I can't seem to find any information on this but I always understood that fair-queue was for low bandwidth links i.e. sub 2Mb.
Is fair-queue viable as part of a CBWFQ policy on a 25Mb Ethernet WAN link? And should the conversations be altered as I undesrtand it it would default to 256 which doesn't sound a lot for a link that could support 100's of users.
shape average 23750000 237500 0
service-policy output Shape
I would appreciate some advice on this.
Yes, original WFQ (interface fair-queue) is default on many serial interfaces, E1 and slower. However, CBWFQ policy map class fair-queue is different technology. It scales, and works, on higher bandwidth interfaces.
Regarding your concern about CBWFQ providing only 256 queues for hundreds of users, often many users don't have need for long term flows (not to be confused with sessions). Even on a congested interface, many users flows are likely short lived. So the issue than becomes, is some number such as 256 enough for concurrent active class flows? If it's not, results could be suboptimal, but then at that point you might need to reconsider either your AQM (active queue management) approach or whether there's need for more bandwidth.