指明了如何解析可变长度字段，有效值被描述在表1。

Indicates how to interpret the variable length type field. Valid values are described in described in Table 1.

youdao

使用一系列固定格式的扩展头部取代了IPV 4中可变长度的选项字段。

Using a series of fixed format extension head replaced IPV4 variable-length options in the fields.

youdao

使用一系列固定格式的扩展头部取代了IPV 4中可变长度的选项字段。

Using a series of fixed format extension head replaced IPV4 variable-length options in the fields.

youdao