Building Network Automation Solutions
6 week online course starting in September 2017

Video: Routing on Hosts Deep Dive

Wondering how exactly routing on hosts works? Dinesh Dutt explained the details in this 10-minute video during the Leaf-and-Spine Fabric Designs webinar.

Optimize Data Center Infrastructure: Go with 10GE

I published the third installment of the Optimize Your Data Center Infrastructure story on my main web site. In this part I’m telling you to go with 10GE and consider 25GE.

Amazing Discovery: Stability Matters

Here’s an interesting blog post (particularly as it’s coming from a well-known cloud evangelist): at the infrastructure level stability matters more than agility or speed-of-deployment. Welcome to real world ;)

Automate Everything: ipSpace.net Is Coming Back to US

After the last US-based ipSpace.net workshop a lot of people asked me about the next one. It took a long time, but here it is: I’m running an on-site automation workshop together with several friends with outstanding hands-on experience in Colorado in late May.

Programmable ASICs on Software Gone Wild

During Cisco Live Europe 2017 (where I got thanks to the Tech Field Day crew kindly inviting me) I had a nice chat with Peter Jones, principal engineer @ Cisco Systems. We started with a totally tangential discussion on why startups fail, and quickly got back to flexible hardware and why one would want to have it in a switch.

Leaf-and-Spine Fabrics: Featured Webinar in April 2017

I recently finished editing the videos from the Leaf-and-Spine Designs update to the Leaf-and-Spine Fabrics webinar, so it wasn’t hard to select the featured webinar for April 2017. The featured videos now include BGP in the Data Center by Dinesh Dutt, SPB Deep Dive by Roger Lapuh, and VXLAN with EVPN control plane by Lukas Krattiger.

Starting with Network Automation

One of my readers considered joining the Building Network Automation Solutions course but wasn’t sure whether it would help him solve the challenges he’s facing in his network.

Fortunately, his challenges aren’t that hard to solve.

NETCONF Agent(s) on Cisco IOS XE 16.x

Evgeny made an interesting observation while testing the NETCONF client on IOS XE 16.x (see also this comment on my blog):

The most interesting part: for unknown reason IOS-XE gives different answers about capabilities on ports 830 and 22.

Einar quickly explained the mysterious behavior:

Worth Reading: Legacy software and Evolution

In case you’re wondering why we’re stuck with old stuff like TCP, IPv4, OSPF, and a few other bits and pieces that were invented decades ago when we could be using the glitzy controller-based software-defined whatever, read the blog post by Martin Sustrik. He talks about software, but we’re facing the same challenges in networking.

Video: Overlays in Data Center Fabrics

Lukas Krattiger (Cisco Systems) was the guest speaker in Layer-2+3 fabrics part of the Leaf-and-Spine Fabric Design webinar, and he started his presentation with an overview of how we use overlays in data center fabrics.

Network Automation Is Much More than Configuration Management

Most network automation presentations you can find on the Internet focus on configuration management, either to provision new boxes, or to provision new services, so it’s easy to assume that network automation is really a fancy new term for consistent device configuration management.

However, as I explained in the Network Automation 101 webinar, there’s so much more you can do and today I’d like to share a real-life example from Jaakko Rautanen, an alumni of my Building Network Automation Solutions online course.

Practice Your Wireshark-Fu with PCAP Challenges

Johannes Weber built a CCNP practice lab, configured 22 different protocols in it, and took packet captures of all of them happily chatting. To make things more interesting he created 45 challenges that you can solve with Wireshark using the pcap file he published.

Let’s Drop Some Random Commands, Shall We?

One of my readers sent me a link to CCO documentation containing this gem:

Beginning with Cisco NX-OS Release 7.0(3)I2(1), Cisco Nexus 9000 Series switches handle the CLI configuration actions in a different way than before the introduction of NX-API and DME. The NX-API and DME architecture introduces a delay in the communication between Cisco Nexus 9000 Series switches and the end host terminal sessions, for example SSH terminal sessions.

So far so good. We can probably tolerate some delay. However, the next sentence is a killer…

2017-04-05: The wonderful information disappeared from Cisco's documentation within 24 hours with no explanation whatsoever. However, I expected that and took a snapshot of that page before publishing the blog post ;)

Follow-up: Load Balancers and Session Stickiness

My Why Do We Need Session Stickiness in Load Balancing blog post generated numerous interesting comments and questions, so I decided to repost them and provide slightly longer answers to some of the questions.

Warning: long wall of text ahead.