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Index Sr. No. | Topics| Page no. | 1. | INTRODUCTION| | 2. | History| | 3. | Architecture| | 4. | Business oriented APPLICATION| | 5. | Comparision| | 6. | FEATURES| | 7. | CONCLUSION| | 8. | BIBLIOGRAPHY| | INtroduction A Network Control Protocol is a protocol that runs atop the Point-to-Point Protocol (PPP) and that is used to negotiate options for a network layer protocol running atop PPP.
Network Control Protocols include the Internet Protocol Control Protocol for the Internet Protocol, the Internetwork Packet Exchange Control Protocol for the Internet Packet Exchange protocol, and the AppleTalk Control Protocol for AppleTalk This protocol operates on the Data Link layer. Point to point protocol In networking, the Point-to-Point Protocol (PPP) is a data link protocol commonly used in establishing a direct connection between two networking nodes. It can provide connection authentication, transmission encryption (using ECP, RFC 1968), and compression.
PPP is used over many types of physical networks including serial cable, phone line, trunk line, cellular telephone, specialized radio links, and fiber optic links such as SONET. PPP is also used over Internet access connections (now marketed as “broadband”). Internet service providers (ISPs) have used PPP for customer dial-up access to the Internet, since IP packets cannot be transmitted over a modem line on their own, without some data link protocol. Two encapsulated forms of PPP, Point-to-Point Protocol over Ethernet (PPPoE) and Point-to-Point Protocol over ATM (PPPoA), are used most ommonly by Internet Service Providers (ISPs) to establish a Digital Subscriber Line (DSL) Internet service connection with customers. A PPP Network Control Protocol (NCP) for IP The IP Control Protocol (IPCP) is responsible for configuring, enabling, and disabling the IP protocol modules on both ends of the point-to-point link. IPCP uses the same packet exchange machanism as the Link Control Protocol (LCP). IPCP packets may not be exchanged until PPP has reached the Network-Layer Protocol phase. IPCP packets received before this phase is reached should be silently discarded.
The IP Control Protocol is exactly the same as the Link Control Protocol with the following exceptions: Data Link Layer Protocol Field Exactly one IPCP packet is encapsulated in the Information field of PPP Data Link Layer frames where the Protocol field indicates type hex 8021 (IP Control Protocol). Code field Only Codes 1 through 7 (Configure-Request, Configure-Ack, Configure-Nak, Configure-Reject, Terminate-Request, Terminate-Ack and Code-Reject) are used. Other Codes should be treated as unrecognized and should result in Code-Rejects. Timeouts
IPCP packets may not be exchanged until PPP has reached the Network-Layer Protocol phase. An implementation should be prepared to wait for Authentication and Link Quality Determination to finish before timing out waiting for a Configure-Ack or other response. It is suggested that an implementation give up only after user intervention or a configurable amount of time. History The Internet is made up of thousands of computer networks that are connected (networked) to each other. These connected computer networks are using the communication method called TCP/IP. 957 During the Cold War, on October 4, 1957 the Soviet Union (now Russia) quietly launched its first spacecraft satellite called Sputnik into orbit. This launch challenged the United States Department of Defense to put a high priority on research and projects in science and technology and created an agency called ARPA (Advanced Research Projects Agency). 1961 The United States Air Force commissioned the Rand Corporation to proceed with a research project that consisted of protection and transfer of vital information in case of an attack in a nuclear war. 962 Paul Baran of the Rand Corporation created the concept of dividing information into blocks or packets and marking the origin and destination. Then sending the packets individually from one computer to another until they all hit the final destination. In the case of a nuclear attack, packets of information will continue transmitting between computers. 1968 The ARPANET project was handed over to BBN Planet (GTE). BBN received its first Honeywell mini-computer (Honeywell 516) containing only 12 kilobytes of ram. 1971
ARPANET was connecting 23 mini-computers in different universities and institutes in the United States, and was using the network control protocol (NCP) to transfer data. THE FIRST HOST TO HOST PROTOCOL IS implemented i. e network control protocol. 1972 The idea of open-architecture networking was first introduced by Kahn shortly after having arrived at DARPA 1973 Vinton “Vint” Cerf, an American computer scientist, and Robert E. “Bob” Kahn, an American engineer and computer scientist, start a project to develop Transmission-Control Protocol (TCP), while at the University of California, Los Angeles (UCLA).
ARPANET went international, connecting to England and Norway. ARCHITECTURE Point-to-point links tend to worsen many problems with the current family of network protocols. For instance, assignment and management of IP addresses, which is a problem even in LANenvironments, is especially difficult over circuit-switched point-to-point links (such as dialup modemservers). PPP addresses these issues using NCPs PPP permits multiple network layer protocols to operate on the same communications link. For every network layer protocol used, PPP uses a separate NCP.
For example, IP uses the IP Control Protocol (IPCP), and IPX uses the Novell IPX Control Protocol (IPXCP). NCPs include functional fields containing standardized codes (PPP protocol field numbers shown in the figure) to indicate the network layer protocol that PPP encapsulates. Each NCP manages the specific needs required by its respective network layer protocols. The various NCP components encapsulate and negotiate options for multiple network layer protocols. Using NCPs to configure the various network layer protocols is explained and practiced later in this chapter.
Link Control Protocol ? The LCP providesautomatic configurationof the interfaces ateach end, including: ? Handling varying limitson packet size ? Detecting commonmisconfiguration errors ? Terminating the link ? Determining when alink is functioningproperly or when it isfailing Network Control Protocol Layer PPP permits multiple network layer protocols to operateon the same communications link. For every networklayer protocol used, PPP uses a separate NCP. ? For example, IP uses the IP Control Protocol (IPCP),and IPX uses the Novell IPX Control Protocol (IPXCP). Each NCP manages the specific needs required by itsrespective network layer protocols. FEATURES Network Control Protocols (NCPs) The most popular protocol stack used with PPP today is TCP/IP. Millions of people each day use TCP/IP to connect to the public Internet. PPP is used to encapsulate the data and pass it to the next point, which allows for the use of multiple NCPs that further configure the protocols that are carried across the PPP link. For example, in the case of IP, the dial-in client must be provided with IP addressing information, which usually is done by a DHCP server.
The Internet Protocol Control Protocol (IPCP) is the NCP used to configure parameters for using the PPP link for transmitting IP packets. The Internetwork Packet Exchange Control Protocol (IPXCP) is used to set up IPX. Other protocols for which there are NCPs include AppleTalk, DECnet Phase IV (oh, the good old days! ), and NetBIOS, among others. The important thing to remember is that the PPP link parameters are negotiated before any actual network protocols are configured or are able to use the link.
After the link is established, one or more NCPs use the link to configure the parameters for the protocol that will be carried in the payload section of PPP frames that use the link. PPP Features PPP supports the following features: * PPP client and server connection support (either active or passive mode). In active mode (default), the PPP software attempts to initiate a PPP link with the peer. In passive mode, the PPP software waits for a peer to try to open a link. * Multiple unit support. Up to 16 PPP interfaces can be active at any one time. Asynchronous character mapping. Users can specify control characters that should be escaped by the peer upon transmission to avoid misinterpretation by the serial driver library or by lower-level modem software. The Point-to-Point network control Protocol Compared to SLIP For many years, transferring Internet Protocol (IP) packets over serial lines was handled almost exclusively by the Serial Line Internet Protocol (SLIP). SLIP is a simple link-layer driver that is installed between IP stack code and a serial driver.
While SLIP uses less object code than PPP and processes packets more efficiently (using compressed headers in CSLIP), it can carry only IP packets and it is not extensible. Furthermore, SLIP has several different protocol implementations that do not always communicate smoothly with each other. Nevertheless, its general ease of use and large installed base has made it the de facto standard for using IP over point-to-point serial lines. The Point-to-Point Protocol (PPP) was developed to address the shortcomings of SLIP.
Unlike SLIP, PPP is being defined and tracked by the Internet Engineering Task Force (IETF), and the protocol specifications have been published in multiple Request For Comments (RFC) documents. Although SLIP is still an attractive choice for systems that only require basic IP-packet transfers, the advantages of PPP are prompting the rapid growth of its installed base. PPP supports several features that make it more suitable than SLIP for certain applications: * Multi-Protocol Support. PPP packet framing includes a protocol field in the header.
This allows for the transfer of packets among different network-layer protocols over a link. At present, the only protocols supported by this PPP implementation are IP and the basic PPP protocols (LCP, IPCP, PAP, and CHAP). * Extensibility. The protocol field in the frame header makes PPP able to accommodate new protocols (both public and proprietary). The Internet Assigned Numbers Authority (IANA) tracks the allocation of protocol field values. * Error Detection. PPP framing also includes a Frame Check Sequence (FCS). This field automatically ensures the data integrity of every packet received by the PPP network interface driver.
If an error is detected, the received packet is dropped and an input error is recorded. * Link Management. The entire structure of PPP is based around the concept of a point-to-point link which is established between peers (the local and remote systems on either end of the serial connection). The link has several phases and states associated with its life and is managed by its own separate protocol, the Link Control Protocol (LCP). This concept of a link creates an environment that can support features like option negotiation, link-layer user authentication, link quality management, and loopback detection. Option Negotiation. PPP allows for the dynamic negotiation of options between peers. To some extent, this allows one end of the link to configure the peer. This is especially useful in heterogeneous environments where a PPP server may need to assign certain properties to the peer, such as the Maximum Receive Unit (MRU). * Authentication. PPP supports link-layer authentication through two widely used authentication protocols: PAP and CHAP. Both of these protocols check that the peer is authorized to establish a link with the local host by sending and/or receiving password information. IP Address Negotiation. Built into the PPP control protocol for IP is the ability to assign an IP address to a peer. This feature allows one peer to act as a PPP server and assign addresses as clients dial in. The IP address can be re-used when the PPP link is terminated. While many applications do not require any of the features above, they may need to interact with other systems that are using PPP and not SLIP. These two protocols can not communicate with each other; this is perhaps the most compelling reason for using PPP. CONCLUSION