Blog Posts in May 2026
MUST READ: The Future of Everything is Lies, I Guess
Kyle Kingsbury published a long (10-part) article about his frustrations with AI, aptly named The Future of Everything is Lies, I Guess.
Regardless of where you are on the skeptic-to-fanboy spectrum, I would highly recommend you read it, even if you believe you’ll disagree with everything he wrote.
Reorganized ipSpace.net Segment Routing Resources
I created nine sample SR-MPLS topologies for the ITNOG 10 SR-MPLS workshop, and of course, we ran out of time. I plan to cover those topologies and resulting printouts in a series of blog posts; to prepare for those, I cleaned up and reorganized the Segment Routing blog category, which is now split into two:
Hope you’ll find them useful! Also, if you know of other non-vendor Segment Routing resources, please leave a comment, email me, or submit a pull request.
Public Videos: Segment Routing 101
In the spring of 2017, Jeff Tantsura, the IETF Routing Area chair, delivered a short “Introduction to Segment Routing” webinar. In mid-April 2026, we had ~100 people at ITNOG 10 attending the excellent “Segment Routing: From Theory to Practice” workshop by the great Tiziano Tofoni. The future is obviously not evenly distributed.
If you’re in the early stages of your Segment Routing journey, you might appreciate the videos from Jeff’s webinar; you can now watch them without an ipSpace.net account.
On ARP and MAC Aging Timers
Naveen Kumar Devaraj mentioned an interesting fact in his EVPN-related comment:
The EOS default ARP timeout is 4 hours, and MAC aging is 5 minutes.
Arista is not the only platform using these default values; did you ever wonder where they came from?
Hmmm: Cloudflare's Automatic Return Routing
A while ago, I found the How Automatic Return Routing solves IP overlap article on Cloudflare’s blog. They evidently have a technology that addresses a pain point well worth solving (access to shared resources from clients using overlapping address ranges). I just hate how they’re selling it. Go read the article first; I’ll wait.
OK, here’s what bothers me: the “VRFs and NAT are bad” claims, while they use the same technology in disguise.
ARP Issues in EVPN Centralized Routing Design
TL&DR: SIP of Networking Was an Understatement 🤦♂️
Adding IRB to a EVPN MAC-VRFs (the fancy way of saying stretched VLANs) seems like a no-brainer:
- Add IP addresses to VLAN interfaces
- Optionally add a shared anycast gateway
- Declare “Mission Accomplished” (and try to ignore the inevitable phone call at 2 AM on a Sunday night)
Making that work in a multi-vendor environment is even more fun1, as I sadly discovered when creating the EVPN lab exercises or trying to figure out why some EVPN implementations were failing netlab EVPN integration tests.
SwiNOG 41: It Was Nice to Be Back
Last week’s SwiNOG was (as expected) great fun at a phenomenal location, starting with the first slide of the first presentation: “6 Stages of Network De-sh*tification”. I particularly loved the “talk less, chat more” schedule. The longer breaks gave us plenty of time to catch up with old friends and discuss interesting, sometimes completely unexpected, topics. For example, I learned that SIP MESSAGE is used to carry SMS messages these days.
As much as I loved chatting with fellow networking engineers, I also found these presentations highly interesting: