Bruce Schneier wrote an excellent essay explaining why we need trustworthy AI and why we won’t get it as long the AI solutions are created by large tech companies with you are a product business model.

Sometime last autumn, I was asked to create a short “network security challenges” presentation. Eventually, I turned it into a webinar, resulting in almost four hours of content describing the interesting gotchas I encountered in the past (plus a few recent vulnerabilities like turning WiFi into a thick yellow cable).

Each webinar section started with a short “This is why we have to deal with these stupidities” introduction. You’ll find all of them collected in the Root Causes video starting the Network Security Fallacies part of the How Networks Really Work webinar.

Previous posts in this series covered numerous intricacies of DHCP relaying:

• DHCP relaying principles described the basics
• In Inter-VRFs relaying we figured out how a DHCP client reaches a DHCP server in another VRF without inter-VRF route leaking
• Relaying in VXLAN segments and relaying from EVPN VRF applied those lessons to VXLAN/EVPN environment.
• DHCP Relaying with Redundant DHCP Servers added relay- and server redundancy.

Now for the final bit of the puzzle: what if we want to do inter-VRF DHCP relaying with redundant DHCP servers?

Sebastian described an interesting Cisco ACI quirk they had the privilege of chasing around:

We’ve encountered VM connectivity issues after VM movements from one vPC leaf pair to a different vPC leaf pair with ACI. The issue did not occur immediately (due to ACI’s bounce entries) and only sometimes, which made it very difficult to reproduce synthetically, but due to DRS and a large number of VMs it occurred frequently enough, that it was a serious problem for us.

Here’s what they figured out:

Last month I described how you can simplify your VLAN- or VRF lab topologies with VRF- and VLAN links, automatically setting vlan.access or vrf attribute on a set of links. Link groups allow you to do the same for any set of link attributes.

Sample Topology

Imagine you have a small network with three PE-routers connected to a central P-router:

Michele Chubirka published a must-read article on technology fallacies including this gem:

Technologists often assume that all problems can be beaten into submission with a technology hammer.

As I’ve been saying for ages (not that anyone would listen): all the technology in the world won’t save you unless you change the mentality and rearchitect broken processes.

I mentioned IP source address validation (SAV) as one of the MANRS-recommended actions in the Internet Routing Security webinar but did not go into any details (as the webinar deals with routing security, not data-plane security)… but I stumbled upon a wonderful companion article published by RIPE Labs: Why Is Source Address Validation Still a Problem?.

Pete Lumbis concluded his ASICs for Networking Engineers presentation with a brief overview of types of switching ASICs and a wrap-up.

You can watch his entire 90-minute presentation (sliced into shorter videos) with Free ipSpace.net Subscription.

Tom Ammon sent me his thoughts on choosing the right level of abstraction in your network automation solution as a response to my What Is Intent-Based Networking blog post, and allowed me to publish them on ipspace.net.

I totally agree with your what vs how example with OSPF. I work on a NOS team where if we wanted, we could say, instead of “run OSPF on these links”, do this:

I wrote dozens of blog posts debunking disaster recovery fairy tales (mostly of the long-distance vMotion and stretched clusters variety) over the years. They are collected and sorted (and polished a bit) in the new Disaster Recovery Resources page. Hope you’ll find them useful.