Ipv6 Headers; Ipv6 Header Fields - Dell Force10 S4810P Configuration Manual

IPv6 Headers

The IPv6 header has a fixed length of 40 bytes. This provides 16 bytes each for Source and Destination
information and 8 bytes for general header information. The IPv6 header includes the following fields:
• Version (4 bits)
• Traffic Class (8 bits)
• Flow Label (20 bits)
• Payload Length (16 bits)
• Next Header (8 bits)
• Hop Limit (8 bits)
• Source Address (128 bits)
• Destination Address (128 bits)
IPv6 provides for Extension Headers. Extension Headers are used only if necessary. There can be no
extension headers, one extension header or more than one extension header in an IPv6 packet. Extension
Headers are defined in the Next Header field of the preceding IPv6 header.

IPv6 Header Fields

The 40 bytes of the IPv6 header are ordered as show in
Figure 25-1. IPv6 Header Fields
0 4
Version Traffic Class
Payload Length
Version (4 bits)
The Version field always contains the number 6, referring to the packet's IP version.
8 12
Source Address
Destination Address
Figure 25-1.
16 20
Flow Label
Next Header
24 28
Hop Limit
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64
128
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