Network Protocols Review
Copyright Paul W. Nieto 2005
This document reviews various network protocols. Use your search edit function to speed up your search.
Hyper Text Transfer Protocol (HTTP) is an Application-level protocol that can be used to transport, retrieve, search for, update, and change, information that is distributed and collaborative (including hypermedia).
HTTP is based on a Uniform Resource Locator (URL), which indicates the host where the information is stored and the exact path to the information. HTTP is also used as a generic protocol for communication between other Internet systems including those supported by the SMTP, NNTP, and FTP protocols.
User Datagram Protocol (UDP) allows application programs to send messages to other programs. It is often used by applications that use multicast or broadcast delivery. UDP is a Transport-layer protocol.
Address Resolution Protocol (ARP) works at the OSI Network layer and resolves IP addresses to Media Access
Control (MAC) addresses.
Transmission Control Protocol (TCP)
is a Transport-layer protocol used to provide a connection-oriented transport
mechanism.
|
Explanation: The subnet mask enables TCP/IP to find the destination host's location on either the local network or a remote location. Subnets are used for the following reasons: * Expand the network * Reduce congestion * Reduce CPU use * Isolate network problems * Improve security * Allow use of multiple media -
subnets allow you to combine different media by putting each type of media on
a different subnet. |
Explanation:
Point-to-Point Tunneling Protocol (PPTP) was created by Microsoft so that two networks can obtain a secure, private network using the Internet as the WAN link. PPTP works with PPP (Point-to-Point Protocol) and TCP/IP. It is known as "tunneling" because the PPTP protocol tunnels through the PPP connection, which results in a secure connection between the client and server. This method of connection to the Internet allows for private network security over an insecure network, and is known as a virtual private network (VPN). Once the connection is created, TCP/IP can be used to transport data.
Which characteristic describes Frame
Relay?
|
|
It sends
data in fixed-length cells of 53 bytes. |
|
|||
|
|
It performs
error checking at each node. |
|
|||
|
|
It utilizes
Plain Old Telephone Service (POTS). |
|
|||
|
|
It offers a
Committed Information Rate (CIR). |
|
|||
|
Frame Relay is an efficient, point-to-point, packet-switched WAN technology. When ordering Frame Relay service, you can select a Committed Information Rate (CIR). A CIR is a guaranteed minimum bandwidth. When network traffic is light on this shared network, you could experience higher levels of bandwidth, up to 1.544 Mbps. When network traffic is high, you should experience at least your CIR speed. Frame Relay does not use the Public Switched Telephone Network (PSTN). Instead, Frame Relay is typically implemented over a T1 line for a bandwidth of up to 1.544 Mbps. Some vendors do offer Frame Relay over T3 lines, increasing the bandwidth potential to 44.736 Mbps. Integrated Services Digital Network (ISDN) is a WAN technology that uses PSTN. Frame Relay does not transmit fixed-length packets. Instead, it transmits variable length frames using Permanent Virtual Circuits (PVCs), which are logical paths through the network. Asynchronous Transfer Mode (ATM) is a cell-switched network that transmits fixed-length cells of 53 bytes. Frame Relay does not perform error checking at each node. In fact, Frame Relay eliminates as much error checking as possible during the transmission, which makes it a very efficient packet-switching technology. Frames that have errors are dropped. It is up to the receiving end to determine if an error has occurred. A technology that performs error checking at each node is X.25, which is an out-of-favor, packet-switched network technology |
|||||
Frame relay is a point-to-point,
packet-switched wide area network (WAN) technology. Networks that use Frame
Relay tend to perform faster than other packet-switched networks. This
efficiency is due in part to using permanent virtual circuits (PVCs) to send
variable-length frames. PVCs mean that the end-to-end path of the destination
is known. In turn, Frame Relay networks do not need to fragment or reassemble
packets or provide best-path routing. Also, Frame Relay networks are not
concerned with error checking, which also adds to their efficiency. Frame Relay
is a technology that is well suited for unpredictable network traffic patterns.
It was developed to deliver data in high-speed bursts across a digital network.
Post Office Protocol (POP3) and Internet Message Access Protocol (IMAP) are the most popular protocols for receiving e-mail. These protocols are normally combined with Simple Mail Transfer Protocol (SMTP), which is used to send e-mail from the client to the e-mail server.
Simple Mail Transfer Protocol
(SMTP) is an application protocol; therefore, it operates at the top layer of
the OSI model. SMTP is the default protocol for sending e-mail in Microsoft
operating systems.
Point-to-Point Protocol (PPP) is a dial-up connection protocol (serial line protocol) that can be used to allow a computer to become a node on the Internet. The benefit of doing this is the ability to run network applications on your computer.
PPP provides error checking,
password encryption, and automatic configuration, as well as the ability to use
multiple protocols, such as Internetwork Packet Exchange (IPX) and AppleTalk.
PPTP stands for Point-to-Point Tunneling Protocol. PPTP was created by Microsoft to work with the Point-to-Point protocol (PPP) to create a virtual Internet connection so that networks can use the Internet as their WAN link. This method of connection creates a virtual private network (VPN), allowing for private network security. In effect, PPTP creates a secure WAN connection using dial-up access.
PPTP is known as a tunneling protocol because the PPTP protocol dials through the PPP connection, which results in a secure connection between client and server.
Layer Two Tunneling Protocol (L2TP) is an enhancement of PPTP and can also be used to create a VPN. L2TP is a combination of PPTP and Cisco's Layer 2 Forwarding (L2F) tunneling protocols. L2TP uses User Datagram Protocol (UDP) for sending packets as well as for maintaining the connection. Internet Protocol Security (IPsec) is used in conjunction with L2TP for encryption of the data.
Point-to-Point protocol (PPP) is a protocol used to establish dial-up network connections.
Secure Sockets Layer (SSL) is a security protocol that uses both encryption and authentication to protect data sent in network communications.
Remote Access Service (RAS) is a service provided by the network operating system that allows remote access to the network via a dial-up connection.
The SONET rate standards are known as Optical Carrier levels or OCx. For example, the base rate is OC-1, which is 51.84 Mbps. Other OCx rates are multiples of the base rate. The OCx rates are:
OC-1 - 51.84 Mbps
OC-3 - 155.52 Mbps
OC-12 - 622.08 Mbps
OC-24 - 1.244 Gbps
OC-48 - 2.488 Gbps
OC-192 - 10 Gbps
OC-256 - 13.271 Gbps
OC-768 - 40 Gbps
Asynchronous Transfer Mode (ATM) runs as a layer on top of SONET.
TCP port 21 is a well-known port number used by the File Transfer Protocol (FTP) service.
TCP port 80 is used by the HyperText Transfer Protocol (HTTP) for browsing the World Wide Web.
UDP port 161 is used by the Simple
Network Management Protocol (SNMP).
Network Time Protocol (NTP) evolved
from the Time Protocol and the ICMP Timestamp. NTP specifies the precision and
estimated error of both the local clock and the reference clock. It does not
specify the synchronizing algorithms or filtering mechanisms. NTP synchronizes
a set of network servers using a set of distributed clients and servers. NTP is
built on User Datagram Protocol (UDP), which provides a connectionless
transport mechanism.
T1 - up to 1.544 Mbps
T3 - up to 44.736 Mbps
FDDI - up to 100 Mbps
OC-3 - up to 155 Mbps
IPv6 (version 6) or IPng (next generation) offers the following improvements:
* Expanded routing and addressing capabilities - IP address size will increase from 32 bits to 128 bits.
* Header format simplification - Some of the header fields have been dropped.
* Better support for options - Version 6 has less rigid length limits and the ability to introduce new options.
* Quality-of-Service packets - Packets will indicate particular traffic type.
* Authentication and privacy
capabilities - Support will be provided for data integrity and confidentiality.
# of Networks # of Hosts
Class A 126 16,277,214
Class B 16,384 65,534
Class C 2,097,152 254
There are three blocks of IP addresses that have been reserved by the Internet Assigned Numbers Authority (IANA) for private networks. These addresses can be used for IP addressing on a private network that does not have a need to connect to the Internet. The three blocks of addresses are:
10.0.0.0 to 10.255.255.255
172.16.0.0 to 172.31.255.255
192.168.0.0 to 192.168.255.255