IPV6 Header格式
下面分别是ipv6和ipv4 header
图1.1 IPV6 Header
IPV6 Header共40byte
- Version 4-bit Internet Protocol version number = 6.
- Traffic Class 8-bit traffic class field
- Flow Label 20-bit flow label
- Payload Length 16-bit unsigned integer,Length of the IPv6 payload, i.e., the rest of the packet following this IPv6 header, in octets
- Next Header 8-bit selector. Identifies the type of header immediately following the IPv6 header
- Hop Limit 8-bit unsigned integer. Decremented by 1 by each node that forwards the packet. The packet is discarded if Hop Limit is decremented to zero.
- Source Address 128-bit address of the originator of the packet
- Destination Address 128-bit address of the intended recipient of the packet
IPV6与IPV4 Header的差别
图1.2 IPV4 Header
1.移除6个栏位
header length(IHL)
Type of Service
Identification
Flags
Fragment Offset
Header Checksum
2.重命名3个栏位
Total Length(Payload Length)
Time to Live(Hop Limit)
Protocol
3.选项机制重定义
Source Routing
Route Recording
4.新增两个栏位
Traffic Class(Priority)
Flow Label
5.V6主要简化
- 所有header格式固定(40byte)
- 移除了checksum
- 移除了router封包切割机制
IPV6选项机制
IPV4的选项机制导致了Header长度变化，IPV6定义了扩展Header来解决该问题。
1. IPV6扩展Header类型
- Hop-by-Hop Options header
- Destination Options header
- Routing header
- Fragment header
- Authentication header
- Encapsulating Security Payload header
- Destination Options header
- upper-layer header
2. 扩展Header使用方式
由IPV6 Header+ex-header’s+Data组成
3. 扩展header示例
路由header
fragment header
fragement 扩展header
参考
以上图片部分取至台湾清华大学黄能富教授《物联网概论》课件