多项选择题 ThenetworkadministratoristryingtoaddSwitch1tothenetwork，butthe802.1Qtrunkisnotcomingup.Switch1waspreviouslytestedinthelaboratoryanditstrunkconfigurationworkedfine.Whatarethreepossiblecausesofthisproblem？（）

单项选择题 Refer to the exhibit. When applying this policy map on the tunnel1 interface，you see packet loss for the TCP class starting at around 100000 b/s，instead of the configured 150000 b/s. What is the most likely？（）

单项选择题 Youhavedoneapartialmigrationfrom802.1DSTPto802.1wSTP.Whichofthefollowingistrue？（）