UPCOMING TOPICS

• computer programming basics
• c/c++ tutorials
• computer hardware basics
• the fun of blogging

common error messages in internet

INTERNET CONTROL MESSAGE PROTOCOL (ICMP):

Works at the Network layer and is used by IP for different
services. It is a management protocol and messaging service
provider for IP.Listed below are some common events and
messages that ICMP relates to:-

DESTINATION UNREACHABLE - If a router can't send an IP
datagram any further, it uses ICMP to send a message back
to the sender, advising it of the situation. For example,
if a router receives a packet destined for a network that
the router doesn't know about, it will send an ICMP
Destination unreachable message back to the sending station.

BUFFER FULL - If a routers buffer for receiving incoming data
is full, it will use ICMP to send out this message.

HOPS - Each IP datatgram is allotted a certain number of routers,
called hops, that it may go through. If it reaches it's limit of hops
before arriving at it's destination the last router to receive that
datagram deletes it. That router then uses ICMP to send an obituary
message, informing the sending machine of the demise of its datagram.

PING - Packet internet groper uses ICMP echo messages to check the
physical connectivity of machines on an internetwork.

TRACEROUTE - Using ICMP timeouts, traceroute is used to find a path
a packet takes as it traverses an internetwork.

tcp tutorial part 2

TCP Segment format:

The figure below show the TCP segment format. It show the different
field within the TCP header.

bit 0 bit 16 bit 32
------------------------------------------------------------------
Source port (16) Destination port (16)
________________________________________________________________

Sequence number (32)
_________________________________________________________________

Acknowledgement number (32)
_________________________________________________________________

Header Reserved Code Bits Window (16)
Length (6) (6)
(4)
______________________________________________________________

Checksum (16) Urgent (16)
________________________________________________________________

Options (0 or 32 if any)
_________________________________________________________________

Data (varies)
_________________________________________________________________

ftp basic

FILE TRANSFER PROTOCOL (FTP):

This (Surprisingly) is the protocol that allows us to
transfer files.
FTP is not just a protocol, it is also a program. Operating
as a protocol, FTP is used by applications. As a program, it
is employed by usersto perform file tasks by hand.
FTP allows for access to both directories and files.
FTP actually teams up with Telnet to transparently log you in
to the FTP server.

tcp tutorial part 1

TRANSMISSION CONTROL PROTOCOL (TCP):

TCP takes large blocks of information from an application and
breaks them into segments. It numbers and sequences each
segment so that the destinations TCP protocol can put the
segments back into the order the application intended.
After these segments are sent, TCP (on the transmitting host)
waits for an acknowledgement of the receiving ends TCP virtual
circuit session, retransmitting those that are not acknowledged.

Before a transmitting host starts to send segments down the model,
the senders TCP protocol contacts the destinations TCP protocol
to estasblish a connection. What is created is known as a virtual
circuit. During this initial handshake, the two TCP Layers also
agree on the amount of inforamtion that is going to be sent before
the recipients TCP sends back an acknowledgement. With everything
agreed upon in advance, the path is paved for reliable communication
to take place.