● 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(xié)議使用各種技術(shù)來(lái)確定到達(dá)不同網(wǎng)絡(luò)的跳數(shù)。此外，每個(gè)路由協(xié)議用不同的方法形成一個(gè)跳數(shù)聚集。大多數(shù)路由協(xié)議可以使用多條路徑，如果它們代價(jià)相等，一些路由協(xié)議甚至可以在路徑代價(jià)不等時(shí)也使用多條路徑。在任何情況下，負(fù)載均衡可以提高整體的網(wǎng)絡(luò)帶寬分配。當(dāng)使用多條路徑時(shí)，有幾種方法分配數(shù)據(jù)包。最常見(jiàn)的兩種機(jī)制是按包負(fù)載平衡和按目的地負(fù)載平衡。按包負(fù)載均衡是按路由跳數(shù)成比例地分配數(shù)據(jù)包。按目的地負(fù)載平衡是基于目的地來(lái)分配數(shù)據(jù)包。