Who does load−balancing when there are multiple links to a destination, Cisco Express Forwarding (CEF), or the routing protocol?

the load balance depends on switahig scheme:

1'fast Switching: load balance per destination for example If You have multiple link and number  of packets are  sent  to destination   these packets will use  one of these links.if  there  is  another  destination  thepacket gonna use use the second  link  ...etc

2.the processing   switching  .load balancing  per packet.  U can use it by  typing   no  ip  route-cach  under interface. This  mode  use by cpu and can be effected.one packet  per link  to be sent to  one destination

3. Ip cef  can be use  for  load balancing  per  destination  ( by default)  or per packet.

The command  :  ip  cef load-balance  per packet or  per  destination 

CEF, by default, performs per-destination load sharing.

In IOS software11.1CC a new forwarding mechanism for IP packets was introduced: Cisco Express Forwarding (CEF). The design of Cisco Express Forwarding includes enhancements that allow to use load balancing without sacrificing forwarding performance even when using per packet load balancing. Previously per packet load balancing required disabling of route-caching mechanisms like fast switching or optimum switching that mean you can loadbalance with routing protocols and CEF but CEF the best