In previous posts I described VXLAN using flood and learn behavior using multicast or ingress replication. The drawback to flood and learn is that frames need to be flooded/replicated for the VTEPs to learn of each other and for learning
Trunk to Access – Will It Work?
Recently a posted a question to Twitter about connecting two Cisco Catalyst switches. One switch has already booted and has the following configuration: The other switch is connected to Gi1/0/48 and has just been powered on. It has no configuration
How to Interview a Network Engineer Using a Single Scenario
Most organizations are terribly bad at interviewing people. They overcomplicate things by holding too many interviews (more than 2-3) and often focus their interview on trivia and memorization rather than walking through a scenario. Every interview should have some form
SPCOR Exam Experience by Nick Russo
On 31 October 2023, I took and passed the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) exam on my first attempt. Most of you know that I am recognized as an expert on Cisco Service Provider technologies
DCAUTO Exam Experience by Nick Russo
On 17 October 2023, I took and passed the Automating and Programming Cisco Data Center Solutions (DCAUTO) exam on my first attempt. This is the seventh DevNet exam I’ve passed. After the retirement of the Webex and IoT specialty exams,
Forwarding BUM Frames in VXLAN Network With Static Ingress Replication
In the last post we used multicast to forward BUM frames. In this post, static ingress replication is used which removes the requirement for multicast in the underlay. Before setting this up, let’s do a comparison of multicast vs ingress
Forwarding BUM Frames in VXLAN Network With Multicast in Underlay
There are two main methods that can be used to forward broadcast, unknown unicast, and multicast (BUM) frames in a VXLAN network: In this post, we take a detailed look at how multicast can be used to forward BUM frames
Path Hunting in BGP
BGP is a path vector protocol. This is similar to distance vector protocols such as RIP. Protocols like these, as opposed to link state protocols such as OSPF and ISIS, are not aware of any topology. They can only act
Valley-free Routing in Leaf and Spine Topology
Valley-free routing is a concept that may not be well known but that is relevant to datacenter design. In this post, we’ll valley-free routing based on a leaf and spine topology. There are many posts about leaf and spine topology
Nexus9000v and “Missing” Routes
I have built my lab for VXLAN on the Nexus9300v platform. Since I have a leaf and spine topology, there are ECMP routes towards the spines for the other leafs’ loopbacks. When performing labs though, I noticed that I didn’t