This object counts the number of incoming bytes seen for this specific transit tunnel, giving a finer-grained view than the packet counter alone since it reveals shifts in average frame size rather than just frame count, and as the description notes, is only supported on certain platforms. Combining this with cienaCesMplsStaticTransitTunnelIncomingPackets lets an admin compute the average frame size traversing this transit LSP, which can flag something like a jump to larger frames that a packet count alone would never surface. For example, incoming bytes growing much faster than incoming packets over the same period suggests the average frame size riding this transit tunnel has increased, perhaps because jumbo frames are now being carried where they weren't before.