If you’re not a network engineer and my generation or older, “ATM” means Automatic Teller Machine. If you’re younger, you don’t know what that means because you’ve never paid for anything in cash. If you’re a network engineer of a certain age, ATM means something else: Asynchronous Transfer Mode. ATM was a potential god technology […]
Tag: mpls
Some thoughts on “digital twins”
As I mentioned in my last post, I like modeling networks using tools like Cisco Modeling Labs or GNS3. I recalled how, back in TAC, I had access to a Cisco-internal (at the time) tool called IOS on Unix, or IOU. This enabled me to recreate customer environments in minutes, with no need to hunt […]
A nauseating outage
When I worked for the Gold partner I generally serviced clients in the San Francisco Bay Area, but because we were a national partner I was occasionally called to other locations around the country. Being a double CCIE who had worked in TAC, I had a unique skill set among our engineers, which was often […]
The tech industry and the worship of the new
“Progress might have been alright once, but it has gone on too long.” – Ogden Nash The book The Innovator’s Dilemma appears on the desk of a lot of Silicon Valley executives. Its author, Clayton Christiensen, is famous for having coined the term “disruptive innovation.” The term has always bothered me, and I keep waiting for the […]
TAC Tales #18: All at once
The case came into the routing protocols queue, even though it was simply a line card crash. The RP queue in HTTS was the dumping ground for anything that did not fit into one of the few other specialized queues we had. A large US service provider had a Packet over SONET (PoS) line card […]
Hub and Spoke with BGP
In my previous post, we saw the theory behind hub-and-spoke VPN. We saw how H/S involves multiple VRFs with cross-importation between them, and we traced the basic flow of a route advertised from one spoke to another. Next, we are going to look at two options for configuring H/S VPNs. In this post, I will […]
Hub and Spoke VPN Part 1
One of the JNCIE-SP exam objectives I found difficult was hub and spoke VPN. Conceptually it’s not easy, and as is often the case, the documentation is only somewhat helpful. This series of posts is designed to walk you through the concepts of hub and spoke VPN, as well as its basic configuration using BGP, […]
RIB Group Confusion
This article continues to be the most popular one on this blog. However, I published it back in 2014 while I was working on my JNCIE-SP, and that was a long time ago. I now work at Cisco and do not have access to Junos, and my memory of Junos is getting spotty. I am […]
Juniper’s mysterious inet.3 table
When I first started configuring MPLS on Juniper routers, I came across the strange and mysterious inet.3 table. What could it possibly be? When I worked in Cisco TAC I handled hundreds of MPLS VPN cases, but I never had encountered anything quite like inet.3 in IOS land. As I researched inet.3 I found the […]