puffyyaphankyonkersNetworking and Communications

Oct 26, 2013 (3 years and 5 months ago)


TCP/IP Lecture Extra


Developed by DARPA (Defense Advanced
Research Projects)

TCP is a connection
oriented transport
protocol that sends data as an unstructured
stream of bytes.

By using sequence numbers and
acknowledgment messages, TCP can
provide a sending node with delivery
information about packets transmitted to a
destination node.

TCP/IP Continued

Where data has been lost in transit from source to
destination, TCP can retransmit the data until either a
timeout condition is reached or until successful
delivery has been achieved.

TCP can also recognize duplicate messages and will
discard them appropriately.

If the sending computer is transmitting too fast for the
receiving computer, TCP can employ flow control
mechanisms to slow data transfer.

TCP can also communicate delivery information to
the upper
layer protocols and applications it supports.

TCP/IP versus OSI

TCP/IP Applications

SMTP (Simple Mail Transport Protocol)

FTP (File Transfer Protocol)


Other things about TCP

Heaving processing burden on source
and destination hosts

It adds to network traffic

Error correction of TCP adds to network

Internet Protocol

IP Basics



IP Datagrams

Hop by Hop

Traceroute example

IP Addressing

Hierarchical Addressing

At the local computer level

At the gateway

Loopback address

IP Addressing Continued

Network Mask

Tells the router where to go

Subnet Part

Allows the message to be routed to the host

Subnet Mask

Generally listed as but it can be
manipulated to expand on the number of
computers that can use one IP Address.

Other Facts about IP address

Rule 1: A prefix length of 0 matches

A prefix of, or 0/0, is the shortest
possible IP address prefix and matches
any IP address. We'll see later how this
prefix can used to construct
default routes

to handle routing in cases where no other
information is available.

Rule 2: A prefix length of 32 is an
exact match

A prefix length of 32 bits, the width of a
complete IP address, is the longest
possible address prefix and matches one
IP address exactly. 32 bit prefixes are
used to construct
host routes
, which
specify routing behavior for a single IP

Rule 3: Prefix lengths of 8, 16, and 24
match whole bytes

Any prefix length that's a multiple of 8
matches on byte boundaries. For example,
a prefix of 172.30/16 matches any IP
address that begins with 172.30 in the first
two bytes, and ends with anything in the
last two bytes. Similarly, an 8 bit prefix
matches the first byte exactly and a 24 bit
prefix matches the first three bytes


Source/Destination on the Same Subnet

Source/Destination Different Subnets

Router Forwarding to Another Router

Border Routers

Router Forwarding Tables

Next hop

Simple match


tell how long the match should be

Longest Match Selection

The longer the prefix the better the match

based selection

Used when two routers are tied when using
longest match

Default Router