以太网转储中的TSV和TSER字段的含义是什么？

Question

以太网转储中的TSV和TSER字段的含义是什么？我试着用谷歌搜索，但找不到答案。

Answer 1

TSV是Timestamp Value字段。它与序列号一起使用来唯一地标识数据段(因为序列号可以换行)。

TSER是Timestamp Echo Reply字段。这在ACK消息中使用。它保存最后接收到的TSV值的副本。它可用于往返时间估计(RTT =当前时间- TSER)。

这些字段使用RFC 1323 (TCP Extensions for High Performance)进行正式描述

  TCP Timestamps Option (TSopt):

     Kind: 8

     Length: 10 bytes

      +-------+-------+---------------------+---------------------+
      |Kind=8 |  10   |   TS Value (TSval)  |TS Echo Reply (TSecr)|
      +-------+-------+---------------------+---------------------+
          1       1              4                     4

     The Timestamps option carries two four-byte timestamp fields.
     The Timestamp Value field (TSval) contains the current value of
     the timestamp clock of the TCP sending the option.

     The Timestamp Echo Reply field (TSecr) is only valid if the ACK
     bit is set in the TCP header; if it is valid, it echos a times-
     tamp value that was sent by the remote TCP in the TSval field
     of a Timestamps option.  When TSecr is not valid, its value
     must be zero.  The TSecr value will generally be from the most
     recent Timestamp option that was received; however, there are
     exceptions that are explained below.