This post is a legacy post from my old weblog, it has been included as it seems to still have some hits. Old comments are included
Thanks to Saku Ytti, I have a little config snippet that will enable low delay QoS for Cisco 877W (with Advanced IP services) (Your mileage may vary on other Cisco's). It guarantees bandwidth on packets with a max of 200 bytes. This includes interactive SSH, icmp, VOIP and most games.
class-map match-any LOW-DELAY match packet length max 200 ! policy-map EGRESS class LOW-DELAY priority percent 75 class class-default fair-queue random-detect ! interface ATM0 pvc 0/35 vbr-nrt 800 800 tx-ring-limit 3 service-policy output EGRESS ! Make vbr-nrt to match your current DSL upstream speed or lower. As you want it to prioritize as soon as possible! This QoS implementation will NOT limit your upstream. This is different to other implementations like the Linux LARTC Wondershaper implementation.