IPv4 was originally deployed without any local IP subnet conguration protocol.Because only a small, xed number of terminals were connected to the Internet, aterminals and access router were congured by hand. As the number of terminalsgrew, and especially with the introduction of wireless terminals, a server-basedprotocol, DHCP, was developed to handle conguration of es and other localsubnet parameters. Address resolution in IPv4 uses ARP. Though this protocol dealswith es, ARP is actually a link layer protocol. ARP was standardized in theearly days of the Internets development, and consequently has changed little since.Because it is so widely deployed, changes to ARP would be hard to propagate.
IPv6 was originally designed with both local IP subnet conguration and addressresolution handled by Neighbor Discovery, to promote better scalability. Neighbor Discoveryallows terminals and routers to autocongure their without any humanintervention. In particular, Neighbor Discovery does not require a server, reducing theadministrative overhead of server maintenance. However, since many network administratorswere familiar with DHCP and wanted to maintain control over conguration, local IP subnet conguration with DHCP was added to IPv6. DHCP canalso be used in IPv6 to congure other parameters such as the name of aDNS server.In IPv6, conguration of the with Neighbor Discovery is called statelessautoconguration while conguration using DHCP is called stateful conguration.
ARP was dened in the early days of the Internet in RFC 826 (RFC 826, 1982). In thosedays, it was an unsolved problem about how to deliver an IP packet that had been routedacross the Internet to the end terminal on the last hop. When the packet arrived at theaccess router, the router had the of thedestinationterminal but it needed theEthernet address to deliver the packet. ARP allows the access router to obtain a mappingbetween the and the Ethernet address of the network interface card that hasbeen congured with the . The access router caches the mapping in the ARPcache for some period of time, allowing the access router to perform address resolutionfor further incoming packets without having to perform ARP. After the cache times out,however, the access router must perform ARP again to conrm the mapping. ARP canalso be used by terminals on the last hop to deliver packets directly to another terminal,rather than having to go through the access router. Figure 5.1 illustrates the protocol.
IPv4 was originally deployed without any local IP subnet conguration protocol.Because only a small, xed number of terminals were connected to the Internet, aterminals and access router were congured by hand. As the number of terminalsgrew, and especially with the introduction of wireless terminals, a server-basedprotocol, DHCP, was developed to handle conguration of es and other localsubnet parameters. Address resolution in IPv4 uses ARP. Though this protocol dealswith es, ARP is actually a link layer protocol. ARP was standardized in theearly days of the Internets development, and consequently has changed little since.Because it is so widely deployed, changes to ARP would be hard to propagate.
IPv6 was originally designed with both local IP subnet conguration and addressresolution handled by Neighbor Discovery, to promote better scalability. Neighbor Discoveryallows terminals and routers to autocongure their without any humanintervention. In particular, Neighbor Discovery does not require a server, reducing theadministrative overhead of server maintenance. However, since many network administratorswere familiar with DHCP and wanted to maintain control over conguration, local IP subnet conguration with DHCP was added to IPv6. DHCP canalso be used in IPv6 to congure other parameters such as the name of aDNS server.In IPv6, conguration of the with Neighbor Discovery is called statelessautoconguration while conguration using DHCP is called stateful conguration.
ARP was dened in the early days of the Internet in RFC 826 (RFC 826, 1982). In thosedays, it was an unsolved problem about how to deliver an IP packet that had been routedacross the Internet to the end terminal on the last hop. When the packet arrived at theaccess router, the router had the of thedestinationterminal but it needed theEthernet address to deliver the packet. ARP allows the access router to obtain a mappingbetween the and the Ethernet address of the network interface card that hasbeen congured with the . The access router caches the mapping in the ARPcache for some period of time, allowing the access router to perform address resolutionfor further incoming packets without having to perform ARP. After the cache times out,however, the access router must perform ARP again to conrm the mapping. ARP canalso be used by terminals on the last hop to deliver packets directly to another terminal,rather than having to go through the access router. Figure 5.1 illustrates the protocol.
access point vs router
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