Information Technology Reference
In-Depth Information
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Version
Traffic Class
Flow Label
Payload Length
Next Header
Hop Limit
128-Bit
Source
Address
128-Bit
Destination
Address
Figure 9-1
IPv6 Header Format
Payload Length:
This field is 16 bits in length. It indicates the payload's size in
bytes. Its length includes any extension headers.
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Next Header:
This field is 8 bits in length. It indicates the type of header that fol-
lows this IPv6 header. In other words, it identifies the upper-layer protocol. It uses
values defined by the Internet Assigned Numbers Authority (IANA). Table 9-2 shows
some key protocol numbers. You can find a full list a
twww.iana.org/assignments/
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Ta b l e 9 - 2
IP Protocol Numbers
Protocol Number
Protocol
6
Tran s mis s ion Cont rol P rotocol (TCP)
17
User Datagram Protocol (UDP)
50
Encapsulating Security Payload (ESP)
51
Authentication Header (AH)
85
ICMP for IPv6
59
No Next Header for IPv6
60
Destination Options for IPv6
88
Enhanced IGRP (EIGRP)
89
Open Shortest Path First (OSPF)
Hop Limit:
This field is 8 bits in length. It is decremented by 1 by each router that
for wards the packets. If this field is 0, the packet is dis c arded.
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Source Address:
This field is 128 bits in length. It indicates the sender's IPv6 address.
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