IPv6:中国“新干线”

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中国在IPv4上已经落后，但在IPv6上一定要成为赢家。一直在寻找跨越式发展良机的中国将有可能因此进入世界互联网的第一阵营，甚至成为被追赶的对象。

三年以前，整个产业都注意到了这个机会，但疑虑与观望毕竟占了上风。然而能量从来都在积蓄，三年以后的今天，中国架设IPv6互联网“新干线”的工程终于启动，整条产业链也发生了些许微妙的变化――在一张渐次清晰的时间表下，带有不同利益主张的力量开始集结、变化、渗透，或者加速、或者模糊了“新干线”的未来。
　
来源：互联网周刊

IPv6:中国“新干线”

这只是一个开端，却意味着IPv6在中国终于有了实质性的进展。11月26日，全球著名的IPv6专家再一次聚集在北京的中国科技会堂。在此前后，已传来了众多令人兴奋的消息：到2005年底，中国将建成世界上最大的IPv6网络；连接中国和日本的国际IPv6网络有望于12月中旬正式开通；即便是一直对IPv6“态度不明朗”的美国，也决定在美国军网中全面部署IPv6。

种种“萌动”似乎即将化开封冻已十年之久的IPv6。作为IPv4的“接班人”，IPv6能够创造出比IPv4多近1600亿亿倍的地址空间。此前早有专家预计，IPv4地址将很快用尽，那个时间将是2005年。

这种紧迫性在亚洲，在中国显得尤为突出。按照IPv4的分配规则，70%的地址已被美国占有，一个美国人大概可以分到10个IP地址。而诺大的中国居然没有一个A类地址，6000多万网民，只有3000多万个IP地址，与麻省理工学院拥有的地址数目差不多。

于是在很多人眼里，IPv6成为改变旧规则，重新划定起跑线的绝好机会。

 

[路人丁]

什么意思呀 看不懂呀 什么是IPv6呀

 

[gdntfrank]

Interesting. The most significant difference between IP V4 and V6 is the
number of IP addresses they support. In IPV6, each sand in the planet
can be assigned a IP address. Therefore, you can have enough IP addresses
no matter how big your network is. But I cannot see big chance from building
the IPV6 network. Maybe it is just another "concept" that people chasing for.

 

[aruba]

Main differences between IPv4 and v6

1. address space: 32-bit -> 128-bit
2. host config: DHCP -> built-in auto config
3. QoS & CoS:RSVP & RTCP ->bandwidth reservation in IP header options

4 Performance:

a. IPv4 header includes a checksum which must be computed by each intervening node on a per packet basis. The designers of IPv6 resigned this time consuming and costly processing mechanism because most higher level protocols have their own checksum control mechanism.

b. According to the IPv4 specification, each router along the transmission path must process the variable length Option Field, again, on a per packet basis even though an option might be effectively used only by the end hosts. In IPv6, the new concept of an "ordered" linked list of Extension Headers ensures that routers process only the options necessary for correct operation. Hence,IPv6 has the capability to reduce end-to-end delay due to faster packet processing in each single node along a given route.

 

[gdntfrank]

Regarding to fast forwarding, MPLS is much faster than IP.
One advantage of IPV6 maybe its potential to support QoS.
In the IpV6 header, there is a flow field. Although the designer
don't know how these field can be used. They foresee the need of
identifying flows. Resource reservation or premium service can
be given to the packets belong to particular flows.