A.usearedundantlinktothecore
B.useaLayer2linkbetweendistributionswitches
C.neverusearedundantlinktothecorebecauseofconvergenceissues
D.useaLayer3linkbetweendistributionswitcheswithroutesummarization
E.useaLayer3linkbetweendistributionswitcheswithoutroutesummarization
正确答案：参考A, D
