1) DHCP: Dynamic Host Configuration Protocol, Dynamic Host Configuration Protocol
Dynamic Host Configuration Protocol is a network protocol LAN, using the UDP protocol to work, there are two main purposes: to automatically assign IP addresses to the internal network or Internet service provider to the user to the internal network administrators as a means for central management of all computers
2) ARP: Address Resolution Protocol, ARP
Converting the 32-bit IP address for the 48-bit physical address. When the router or host is selected a route, first looks ARP cache, if there is an IP address corresponding to a physical address cache, thereby encapsulating the Ethernet frame, otherwise the broadcast (broadcast of Layer) ARP packets, each after the host receives the ARP request packet, the transmission source cached IP - MAC of the ARP cache, the destination host sends an ARP response (in this case, unicast), when the transmission source receives the response destination will the IP - MAC to be stored in the ARP cache. In point of physical connection, it is not used in ARP packets, when you start the other two sides will announce its own IP address, then the package does not require the physical layer MAC address. You can use arp -a view of the machine ARP cache on windows. The maximum survival time of each entry in the ARP cache is 20 minutes.
Function: For the IP address of the network layer, the parsed hardware address used by the data link layer. Note: ARP mapping problem is solved by IP address and hardware address of the hosts and routers on the same LAN.
How it works: Each host has told an ARP cache, there are IP addresses of the hosts and routers on the local LAN hardware address mapping. When the B on the A wants to send this LAN IP datagram, the IP address A first check whether the ARP cache of B:
If yes: to find the hardware address of the IP address in the ARP cache, this hardware address MAC frame is written, and then through the LAN MAC frames destined to this hardware address.
If no: ARP broadcast to this local area network (request packet is broadcast, the response packet is a unicast) sends an ARP request packet, indicating its own IP address and hardware address and IP addresses are looking for. B after receiving the request packet, and transmits the corresponding packet to accept A, corresponding to the remaining hosts do. A packet is received before the corresponding B for regular data transmission.
Survival Time: ARP address mapping for each project are provided with survival time (for example, 10 to 20 minutes), which is to prevent the situation in some host LAN hardware address has changed.
3) ICMP
ICMP (Internet Control Message Protocol) Internet Control Message Protocol. It is a sub-protocol IPv4 protocol suite for IP host, passing control messages between routers. It is a network control message through the operation fails, the host is reachable, if routes are available in the peer network message itself. These control messages, while not transmit user data, but for the transfer of user data plays an important role.
ICMP and ARP protocol different protocol, ICMP by IP protocol to complete the task, so the ICMP packets to be encapsulated IP header. It is the transport layer protocol (such as TCP and UDP) different purposes, generally not used to transfer data between end systems, the network is not directly user program, except such as Ping and Tracert diagnostic procedures.
4) IGMP: Internet Group Management Protocol, Internet Group Management Protocol
Function: IGMP protocol is to allow multicast router attached to this LAN to know whether there is a host on this LAN (strictly speaking is a process on the host) to participate or withdraw from a certain multicast group.