January 20, 2010

QinQ Vlan tagging and S-Vlans

Pre-requiste: Understanding of the 802.1Q Protocol The purpose of this post is to shed a light on how QinQ Vlan takes place in a bridged network environment. Before continuing, it is important to keep in mind that 802.1QinQ or 802.1ad isn’t a defined protocol in itself but a mere amendment of the already existing 802.1Q protocol. Having said that, in a nutshell where a single frame can hold a maximum of 4096 tags, QinQ extends the number of maximum tags to 16777216 tags, thus allowing switches to freely manipulate the tags of a single packet. ... Read more