FrameSize is a read-only Gauge32, expressed in bytes, giving the average frame size across both transmitted and received traffic for this IP host. A shrinking average frame size for a IP host can indicate a shift toward small control or VoIP-style packets, while a size hovering near the link's MTU suggests bulk data transfer, and — since this isb table duplicates the row layout of the MIB's ilb table but is sampled and indexed independently — a given host can show different collection intervals in isb than it does in ilb. Watching this gauge for host 10.4.12.30 settle around, say, 1200 bytes versus dropping to under 100 bytes tells an admin whether that traffic looks like file transfer or short signalling exchanges.