We Have to Get Away from the Box-Focused Mentality

I had a great SDN-focused conversation with Terry Slattery during last Interop New York, ago and of course we came to the argument that the CLI is the root of all evil, which started my usual rant. Guess what: not surprisingly that wasn’t what Terry had in mind. He was using the “CLI mentality is bad” as a synonym for “we’re used to configuring our networks one box at a time” (so we should really be talking about box-focused mentality).

TCP Optimization with Juho Snellman on Software Gone Wild

Achieving 40 Gbps of forwarding performance on an Intel server is no longer a big deal - Juniper got to 160 Gbps with finely tuned architecture - but can you do real-time optimization of a million concurrent TCP sessions on that same box at 20 Gbps?

Juho Snellman from Teclo Networks explained how they got there in Episode 25 of Software Gone Wild… and you’ll learn a ton of things about radio networks on the way.

Enjoy the show!

Reducing BGP SNMP Traps in DMVPN Networks

One of my readers decided to build a large DMVPN network with BGP as the WAN routing protocol (good choice!) and configured BGP SNMP traps with snmp-server enable traps bgp command on the hub router to detect spoke router failures. Turns out that’s not exactly a good idea.

Video: Routing over VXLAN

Even though I wrote about the challenges of routing from VXLAN VNI to VLAN segment on a certain popular chipset a while ago, many engineers obviously still find the topic highly confusing (no surprise there, it is).

Maybe a video is worth a thousand words ;) – I published the part of recent VXLAN webinar where I described the issue in as many details as I could.

Whitebox Switching and Open-Source Networking Are not SDN

One of my readers left this comment to the Four Paths to SDN blog post:

You didn't mention Cumulus. SDN protocols become much less important when you have an open Linux switch platform. You can compile and install your own management daemon and implement whatever protocol best suits the task (and blend local and remote control).

Here’s my usual response to this line of thinking:

Estimating BGP Convergence Time

One of my readers sent me this question:

I have an Internet edge setup with two routers connected to two upstream ISPs and receiving full BGP routing table from them. I’m running iBGP between my Internet routers. Is there a formula to estimate convergence time if one of my uplinks fail? How many updates will I need to get the entire 512K routes in BGP table and also how much time it would take?

As always, the answer is it depends.

Scalable Load Balancing with Avi Networks on Software Gone Wild

How many times have you received exact specifications of the traffic the e-commerce platform you have to deploy will generate? How do you buy a load balancer (application delivery controller in marketese) to support that (somewhat unknown) amount of traffic? In most cases, you buy a box that’s several times too big for the traffic the site is receiving most of the time, and still crashes under peak load.

Cisco ACI – a Stretched Fabric That Actually Works

In mid-February a blog post on Cisco’s web site announced stretched ACI fabric (bonus points for not using marketing grammar but talking about a shipping product). Will it work better than other PowerPoint-based fabrics? You bet!

What’s the Big Deal?

Cisco’s ACI fabric uses distributed (per-switch) control plane with APIC controllers providing fabric configuration and management functionality. In that respect, the ACI fabric is no different from any other routed network, and we know that those work well in distributed environments.

Free Online Introduction to SDN and Network Automation Training

Want to know more about SDN and network automation/programmability, but don’t know where to start? Why don’t you try the free Introduction to SDN and Network Automation training available on ipSpace.net – you’ll get seven hours of high-quality content that will help you understand where it might make sense to use SDN technologies in your network and what SDN, OpenFlow, NFV, NETCONF, Ansible, YAML, Jinja and a few other acronyms are all about.

Response: Why Technology Still Matters

My good friend Tom Hollingsworth wrote a great blog post about hypermyopia in the networking industry. I agree with most everything he wrote (I have to – I’m always telling people to focus on business needs and to change their mentality before relying on shiny new gizmos), but I still think it’s crucial to consider the technology used in products we’re looking at.

Vendor-Independent European Network Conferences?

One of my readers was trying to find interesting vendor-independent network conferences in Europe. Here are a few I could recommend, please leave your feedback and additional suggestions in the comments!

Do We Need QoS in the Data Center?

Whenever I get asked about QoS in the data center, my stock reply is “bandwidth is cheaper than QoS-induced complexity.” This is definitely true in most cases, and ideally the elephant problems should be solved higher up in the application stack, not with network-layer kludges, but are there situations where you actually need data center QoS?

Scaling Overlay Networks: Scale-Out Control Plane

A week or so ago I described why a properly implemented hypervisor-based overlay virtual networking data plane is not a scalability challenge; even though the performance might decrease slightly as the total number of forwarding entries grow, modern implementations easily saturate 10GE server uplinks.

Scalability of the central controller or orchestration system is a totally different can of worms. As I explained in the Scaling Overlay Networks, the only approach that avoids single failure domain and guarantees scalability is scale-out control plane architecture.

Response: We Dislike People Quoting Gartner

John Herbert wrote a wonderful post explaining why he (and a lot of other people including myself) hates seeing Gartner quotes in vendor presentations. Let me elaborate a bit on this apparent anti-Gartner sentiment.

Lisa Caywood from Brocade is an exception – watch the video of her Network Field Day 9 presentation to see how a vendor Gartner slide should look like.

Let’s Get Rid of the Thick Yellow Cable

Whenever I write about the crazy things vendors are trying to sell us, and the kludges we have to live with, I keep wondering, “Is it just me, or is the whole industry really as ridiculous as it seems?” It’s so nice to see someone else coming to the same conclusions, like Mark Burgess (the author of CFEngine and the Promise Theory) did in a lengthy essay on whether SDN makes sense.

BGP Configuration Made Simple with Cumulus Linux

BGP is without doubt the most scalable routing protocol, which made it a popular choice for large-scale deployments from service provider networks to enterprise WAN/VPN networks and even data centers. Its only significant drawback is the tedious configuration process (which almost reminds me of writing COBOL programs decades ago).

RFC 7454: BGP Operations and Security

After almost exactly three years of struggles our BGP Operations and Security draft became RFC 7454 – a cluebat (as Gert Doering put it) you can use on your customers and peers to help them fix their BGP setup.

Without Jerome Durand this document would probably remain forever stuck in the draft phase. It’s amazing how many hurdles one has to jump over to get something published within IETF. Thanks a million Jerome, you did a fantastic job!

Performance of Hypervisor-Based Overlay Virtual Networking

Years ago I managed to saturate a 10GE uplink on a vSphere server I tested with a single Linux VM using less than one vCPU. On the other hand, squeezing 1 Gbps out of Open vSwitch using GRE encapsulation was called ludicrous speed not so long ago. Implementing overlay virtual networking in the hypervisor obviously carries a huge performance penalty, right? Not so fast…

Update: Performance of Hash Table Lookups

In the Myths That Refuse to Die: Scalability of Overlay Virtual Networking blog post I wrote “number of MAC addresses has absolutely no impact on the forwarding performance until the MAC hash table overflows”, which happens to be almost true.

Hands-On Tail-F Experience – Part 2

Want to know even more about Tail-F NCS after listening to Episode 22 of Software Gone Wild? Boštjan Šuštar and Marko Tišler from NIL Data Communications continue their deep dive into the secrets of NCS in Software Gone Wild Episode 23.