Search results
Results From The WOW.Com Content Network
MTR also has a User Datagram Protocol (UDP) mode (invoked with "-u" on the command line or pressing the "u" key in the curses interface) that sends UDP packets, with the time to live (TTL) field in the IP header increasing by one for each probe sent, toward the destination host. When the UDP mode is used, MTR relies on ICMP port unreachable ...
Destination unreachable is generated by the host or its inbound gateway [2] to inform the client that the destination is unreachable for some reason. Reasons for this message may include: the physical connection to the host does not exist (distance is infinite); the indicated protocol or port is not active; the data must be fragmented but the ...
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.
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.
Port Control Protocol (PCP) is a computer networking protocol that allows hosts on IPv4 or IPv6 networks to control how the incoming IPv4 or IPv6 packets are translated and forwarded by an upstream router that performs network address translation (NAT) or packet filtering.
Cisco's implementation of traceroute also uses a sequence of UDP datagrams, each with incrementing TTL values, to an invalid port number at the remote host; by default, UDP port 33434 is used. An extended version of this command (known as the extended traceroute command) can change the destination port number used by the UDP probe messages. [13]
Then, similar to IPv4, any device along the path whose MTU is smaller than the packet will drop the packet and send back an ICMPv6 Packet Too Big (Type 2) message containing its MTU, allowing the source host to reduce its path MTU appropriately. The process is repeated until the MTU is small enough to traverse the entire path without fragmentation.
The native IPv6 host then responds as usual to the client's Teredo IPv6 address, which eventually causes the packet to find a Teredo relay, which initiates a connection to the client (possibly using the Teredo server for NAT piercing). The Teredo Client and native IPv6 host then use the relay for communication as long as they need to.