The right PING!!

I am a total network freak and just love to network computers and do all sorts of R&D on it.. Yest, when I wanted to Remote Login on a Machine, I just couldnt do it.. Then called for "GOD" and he asked me to use "PING".. So finally my "neck" savor told me the problem and i rectified the errors in IP Address..

Well, most of US definately must have or will have to use "PING" at one point or other.. So here is something to give you and Inside Story on How does Ping work..

The source device generates an ICMP protocol data unit.

The ICMP PDU is encapsulated in an IP datagram, with the source and destination IP addresses in the IP header.

The source machine notes the local time on it's clock as it transmits the IP Datagram towards the destination. Each machine that receives the datagram checks the destination address to see if it matches their own, or is the 'all hosts' address.

If the destination IP address in the IP datagram does not match the local machine's address, the datgram is forwarded to the network where the IP address resides.

The destination machine receives the packet, finds a match between itself and the destination address in the IP packet.

The destination machine notes the ICMP information in the ICMP ECHO, performs any necessary work, and destroys the complete original IP/ICMP Echo packet.

The destination machine creates an ICMP Echo Reply, encapsulates it in IP placing it's own address in the source IP address field, and the original sender's IP address in the destination field of the IP datagram.

The packet is routed back to the originator of the first ICMP Echo, who receives it, notes the time on the clock, prints PING output information, including the elapsed time.

The process above is repeated until all requested Echo packets have been sent, and responses have been received or timed out.

Note that since ICMP requires responses, a fully functioning duplex communication environment (a downlink and uplink path) must be in place and be functioning for the PING to work.

PING does not work where there is a single, one way link.