xdsl需要分组交换。
Very-high-speed digital subscriber line(VDSL) is the fastest access technology of the xDSL family.
甚高速数字用户线（VDSL）是数字用户线（DSL）家族中速率最高的接入方式。
POTS requires a special modulation and conversion schemes with HDSL, unlike other XDSL variations.
与其它的XDSL变型不一样，用HDSL时，POTS需要特殊的调制和转换方案。
POTS requires a special modulation and conversion schemes with HDSL, unlike other XDSL variations.
与其它的XDSL变型不一样，用HDSL时，POTS需要特殊的调制和转换方案。
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