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

September 19, 2009

Cisco Switch Ether-Channel - misconceptions

I decided to write this post to address some of the many misconceptions out there on many mailing lists, forums etc… 1. More bandwidth That is one of the first common misconception I often read or hear, if I “trunk” (Solaris term actually) many ports together, the number of ether-channeled port is equal of the number of ports multiplied by the bandwidth of each port. In other words… 8 * 100Mbps port ether-channeled would create a single logical port with 800Mbps… Now while this is somewhat the anticipation, it isn’t really true. ... Read more