The following figure illustrates the effect on a class B address of extending a network mask from to : Subnets are created by extending network ID portion of an address by taking some bits from the host portion to create a subnet portion.

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. 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 and a network mask of , 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 Convert the binary value back to octal and the resulting value is

Class A a.This class is for very large network such as major international company. b.The IP addresses with first octet from 1 to 126 are part of this class. c.The other three octets are used to identify each host. d.The class A networks, the high order bit value in the first octet is always zero. NetHost or Node 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. NetHost or Node

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. NetHost or Node 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. NetHost or Node

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( ) 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 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. Send message and start timer Acknowledgement received Send message and start timer Acknowledgement not received Timer Expiration Resend message and start new timer Acknowledgement Received Receive message Send Acknowledgement Message Lost Acknowledgement not send Receive recent message Send Acknowledgement Message Acknowledgement Message 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 TCP send buffer TCP receive buffer Segment