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来源：百度知道 编辑：UC知道 时间：2024/05/26 22:53:53
which three of there statements about penultimate hop popping are true?
A it is used only for directly connected subnets or aggregate routes
B it can only be used with LDP
C it is only used when two or more labels are stacked
D it enables the Edge LSR to request a label pop operation from its upstream ndighbors
E it is requested through TDP using a special label value that is also called the implicit_null value
F it is requested through LDP using a special label value that is also called the implicit-nutt value
A it is used only for directly connected subnets or aggregate routes
B it can only be used with LDP
C it is only used when two or more labels are stacked
D it enables the Edge LSR to request a label pop operation from its upstream ndighbors
E it is requested through TDP using a special label value that is also called the implicit_null value
F it is requested through LDP using a special label value that is also called the implicit-nutt value
答案为ADF
MPLS 中PHP 为倒数第二跳弹出。
用于直连网段或汇总路由。A 正确。
用于Edge LSR 来请求upstream neighbor 进行label 的POP 操作。D 正确。
LDP 中使用implicit-null value=3 表示PHP。F 正