Access lists and SVIs have been around forever, and while applying access lists to physical interfaces seems to logically sink it quite easily, access lists on SVIs interfaces seem to trip people up. This blog will cover that scenario as well as some other access list basics, hopefully by the end you’ll find the concepts cemented.

This past week I have been working on a new campus build-out for one of our customers and came across some interesting behavior regarding 100Gbps and 25Gbps uplinks between switches.

A simplified view of the setup in question is shown below:

In the modern networking world routing protocols fall into two distinct camps, Link-state and Distance Vector. Being a network consultant I often have customers asking me which routing protocol is better so I figure I would create a post comparing the different routing protocols.

As an experienced Cisco network engineer, you have often saved yourself from being locked out of a router when you make a change with a “reload in x” command. This handy command reboots most Cisco devices (routers, switches, firewalls) in the x number of minutes that you had specified. Thus, if you made a change that killed your connection to it, then you just have to wait until the time expires...

Introduction

Recently, I have been working to upgrade Cisco network devices, mainly routers and switches, for a client. A recent network audit identified fragmentation in the IOSes and also security advisories. As a result, all the routers and switches required upgrades and it was a good opportunity for the client to standardize the IOSes for the different type of network devices in the...

Have you ever found yourself in a position where throughput between devices, either local or across a WAN, seemed lower than expected? You may start by checking the configuration and logs on the network devices along the path, hoping to identify something out of the ordinary or unusual. Often a smoking gun isn’t immediately identifiable which then requires a coordinated approach to...

Hello, my loyal blog post readers, in this my third installment of our SD-WAN series I am going to walk you through how our vEdge router locates, communicates and authenticates itself onto our SD-WAN fabric. Along the way we will take a look at a few packets captures and command line output to see what is going on under the hood.