ICMP and IGMP protocols are the basic protocols in the tcp ip protocol stack. Therefore, message control is the main task of ICMP. For IGMP, the main task is to pass the information to the router. Let's take a look at the specific explanations of the two protocols below.
Internet Control Message Protocol ICMP is used to report errors and control messages on behalf of IP addresses. The IP address uses the IGMP protocol to tell the router that there are available hosts in the Guidance Group on a network.
ICMP protocol
ICMP Source suppression message: When the TCP/IP host sends data to another host, if the speed reaches the saturation of the router or link, the router sends an ICMP Source suppression message.
ICMP packet structure
Type: an 8-bit field indicating the ICMP data packet type.
Code: an 8-bit code field, indicating a function of the specified type. If one type has only one function, the code field is set to 0.
Check: A 16-bit check on the ICMP part of the data packet.
The additional data of the specified type changes with each ICMP type.
IGMP Protocol
IGMP information is sent to other routers so that each vro supporting multi-channel broadcasting knows which host group and which network.
IGMP protocol Package Structure
Version: IGMP version. The value is generally 0x1 h.
Type: IGMP message type. The 0x1 H type is a host Member request. It is used on a multicast router to specify that any member in a multi-level group polls a network. The 0x2 H type is called host Member report. It is used to publish members in a specified group on the host or to answer requests from host members of a vro.
Unused: unused domain names are set to zero by the sender and ignored by the recipient.
Verification: A 16-bit verification of the IGMP header.
Group address: the host uses this group address to store IP multicast addresses in a host Member request. In host Member requests, the Group address is set to zero, and the hardware-level multi-channel broadcast address is used to mark the Host group.