The following figure illustrates the effect on a class B address of
extending a network mask from 255.255.0.0 to 255.255.255.0:
Subnets are created by extending network ID portion of an address
by taking some bits from the host portion to create a subnet portion.
Network Address
a. A network address serves as unique identifier for a computer on a
network.
b. When setup correctly, computers can determine the addresses of other
computers on network and use these addresses to send messages to
each other.
c. Best known form of network addressing is the IP address.
d. Another form of address is Media Access Control (MAC). It has 6 bytes
that manufactures network address.
Broadcast Address
a. Broadcast address is logical address at which all devices are connected
to multiple access communications network are enabled to receive
datagram's.
b. IP allows information to be sent to all machines on given subnet rather
than specific machine.
c. Generally broadcast address is found by taking the bit complement of the
subnet mask and then ORing it bitwise with the IP addresses
Math Example
If a system has the IP address 192.168.12.220 and a network mask of
255.255.255.128, what should the broadcast address for the system be?
To do this calculation, convert all numbers to binary values. For bitwise,
remember that any two values where at least one value is 1, the result will
be 1, otherwise the result is 0.
IP Address
Reverse Mask
Bitwise OR
Broadcast Address
11000000.10101000.00001100.11011100
00000000.00000000.00000000.01111111
———————————————–
11000000.10101000.00001100.11111111
Convert the binary value back to octal and the resulting value is
192.168.12.255.
Class A
a.
b.
c.
d.
This class is for very large network such as major international company.
The IP addresses with first octet from 1 to 126 are part of this class.
The other three octets are used to identify each host.
The class A networks, the high order bit value in the first octet is always
zero.
Net
Host or Node
115.
24.53.107
Class B
a. Class B is used for medium size network e.g. large collage campus.
b. IP addresses with first octet from 128 to 191 the part of this class.
c. Class B addresses also include the second octet as the part of the net
identifier.
d. The other two octets are used to identify each host.
Net
Host or Node
145.24.
53.107
Class C
a. Class C addresses are commonly used for small to mid-size
business.
b. IP addresses with a first octet from 192 to 223 are part of this
class.
c. Class C addresses also include the second and third octets as
part of the Net Identifier.
d. The last octet is used to identify each host.
Net
Host or Node
195.24.53.
107
Class D
a. Used for multicast, Class D is slightly different from the first three
classes.
b. The first 4 bits values are 1,1,1,0 respectively.
c. The other 28 bits are used to identify the group of computers the
multicast message is intended for.
Net
Host or Node
224.
24.53.107
Loopback
a. In telecommunication, loopback is a method used to perform
transmission test of the line at the switching center.
b. Loopback is communication channel with only one endpoint.
c. TCP/IP network specify a loopback that allows client software to
communicate with server software on the same computer.
Loopback Address
a. It is a special IP number(127.0.0.1) that is designated for the
software loopback interface of a machine.
b. The loopback interface has no hardware associated with it and it
is not physically connected to network.
c. The loopback interface allows IT professionals to test IP software
without worrying about broken or corrupted drivers.
d. It is commonly used for troubleshooting and network testing.
a. Routing is the process of forwarding packets between connected
networks OR It is process of forwarding packet based on the
destination IP address.
b. Routing occurs at a sending TCP/IP host and at on IP router.
c. TCP/IP networks segments are interconnected by routers.
d. A router is a device that forwards the packets from one network
to another.
e. Router are also commonly referred to as gateways.
Two Characteristics of routers
1. IP routers are multihomed host.
2. IP routers provide packet forwarding other TCP/IP hosts.
Direct Routing
Direct routing is used when both the source and destination
addresses have the same network number.
Indirect Routing
Indirect routing is used when both the source and destination do
not match.
Static Routing
a. Static routing is performed using a preconfigured routing table
which remains in effect indefinitely.
b. This is the most basic form of routing, and it usually requires that
machines have statically configured addresses.
Dynamic Routing
a. Dynamic routing uses special routing information protocols to
automatically update the routing table with routes.
b. These protocols are grouped according to whether they are
Interior Gateway protocols (IGPs) or Exterior Gateway Protocols.
a. Routing table is present on all IP nodes.
b. The routing table stores information about IP networks and how they
can be reached, because all IP nodes perform some form of routing,
routing tables are not exclusive to IP routers.
IP routing tables entry types
An entry in IP routing table contains the following information in
order presented.
1. Network ID:
Network ID corresponding to the route. The network ID
can be class based, Subnet or an IP address for Host
route.
2. Network Mask:
The mask that is used to match destination IP address to
the network ID.
3. Next Hop:
The IP address of the next hop.
4. Interface:
An indication of which network interface is used to
forward the IP packet.
5. Metric:
The number is used to indicate the cost of route.
Common use is to indicate the number of hopes to the
network ID.
Routing table entries can be used to store the following types of routs.
i. Directly attached network ID’s
ii. Remote network ID’s
iii. Host routs.
iv. Default routs
TCP Characteristics:
1. Connection oriented.
2. Bi-directional.
3. Multiple connected and end point identified.
4. Reliable.
5. Acknowledge
6. Stream oriented
7. Data unstructured.
8. Data flow manage.
It providing basic reliability using positive acknowledgement
with retransmission (PAR). Following figure shows one of the most
common simple technique for ensuring reliability.
Message
Send message
and start timer
Receive message
Acknowledgement
Acknowledgement
received
Send message
and start timer
Send
Acknowledgement
Message
Message Lost
Acknowledgement
not send
Acknowledgement
not received
Timer Expiration
Message
Resend message
and start new timer
Acknowledgement
Acknowledgement
Received
Receive recent
message
Send
Acknowledgement
1. TCP provides multiplexing and De multiplexing and error detection in
exactly the same manner as UDP.
2. TCP is connection oriented.
3. Before one application process can begin to send data to another,
the two processes are happen they must send some preliminary
segments to each other establish the parameters of the data transfer.
4. TCP provide for full duplex data transfer.
5. TCP is also always point to point.
Application writes
data
Application reads
data
Socket door
Socket door
TCP receive
buffer
TCP send buffer
Segment