Internet Protocol Versions; Figure 3: Ipv6 Header Format - Alcatel-Lucent 7710 SR OS Configuration Manual

Internet Protocol Versions

The TiMOS implements IP routing functionality, providing support for IP version 4 (IPv4) and IP
version 6 (IPv6). IP version 6 (RFC 1883, Internet Protocol, Version 6 (IPv6)) is a newer version
of the Internet Protocol designed as a successor to IP version 4 (IPv4) (RFC-791, Internet
Protocol). The changes from IPv4 to IPv6 effect the following categories:
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Expanded addressing capabilities — IPv6 increases the IP address size from 32 bits (IPv4)
to 128 bits, to support more levels of addressing hierarchy, a much greater number of
addressable nodes, and simpler auto-configuration of addresses. The scalability of
multicast routing is improved by adding a scope field to multicast addresses. Also, a new
type of address called an anycast address is defined that is used to send a packet to any one
of a group of nodes.
Header format simplification — Some IPv4 header fields have been dropped or made
optional to reduce the common-case processing cost of packet handling and to limit the
bandwidth cost of the IPv6 header.
Improved support for extensions and options — Changes in the way IP header options are
encoded allows for more efficient forwarding, less stringent limits on the length of options,
and greater flexibility for introducing new options in the future.
Flow labeling capability — The capability to enable the labeling of packets belonging to
particular traffic flows for which the sender requests special handling, such as non-default
quality of service or "real-time" service was added in IPv6.
Authentication and privacy capabilities — Extensions to support authentication, data
integrity, and (optional) data confidentiality are specified for IPv6.
Payload Length
Destination Address

Figure 3: IPv6 Header Format

Flow Label
| Next Header
Source Address
7710 SR OS Router Configuration Guide
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