Figure 5: The Internet model mapped to the OSI model
What are the Protocols?
A protocol is a set of rules for communication or sending information over a network. Protocols can include rules concerning data transmission mechanisms, communication session initialization and termination, addressing and routing, authentication and verification, encryption and compression, and error correction.
Types of protocols are data-link protocols, network protocols, transport protocols, and application layer protocols. Data-link protocols govern the framing of data, physical addressing of network nodes, and media access control methods. For local area networks (LANs), these primarily include Ethernet, Token Ring, and Fiber Distributed Data Interface (FDDI). For wide area networks (WANs), they include Point-to-Point Protocol (PPP), High-level Data Link Control (HDLC), frame relay, Asynchronous Transfer Mode (ATM), and X.25.
Network protocols handle link services and are responsible for addressing, routing, and error checking. Examples include NetBEUI, Internetwork Packet Exchange (IPX), NWLink, and Internet Protocol (IP).
Transport protocols enable the establishment of sessions and ensure reliable flow of data. Examples include NetBEUI, Sequenced Packet Exchange (SPX), NWLink, and Transmission Control Protocol (TCP).
Application layer protocols enable applications to access network services. Examples include Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Telnet, Simple Mail Transfer Protocol (SMTP), Simple Network Management Protocol (SNMP), Network News Transfer Protocol (NNTP), X.400, X.500, Server Message Block (SMB), and Network File System (NFS).
Novell NetWare's protocols
NetWare protocols are one of the major protocol suites used in real world. Novell, Inc. first developed NetWare based on the Xerox Network Systems (XNS) created in the late 1970s by Xerox at its Palo Alto Research Center (PARC). The more important NetWare protocols are Multiple Link Interface Driver (MLID), Internetwork Packet Exchange (IPX), Routing Information Protocol (PIP), Sequenced Packet Exchange (SPX), NetWare Core Protocol (NCP), NetBIOS, and Service Advertising Protocol (SAP).
Multiple Link Interface Driver (MLID) is the network driver of LAN driver that communicate directly with the hardware network card. The MLID is independent of upper-layer protocols because of the LSL (Link Support Layer) module at the LLC sublayer of the data link layer, which acts as an interface between the MLID and network layer protocols.
Internetwork Packet Exchange (IPX) is a network layer (layer 3) protocol that identifies stations and the networks they reside on and can be used to route packets from one network to another on an IPX internetwork.
Routing Information Protocol (PIP) is a network layer (layer 3) protocol that NetWare uses as the default protocol for routing. RIP periodically broadcasts routing table information across the internetwork. This can create a bottleneck when the information must be transmitted over wide area links
Sequenced Packet Exchange (SPX) is a transport layer (layer 4) protocol that provides reliable, connection-oriented communication sessions between hosts on a network.
NetWare Core Protocol (NCP) is an upper-layer (layers 5 and 6) protocol that services requests from applications such as the NetWare shell. NCP supports file and print services, management of network and host names, and accounting and security functions. NetBIOS is an upper-layer protocol that provides session-layer interoperability with other NetBIOS-enabled operating systems such as LAN Manager and Microsoft Windows NT.
Service Advertising Protocol (SAP) is enables NetWare servers to advertise themselves as present on the network and allows clients to find and access resources.
Apple Computer's protocols
AppleTalk is the original networking protocol for Apple Macintosh networks. AppleTalk enables users to share folders and printers for access by other network users.
AppleTalk lower-layer (layer 1 and 2 of OSI
model) protocols are following:
LocalTalk or LocalTalk Link Access Protocol (LLAP) is Apple's original
data link and physical layer protocol.
EtherTalk or EtherTalk Link Access Protocol (ELAP) is an
implementation of AppleTalk that uses the Ethernet protocol.
TokenTalk or TokenTalk Link Access Protocol (TLAP) is an adaptation of
AppleTalk at the physical and data link layer.
AppleTalk Address Resolution Protocol (AARP) maps AppleTalk addresses
to Ethernet and Token Ring physical addresses. AARP allows upper-layer
protocols to use data link layer protocols other than LocalTalk.
AppleTalk middle-layer (layer 3 and 4 of OSI
model) protocols are following:AppleTalk middle-layer (layer 3 and 4 of
OSI model) protocols are following:
Datagram Delivery Protocol (DDP) is the workhorse of AppleTalk's
network layer protocols. It provides connectionless or datagram service
Routing Table Maintenance Protocol (RTMP) is a distance-vector routing
protocol, similar to RIP, which functions at the network layer.
Name Binding Protocol (NBP) is the transport layer to match a logical
device name with its associated address.
AppleTalk Transaction Protocol (ATP) is an acknowledged connectionless
protocol that functions at the transport layer. ATP acknowledges packet
delivery and initiates retransmission if a packet remains unacknowledged
for too long.
AppleTalk upper-layer (layer 5, 6 and 7 of OSI
model) protocols are following:
AppleTalk Data Stream Protocol (ADSP) is a session layer protocol but
it actually runs at both the transport and session layer.
AppleTalk Session Protocol (ASP) provides session layer services by
establishing, maintaining, and releasing connections.
Printer Access Protocol (PAP) is a session layer protocol and allows
connections between file servers and workstations, as well as workstations
and print servers.
Zone Information Protocol (ZIP) allows devices to be organized into
logical groups called zones that can reduce the apparent complexity of an
internetwork.
AppleTalk Filing Protocol (AFP) allows for file sharing. It works at
the session and presentation layers to translate local file system
commands into a format that can be used for network file service.
AppleShare is a suite of three protocols or applications that provide
AppleTalk's application layer services. The first one is AppleShare File
Server that registers users and allows those users to log in and access
resources. The second one is AppleShare Print Server that provides printer
sharing on the network. The last one is AppleShare PC that allows DOS
workstations to access AppleShare file services.
Internet protocol
The Internet is the global TCP/IP public internetwork that originated in the ARPAnet (Advanced Research Projects Agency Network) project of the U.S. Department of Defense in the 1970s. The original purpose of ARPANET was to create a wide area network (WAN) that would interconnect universities and government installations. When ARPAnet grew larger and an increasing number of universities and networking companies wanted access to it, administration of Internet was given to the National Science Foundation (NSF) and then to Internet Network Information Center (InterNIC).
The Internet protocols do not cover the lower two layers of the OSI model as figure 5. This is because the designers of TCP/IP used existing physical and data link standards to make TCP/IP hardware independent. Internet protocols are widely used to connect heterogeneous systems.
Internet middle-layer (layer 3 and 4 of OSI
model) protocols are following:
IP (Internet Protocol) is the network layer that uses the logical
network address and the packet-switching method and the dynamic method for
route selection and provides error control for connection services. IP is
a connectionless, datagram protocol.
ARP (Address Resolution protocol) is a network layer protocol
concerned with mapping node names to IP addresses. ARP equates logical and
physical device addresses.
ICMP (Internet Control Message Protocol) is a network layer protocol
used with IP to augment error handling and control procedures. ICMP
provides error control and network layer flow control.
RIP (Routing Information Protocol) is a network layer protocol. RIP is
a distance-vector routing protocol.
OSPF (Open Shortest Path First) is a network layer protocol that
addresses route discovery. OSPF provides load balancing and routing based
on class of service.
TCP (Transmission Control Protocol) is the main transport layer
protocol that provides reliable, full-duplex, connection-oriented
transport service to upper-layer protocol and addressing services at the
network layer too.
UDP (User Datagram Protocol) is a connectionless protocol that works
at the transport layer. UDP transports datagrams but does not acknowledge
their receipt.
DNS (Domain Name System) is a distributed database system that works
at the transport layer to provide name-to-address mapping for client
applications.
Internet upper-layer (layer 5, 6 and 7 of OSI
model) protocols are following:
FTP (File Transfer Protocol) is a peer-to-peer protocol that functions
at the top three layers of the OSI model.
Telnet is used for remote terminal emulation. Telnet provides
connectivity between dissimilar operating systems.
SMTP (Simple Mail Transfer Protocol) is an application layer protocol
for routing e-mail messages.
NFS (Network File System) is an application layer protocol that
provides file services and remote operation service use. It allows remote
file systems to appear as though they were part of the local machine's
file system.
XDR (External Data Representation) is a presentation layer protocol
that handles translation. XDR is used for the representation of data in a
machine-independent format.
RPC (Remote Procedure Call) is a session layer protocol that allows a
software redirector determines whether a request can be satisfied locally
or whether it requires network access.
Other protocol
Serial Line Internet Protocol (SLIP) is used with dial-up connections to the Internet. It functions at the physical layer only and does not provide error control or security.
Point-to-Point Protocol (PPP) is also used with dial-up connections. The functions it provides encompass both the physical and data link layers and include error control, security, dynamic IP addressing, and support for multiple protocol.