Cisco Nexus 7000 Series Configuration Manual page 74

Information About IPv6
S e n d d o c u m e n t c o m m e n t s t o n e x u s 7 k - d o c f e e d b a c k @ c i s c o . c o m .
Table 3-2
Field
Next Header
Hop Limit
Source Address
Destination Address
Figure 3-9
Version
Next Header
Optional extension headers and the data portion of the packet are after the eight fields of the basic IPv6
packet header. If present, each extension header is aligned to 64 bits. There is no fixed number of
extension headers in an IPv6 packet. Each extension header is identified by the Next Header field of the
previous header. Typically, the final extension header has a Next Header field of a transport-layer
protocol, such as TCP or UDP.
Cisco Nexus 7000 Series NX-OS Unicast Routing Configuration Guide, Release 4.x
3-10
Basic IPv6 Packet Header Fields (continued)
Description
Similar to the Protocol field in the IPv4 packet header. The value of
the Next Header field determines the type of information following
the basic IPv6 header. The type of information following the basic
IPv6 header can be a transport-layer packet, for example, a TCP or
UDP packet, or an Extension Header, as shown in
Similar to the Time to Live field in the IPv4 packet header. The value
of the Hop Limit field specifies the maximum number of routers that
an IPv6 packet can pass through before the packet is considered
invalid. Each router decrements the value by one. Because no
checksum is in the IPv6 header, the router can decrement the value
without needing to recalculate the checksum, which saves processing
resources.
Similar to the Source Address field in the IPv4 packet header, except
that the field contains a 128-bit source address for IPv6 instead of a
32-bit source address for IPv4.
Similar to the Destination Address field in the IPv4 packet header,
except that the field contains a 128-bit destination address for IPv6
instead of a 32-bit destination address for IPv4.
IPv6 Packet Header Format
Traffic Class
Payload Length
Source Address
Destination Address
Extension Header information
Data Portion
Figure 3-10
Flow Label
Next Header
32 bits
shows the IPv6 extension header format.
Chapter 3 Configuring IPv6
Figure 3-9.
Hop Limit
40
octets
Variable
length
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