QoS Bandwidth Reservation Calculator

G.711 is an uncompressed codec that consumes about 87.2 kbps per call once Layer 2 overhead is added, while G.729 compresses audio down to roughly 31.2 kbps per call -- less than half the bandwidth. That difference means the same VoIP reservation supports about 2.8 times more G.729 calls than G.711 calls, which is why bandwidth-constrained links often use G.729 despite its slightly lower audio quality.

The calculator flags this as over-allocated because QoS scheduling can only reserve bandwidth that physically exists on the link. In practice, most switches and routers either silently cap the total reservation at 100% (proportionally shrinking every class) or let lower-priority classes starve unpredictably when congestion hits, depending on the platform's queuing implementation -- neither outcome is something you want to discover during an outage rather than in planning.

No -- these are guaranteed minimums during congestion, not hard caps. When the link isn't saturated, best-effort traffic can burst into bandwidth that other classes (like VoIP or video) aren't currently using. The reserved percentage only becomes a firm ceiling once the link is fully loaded and every class is actually competing for its share.

Raw Mbps numbers are hard to reason about operationally, so the calculator divides the video class's allocated bandwidth by two common bitrate assumptions -- about 4 Mbps for HD and 1.5 Mbps for SD -- to answer a more practical question: how many simultaneous video calls or streams can this reservation actually support. It's a planning estimate, not a guarantee, since real video codecs vary their bitrate with content complexity and resolution settings.