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The ICMP header starts after the IPv4 header and is identified by its protocol number, 1. [6] All ICMP packets have an eight-byte header and variable-sized data section. The first four bytes of the header have fixed format, while the last four bytes depend on the type and code of the ICMP packet.
The ICMP Router Solicitation message is sent from a computer host to any routers on the local area network to request that they advertise their presence on the network. The ICMP Router Advertisement message is sent by a router on the local area network to announce its IP address as available for routing. When a host boots up, it sends ...
ICMP hole punching is a technique employed in network address translator (NAT) applications for maintaining Internet Control Message Protocol (ICMP) packet streams that traverse the NAT. NAT traversal techniques are typically required for client-to-client networking applications on the Internet involving hosts connected in private networks ...
ICMPv6 provides a minimal level of message integrity verification by the inclusion of a 16-bit checksum in its header. The checksum is calculated starting with a pseudo-header of IPv6 header fields according to the IPv6 standard, [6] which consists of the source and destination addresses, the packet length and the next header field, the latter of which is set to the value 58.
The most common form of black hole is simply an IP address that specifies a host machine that is not running or an address to which no host has been assigned.. Even though TCP/IP provides a means of communicating the delivery failure back to the sender via ICMP, traffic destined for such addresses is often just dropped.
Ping measures the round-trip time for messages sent from the originating host to a destination computer that are echoed back to the source. The name comes from active sonar terminology that sends a pulse of sound and listens for the echo to detect objects under water. [1] Ping operates by means of Internet Control Message Protocol (ICMP) packets.
The process repeats until a packet is delivered to the destination host, or earlier along the route, when a router has no default route available and cannot route the packet otherwise. In the latter case, the packet is dropped and an ICMP Destination Unreachable message may be returned. [1]
A functionality which lets a computer A find out whether a computer B is reachable and responding is built into the Internet Control Message Protocol (ICMP). Through an "Echo Request" Computer A asks B to send back an "Echo Reply". [2] These two messages are also sometimes called "ping" and "pong" for historical purposes. [citation needed]