《TCPIP协议原理教学课件：Chapter 6 ARP and RARP》由会员分享，可在线阅读，更多相关《TCPIP协议原理教学课件：Chapter 6 ARP and RARP（38页珍藏版）》请在金锄头文库上搜索。
1、Chapter 6 ARP and RARPl lARPl lARP package（ARP软件包）软件包）l lRARP8/2/20248/2/20241 1TCP/IP Protocol SuiteTCP/IP Protocol Suite两级地址两级地址l lIP分组交付到主机或路由器需要分组交付到主机或路由器需要两级地址两级地址l l互连网级：互连网级：互连网级：互连网级：逻辑地址逻辑地址逻辑地址逻辑地址标识主机标识主机标识主机标识主机/ /路由器路由器路由器路由器l l全网统一编址，具有全局唯一性全网统一编址，具有全局唯一性全网统一编址，具有全局唯一性全网统一编址，具有全局唯一性全局
2、地址全局地址全局地址全局地址l l所有与互联网打交道的所有与互联网打交道的所有与互联网打交道的所有与互联网打交道的软件软件软件软件都要使用都要使用都要使用都要使用逻辑地址逻辑地址逻辑地址逻辑地址l l在在在在InternetInternet中，逻辑地址就是中，逻辑地址就是中，逻辑地址就是中，逻辑地址就是IPIP地址地址地址地址（32bit32bit）l l物理网级：物理网级：物理网级：物理网级：物理地址物理地址物理地址物理地址标识主机标识主机标识主机标识主机/ /路由器路由器路由器路由器l l本地范围内具有唯一性，但在整个互联网内不一定具有本地范围内具有唯一性，但在整个互联网内不一定具有本地范
3、围内具有唯一性，但在整个互联网内不一定具有本地范围内具有唯一性，但在整个互联网内不一定具有全局唯一性全局唯一性全局唯一性全局唯一性本地地址本地地址本地地址本地地址l l分组需要通过物理网络才能到达路由器或主机分组需要通过物理网络才能到达路由器或主机分组需要通过物理网络才能到达路由器或主机分组需要通过物理网络才能到达路由器或主机l l以太网中，物理地址就是以太网中，物理地址就是以太网中，物理地址就是以太网中，物理地址就是MACMAC地址地址地址地址（48bit48bit）8/2/20248/2/20242 2TCP/IP Protocol SuiteTCP/IP Protocol SuiteMa
4、ppingl lLogical address (IP)l lPhysical addressNetworkNetworkData LinkData LinkPhysicalPhysicalMappingMappingToTo：电子科技大学：电子科技大学：电子科技大学：电子科技大学成都市建设北路成都市建设北路成都市建设北路成都市建设北路2 2段段段段4 4号号号号单位名称（逻辑）单位名称（逻辑）单位名称（逻辑）单位名称（逻辑）单位地址（物理）单位地址（物理）单位地址（物理）单位地址（物理）8/2/20248/2/20243 3TCP/IP Protocol SuiteTCP/IP Protoc
5、ol Suite Issuesl lA送往送往E的分组需封装在的分组需封装在Ethernet帧中传送帧中传送l lIPIP地址：全局性地址：全局性地址：全局性地址：全局性l l物理地址：本地性物理地址：本地性物理地址：本地性物理地址：本地性AA A仅知道：仅知道：仅知道：仅知道：IPIPA A，MACMACA A，IPIPE EEthernet FrameEthernet Frame：IP PacketIP Packet？EB BC CD D目的目的目的目的MACMAC类型类型类型类型FCSFCS源源源源MACMACMACMACA A8/2/20248/2/20244 4TCP/IP Prot
6、ocol SuiteTCP/IP Protocol SuiteAddress Mapping（地址映射）（地址映射）l lLogical address Physical addressStatic mappingStatic mapping映射表固定设置映射表固定设置映射表固定设置映射表固定设置Dynamic mappingDynamic mappingStatic TableStatic TableLogical addressLogical addressPhysical addressPhysical addressConsider:Consider:n nNIC changedNIC
7、 changedn nMobile computerMobile computerCacheCacheLogical addressLogical addressPhysical addressPhysical addressLook for the target on demanding, using dynamic Address Resolution Protocol 8/2/20248/2/20245 5TCP/IP Protocol SuiteTCP/IP Protocol SuiteARP and RARPARPARPLogical addressLogical addressPh
8、ysical addressPhysical addressRARPRARPLogical addressLogical addressPhysical addressPhysical address8/2/20248/2/20246 6TCP/IP Protocol SuiteTCP/IP Protocol SuiteARPl lAddress Resolution Protocol，RFC 826l l地址解析协议：地址解析协议：地址解析协议：地址解析协议：IP address IP address MAC address MAC addressIPLANsMANsWANsICMPIGMP
9、ARPARPRARPNetworkLayerNetworkAccessLayer8/2/20248/2/20247 7TCP/IP Protocol SuiteTCP/IP Protocol SuiteARP OperationA: 1.2.3.1A: 1.2.3.1E: 1.2.3.5E: 1.2.3.5Im looking for the physical address of a node whose IP address is: 1.2.3.5I am the node you are looking for, and my physical address is: 0005.5D06
10、.1418RequestRequestRequestRequestRequestRequestReplyReplyRequestRequestBroadcastBroadcastUnicastUnicastB: 1.2.3.2B: 1.2.3.2C: 1.2.3.3C: 1.2.3.3D: 1.2.3.4D: 1.2.3.4IP addressIP addressMAC addressMAC addressAs ARP CacheAs ARP Cache：1.2.3.51.2.3.50005.5D06.14180005.5D06.1418bindbind8/2/20248/2/20248 8T
11、CP/IP Protocol SuiteTCP/IP Protocol SuiteARP Cache l lARP cachel lTo maintain the To maintain the recentrecent mappingsmappings from logical from logical addresses (IP) to hardware addresses (MAC)addresses (IP) to hardware addresses (MAC)l l典型存活时间：典型存活时间：典型存活时间：典型存活时间：2 minutes2 minutesl lEssential
12、to the Essential to the efficient operation of ARPefficient operation of ARP l l举例：主机举例：主机举例：主机举例：主机 ARP CacheARP CacheC:C:arparp a aInterface: 172.18.64.38 - 0x50002Interface: 172.18.64.38 - 0x50002Internet AddressInternet AddressPhysical AddressPhysical AddressTypeType172.18.64.62 00-03-31-b5-50-0
13、0 Dynamic172.18.64.62 00-03-31-b5-50-00 Dynamic8/2/20248/2/20249 9TCP/IP Protocol SuiteTCP/IP Protocol Suite用户输入命令用户输入命令“ftp 主机名主机名”时的操作时的操作FTPFTPTCPTCPIPIPARPARP以太网以太网以太网以太网驱动程序驱动程序驱动程序驱动程序主机名主机名主机名主机名解析器解析器解析器解析器以太网以太网以太网以太网驱动程序驱动程序驱动程序驱动程序以太网以太网以太网以太网驱动程序驱动程序驱动程序驱动程序主机名主机名主机名主机名IPIP地址地址地址地址（1 1）（
14、2 2）（3 3）（4 4）（6 6）ARPARPARPARPFTPFTPTCPTCPIPIP（5 5）（7 7）目的目的目的目的源源源源8/2/20248/2/20241010TCP/IP Protocol SuiteTCP/IP Protocol SuiteARP PacketHardware TypeHardware TypeProtocol TypeProtocol TypeHardware Hardware address address lenlenProtocol Protocol address address lenlenOperation Operation Request
15、 1, Reply 2Request 1, Reply 2Sender hardware address（For example，6 bytes for Ethernet）Sender protocol address（For example，4 bytes for IP）Target hardware addressTarget hardware address（For exampleFor example，6 bytes for Ethernet6 bytes for Ethernet）Target protocol address（For example，4 bytes for IP）I
16、t is not filled It is not filled in a requestin a request8/2/20248/2/20241111TCP/IP Protocol SuiteTCP/IP Protocol SuiteEncapsulation of ARP packetl lThe byte order of ARP packetl lExample：Ethernet frameHTypeHTypePTypePTypeHLHLPLPLOPOPsMACsMACsIPsIPtMACtMACtIPtIP2 22 22 21 11 16 66 64 44 4bytebyteARP
17、 PacketARP Packet目的目的目的目的MACMAC类型类型类型类型FCSFCS源源源源MACMACPacketPacket6 66 62 246 150046 15004 4padpad28 bytes28 bytes46460x08060x0806bytebyte8/2/20248/2/20241212TCP/IP Protocol SuiteTCP/IP Protocol SuiteExample: ARP Request Packet8/2/20248/2/20241313TCP/IP Protocol SuiteTCP/IP Protocol SuiteExample: A
18、RP Reply Packet8/2/20248/2/20241414TCP/IP Protocol SuiteTCP/IP Protocol SuiteIP Packet and ARP PacketIPIPIPIPARP requestARP replyIP packetBindingBindingIP packetIP packetIP packetNo bindingNo binding8/2/20248/2/20241515TCP/IP Protocol SuiteTCP/IP Protocol SuiteARP Processl lCase 1：A Bl lIn same IP I
19、n same IP networknetworkl lCase 2：A Dl lIn different IP In different IP networknetworkACBDR1R1R2R2IPIPA A，MACMACA AIPIPB B，MACMACB BIPIPC C，MACMACC CIPIPD D，MACMACD DIPIP1 1MACMAC1 1IPIP2 2MACMAC2 2IPIP3 3MACMAC3 3IPIP4 4MACMAC4 48/2/20248/2/20241616TCP/IP Protocol SuiteTCP/IP Protocol SuiteCase 1Ca
20、se 1：A A B BACBDR1R1R2R2IPIPA A，MACMACA AIPIPB B，MACMACB BIPIPC C，MACMACC CIPIPD D，MACMACD DIPIP1 1MACMAC1 1IPIP2 2MACMAC2 2IPIP3 3MACMAC3 3IPIP4 4MACMAC4 4IP AddressIP AddressMAC AddressMAC AddressAs ARP CacheAs ARP Cache：IPIPB BMACMACB BBs ARP CacheBs ARP Cache：IPIPA AMACMACA AR1s ARP CacheR1s ARP
21、 Cache：IPIPA AMACMACA AsIPsIP=IP=IPA A，dIPdIP=IP=IPB BARPARPrequestrequestARPARPrequestrequestARPARPrequestrequestARPARPrequestrequestARPARPreplyreplyIPIPIPIPsMACsMAC=MAC=MACA A，dMACdMAC=MAC=MACB BsIPsIP=IP=IPA A，dIPdIP=IP=IPB BdMACdMAC= =广播，广播，广播，广播，Target_IPTarget_IP=IP=IPB BSender hardware addres
22、s: MACASender protocol address: IPATarget hardware address: 0x000000000x00000000Target protocol address: IPBSender hardware address: MACBSender protocol address: IPBTarget hardware address: MACMACAATarget protocol address: IPA8/2/20248/2/20241717TCP/IP Protocol SuiteTCP/IP Protocol SuiteCase 2：A DAC
23、BDR1R1R2R2IPIPA A，MACMACA AIPIPB B，MACMACB BIPIPC C，MACMACC CIPIPD D，MACMACD DIPIP1 1MACMAC1 1IPIP2 2MACMAC2 2IPIP3 3MACMAC3 3IPIP4 4MACMAC4 4IP AddressIP AddressMAC AddressMAC AddressAs ARP CacheAs ARP Cache：IPIP1 1MACMAC1 1Bs ARP CacheBs ARP Cache：IPIPA AMACMACA AR1s ARP CacheR1s ARP Cache：IPIPA A
24、MACMACA AsIPsIP=IP=IPA A，dIPdIP=IP=IPD DARPARPrequestrequestARPARPrequestrequestARPARPrequestrequestARPARPrequestrequestARPARPreplyreplyIPIPIPIPsMACsMAC=MAC=MACA A，dMACdMAC=MAC=MAC1 1sIPsIP=IP=IPA A，dIPdIP=IP=IPD DdMACdMAC= =广播，广播，广播，广播，Target_IPTarget_IP=IP=IP1 1IPIPD D不在本网内，分不在本网内，分不在本网内，分不在本网内，分组
25、由组由组由组由R1R1转发转发转发转发sMACsMAC=MAC=MAC2 2，dMACdMAC=MAC=MAC3 3sIPsIP=IP=IPA A，dIPdIP=IP=IPD DsMACsMAC=MAC=MAC4 4，dMACdMAC=MAC=MACD DsIPsIP=IP=IPA A，dIPdIP=IP=IPD DIPIP1 1是是是是A A的缺省网关的缺省网关的缺省网关的缺省网关（Default GatewayDefault Gateway）8/2/20248/2/20241818TCP/IP Protocol SuiteTCP/IP Protocol Suite关键问题：关键问题：ARP
26、解析谁的解析谁的IP地址？地址？8/2/20248/2/20241919TCP/IP Protocol SuiteTCP/IP Protocol SuiteExamplelA host with IP address 130.23.43.20 and physical address 0xB23455102210 has a packet to send to another host with IP address 130.23.43.25 and physical address 0xA46EF45983AB. The two hosts are on the same Ethernet
27、network. Show the ARP request and reply packets encapsulated in Ethernet frames.8/2/20248/2/20242020TCP/IP Protocol SuiteTCP/IP Protocol SuiteExample: ARP Request8/2/20248/2/20242121TCP/IP Protocol SuiteTCP/IP Protocol SuiteExample: ARP Request8/2/20248/2/20242222TCP/IP Protocol SuiteTCP/IP Protocol
28、 SuiteProxy ARP（代理（代理ARP）l lProxy ARP: Proxy ARP: 产生子网效应产生子网效应产生子网效应产生子网效应l l代表代表代表代表另一个物理网络另一个物理网络另一个物理网络另一个物理网络中一组主机回答中一组主机回答中一组主机回答中一组主机回答ARP RequestARP Request，在，在，在，在ARP ReplyARP Reply中中中中通告自己的通告自己的通告自己的通告自己的MACMAC地址（即将解析的地址（即将解析的地址（即将解析的地址（即将解析的IPIP与代理与代理与代理与代理ARPARP的的的的MACMAC绑定）绑定）绑定）绑定）l lTo
29、 To foolfool the sender of the ARP request into thinking that the the sender of the ARP request into thinking that the router is the destination host, when in fact the destination router is the destination host, when in fact the destination host is on the other side of the router host is on the othe
30、r side of the router “Honest”“Honest”HidedQ: In the same IP network or not?8/2/20248/2/20242323TCP/IP Protocol SuiteTCP/IP Protocol SuiteAnswerl lRFC 925: Multi-LAN Address Resolutionl lExplicit subnetsExplicit subnetsl lTransparent subnetsTransparent subnets（Extended ARPExtended ARP）l lRFC 1027: Us
31、ing ARP to Implement Transparent Subnet Gatewaysl lRouters: Explicit subnetsRouters: Explicit subnetsl lHosts: Transparent subnetsHosts: Transparent subnets“ From the host point of view, there are no subnets, and “ From the host point of view, there are no subnets, and their physical networks are si
32、mply one big IP network. ”their physical networks are simply one big IP network. ”8/2/20248/2/20242424TCP/IP Protocol SuiteTCP/IP Protocol SuiteProxy ARPl l功能功能功能功能l lTo be used to create a To be used to create a subnettingsubnetting effect effect l l两个物理网络两个物理网络两个物理网络两个物理网络，具有相同网络地址（即不需要重新划分子网），具有相
33、同网络地址（即不需要重新划分子网），具有相同网络地址（即不需要重新划分子网），具有相同网络地址（即不需要重新划分子网）l l使用路由器分别连接这两个网络，并执行使用路由器分别连接这两个网络，并执行使用路由器分别连接这两个网络，并执行使用路由器分别连接这两个网络，并执行ARPARP代理，实现代理，实现代理，实现代理，实现两个两个两个两个逻辑子网逻辑子网逻辑子网逻辑子网l l方案：路由器上运行方案：路由器上运行方案：路由器上运行方案：路由器上运行Proxy ARPProxy ARP软件软件软件软件 transparent subnet gatewaytransparent subnet gatew
34、ayl l当路由收到对当路由收到对当路由收到对当路由收到对特定主机特定主机特定主机特定主机的的的的ARPARP请求请求请求请求时，用自己的时，用自己的时，用自己的时，用自己的物理地物理地物理地物理地址（接收端口）址（接收端口）址（接收端口）址（接收端口）进行进行进行进行ARPARP应答应答应答应答l l代理代理代理代理ARPARP应答的条件（同时满足）：应答的条件（同时满足）：应答的条件（同时满足）：应答的条件（同时满足）：1.1.与源站点不在同一逻辑子网的主机与源站点不在同一逻辑子网的主机与源站点不在同一逻辑子网的主机与源站点不在同一逻辑子网的主机2.2.路由器有到达该节点的路由（非默认路由
35、）路由器有到达该节点的路由（非默认路由）路由器有到达该节点的路由（非默认路由）路由器有到达该节点的路由（非默认路由）3.3.且路由表项记录的发送接口且路由表项记录的发送接口且路由表项记录的发送接口且路由表项记录的发送接口接收该接收该接收该接收该ARPARP请求的接口请求的接口请求的接口请求的接口关键：创建子网，关键：创建子网，关键：创建子网，关键：创建子网，但不需要重新划但不需要重新划但不需要重新划但不需要重新划分子网地址分子网地址分子网地址分子网地址8/2/20248/2/20242525TCP/IP Protocol SuiteTCP/IP Protocol SuiteDiscussion
36、l l.3.3向向向向.35.35发送发送发送发送IPIP分组分组分组分组l l.3.3广播请求广播请求广播请求广播请求.35.35的的的的ARPARP分组，分组，分组，分组，R R不转发广播不转发广播不转发广播不转发广播l l.35.35向向向向.3.3发送发送发送发送IPIP分组分组分组分组l l.35.35广播请求广播请求广播请求广播请求.62.62的的的的ARPARP分组分组分组分组R R200.6.8.0/24200.6.8.0/24Main networkMain network200.6.8.32/27200.6.8.32/27Hided networkHided network
37、.33.33.34.34.35.35.62.62.1.1.3.3.100.100.201.201 IPIP发送失败发送失败发送失败发送失败 IPIP发送成功发送成功发送成功发送成功 ARPARP失败失败失败失败 ARPARP成功成功成功成功设想：设想：设想：设想：R R代替代替代替代替.35.35向向向向.3.3返返返返回回回回ARPARP应答应答应答应答 Proxy ARP Proxy ARP（RFC 925RFC 925）8/2/20248/2/20242626TCP/IP Protocol SuiteTCP/IP Protocol SuiteGratuitous ARPl l功能：功能：
38、l lDuplicate address testDuplicate address testA AB B202.115.12.34202.115.12.34202.115.12.34202.115.12.341. ARP request: 1. ARP request: sIPsIP = = tIPtIP = = 202.115.12.34202.115.12.342. ARP reply: 2. ARP reply: sIPsIP = = tIPtIP = = 202.115.12.34202.115.12.343. Disable local interface: 3. Disable
39、local interface: 202.115.12.34202.115.12.34Startup orStartup orChange IP addressChange IP addressW. Stevens, TCP/IP Illustrated W. Stevens, TCP/IP Illustrated Volume 1: The ProtocolVolume 1: The Protocol8/2/20248/2/20242727TCP/IP Protocol SuiteTCP/IP Protocol SuiteGratuitous ARP PacketThe same sende
40、r and The same sender and target IP addresstarget IP address8/2/20248/2/20242828TCP/IP Protocol SuiteTCP/IP Protocol SuiteChapter 6 ARP and RARPl lARPl lARP package（ARP软件包）软件包）l lRARP8/2/20248/2/20242929TCP/IP Protocol SuiteTCP/IP Protocol SuiteARP Package8/2/20248/2/20243030TCP/IP Protocol SuiteTCP
41、/IP Protocol SuiteARP Cachel lHostHost（Windows XPWindows XP）l lRouterRouter（CiscoCisco）C: C: arparp a aInterface: 202.115.12.34 - 0x2Interface: 202.115.12.34 - 0x2 Internet Address Internet Address Physical Address Physical Address Type Type 202.115.12.33 202.115.12.33 00-90-27-a7-98-41 00-90-27-a7-
42、98-41 dynamicdynamic 202.115.12.47 202.115.12.47 00-90-27-1d-d9-94 00-90-27-1d-d9-94 dynamicdynamic 202.115.12.62 202.115.12.62 00-90-27-1a-67-e7 00-90-27-1a-67-e7 dynamicdynamicRouter# show Router# show arparpProtocol Address Age (min) Hardware Protocol Address Age (min) Hardware AddrAddr Type Inte
43、rface Type InterfaceInternetInternet 202.115.12.33 202.115.12.33 - - 0090.27a7.9841 ARPA Ethernet0 0090.27a7.9841 ARPA Ethernet0InternetInternet 202.115.12.34 202.115.12.34 5 5 0005.5d06.1418 ARPA Ethernet0 0005.5d06.1418 ARPA Ethernet0InternetInternet 202.115.13.1 202.115.13.1 - - 00e0.7bc0.b205 AR
44、PA Ethernet1 00e0.7bc0.b205 ARPA Ethernet18/2/20248/2/20243131TCP/IP Protocol SuiteTCP/IP Protocol Suite思考思考l l更新更新ARP绑定时，发现已有的绑定与新的绑绑定时，发现已有的绑定与新的绑定不一样，是保持已有的还是替换它？定不一样，是保持已有的还是替换它？l l封装封装IP报文的以太帧中的源报文的以太帧中的源MAC和和IP报文报文中的源中的源IP可否用于刷新可否用于刷新ARP表项？目的表项？目的MAC和目的和目的IP呢？呢？l l教材中教材中ARP输入模块描述与输入模块描述与RFC 82
45、6中的中的Packet Reception一节有一节有矛盾矛盾8/2/20248/2/20243232TCP/IP Protocol SuiteTCP/IP Protocol SuiteRFC Referencesl lRFC 1122: Requirements for Internet RFC 1122: Requirements for Internet Hosts - Communication LayersHosts - Communication Layersl lSection 2.3.2: Section 2.3.2: ARP cache, ARP ARP cache, ARP
46、 packetpacket queue queuel lRFC 1812: Requirements for IPv4 RoutersRFC 1812: Requirements for IPv4 Routersl lSection 3.3.2Section 3.3.2l lRFC 1433: Directed ARPRFC 1433: Directed ARPl lARP helper addressARP helper addressl lRFC 1868: ARP Extension UNARPRFC 1868: ARP Extension UNARPl lAnnounce leavin
47、gAnnounce leaving8/2/20248/2/20243333TCP/IP Protocol SuiteTCP/IP Protocol SuiteChapter 6 ARP and RARPl lARPl lARP package（ARP软件包）软件包）l lRARP8/2/20248/2/20243434TCP/IP Protocol SuiteTCP/IP Protocol SuiteRARPl lReverse Address Resolution Protocoll lRFC 903RFC 903：MACMAC地址地址地址地址 IPIP地址地址地址地址IPLANsMANsW
48、ANsICMPIGMPARPRARPNetworkLayerNetworkAccessLayer8/2/20248/2/20243535TCP/IP Protocol SuiteTCP/IP Protocol SuiteRARP Operationl lPurposePurposel l无盘机器的引导、动态无盘机器的引导、动态无盘机器的引导、动态无盘机器的引导、动态IPIP地址配置地址配置地址配置地址配置l lPacket formatPacket formatl l与与与与ARPARP分组相同分组相同分组相同分组相同l lOperationOperation：3 RARP request3
49、RARP request，4 RARP reply4 RARP replyl lEthernet frame encapsulationEthernet frame encapsulationl l类型：类型：类型：类型：0x80350x8035l lOperationOperationl lRARP requestRARP request：广播发送，：广播发送，：广播发送，：广播发送，sIPsIP、tIPtIP不填，不填，不填，不填，sMACsMAC tMACtMACl lRARP replyRARP reply：仅由：仅由：仅由：仅由RARPRARP服务器单播发送服务器单播发送服务器单播发
50、送服务器单播发送8/2/20248/2/20243636TCP/IP Protocol SuiteTCP/IP Protocol SuiteAlternative Solutions to RARPRARP RARP 只能只能只能只能获得获得获得获得IPIP地址地址地址地址DHCPDHCPBOOTP BOOTP 掩码掩码掩码掩码默认网关默认网关默认网关默认网关DNS DNS 服务器服务器服务器服务器8/2/20248/2/20243737TCP/IP Protocol SuiteTCP/IP Protocol SuiteSummaryl lARPl l作用、分组格式作用、分组格式作用、分组格式
51、作用、分组格式l l操作操作操作操作l l何时发送、送给谁何时发送、送给谁何时发送、送给谁何时发送、送给谁l l发送方式（单播、广播）发送方式（单播、广播）发送方式（单播、广播）发送方式（单播、广播）l l发送内容（发送内容（发送内容（发送内容（ARPARP分组各字段的具体取值，以及封装分组各字段的具体取值，以及封装分组各字段的具体取值，以及封装分组各字段的具体取值，以及封装该分组的以太帧中各字段的具体取值）该分组的以太帧中各字段的具体取值）该分组的以太帧中各字段的具体取值）该分组的以太帧中各字段的具体取值）l lProxy ARPProxy ARP、Gratuitous ARPGratuitous ARPl lRARPl l作用、操作、缺陷作用、操作、缺陷作用、操作、缺陷作用、操作、缺陷8/2/20248/2/20243838TCP/IP Protocol SuiteTCP/IP Protocol Suite
