Showing posts from May, 2014

Ethernet Switching with Virtual Output Queuing

Imagine a building with three floors - a lobby, a second and a third floor.

This building has an elevator [Think: An Ethernet Switch] that services people [Frames] between the three floors [Ports].

However let’s also pretend that this is a fairly busy little building, and since there’s just one elevator car [Fabric Bus], people entering the lobby are having to queue to get into the elevator while it’s busy transporting earlier-arriving people to their desired floors. So regardless of the destination floor that people wish to go, they’re being held up in an elevator line in the lobby.

At this point some of the people now entering the lobby will see this impasse of a line and decide to turn away (take the stairs, leave for the pub, etc). Regardless of the floor that newly arriving people wish to go, they’re being discouraged [prevented] from even queuing in the lobby for the elevator because of the time it will take to service the folks already ahead of them [Head of Line], let alone t…