TCPIP协议课件：第27章 IPv6协议

1、1第27章 IPv6协议IPv6概述IPv6地址IPv6分组ICMPv6IPv4过渡到IPv6的技术2引言：IPv4的缺陷地址空间的使用效率低地址长度：32bit层次结构：Net id + Subnet id + Host id地址分类：A、B、C、D、E路由瓶颈地址空间的2或3层结构 路由表的大小分组首部长度不定：不利于硬件处理每个分组独立选路：没有利用前后分组的相关性逐段的分片和校验：未能完全遵循端到端的通信原则不保证QoSBest-effort327.1 IPv6概述设计目标继承和取代 IPv4（RFC 791）改进地址和路由：极大的地址空间、结构化的路由层次首部格式：基本首部长度固定、

2、结构化的扩展首部网络管理：一系列自动发现和自动配置技术安全性：IPsec身份验证（AH）和数据加密（ESP）QoS：用流标号（flow label）取代ToS移动性：若干利于实现移动计算的技术427.2 IPv6地址（RFC 3513）FDECBA9876543210AEBFBBFF2922FFFF:1111110111101100 1111111111111111128 bits = 16 bytes = 32 hex digits十六进制冒号表示527.2.1 十六进制冒号表示法缩写表示一段中开始的“ 0 ”可以忽略FDEC : BA98 : 0074 : 3210 : 000F : BB

3、FF : 0000 : FFFFFDEC : BA98 : 74 : 3210 : F : BBFF : 0 : FFFF连续几个0段可用“ : : ”代替FDEC : 0 : 0 : 0 : F : 0 : 0 : FFFFFDEC : : F : 0 : 0 : FFFFIPv4和IPv6混合环境x : x : x : x : x : x : d . d . d . d一个地址中只能用一次“ : : ”x：十六进制，16bitd：十进制，8bit6地址前缀表示IPv6地址 / 前缀长度例：表示 60 bit 长的前缀 12AB00000000CD3正确12AB : : CD30 : 0 :

4、 0 : 0 : 0 / 6012AB : 0 : 0 : CD30 : : / 60错误12AB : : CD30 / 6012AB : : CD3 / 60掩码 12AB : 0 : 0 : 0 : 0 : 0 : 0 : CD30 / 60 12AB : 0 : 0 : 0 : 0 : 0 : 0 : 0CD3 / 60727.2.2 地址类型单播（Unicast）标识一个IPv6网络接口等同于IPv4的主机地址多播（Multicast）标识一组计算机，可共享或不共享相同的前缀目的是多播地址的分组必须交付给该组中的所有成员等同于IPv4的多播地址和广播地址任意点播（Anycast）标识一

5、组计算机，具有相同的前缀目的是任意点播地址的分组只须交付给该组中“最近”的一个成员依据路由协议的距离度量8地址结构和地址空间分配128 bitsFormat PrefixRest of address变长变长FPAddress type: : /128Unspecified: : 1 /128LoopbackFF00 : : /8MulticastFE80 : : /10Link-local unicastFEC0 : : /10Site-local unicastOthersGlobal unicastAnycast addresses are taken from the unicast

6、spaces927.2.3 单播地址Interface identifiersIdentify interfaces on a linkBe derived directly from the interfaces link-layer address64 bits long, Modified EUI-64 formatUnspecified address等同于 IPv4 的 0.0.0.0Loopback address等同于 IPv4 的 127.0.0.0 127.255.255.255Global unicast addressesIPv6 addresses with embed

7、ded IPv4 addressesLocal-use IPv6 unicast addresses10Global Unicast Addresses通用格式Global routing prefixn bitsSubnet IDInterface IDm bits128-n-m bitsAssign to a site（a cluster or subnets/links）An ID of a link within the siteAll global unicast addresses other than those start with binary 000 have a 64-b

8、it interface ID11IPv6 Addresses with Embedded IPv4 AddressesIPv4-compatible IPv6 addressThe hosts and routers dynamically tunnel IPv6 packets over IPv4 routing infrastructure: : d . d . d . dIPv4-mapped IPv6 addressRepresent the addresses of IPv4 nodes as IPv6 addresses: : FFFF : d . d . d . d12Loca

9、l-Use IPv6 Unicast AddressesLink-Local addressUse on a single link作用：自动地址配置、邻居发现、没有路由器Site-Local addressUse in a single site作用：不需要全局前缀111111101010 bits0Interface ID54 bits64 bits111111101110 bitsSubnet IDInterface ID54 bits64 bits类似IPv4的私有地址路由器不转发任何以本地地址为源或者目的的分组1327.2.4 任意点播地址FormatUsing any of the

10、 defined unicast address formatsUsageIdentify the set of routers belonging to an organization providing internet serviceIdentify the set of routers attached to a particular subnet，or the set of routers providing entry into a particular routing domainRestriction不能作为IPv6分组的源地址不能分配给IPv6主机，只能分配给IPv6路由器

11、Little experience1427.2.5 A Nodes Required AddressesHostLink-Local address for each interfaceAny additional Unicast and Anycast addresses that have been configured for its interfacesLoopback addressMulticast address: All-Nodes, all groups it belongs toRouterA hosts required addressesAnycast addresse

12、s it has been configuredAll-Routers Multicast addresses1527.3 IPv6 分组（RFC 2460）基本格式+16Extension Header Format17Extension HeaderHop-by-Hop OptionsRoutingFragmentDestination OptionsAuthenticationEncapsulating Security Payload18IPv4和IPv6分组首部比较取消HLEN、Checksum替代ToS字段 优先级和流标号字段总长度字段 有效载荷长度字段协议字段 下一个首部字段跳数

13、限制字段 TTL字段扩展首部中实现分片字段（标识/标志/片偏移）、选项字段1927.4 ICMPv6Network layer in IPv6取消RARPICMP 、ARP 、IGMP ICMPv6ICMPv6差错报告、查询（RFC 2463）Neighbor Discovery Protocol for IPv6，RFC 2461、3122Multicast Listener Discovery for IPv6，RFC 271020ICMPv6 Error Messages报文类型版本4版本6Destination UnreachableTime ExceededParameter Pro

14、blemSource QuenchRedirect（邻居发现）Packet Too Big21ICMPv6 Information Messages报文类型版本4版本6Echo RequestEcho ReplyTimestamp RequestTimestamp ReplyInformation RequestInformation Reply22Neighbor Discovery Protocolfor IPv6FunctionMessageRouter and prefix discoveryRouter solicitationRouter advertisementAddress

15、resolution and neighbor unreachability detectionNeighbor solicitationNeighbor advertisementRedirectRedirect2327.5 从IPv4过渡到IPv6TransitionstrategiesDualstackTunnelingHeadertranslation24Dual StackIPv4TCPorUDPApplication LayerUnderlying LAN or WAN TechnologyIPv6ICMPv4IGMPARP RARPICMPv6To IPv4 systemTo IPv6 system25IPv4 NetworkTunnelingAutomatic tunnelingConfigured tunnelingIPv6HostIPv6/v4HostIPv6 headerPayloadIPv4 headerIPv6 headerPayloadIPv4 headerIPv4 NetworkIPv6HostIPv6HostIPv6 headerPayloadIPv4 headerIPv6 headerPayloadIPv4 headerIPv6 headerPayloadIPv6 headerPayloadIPv6 h