Comunication Layers

Chapter 2

8a) The internet and Transport layer broad function is to transmit information across the internet.

b) Transport layer is engaged in the end to end communication between the end hosts. This is not handled by the internet layer. The internet layer administers the transmission of the packets through an internet.

c) The main internet layer standard is the Internet Protocol.

d) The transport layer fixes any errors that are created at lower layers i.e. from the internet, data link and physical layer and delivers error free data to the application program.

18a) IP is a connectionless protocol b) it is unreliable protocol. Even though it has a header checksum field which checks for errors but it simply discards it with out trying to fix the problem. There is only error detection not correction and so is not considered reliable.

Thought Questions

1) If the acknowledgment is lost the TCP sender retransmits the information. The sender receives the information a second time. Since the information is received again, the receiving TCP will know that its acknowledgment was lost and so send another acknowledgment and it discards of the duplicated information.

3) For the TCP/IP client it would send the messages with the address of its own server. So the destination address would contain the address of the TCP/IP server. The same thing applies to the IPX clients and server. The message that the client send to the server will have the destination address with IPX client on it instead of an Ethernet address of the server.

4) Sometimes hosts can have the same IP address if there is IP address starvation or the IP address can be shared between hosts using NAT. However, it is impossible for 2 hosts to have the same IP address while both are connected to the internet since to get the IP address to each host it has to refer to the DHCP which has a pool of IP addresses that it manages making sure that no 2 hosts have the same IP address. In the case if 2 hosts have same IP address some information could be send to the wrong host and some inflrmation may not be received by the other host.

5) Yes since it is an Ethernet switches this implies that it is being used in a local area network (LAN) and for the information to be able to move from one switch to the other on a LAN network they will need an Ethernet address to identify the switch it is being forwarded to.

Chapter 3

14) Optical fiber is based on light passing through a glass rod. Optical fiber represents 1 s and 0 s by on and off signaling. The light on represents a 1 the light turned off represents a 0.

b) Optical fiber attenuation is between 0.3 db/Km and 3.0 db/Km.

20a) A network topology is the physical arrangement of a networks computers switches routers and transmission lines.

b) Topology is found at the physical layer

c) Point to point: