A few weeks ago I got into an interesting discussion about the potential harm caused by unnumbered IPv4/IPv6 interfaces.
Ignoring for the moment the vendor-specific or media-specific implementation details, these two arguments usually pop up in the first 100 milliseconds (assuming engineers involved in the discussion have some hands-on operational experience):
Read more ...John wrote an optimistic comment to my fashionable designs rant:
Nobody in their right mind does "fashionable" things when dealing with infrastructures that are required to be solid, dependable and robust.
Unfortunately many enterprises aren’t that prudent – the last Expert Express engagement I had in 2015 was yet another customer who lost two major data centers due to a bridging loop spilling over a stretched VLAN infrastructure.
Read more ...As you know I always promise my loyal subscribers at least 6 new webinars per year. Well, 2015 was a bit more fruitful. Let’s start with the easy ones:
However, I spent most of my time developing the SDN and network automation curriculum:
Read more ...I was often asked about two emerging technologies that enable standard controller-based WAN traffic engineering: BGP-LS to extract the network topology and PCEP to establish end-to-end tunnels from a controller.
Unfortunately, I never found time to explore these emerging technologies and develop a webinar. However, after Julian Lucek from Juniper did such a great job on the NorthStar podcast, I asked him whether he would be willing to do a deep dive technology webinar on the two technologies and he graciously agreed to do it.
Read more ...The number of visits to my web site is slowly going down – you’re giving me a very clear signal that it’s time to stop blogging.
I hope you’ll manage to catch at least a few quiet days with your loved ones and I wish you all the best in 2016!
More in 3 weeks or so ;)
Juniper recently launched their Tomahawk-based switch (QFX5200) and included a lot of information on the switching hardware in one of their public presentations (similar to what Cisco did with Nexus 9300), so I got a non-NDA glimpse into the latest Broadcom chipset.
You’ll get more information on QFX5200 as well as other Tomahawk-based switches in the Data Center Fabrics Update webinar in spring 2016.
Here’s what I understood the presentation said:
Read more ...If you have some leftover training budget for 2015, there’s no better way to spend it than to invest it in a workgroup ipSpace.net subscription ;)
You can choose between two standard packages (6 or 21 users) which include online consulting sessions, or create your own customized package.
Finally, if you plan to buy one of the standard packages, hurry up – the Dec15 promotional code gives you 10% discount till the end of the year.
Nick Buraglio used OpenDaylight and OpenFlow-enabled switches to build a part of the exhibition network of a large international supercomputing conference and was kind enough to talk about his real-life experience in Episode 47 of Software Gone Wild.
We covered:
Read more ...When I wrote a blog post explaining the difference between centralized control and centralized control plane, John Casey, CEO of CPLANE Networks wrote a comment saying “yeah, that’s exactly what we’re doing.”
It took us a while to get the stars aligned, but finally we managed to sit down and chat about what they’re doing, resulting in Episode 46 of Software Gone Wild.
Nuno wrote an interesting comment to my Stretched Firewalls across L3 DCI blog post:
You're an old school, disciplined networking leader that architects networks based on rock-solid, time-tested designs. But it seems that the prevailing fashion in network design and availability go against your traditional design principles: inter-site firewall clustering, inter-site vMotion, DCI, etc.
Not so fast, my young padawan.
Let’s define prevailing fashion first. You might define it as Kool-Aid id peddled by snake oil salesmen or cool network designs by people who know what they’re doing. If we stick with the first definition, you’re absolutely right.
Now let’s look at the second camp: how people who know what they’re doing build their network (Amazon VPC, Microsoft Azure or Bing, Google, Facebook, a number of other large-scale networks). You’ll find L3 down to ToR switch (or even virtual switch), and absolutely no inter-site vMotion or clustering – because they don’t want to bet their service, ads or likes on the whims of technology that was designed to emulate thick yellow cable.
Want to know how to design an application to work over a stable network? Watch my Designing Active-Active and Disaster Recovery Data Centers webinar.
This isn't the first Continue reading
The featured webinar of December 2015 is vSphere 6 Networking, a 6-hour deep dive into vSphere 6 networking features covering almost every single vSphere network-related feature.
Trial subscribers get free access to select videos from this webinar (those marked with a yellow star in this listing) and can purchase it at significant discount.
Yesterday I described the theoretical limitations of using OpenFlow for load balancing purposes. Today let’s focus on the practical part and answer another question:
@colin_dixon @ioshints and for a fair comparison: Would a $100k OF switch be able to act as proper LB?
— Kristian Larsson (@plajjan) December 3, 2015I wrote about the same topic years ago here and here. I know it’s hard to dig through old blog posts, so I collected them in a book.
Read more ...It all started with a tweet Kristian Larsson sent me after I published my flow-based forwarding blog post:
@ioshints sure but can't OpenFlow be used to implement an LB? It feels like a mix of terms here
— Kristian Larsson (@plajjan) December 3, 2015Do you need VXLAN in your data center or could you continue using traditional bridging? Do layer-2 fabrics make sense or are they a dead end in the evolution of virtual networking?
I tried to provide a few high-level answers in the Introduction to VXLAN video which starts the VXLAN Technical Deep Dive webinar. The public version of the video is now available on ipSpace.net Free Content web site.
Marek Majkowski published an awesome real-life story on CloudFlare blog: users experienced occasional short-term sluggish performance and while everything pointed to a network problem, it turned out to be a garbage collection problem in Linux kernel.
Takeaway: It might not be the network's fault.
Also: How many people would be able to troubleshoot that problem and fix it? Technology is becoming way too complex, and I don’t think software-defined-whatever is the answer.
When writing the Packet- and Flow-Based Forwarding blog post, I tried to find a good definition of flow-based forwarding (and I was not the only one being confused), and the one from Junos SRX documentation is as good as anything else I found, so let’s use it.
TL&DR: Flow-based forwarding is a valid technical concept. However, when mentioned together with OpenFlow, it’s mostly marketing fluff.
Read more ...If you’re a host running on an IPv6-only network, you might want to detect the IPv6 prefix used for NAT64 (for example, to transform IPv4 literals a clueless idiot embedded into a URL into IPv6 addresses).
Apple has a wonderful developer-focused page describing NAT64 and DNS64, including the way they synthesize IPv6 addresses from IPv4 literals. You (RFC 6919) MUST read it.
Read more ...I don’t like to correct my friends in public, but if someone says “I still believe that flow-based technologies will exceed the capabilities of packet-based technologies” (see Network Break 53), it’s time to revisit the networking fundamentals.
According to Wikipedia (but what do they know…):
Read more ...You might be familiar with the idea of using BGP as an SDN tool that pushes forwarding entries into routing and forwarding tables of individual devices, allowing you to build hop-by-hop path across the network (more details in Packet Pushers podcast with Petr Lapukhov).
Researchers from University of Louvain, ETH Zürich and Princeton figured out how to use OSPF to get the same job done and called their approach Fibbing. For more details, listen to Episode 45 of Software Gone Wild podcast with Laurent Vanbever (one of the authors), visit the project web site, or download the source code.
Wow, another year swooshed by. I can’t believe it’s almost gone. Maybe it’s all the travels I had throughout the year, and I MUST start with a huge THANK YOU to whoever is watching after me – there wasn’t a single major SNAFU.
Next, I’d like to thank the people who caused all that travel: attendees of my workshops.
Read more ...