Others, such as those in the European Union, are moving toward IPv6, and
China is considering building new networks dedicated for IPv6.
As of October 1, 2003, the U.S. Department of Defense mandated that all new equipment
purchased be IPv6-capable. In fact, all U.S. government agencies must start using IPv6
across their core networks by 2008, and the agencies are working to meet that deadline. As
these examples illustrate, IPv6 enjoys strong momentum.
11000000.10101000.11001001.0111000
192.168.201.113
4,294,467,295 IP Addresses
IPv4: 4 Octets
A524:72D3:2C80:DD02:0029:EC7A:002B:EA73
3.4 x 1038 IP Addresses
IPv6:
11010001.11011100.11001001.01110001.11010001.11011100.
11001100.01110001.11010001.11011100.11001001.01110001.
11010001.11011100.11001001.01110001
16 Octets
272 Chapter 7: Managing Address Spaces with NAT and IPv6
IPv6 is a powerful enhancement to IPv4. Several features in IPv6 offer functional
improvements. What IP developers learned from using IPv4 suggested changes to better
suit current and probable network demands:
?– Larger address space: Larger address space includes several enhancements:
??” Improved global reachability and ?¬‚exibility
??” The aggregation of pre?¬?xes that are announced in routing tables
??” Multihoming to several ISPs
??” Autocon?¬?guration that can include data link layer addresses in the
address space
??” Plug-and-play options
??” Public-to-private readdressing end to end without address translation
??” Simpli?¬?ed mechanisms for address renumbering and modi?¬?cation
?– Simpler header: A simpler header offers several advantages over IPv4:
??” Better routing ef?¬?ciency for performance and forwarding-rate
scalability
??” No broadcasts and thus no potential threat of broadcast storms
??” No requirement for processing checksums
??” Simpler and more ef?¬?cient extension header mechanisms
??” Flow labels for per-?¬‚ow processing with no need to open the transport
inner packet to identify the various traf?¬?c ?¬‚ows
?– Mobility and security: Mobility and security help ensure compliance with mobile IP
and IPsec standards functionality.
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