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
Is One Protocol Simpler Than Two?
I’ve been in a lot of interesting discussions the last couple of days on what protocol to use for the underlay when building a VXLAN datacenter network. Do you use an IGP such as OSPF or ISIS or do you
Choosing the Underlay Protocol in a VXLAN Network
When building a VXLAN network, what are the considerations for choosing the underlay protocol such as OSPF, IS-IS, or BGP? You obviously want the design to be supported by your vendor of choice. Your staff should also be able to
Unnumbered Links In OSPF
This post is going to be a real deep dive! First, I want to send my sincere thanks to the maestro Peter Palúch and the guru Ivan Pepelnjak for helping me research this topic. Ivan wrote a couple of great