Load on GRE tunnel interface.

Hi Experts,



R1#sh run int tu 0
Building configuration...

Current configuration : 216 bytes
!
interface Tunnel0
 bandwidth 4000
 ip address 1.1.1.1 255.255.255.0
 load-interval 30
 tunnel source FastEthernet0/0
 tunnel destination 12.1.1.2
 tunnel bandwidth transmit 4000
 tunnel bandwidth receive 4000
end


R1#sh int tu0
Tunnel0 is up, line protocol is up
  Hardware is Tunnel
  Internet address is 1.1.1.1/24
  MTU 1514 bytes, BW 4000 Kbit/sec, DLY 500000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation TUNNEL, loopback not set


Can you please tell me based on what value are the tx and rx load of a GRE tunnel is calculated. Is it the interface bandwidth or the receive and transmit BW.