文档介绍：新一代互联网网络层协议IPv6
徐恪
清华大学计算机系
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Outline
Protocol Background
Technology Highlights
Enhanced Capabilities
Transition Issues
Next Steps
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新一代互联网的定义和主要特征
目前还没有统一的严格定义,新一代互联网将是一个渐进的发展过程
目前已取得共识的主要特征
更大:IPv6的地址空间,网络的规模更大,接入网络的终端种类和数量更多,网络应用更广泛
更快:100Mbps以上的端到端高性能通信
更安全可信:对象识别,身份认证和访问授权,数据加密和完整性,基于真实IPv6源地址的可信任网络
更及时:组播服务,服务质量(QoS),大规模实时交互应用
更方便:基于移动和无线通信的丰富应用
更可管理:有序的管理、有效的运营、及时的维护
更有效:有盈利模型,获得重大社会效益和经济效益
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Why a New IP?
1991 – ALE WG studied projections about address consumption rate showed exhaustion by 2008
Bake-off in mid-1994 selected approach of a new protocol over multiple layers of encapsulation
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What Ever Happened to IPv5?
0 IP March 1977 version (deprecated)
1 IP January 1978 version (deprecated)
2 IP February 1978 version A (deprecated)
3 IP February 1978 version B (deprecated)
4 IPv4 September 1981 version (current widespread)
5 ST Stream Transport (not a new IP, little use)
6 IPv6 December 1998 version (formerly SIP, SIPP)
7 CATNIP IPng evaluation (formerly TP/IX; deprecated)
8 Pip IPng evaluation (deprecated)
9 TUBA IPng evaluation (deprecated)
10-15 unassigned
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Technologies & efforts to slow the consumption rate
Dial-access / PPP / DHCP
Provides temporary allocation aligned with actual endpoint use
Strict allocation policies
Reduced allocation rates by policy of “current-need” vs. previous policy based on “projected-maximum-size”
CIDR
Aligns routing table size with needs-based address allocation policy. Additional enforced aggregation actually lowered routing table growth rate to linear for a few years
NAT
Hides many nodes behind limited set of public addresses
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Would increased use of NATs be adequate?
NO!
NAT enforces a “client-server” application model where the server has topological constraints
They won’t work for peer-to-peer or devices that are “called” by others (., IP phones)
They inhibit deployment of new applications and services, because all NATs in the pa