现代通信网络课件4

1、2021/6/161现代通信网络现代通信网络Modern Telecommunication NetworkLecture 4PS分组交换与分组交换与IP 互联网互联网北邮软件学院：陈候武北邮软件学院：陈候武C电话：电话：189118158952021/6/162Communication Networks 【通信网络的分类通信网络的分类】Communication NetworkSwitchedCommunication NetworkVirtual Circuit Network: MPLSBroadcastCommunication Network 广播，电视，卫星广播，电视，卫星Pac

2、ket Switch(PS) - 分组交换分组交换Datagram Network: InternetCircuit-Switched(CS) - 电话电话2021/6/163PS:Packet Switch分组交换网原理分组交换网原理2021/6/164Simple Switched Network2021/6/165Packet Switching (PS) PrincipleslCircuit switching designed for voicep Resources dedicated to a particular callp Much of the time a data co

3、nnection is idlep Data rate is fixeduBoth ends must operate at the same rate2021/6/166PS：Basic Operation【基本操作原理基本操作原理】lData transmitted in small packetspTypically 1000 octetspLonger messages split into series of packetspEach packet contains a portion of user data plus some control infolControl info

4、【控制信息控制信息】p Routing (addressing) infolPackets are received, stored briefly (buffered) and past on to the next nodep Store and forward2021/6/167PS：Using Packets2021/6/168PS：Advantages 【优点优点】lLine efficiencypSingle node to node link can be shared by many packets over timepPackets queued and transmitte

5、d as fast as possiblelData rate conversionpEach station connects to the local node at its own speedpNodes buffer data if required to equalize rateslPackets are accepted even when network is busypDelivery may slow downlPriorities can be used2021/6/169PS：Switching Technique 【交换技术交换技术】lStation breaks l

6、ong message into packetslPackets sent one at a time to the networklPackets handled in two wayspDatagram 【数据报数据报】pVirtual Circuit 【虚电路虚电路】u PVC: Permanent Virtual Circuit 【永久虚电路永久虚电路】u SVC: Switch Virtual Circuit 【交换虚电路交换虚电路】2021/6/1610PS：Datagram 【数据报数据报】lEach packet treated independentlylPackets ca

7、n take any practical routelPackets may arrive out of orderlPackets may go missinglUp to receiver to re-order packets and recover from missing packets2021/6/16112021/6/1612PS：Virtual Circuit 【虚电路虚电路】lPreplanned route established before any packets sentlCall request and call accept packets establish c

8、onnection (handshake)lEach packet contains a virtual circuit identifier instead of destination addresslNo routing decisions required for each packetlClear request to drop circuitlNot a dedicated path2021/6/16132021/6/16142021/6/16152021/6/1616Virtual Circuits v DatagramlVirtual circuitspNetwork can

9、provide sequencing and error controlpPackets are forwarded more quicklyuNo routing decisions to makepLess reliableuLoss of a node looses all circuits through that nodelDatagrampNo call setup phaseuBetter if few packetspMore flexibleuRouting can be used to avoid congested parts of the network2021/6/1

10、617虚电路举例：虚电路举例：Frame Relay 【帧中继帧中继】lDLCI (Data Link Connection Identifier) - identification of a virtual circuit 【虚电路虚电路】lDLCI - of local (for a given port) meaninglthere can be max. 976 VCs on an interface user-networklDLCI values: 0 - LMI channel, 1-15 - reserved, 16-991 - available for VCs, 992-1

11、007 - layer 2 management of FR service, 1008-1022 - reserved, 1023 - in channel layer managementABCTo A: DLCI 121To B: DLCI 243To A: DLCI 182To C: DLCI 1212021/6/1618Timing of Datagram Packet SwitchingPacket 3Packet 3Packet 1Packet 2Packet 1Packet 2Packet 1Packet 2Packet 3processing delay of Packet

12、1 at Node 2Host 1Host 2Node 1Node 2propagationdelay betweenHost 1 and Node 2 transmission time of Packet 1at Host 12021/6/1619三种交换的比较三种交换的比较 P1P2P3P4P1P2P3P4P3P4报文报文报文A B C D A B C DA B C D报文交换电路交换分组交换t连接建立连接建立数据传送数据传送报文P2P1连接释放连接释放数据传送的特点比特流直达终点比特流直达终点报文报文报文分组分组 分组 分组存储转发存储转发存储转发存储转发2021/6/1620【独享独

13、享】 【共享共享】虚电路概念在虚电路概念在TD-SCDMA网络：空间接口的应用网络：空间接口的应用2021/6/16213GPP - HSDPA 概述概述l 为了更好地发展数据业务，3GPP 对空中接口作了改进，在R5版本中引入高速下行分组接入（HSDPA）技术;l HSDPA(高速下行分组接入，High Speed Downlink Packages Access)技术，是3GPP在R5协议中为了满足上下行数据业务不对称的需求提出来的，它可以在不改变已经建设的系统网络结构的基础上，大大提高用户下行数据业务速率(理论上单载波最大值可达2.8Mbps)2021/6/1622l 基站侧物理资源有限

14、，HSDPA资源不可以不可以同时分配给R4业务使用，比如，当系统为3个上行时隙与3个下行时隙的比例配置时，其中2个下行时隙分配给HSDPA使用，则下行业务时隙就剩下1个时隙，此时如果大量用户的业务需求是普通R4业务，则系统会受限于资源而决绝新用户的接入p所以当业务小区内普通R4业务较多时，可以减少或者可以减少或者取消取消HSDPA资源配置，将大部分时隙资源分配给普通资源配置，将大部分时隙资源分配给普通R4业务使用；业务使用；p当业务小区内大部分用户需要使用高速下载的数据业务，则可以将大部分业务时隙分配给HSDPA使用l 灵活的载波配置可以满足运营商网络规划中的不同的需求 HSDPA 载波配置载

15、波配置2021/6/1623TD-SCDMA 无线帧结构无线帧结构 2021/6/1624物理层复用与调度算法物理层复用与调度算法l 用户被调度是HSDPA业务区别于普通R4业务的一个主要特征l 普通R4用户会【“独享独享”】一部分物理资源，直到其业务被释放掉，即使此时并没有在进行数据传输，资源也是被占用的，形成了一种浪费 （类似：电路交换中的实电路类似：电路交换中的实电路）l 而HSDPA业务，可以让多用户【共享共享】整个HSDPA资源，采取的方式是分时分码复用分时分码复用，也就是在每一个TTI内部分或者全部资源为一个用户而用，下一个TTI，资源又给另一个用户使用，这样数据需求量大的用户就可

16、以获得较高的被调用的几率，从而获得较高速率，节省了资源。l 灵活的调度算法也可以满足运营商不同的需求。2021/6/1625PS应用：应用：IP-Internet分组交换网分组交换网 - IP因特网因特网2021/6/16267.1 IP互联网结构互联网结构 2021/6/1627Internetworking Terms (1)lCommunications NetworkpFacility that provides data transfer servicelThe Internet 【因特网因特网】- note upper case I pThe global collection o

17、f thousands of individual machines and networkslIntranet 【内联网内联网 】pCorporate internet operating within the organizationpUses Internet (TCP/IP and http)technology to deliver documents and resources2021/6/1628TelecommuterResidentialCableAggregationISPsEnterpriseEnterpriseIP - Internet ArchitectureTran

18、sport Control Protocol (TCP)Internet Protocol (IP)2021/6/1629lEnd System (ES)pDevice attached to one of the networks of an internetpSupports end-user applications or serviceslIntermediate System (IS)pDevice used to connect two networkspPermits communication between end systems attached to different

19、networks2021/6/1630lBridgepIS used to connect two LANs using similar LAN protocolspAddress filter passing on packets to the required network onlypOSI layer 2 (Data Link)lRouterpConnects two (possibly dissimilar) networkspUses internet protocol present in each router and end systempOSI Layer 3 (Netwo

20、rk)2021/6/1631USA - Internet Infrastructurelocal ISPcampusnetworkcorporatenetworkIXPRegionalNetworkRegionalNetworklocal ISPlocal ISPIXPIXPBackbone NetworkBackbone NetworkRegionalNetworkRegionalNetwork2021/6/1632Internet InfrastructureThe infrastructure of the Internet consists of a federation of con

21、nected networks that are each independently managed (“autonomous system”)pNote: Each “autonomous system may consist of multiple IP networksp Autonomous systems have a number (AS number)Hierarchy of network service providers (NSPs)pTier-1: nation or worldwide network (US: less than 20)pTier-2: region

22、al networks (in US: less than 100)pTier-3: local Internet service provider (in US: several thousand)2021/6/1633Internet Infrastructure - 2Location where a network (ISP, corporate network, or regional network) gets access to the Internet is called a Point-of-Presence (POP). Locations (Tier-1 or Tier-

23、2) networks are connected for the purpose of exchanging traffic are called peering points.pPublic peering: Traffic is swapped in a specific location, called Internet exchange points (IXPs)pPrivate peering: Two networks establish a direct link to each other. 2021/6/1634Internet structure: lroughly hi

24、erarchicallat center: “tier-1” ISPs (e.g., UUNet, BBN/Genuity, Sprint, AT&T), national/international coverageptreat each other as equalsTier 1 ISPTier 1 ISPTier 1 ISPTier-1 providers interconnect (peer) privatelyNAPTier-1 providers also interconnect at public network access points (NAPs)Intercon

25、nect 互联互通（不同公司，不同国家，等） 2021/6/1635【美国美国】Tier-1 ISP: e.g., SprintSprint US backbone networkSeattleAtlantaChicagoRoachdaleStocktonSan JoseAnaheimFort WorthOrlandoKansas CityCheyenneNew YorkPennsaukenRelayWash. DCTacomaDS3 (45 Mbps)OC3 (155 Mbps)OC12 (622 Mbps)OC48 (2.4 Gbps)to/from customerspeering to

26、/from backbone.POP: point-of-presence2021/6/1636CERNET 【中国教育网中国教育网 - AS：4538】 徐闻徐闻长春长春哈尔滨哈尔滨乌鲁木齐乌鲁木齐拉萨拉萨西宁西宁兰州兰州银川银川呼和浩特呼和浩特台北台北沈阳沈阳南昌南昌西安西安徐州徐州武汉武汉合肥合肥郑州郑州石家庄石家庄北京北京南宁南宁广州广州福州福州杭州杭州上海上海南京南京天津天津贵阳贵阳海口海口三亚三亚湛江湛江无锡无锡大连大连太原太原济南济南烟台烟台成都成都长沙长沙重庆重庆黄梅黄梅九江九江昆明昆明青岛青岛汕头汕头唐山唐山汉中汉中宜昌宜昌珠海珠海深圳深圳惠州惠州柳州柳州百色百色厦门厦门Ba

27、ckbone Backbone RegionalRegionalGigaPopPop桂林桂林深圳深圳2021/6/1637五类线五类线核心层核心层业务层业务层汇聚层汇聚层接入层接入层城域城域骨干网骨干网BRASMAN SRDSLAM楼道交换机楼道交换机铜缆铜缆汇聚交换机汇聚交换机/MSTP/RPR(可级连）可级连）CN2 SRCN2CN2骨干网骨干网ChinaNetChinaNet骨干网骨干网宽带宽带接入网接入网核心路由器核心路由器（可级连）（可级连）骨干网骨干网园区交换机园区交换机CPE终端终端城域网城域网IP：国家骨干网：国家骨干网 - 城域网：网络结构城域网：网络结构 2021/6/16

28、387.2 IP 网协议的体系结构和协议地址网协议的体系结构和协议地址7.2.1 IP 网协议的体系结构网协议的体系结构2021/6/1639IP网络网络: 地址结构地址结构2021/6/1640TCP/IP Concepts2021/6/16412021/6/1642IPv4 Packet Format：地址格式：地址格式2021/6/1643Header Fields (20 Bytes)lVersionpCurrently 4：【IPv6：6】pIP v6 - see laterlInternet header lengthpIn 32 bit wordspIncluding optio

29、nslTotal lengthpOf datagram, in octetslProtocolpNext higher layer to receive data field at destination2021/6/1644Internet Address：地址概念层次地址概念层次Internet：地址结构：地址结构Internet网络网络1网络网络nIP地址地址网络号网络号主机号主机号2.编址方式编址方式 IP address = (netid + hostid）3.表示方法表示方法: 二进制表示、点分十进制二进制表示、点分十进制lIP address = 100000

30、00 00000010 00000111 00001001 lThe network number part【netid】 of the IP address is centrally administered by the Internet Network Information Center (the InterNIC) and is unique throughout the Internet. 2021/6/1645Classes of Internet Addresses: 【分类分类IP地址地址】2021/6/16467.2.2. 互联网的协议地址互联网的协议地址 l地址类型地址类

31、型pA A类：类： 0 - 80 - 8位网络号位网络号 首字节首字节1 1261 126pB B类：类： 10 - 1610 - 16位网络号位网络号 首字节首字节128 191128 191pC C类：类： 110 - 24110 - 24位网络号位网络号 首字节首字节192 223192 223pD D类：类： 1110 - 1110 - 组播地址组播地址 首字节首字节224 239224 239pE E类：类： 11110 -11110 -（保留未用）首字节（保留未用）首字节240 - 247240 - 247l特殊特殊IPIP地址地址p广播地址：主机号全广播地址：主机号全11p有限广

32、播地址：有限广播地址：3232位全位全11；p回送地址：回送地址：127.127.* *. .* *. .* *，网络软件测试及本机进程间的通信，网络软件测试及本机进程间的通信。lIPIP地址的实质：地址的实质：pIPIP地址标识的不一定是一台主机，实质上标识的是到一个网络的一条连地址标识的不一定是一台主机，实质上标识的是到一个网络的一条连接。接。2021/6/16472021/6/1648Limited Broadcast Address2021/6/1649All 0 Address2021/6/1650IP Address Space 【IPIP地址空间问题地址空间问题】Original

33、ly, 3 ClassespA, B, CProblem 【问题所在问题所在】pClasses too rigid (刚性的刚性的)(C too small, A too big)pClass A was overkill with more than 16 million hostspClass C had too few hosts per networkpClass B is a fair balance between the number of networks and the number of hostsSolution 【解决方案解决方案】p Subnetting 【子网子网】

34、p Classless Interdomain Routing (CIDR) ：【无分类无分类IP地址地址】2021/6/16513. 子网的划分子网的划分 Subnet classificationlAllow arbitrary complexity of internetworked LANs within organizationlHost portion of address partitioned into subnet number and host number 【IP地址的主机地址部分划分为：子网码：主机码地址的主机地址部分划分为：子网码：主机码】2021/6/1652Sub

35、nets and Subnet Masks【子网掩码子网掩码】lInsulate 【隔离】overall internet from growth of network numbers and routing complexitylSite looks to rest of internet like single networklEach LAN assigned subnet number 【子网号码子网号码】lLocal routers route within subnetted networklSubnet mask 【子网掩码子网掩码】indicates which bits ar

36、e subnet number and which are host number2021/6/1653IP 地址的各字段和子网掩码地址的各字段和子网掩码 145 . 13 .3 . 10两级两级 IP 地址地址子网号为子网号为 3 的网络的网络号的网络的网络号三级三级 IP 地址地址主机号主机号子网掩码子网掩码net-idhost-id子网的子网的网络地址网络地址1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 00net-idsubnet-idhost-id145 . 13 .145 . 13 . 33 . 1020

37、21/6/16540目的网络地址目的网络地址子网掩码子网掩码下一跳下一跳282828接口 0接口 1R23H1子网子网1： 网络地址 子网掩码 2830R1 的路由表（未给出默认路由器）的路由表（未给出默认路由器）R11R2子网子网2：网络地址 28 子网掩码 28H2

38、380129H3子网子网3：网络地址 子网掩码 2【例】已知互联网和路由器 R1 中的路由表。主机 H1 向 H2 发送分组。试讨论 R1 收到 H1 向 H2 发送的分组后查找路由表的过程。 2021/6/16550目的网络地址子网掩码下一跳282828接口 0接口 1R2H1子网1： 网络地址 128.30.33

39、.0 子网掩码 2830R11R2子网2：网络地址 28 子网掩码 28H23380129H3子网3：网络地址 子网掩码 2主机主机 H1 首先将本子网的子网掩码首先将本子网的子网掩码 28与与【to H2】分组的分组的 IP 地址地址 38 逐比特相逐比特相“与与”(AND 操作操作) 255

40、.255.255.128 AND 38 的计算的计算255 就是二进制的全 1，因此 255 AND xyz = xyz，这里只需计算最后的 128 AND 138 即可。128 10000000138 10001010逐比特 AND 操作后：10000000 12828128. 30. 33.138128. 30. 33.128逐比特 AND 操作 H1 的网络地址2021/6/1656路由器 R1 再用路由表中第 2 个项目的子网掩码和 38 逐比特 AND 操作 0目的网络地址子网掩码下一跳128

41、.30.33.0282828接口 0接口 1R2R1 的路由表（未给出默认路由器）3H1子网1： 网络地址 子网掩码 2830R11R2子网2：网络地址 28 子网掩码 28H2380129H3子网3：网络地址 子网掩码 255.255.255.

42、0228 AND 38 = 28匹配匹配!这表明子网 2 就是收到的分组所要寻找的目的网络R1 收到的分组的目的 IP 地址：38一致!2021/6/1657 CIDP- Classless Inter-Domain Routing 【无分类无分类IP地址地址】l CIDR is introduced to overcome the following problemspexhausting of class B networkpexplosion of internet rout

43、ing table 【路由表爆炸增长路由表爆炸增长】l CIDR allows any length of subRouters summarized l net maskpe.g. China Telecom. can assign 2 class C networks(subnet mask length = 23) to a company if he has only 300 hosts= efficient for IP address allocationpRouter can aggregate several routes to a big route with less ma

44、sk length= reduce core routers routing table size2021/6/1658Lookups Must be Fast【路由表搜索必须快路由表搜索必须快】12540Gb/s200331.2510Gb/s20017.812.5Gb/s19991.94622Mb/s199740B packets (Mpkt/s)Line RateYearlookup mechanism must be simple, easy to implementmemory access time long-term bottleneck2021/6/1659Route Aggre

45、gation by CIDRlCIDR permits route aggregationp reduce the Internet routing table2021/6/1660IP Address Lookup：【IP地址搜索地址搜索】CIDR and Longest Prefix Matchingl routing tables contain (prefix, next hop) pairsl address in packet compared to stored prefixes, starting at leftl prefix that matches largest num

46、ber of address bits is desired matchl packet forwarded to specified next hop01*5110*31011*50001*010*70001 0*10011 00*21011 001*31011 010*50101 1*70100 1100*41011 0011*81001 1000*100101 1001*90100 110*6prefixnexthoprouting tableaddress: 1011 0010 1000Problem - large router may have100,000 prefixes in

47、 its list2021/6/1661NAT/PATNAT Network Address TranslationPAT Port Address Translation2021/6/1662IP Private Addresses No two machines that connect to a public network can have the same IP address because public IP addresses are global and standardizedPrivate IP addresses are a solution to the proble

48、m of the exhaustion of public IP addresses. Addresses that fall within these ranges are not routed on the Internet backbone:lConnecting a network using private addresses to the Internet requires the usage of NAT2021/6/16632021/6/16642. IP 地址与物理地址地址与物理地址ARP - The Address Resolution Protocol is respon

49、sible for converting the higher-level protocol addresses (IP addresses) to physical network addresses. Such as Ethernet Address (MAC)2021/6/1665lARP 的协议过程的协议过程XYABARP 请求IP=PA=? IP= PA= XXXIP=PA=YYYIP=PA=AAAIP=PA=BBBARP 应答PA=YYY2021/6/1666C:arp -aInterface

50、: 06 - 0 x2 Internet Address Physical Address Type 29 00-01-30-bd-e9-a0 dynamic 32 00-04-96-05-47-0a dynamic 33 00-04-96-05-47-15 dynamic 34 00-04-96-05-34-f7 dynamic 35 00-04-96-05-47-0e dynamic 36 00-04-96-05-35-11 dynami

51、c 37 00-04-96-05-47-d6 dynamic 38 00-04-96-05-34-ec dynamic 39 00-04-96-05-48-96 dynamic 40 00-04-96-05-34-70 dynamicC:2021/6/1667IP（internet）网络）网络工作原理工作原理2021/6/1668Router and the OSI Model2021/6/1669IP Network: Design Issues【设计因素设计因素】lRouting 【IP 路由选择路由选

52、择】lDatagram lifetime 【生命周期生命周期】lFragmentation and re-assemblylError controllFlow control2021/6/1670IP Routing 【IP选路原理选路原理】lEnd systems and routers maintain routing tables路由表路由表pIndicate next router to which datagram should be sentpStatic 【静态：路由表静态：路由表】uMay contain alternative routespDynamic 【动态：路由表动

53、态：路由表】u Flexible response to congestion and errorslSource routing 【发端路由器选路发端路由器选路】pSource specifies route as sequential list of routers to be followedpSecuritypPrioritylRoute recording2021/6/1671H1H2R1R5R2R3R4IPIP路由表设计原理路由表设计原理 l路径：路径：H1-R1-R2-R4-H2l设计需要考虑到问题设计需要考虑到问题 (4个个)： 路由器（路由器（Routers）的路由表如何获取

54、？）的路由表如何获取？ 为什么选择这条路径？为什么选择这条路径？ 假设假设R2与与R4的连接断掉，如何通知的连接断掉，如何通知R1？在在Internet中，是否每个路由器都必须了解其它路由器的情况？中，是否每个路由器都必须了解其它路由器的情况？2021/6/1672IP网络：网络：路由器（路由器（Routers）的路由表如何获取？）的路由表如何获取？2021/6/1673IPIP路由表的建立和维护路由表的建立和维护 - - 静态配置静态配置l静态配置：管理员手工配置和更新路由表静态配置：管理员手工配置和更新路由表l适用环境：拓扑相对稳定，路由器个数较少适用环境：拓扑相对稳定，路由器个数较少l优

55、点：节省路由器的处理时间、存储空间以及网络带宽优点：节省路由器的处理时间、存储空间以及网络带宽l缺陷：对于链路故障及拓扑结构变化的响应速度慢缺陷：对于链路故障及拓扑结构变化的响应速度慢H1H2R1R5R2R3R42021/6/1674H1H2R1R5R2R3R4IPIP路由表的建立和维护路由表的建立和维护 动态配置动态配置l动态配置：利用路由协议交换路由信息，并根据拓扑结构动态配置：利用路由协议交换路由信息，并根据拓扑结构的变化动态更新路由表的变化动态更新路由表l适用环境：路由器较多的大规模网络适用环境：路由器较多的大规模网络l优点：自动适应链路故障及拓扑结构的变化优点：自动适应链路故障及拓扑

56、结构的变化l缺陷：耗费路由器的处理时间、存储空间以及网络带宽缺陷：耗费路由器的处理时间、存储空间以及网络带宽2021/6/16757.3 IP7.3 IP路由表：选路原理路由表：选路原理1、选路方式选路方式： 表驱动：每个主机和路由器都有一张路由表，指明去往某信宿应该走表驱动：每个主机和路由器都有一张路由表，指明去往某信宿应该走哪条路径。选路时，查询路由表。哪条路径。选路时，查询路由表。 2、路由表格式路由表格式 【IP Destination: 信宿信宿】信宿地址信宿地址去往信宿的路径去往信宿的路径不是主机地址，不是主机地址，而是网络地址而是网络地址不是完整路径，而是不是完整路径，而是(ne

57、xt hop)下一跳地址下一跳地址目标网络目标网络1的网络号的网络号到达网络到达网络1的下一跳路由器的下一跳路由器IP目标网络目标网络2的网络号的网络号到达网络到达网络2的下一跳路由器的下一跳路由器IP2021/6/1676 网 网 4 网 3 网 目的主机所在的网络下一跳地址直接交付，接口 1直接交付，接口 0路由器 R2 的路由表1

58、链路 4链路 3链路 2链路 1R2R3R101R2R3R1在路由表中，对每一条路由，最主要的是（目的网络地址，下一跳地址） 2021/6/1677IP网络结构：网络结构：AS系统设置系统设置AS - 自治系统自治系统2021/6/1678lGroup of routerslExchange informationlCommon routing protocollSet of routers and networks managed by single organizationlA connected

59、 networkpThere is at least one route between any pair of nodes2021/6/16792021/6/1680lPasses routing information between routers within ASlMay be more than one AS in internetlRouting algorithms and tables may differ between different ASlIRP needs detailed model2021/6/1681l Routers need some info abou

60、t networks outside their ASl Used exterior router protocol (ERP)l ERP supports summary information on reachability (网络可达性网络可达性)2021/6/16822021/6/1683CERNET 【中国教育网中国教育网 - AS：4538】 徐闻徐闻长春长春哈尔滨哈尔滨乌鲁木齐乌鲁木齐拉萨拉萨西宁西宁兰州兰州银川银川呼和浩特呼和浩特台北台北沈阳沈阳南昌南昌西安西安徐州徐州武汉武汉合肥合肥郑州郑州石家庄石家庄北京北京南宁南宁广州广州福州福州杭州杭州上海上海南京南京天津天津贵阳贵阳海口海口三