TCP Flow Control and Data Transfer

TCP Flow Control

TCP Data Transfer

  • Selective Repeat ARQ with Positive ACK
  • Window slides a byte basis instead packet basis
  • Dynamically advertising the window size

TCP Window Flow Control

TCP Connection Management

  • Select initial sequence numbers (ISN) to protect against segments from prior connections (delayed duplicates)
  • Use local clock to select ISN sequence number
  • Time for clock to go through a full cycle should be greater than the maximum lifetime of a segment (MSL); Typically MSL=120 seconds
  • High bandwidth connections pose a problem

Sequence Number Wraparound

  • 2^32 = 4.29x10^9 bytes = 34.3x10^9 bits
    • High bandwidth poses a problem; At 1 Gbps, sequence number wraparound in 34.3 seconds (< MSL that is 120 seconds).
  • Timestamp option: Insert 32 bit timestamp in header of each segment
    • Timestamp + sequence no → 64-bit seq. no
    • Timestamp can be in TCP option clock must:
posted @ 2017-10-21 10:04  范加索尔拉  阅读(416)  评论(0)  编辑  收藏  举报