I was recently playing around with the Traffic Mirroring feature in AWS. As a network geek, this is right up my alley because as some colleagues and I used to say, "the wire never lies!". Being able to pick packets off the wire for detailed inspection has saved the day many a time. Until Traffic Mirroring came along, it wasn't possible to do that in an Amazon VPC. Below are my notes and considerations for using this feature.

Given that my technical background is largely in the networking space (exhibit A, exhibit B, exhibit C (CIE)), one of the first things I tried to wrap my head around when being introduced to AWS is how networking works in the AWS cloud.

What I attempted to do was build a mental model by relating cloud networking constructs such as Virtual Private Cloud (VPC), subnets, and routing tables to on-prem, physical networking constructs. This worked pretty well but I did get tripped up at times because some of these constructs don't map exactly one-for-one.

This post will explain the mental model I used while also calling attention to the elements or behaviors that don't map exactly between on-prem and AWS.

CARP is the Common Address Redundancy Protocol. It's a secure, free alternative to the Virtual Router Redundancy Protocol and the Hot Standby Router Protocol. CARP was created and is maintained by the OpenBSD project. The notes here apply to OpenBSD 5.0 and higher. Protocol Information Virtual MAC Address The virtual MAC is in the format 00-00-5e-00-01-XX where the last octet is filled in by the CARP vhid. IP Protocol CARP uses IP protocol number 112 (0x70).