● Routing protocols use different techniques for assigning（71）to inpidual networks．Further, each routing protocol forms a metric aggregation in a different way. Most routing protocols can use multiple paths if the paths have an equal（72）.Some routing protocols can even use multiple paths when paths have an unequal cost.In either case,load（73）can improve overall allocation of network bandwidth. When multiple paths are used,there are several ways to distribute the packets. The two most common mechanisms are per-packet load balancing and per-destination load balancing.Per-packet load balancing distributes the（74）across the possible routes in a manner proportional to the route metrics,Per-destination load balancing distributes packets across the possible routes based on（75）.

（71）A. calls B. metrics C. links D. destinations （72）A. user B. distance C. entity D. cost （73）A. bracketing B. balancing C. downloading D. transmitting （74）A. destinations B. resources C. packets D. sources （75）A. destinations B. resources C. packets D. sources

（71）B（72）D（73）B（74）C（75）A解析：路由協議使用各種技術來確定到達不同網絡的跳數。此外，每個路由協議用不同的方法形成一個跳數聚集。大多數路由協議可以使用多條路徑，如果它們代價相等，一些路由協議甚至可以在路徑代價不等時也使用多條路徑。在任何情況下，負載均衡可以提高整體的網絡帶寬分配。當使用多條路徑時，有幾種方法分配數據包。最常見的兩種機制是按包負載平衡和按目的地負載平衡。按包負載均衡是按路由跳數成比例地分配數據包。按目的地負載平衡是基于目的地來分配數據包。