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RFC 6864 - Updated Specification of the IPv4 ID Field

Internet Engineering Task Force (IETF)
Request for Comments: 6864
Updates: 791, 1122, 2003
Category: Standards Track
ISSN: 2070-1721

Author: J. Touch
Organization: USC/ISI
Date: February 2013

Status of This Memo (本备忘录状态)​

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6864.

Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved.

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Abstract (摘要)​

IPv4 标识 (Identification, ID) 字段用于支持分片 (fragmentation) 和重组 (reassembly)，按照当前规范的要求，对于具有相同源地址/目的地址/协议元组的所有数据报，该字段在最大生存时间内必须唯一。然而，当前的实现并未遵循该规范，而是将 ID 字段视为每个数据报的唯一值，这种做法在高速设备上可能导致 ID 字段耗尽。本文档更新了 RFC 791、RFC 1122 和 RFC 2003 中对 IPv4 ID 字段的规范，使其更贴近当前的实践，并讨论了这些变化对数据报设计者的影响。

Table of Contents (目录)​

1. Introduction (简介)​

2. The IPv4 ID Field (IPv4 ID 字段)​

  • 2.1 IPv4 ID Used for Fragmentation
  • 2.2 IPv4 ID Used for Duplicate Detection
  • 2.3 Background on IPv4 ID Reassembly Issues

3. Updates to the IPv4 ID Specification (IPv4 ID 规范的更新)​

  • 3.1 IPv4 ID for Atomic Datagrams
  • 3.2 IPv4 ID for Non-Atomic Datagrams
  • 3.3 Retaining IPv4 ID Behavior

4. Impact of Proposed Changes (建议变更的影响)​

  • 4.1 Impact on Legacy Internet Devices
  • 4.2 Impact on Datagram Generation
  • 4.3 Impact on Header Compression Schemes

5. Updates to Existing Standards (对现有标准的更新)​

  • 5.1 Updates to RFC 791
  • 5.2 Updates to RFC 1122
  • 5.3 Updates to RFC 2003

6. Security Considerations (安全考虑)​

7. References (参考文献)​

  • 7.1 Normative References
  • 7.2 Informative References

Appendix A. Duplicate Detectability (附录 A: 重复检测能力)​

Appendix B. Acknowledgments (附录 B: 致谢)​

Quick Reference (快速参考)​

Key Terms (关键术语)​

  • Atomic datagram (原子数据报): IPv4 数据报，其 DF (Don't Fragment) 标志位被设置为 1
  • Non-atomic datagram (非原子数据报): IPv4 数据报，其 DF 标志位被设置为 0
  • ID reuse interval (ID 重用间隔): 具有相同源地址/目的地址/协议元组的数据报之间，重用相同 ID 值的最小时间间隔

Core Updates (核心更新)​

  1. 原子数据报的 ID 字段: DF=1 的数据报，其 ID 字段可以设置为任意值
  2. 非原子数据报的 ID 字段: DF=0 的数据报，其 ID 字段必须在重组超时期间内唯一
  3. 接收端行为: 接收端应忽略原子数据报的 ID 字段值

Updates to RFCs (更新的 RFC)​

  • RFC 791: 更新了 IPv4 规范中关于 ID 字段的要求
  • RFC 1122: 更新了主机要求中关于 ID 字段的规定
  • RFC 2003: 更新了 IP-in-IP 封装中关于 ID 字段的处理

Official Source: RFC 6864 at IETF

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