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1、April 15 2003,移动IPv6技术及其研究现状,Chuda Liu XJTU,内 容,背景 IPv6 支持移动性的特征 Mobile IP v4 & v6协议概况 MIPv6的研究领域 MIPv6的QoS研究状况 小结,背景,传统IP协议未考虑节点的移动性（路由和节点标识都靠IP地址） 随无线接入技术的发展（PAN、WLAN、WAN），支持节点移动是发展趋势,IPv6 支持移动性的特征(1/2),大的地址空间:可为每个设备分配唯一的全球地址（地球上每平方米6.65*1023个地址） 自动配置 * Stateless autoconfiguratoin - Network Prefix
2、 + Interface ID * Stateful autoconfiguration - DHCPv6 安全性: AH & ESP 选项头 QoS: TC & Flow Label 字段,IPv6 支持移动性的特征(2/2),Neighbor Discovery * Discover each others presence and find routers * Determine each others link-layer addresses * Maintain reachability information Extension Headers * Routing header -
3、 For route optimization * Destination Options header - For mobile node originated datagrams,Mobile IP v4 & v6协议概况,Mobile IP术语 MIPv4 MIPv6,Mobile IP术语,Static IP Address of the Mobile Node valid at its home network.,Mobile Node,Home Address,A node that can change its point of attachment from one link
4、to another, while still being reachable via its home address,C/o-Address,Temporary IP Address of the Mobile Node valid at the actually visited network of the Mobile Node (c/o = care-of).,Binding,Association of the Home Address with the C/o-Address.,Home Agent,Binding Cache,Router located at the Mobi
5、le Nodes home network used by the Mobile Node for registering its c/o-Address.,Cache for received Bindings.,MIPv4（RFC3220）,MIPv4（RFC3220）,MIPv4（RFC3220）,Care-of-address (COA) The terminal point of tunnel toward a mobile node Foreign Agent COA (for IPv4) Obtained from Foreign Agent Address of foreign
6、 agent, mobile node communicates to home agent through foreign agent Co-located COA (for IPv4, IPv6) Obtained by DHCP, PPP, Mobile node communicates directly with its Home Agent,MIPv4（RFC3220）,Agent Discovery mechanism Mobility Agents Advertise their presence via Agent advertisement message Response
7、 to Agent Solicitation with Agent Advertisement message Mobile Nodes (optional) MN may solicit Agent Advertisement message through an Agent Solicitation message MN receives the Agent Advertisement and determines whether it is on its home network or a foreign network If home network, MN deregisters w
8、ith its home agent If foreign network, MN obtains COA from Agent Advertisement message and registers its new COA with its home agent via a foreign agent,MIPv4（RFC3220）,Registration mechanism Mobile Node The MN sends Registration Request message containing the new COA to its HA, via a FA Foreign Agen
9、t The FA authenticates a MN The FA relays Registration Request to a HA If the FA receives successful Registration Reply, it makes a Mobility binding and relays the Registration Reply to a MN Home Agent The HA authenticates a MN, a FA Creates or modifies mobility binding for the MN Sends Registration
10、 Reply to the the FA,MIPv4（RFC3220）,Tunneling Home Agent Intercepts IP packets destined to the home address of registered mobile node (Gratuitous ARP) Tunnels to the mobile nodes COA IP in IP encapsulation (RFC 2003) Minimal encapsulation (RFC 2004) GRE (Generic Routing Encapsulation ,RFC 1701) Fore
11、ign Agent Recovers original IP packets and delivers to the mobile node,Mobility support in IPv6 （draft-ietf-mobileip-ipv6-21.txt）,Mobile node at home,Mobile node away from home,Route optimization,Mobility support in IPv6,MIPv6的研究领域,Mobility Management (MM) Seamless Handover Security AAA QoS etc.,Mob
12、ility Management (MM),MM分两类： Micro-mobility: inside a domain（A domain is a single administrative entity.） Cellular IP HAWAII Hierarchical Mobile IP Macro-mobility: between domains Mobile IP,Micro-mobility 协议的主要优点,Reduced latency and Control traffic MN registers to the HA only the first time it conne
13、cts to the domain Mobiles movements inside the domain are managed locally: stations outside the domain are not aware of these movements Possibility for the use of private address pools inside the domains The gateway performs network address translation Potential problems with IPsec Reduced path chan
14、ges for QoS The path outside the domain does not change when the mobile changes its point of attachment inside the domain,Seamless Handover,Three kinds of handover operations Smooth Handover Minimizes data loss during the time that the MN is establishing its link to the new access point Fast Handove
15、r Minimizes or eliminates latency for establishing new communication paths to the MN at the new access router Seamless Handover Both Smooth and Fast Handover,Security (1/2),保护HAs和CNs的BU、Prefix Discovery及MIPv6传送数据分组的机制 BU to HA * MN和HA用IPsec SA来保护BU和BA的完整性和真实性 * MNs和CNs在传输模式用ESP头，并使用非空的payload authen
16、tication algorithm来提供数据源认证、无连接完整性保护,Security （2/2）,BU to CNs * 到CNs的BU的完整性和真实性用密钥哈希算法，Kbm * MNs和CNs用非return routability procedure来确定正确的MN在发送消息,MIPv6的QoS研究状况,研究目的 移动主机支持QoS存在的问题 现有方法,研究目的,研究节点移动性对QoS的影响 研究当前的QoS技术在移动环境下的应用 如何增加移动性支持 考虑移动环境下的无线链路特征如何适应,移动主机支持QoS所存问题,移动切换（handover）产生丢包 不能确定在将要移动的位置有足够的
17、资源 隧道技术会隐藏QoS信息 IPsec会引起分类困难 RSVP中存在的问题 需要移动主机通知接收端它当前的位置 -接收端发起的保障 移动主机必须知道它的下一位置及停留时间 -难以预计,现有方法（1/12）,Intserv *由应用给网络提出预留请求 使用RSVP信令 *预留类型 Controlled load Guaranteed services *基本消息类型 PATH RESV,现有方法（2/12）,RSVP支持移动性的限制 * 不支持被动预留 * Per-flow state预留，扩展性差 * 不支持经过IP隧道的资源预留 * 信令开销过大。每当移动主机改变位置后， RSVP都需要
18、在端到端之间重新建立资源预留 MRSVP *协议预测主机未来可能到达的位置，并在这些位 置提前预留资源,现有方法（3/12）,MRSVP *每个子网中的移动代理代替移动主机来完成提前预留资源 *有两种资源预留类型，即主动和被动。 主动预留用于移动主机的当前子网 被动预留用于移动主机未来访问的子网 被动预留的资源可被该子网中其他业务流使用。当移动主机移动到新的子网时，被动预留的资源即转变为主动预留资源，原来使用被动预留资源的业务流需要立刻释放所占有的资源。 * 多个位置预留资源，导致网络资源利用率低 * MRSVP协议的复杂性比较高。,现有方法（4/12）,隧道RSVP *在隧道的两个端点之间新
19、建一个RSVP隧道会话 *端到端的RSVP会话把隧道看作是从源点到目的点之间的一段逻辑链路 *当一个端到端的RSVP会话经过隧道时，它被映射到另一个RSVP隧道会话中 * RSVP隧道会话从隧道的出口向隧道的入口按照通过隧道的总业务量预留资源,现有方法（5/12）,组播的RSVP * 移动主机由一个组播地址唯一标识，主机的移动 可视为组成员的变动 * 移动代理代替移动主机处理与移动相关的RSVP 消息并保存相应的状态 * 所有移动主机发送、接收的RSVP消息和IP数据 包都通过IP组播路由传送 * 采用了类似于MRSVP的预测机制，将移动主机下一步将 要访问的位置提前加入到组播树中并预留资源,
20、现有方法（6/12）,Diffserv支持Mobility存在的问题 * DiffServ没有信令，使用隐式的接纳控制机制，接纳控制是针对会聚流的。当网络资源不足时，本来还可以满足部分用户的质量要求，但在DiffServ机制下却可能没有一个用户能够得到满意的服务质量。 * DiffServ不能动态配置服务质量参数。当某个用 户的服务质量发生变化后，网络提供者需要静态配置变动 的参数，造成了很长的时延，无法适应无线移动网络的应 用需求,现有方法（7/12）,无线环境下的DiffServ * 增加了信令协议：利用ICMP作为DiffServ下的信令，用 于传送移动终端和基站之间的控制消息及相关参数
21、 * 增加了对移动性的支持：在每个区域创建一个称为New-mobile的业务类别，用来为移动主机预留带宽，或者赋予移动主机高优先级，使其在切换时能够抢占低优先级业务的带宽 * 增加了对高误码无线链路的支持：在每个子网中生成补偿业务类别并占用一定的带宽，用来补偿移动终端遇到高误码链路时损失的带宽,现有方法（8/12）,IntServ与DiffServ混合,现有方法（9/12）,* 定义了Home & foreign边缘路由器 边缘路由器有双重功能 - Diffserv edge router (admission control) - Mobility agents in Mobile IP M
22、IP registration request contains two new fields - Home edge router address - Foreign edge router address,现有方法（10/12）,Architecture * Home networks and foreign networks run RSVP and Mobile IP * Backbone is diffserv capable * Edge routers (ER) and border routers (BR) - Admission control and Bandwidth b
23、rokering functions Operation * Two cases: differentiate the operational steps: Border routers and interior DS nodes are RSVP aware -Resource availability indicated by signaling -BR acts as the agent for admission control,现有方法（11/12）,Border routers and interior DS nodes are not RSVP aware - External
24、non-DS node does admission control - Edge routers act as admission control agents Broker bandwidth on behalf of BR (no signaling) Requires the use of protocols like bandwidth broker protocol - Can accommodate only static service level agreements * Requires modification to Mobile IP registration requ
25、est message * Introduction of new ACK and NACK messages,Open issues * Mapping intserv SLA to appropriate DS code points * Edge routers need additional features - Admission control handling on behalf of DS domain - Signaling to get resource availability information of DS domain * Diffserv border routers need signaling capability * Enhancements to registration request messages needed * Need for two additional messages: ACK and NACK,现有方法（12/12）,小结,Mobile IP v4 & v6 协议基本操作 移动环境下QoS的研究状况,谢 谢！,