Good post by Sebastian Thaele (thank you) on one of my favorite topic – Fillwords !
I thought I’d never have to write about fillwords. I thought: there will be a phase of some months and then this topic is dead. Strangely enough it’s still alive. I still get questions about them, I still see people blaming them and I still see evitable problems because of changing them.
For every new line rate (now read “Generation” or “Gen”), usually the switch and HBA vendors are the first ones to adopt the new standard and release their products. It was the same for 8Gbps, which came with a new fillword. Fillwords are 4-byte-words without a special task. A port sends them all the time it doesn’t have to send something else.
Read on here