In 1000BASE-T Part 1, we reviewed the layers and what their purpose is. Now we’re going to go much deeper into the layers that relate to the PHY, which is PCS, PMA, and Autonegotiation. First though, let’s review the objectives
1000BASE-T Part 1 – Introduction
How does Ethernet detect that a link goes down? This, what I thought was a simple question, I asked myself a couple of weeks ago. I realized I didn’t have a very good answer. I realized I had more to
How Anycast VTEP Broke My Lab And What I Learned
I’m preparing a massive blog post on vPC in the context of VXLAN/EVPN and while doing so I accidentally broke my lab. What a great learning experience! I thought I would share it with you and how to perform troubleshooting
Routed Packet Walk in VXLAN/EVPN Network
In a previous post, I walked through how a packet gets bridged in a VXLAN/EVPN network. In this post, I’ll go through how a packet gets routed, that is, packet from one VNI to another VNI. The following topology will
EVPN – Asymmetric vs Symmetric IRB
It is well known that VXLAN supports bridging frames, that is, forwarding frames that belong to the same L2 segment. In the beginning, this is all that was supported. There was no VXLAN routing. In essence, the HW didn’t support
EVPN Terminology
Reading RFCs is a great source of information for understanding all the details of a protocol. Often they do require the reader to be quite technical and the terminology can be confusing if you aren’t used to the type of
Bridging Packet Walk In VXLAN/EVPN Network
In this post I walk you through all the steps and packets involved in two hosts communicating over a L2 VNI in a VXLAN/EVPN network. The topology below is the one we will be using: The lab has the following
Why Is BFD More Light Weight Than Routing Hellos?
There are many articles on BFD. It is well known that BFD has the following advantages over routing protocol hellos/keepalives: What does light weight mean, though? Does it mean that the packets are smaller? Let’s compare a BFD packet to
Catalyst SD-WAN Enhanced Application Aware Routing
Traditionally, Cisco has leveraged BFD to monitor tunnels and their performance and Application Aware Routing (AAR) to reroute traffic. BFD has been used to measure: Additionally, BFD is also used to verify liveliness of the tunnels. This works well, but
Catalyst SD-WAN 20.13 – RBAC
Catalyst SD-WAN has supported Role Based Access Control (RBAC) for a long time. It has been possible to use predefined roles or create custom roles and defining what areas the user should have access to. However, before 20.13 it was