TCP/IP

puffyyaphankyonkersNetworking and Communications

Oct 26, 2013 (3 years and 7 months ago)

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TCP/IP Lecture Extra

TCP/IP


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)


TELNET

Other things about TCP


Heaving processing burden on source
and destination hosts


It adds to network traffic


Error correction of TCP adds to network
delay

Internet Protocol


IP Basics


Connectionless


Unreliable


IP Datagrams


Hop by Hop


Traceroute example


http://www.visualware.com/visualroute/inde
x.html


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
computer


Subnet Mask


Generally listed as 255.255.255.0 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
anything



A prefix of 0.0.0.0/0, 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
address.


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
exactly.


Routers


Source/Destination on the Same Subnet


Source/Destination Different Subnets


Router Forwarding to Another Router


Border Routers

Router Forwarding Tables


Next hop


Simple match


Masks


tell how long the match should be


Longest Match Selection


The longer the prefix the better the match


Metric
-
based selection


Used when two routers are tied when using
longest match


Default Router


0.0.0.0