TCP/IP Tutorial and Technical Overview - IBM Redbooks

Where:
Type The type of the option. The option types all have a
common format (Figure 9-5).
Figure 9-5 IPv6 Type-Length-Value (TLV) option type format
Where:
xx A 2-bit number, indicating how an IPv6 node that does
not recognize the option should treat it:
336 TCP/IP Tutorial and Technical Overview
ty p e le n g th v a lu e
0 1 2 3 4 5 6 7
x x y z z z z z
0 Skip the option and continue.
1 Discard the packet quietly.
2 Discard the packet and inform the sender
with an ICMP Unrecognized Type message.
3 Discard the packet and inform the sender
with an ICMP Unrecognized Type message
unless the destination address is a multicast
address.
y If set, this bit indicates that the value of the option
might change en route. If this bit is set, the entire
Option Data field is excluded from any integrity
calculations performed on the packet.
zzzzz The remaining bits define the option:
0 Pad1
1 PadN
194 Jumbo Payload Length
Length The length of the option value field in bytes.
Value The value of the option. This is dependent on the type.
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