有保证的服务品质包含三种参数：封包传输延迟、封包延迟变异，以及封包遗失率。

Guaranteed QoS includes three basic parameters: packet transfer delay, packet delay variation and packet loss rate.

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因为针对每一个封包标头的IP地址进行转换，所以会带来一些交换路径的延迟。

Switching path delays are introduced because of the translation of each IP address within the packet headers.

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