic networking engineer like me could understand.

Ilya Grigorik fixed that. His Breaking the 1000 msec Time-to-Glass Mobile Barrier talk has some real-world statistics, and a fantastic description of how 3G/4G networks work and what causes the enormous latencies. His High Performance Browser Networking book has even more details. Enjoy!

Dmitry Kalintsev left a great comment on my security paradigm changing post:

I have not yet seen redundant VNIC-level firewall implementations, which stopped me from using [...] them. One could argue that vSwitches are also non-redundant, but a vSwitch usually has to do stuff much less complex than what a firewall would, meaning chances or things going south are lower.

As always, things are not purely black-and-white and depend a lot on the product architecture and implementation.

Almost exactly two years ago I wrote an article describing the benefits and drawbacks of virtual appliances, where I listed virtualization overhead as one of the major sore spots (still partially true). I also wrote: “Implementing routers, switches or firewalls in a virtual appliance would just burn the CPU cycles that could be better used elsewhere.” It’s time to revisit this claim.

With all the Puppet buzz I’m hearing and claims that “compute and storage orchestration problems have been solved” I wanted to check the reality of those claims – is it (for example) possible to create a LUN on a storage array using a standard well-defined API.

Stephen Foskett, Simon Gordon and Scott Lowe quickly pointed me in the right direction: SMI-S. Thank you!

One of my readers wanted to receive my RSS feed as daily email messages. There’s no obvious way to do it, but (as always) there’s a kludge:

• Select Subscribe to ... Posts on any page of my blog;
• Selecting Atom as the subscription format brings you to my Feedburner feed (unless you’ve installed RSS/Atom browser extensions);
• Select Get ipSpace.net delivered by email in the Subscribe Now! Box

The deep dive into TCP and HTTP mechanisms that impact web application performance triggered numerous questions during the live webinar session – it took me almost 10 minutes to answer them all.

In the first part of the TCP, HTTP and SPDY webinar I explained why TCP and HTTP impact the end-to-end web application performance. In the second section of the webinar, we did a deep dive into the actual TCP and HTTP mechanisms that increase end-to-end latency (3-way handshake, initial congestion window, request/response nature of HTTP).

VXLAN, one of the first MAC-over-IP (overlay) virtual networking solutions is definitely a major improvement over traditional VLAN-based virtual networking technologies … but not without its own scalability limitations.

When I wrote the Virtual switches need BPDU guard blog post, I speculated that you could shut down a whole HA cluster with a single BPDU-generating VM ... and got a nice confirmation during the Troopers 13 conference – ERNW specialists successfully demonstrated the attack while testing the security aspects of a public cloud implementation for a major service provider.

For more information, read their blog post (they also have a nice presentation explaining how a VM can read ESXi hard drive with properly constructed VMDK file).

The responses to my What did you do to get rid of manual VLAN provisioning post were easy to predict: a few people sharing their best practices (thank you!), few musings on the future of SDN/networking, and the ubiquitous anonymous rant against stubbornness and stupidity of networking engineers and their OPEX.

I know one should never feed anonymous trolls, but this morsel is simply too juicy to pass, so here it is – let’s see what makes networking so complex.

Kevin left a pretty valid comment to my Are you ready to change your security paradigm blog post:

I disagree that a compromised security zone is game over. Security is built in layers. Those host in a compromised security zone should be hardened, have complex authentication requirements to get in them, etc. Just because a compromised host in a security zone can get at additional ports on the other hosts doesn't mean an attacker will be more successful.

He’s right from the host-centric perspective (assuming you actually believe those other hosts are hardened), but once you own a server in a security zone you can start having fun with intra-subnet attacks.