This is the maximum amount of the link's bandwidth (in kbps) that is actually allowed to be reserved by RSVP-TE for MPLS tunnels, which can be set below the physical maximum bandwidth to intentionally over- or under-subscribe the link for traffic engineering purposes. Network engineers commonly set this higher than the physical line rate to allow oversubscription when tunnels are not all expected to be simultaneously at peak, or lower to keep headroom for non-TE traffic. A link with a physical maximum of 10000000 kbps but a maximum reservable bandwidth of only 7000000 kbps is deliberately keeping 30% of capacity outside the TE reservation system.