#Protocols
A protocol (TCP/IP IPX/SPX, APPLE TALK) is a convention or standard that controls or enables the connection, communication, and data transfer between two computing endpoints. Sending and receiving systems need to use the same protocol unless a gateway service sits between networks and translates from one to the other.
Most protocols specify one or more of the following properties:
*Detection of the underlying physical connection (wired or wireless), or the existence of the other endpoint or node
*Handshaking
*Negotiation of various connection characteristics
*How to start and end a message
*How to format a message
*What to do with corrupted or improperly formatted messages (error correction)
*How to detect unexpected loss of the connection, and what to do next
*Termination of the session or connectio
#NetBIOS
NetBIOS is an acronym for Network Basic Input/Output System. The NetBIOS API allows applications on separate computers to communicate over a local area network. NetBIOS must be enabled for Windows File and Print Sharing to work.
NetBIOS provides three distinct services:
*Name service for name registration and resolution
*Session service for connection-oriented communication
*Datagram distribution service for connectionless communication.
Name service In order to start Sessions or distribute Datagrams, an application must register its NetBIOS name using the Name service. NetBIOS names are 16 bytes in length.
Session service Session mode lets two computers establish a connection for a “conversation,” allows larger messages to be handled, and provides error detection and recovery. In NBT, the session service runs on TCP port 139.
Datagram distribution service Datagram mode is “connectionless”. Since each message is sent independently, they must be smaller; the application becomes responsible for error detection and recovery. In NBT, the datagram service runs on UDP port 138.
IPX/SPX (NWLINK)
Internetwork Packet Exchange (IPX) is the OSI-model Network layer protocol in the IPX/SPX protocol stack. The IPX/SPX protocol stack is supported by Novell’s NetWare network operating system. Because of Netware’s popularity through the late 1980s into the mid 1990s, IPX became a popular internetworking protocol. Novell derived IPX from Xerox Network Services’ IDP protocol. IPX usage is in general decline as the boom of the Internet has made TCP/IP nearly universal.
Computers and networks can run multiple network protocols, so almost all IPX sites will be running TCP/IP as well to allow for Internet connectivity. It is also now possible to run Novell products without IPX, as they have supported both IPX and TCP/IP since NetWare reached version 5.
Sequenced Packet Exchange (SPX) is a transport layer protocol (layer 4 of the OSI Model) used in Novell Netware networks. The SPX layer sits on top of the IPX layer (layer 3 – the network layer) and provides connection-oriented services between two nodes on the network. SPX is used primarily by client/ server applications.
NWLink is a IPX/SPX-compatible protocol developed by Microsoft and used in its Windows NT product line.NWLink is Microsoft’s version of Novell’s IPX/SPX Protocol. The Microsoft version of NWLink includes the same level of functionality as the Novell Protocol. NWLink includes a tool for resolving NetBIOS names.NWLink packages data to be compatible with client/server services on NetWare Networks. However, NWLink does not provide access to NetWare File and Print Services. To access the File and Print Services the Client Service for NetWare needs to be installed.
AppleTalk
AppleTalk is a suite of protocols developed by Apple Computer for computer networking. It was included in the original Macintosh (1984) and is now used less by Apple in favour of TCP/IP networking.
AppleTalk contains two protocols aimed at making the system completely self- configuring. The AppleTalk address resolution protocol (AARP) allowed AppleTalk hosts to automatically generate their own network addresses, and the Name Binding Protocol (NBP) was essentially a dynamic DNS system which mapped network addresses to user-readable names.
For interoperability Microsoft maintains the file services for Macintosh and the print services for Macintosh
TCP/IP
The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. It is sometimes called the TCP/IP protocol suite, after the two most important protocols in it: the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were also the first two defined.The Internet protocol suite like many protocol suites can be viewed as a set of layers, each layer solves a set of problems involving the transmission of data, and provides a well-defined service to the upper layer protocols based on using services from some lower layers. Upper layers are logically closer to the user and deal with more abstract data, relying on lower layer protocols to translate data into forms that can eventually be physically transmitted.The OSI model describes a fixed, seven layer stack for networking protocols.
Comparisons between the OSI model and TCP/IP can give further insight into the significance of the components of the IP suite, but can also cause confusion, as TCP/IP consists of only 4 layers.
The four layers in the DoD model, from bottom to top, are:
*The Network Access Layer is responsible for delivering data over the particular hardware media in use. Different protocols are selected from this layer, depending on the type of physical network.
*The Internet Layer is responsible for delivering data across a series of different physical networks that interconnect a source and destination machine. Routing protocols are most closely associated with this layer, as is the IP Protocol, the Internet’s fundamental protocol.
*The Host-to-Host Layer handles connection rendezvous, flow control, retransmission of lost data, and other generic data flow management. The mutually exclusive TCP and UDP protocols are this layer’s most important members.
*The Process Layer contains protocols that implement user-level functions, such as mail delivery, file transfer and remote login.
Network Services
DNS (Domain Naming System)
The Domain Name System (DNS) stores and associates many types of information with domain names, but most importantly, it translates domain names (computer hostnames) to IP addresses. It also lists mail exchange servers accepting e-mail for each domain. In providing a worldwide keyword- based redirection service, DNS is an essential component of contemporary Internet use.
The DNS pre-eminently makes it possible to attach easy-to-remember domain names (such as “es-net.co.uk”) to hard-to-remember IP addresses (such as 270.146.131.206). People take advantage of this when they recite URLs and e-mail addresses.
WINS (Windows Internet Naming Service)
Windows Internet Naming Service (WINS) is Microsoft’s implementation of NetBIOS Name Server (NBNS) on Windows, a name server and service for NetBIOS computer names. Effectively, it is to NetBIOS names what DNS is to domain names – a central mapping of host names to network addresses. However, the mappings have always been dynamically updated (e.g. at workstation boot) so that when a client needs to contact another computer on the network it can get its up-to-date DHCP allocated address. Networks normally have more than one WINS server and each WINS server should be in push pull replication; the favoured replication model is the hub and spoke, thus the WINS design is not central but distributed. Each WINS server holds a full copy of every other related WINS system’s records.
There is no hierarchy in WINS (unlike DNS), but like DNS its database can be queried for the address to contact rather than broadcasting a request for which address to contact. The system therefore reduces broadcast traffic on the network, however replication traffic can add to WAN / LAN traffic.
DHCP (Dynamic Host Configuration Protocol)
The Dynamic Host Configuration Protocol (DHCP) automates the assignment of IP addresses, subnet masks, default routers, and other IP parameters. The assignment usually occurs when the DHCP configured machine boots up or regains connectivity to the network. The DHCP client sends out a query requesting a response from a DHCP server on the locally attached network. The DHCP server then replies to the client with its assigned IP address, subnet mask, DNS server and default gateway information.The assignment of the IP address usually expires after a predetermined period of time, at which point the DHCP client and server renegotiate a new IP address from the server’s predefined pool of addresses. Configuring firewall rules to accommodate access from machines who receive their IP addresses via DHCP is therefore more difficult because the remote IP address will vary from time to time.
Administrators must usually allow access to the entire remote DHCP subnet for a particular TCP/UDP port. Most home routers and firewalls are configured in the factory to be DHCP servers for a home network. ISPs (Internet Service Providers) generally use DHCP to assign clients individual IP addresses.DHCP is a broadcast-based protocol. As with other types of broadcast traffic, it does not
cross a router.
APIPA (Automatic Private IP Addressing)
If computers are unable to pick an address up from a DHCP server they use Automatic Private IP Addressing (APIPA). This means the computer will assign itself a random address between 169.254.0.1 – 169.254.254.254/16, allowing it to communicate with other clients who are also using
APIPA.
Automatic Private IP Addressing (APIPA), this allows unknowledgeable users to connect computers, networked printers, and other items together and expectthem to work. Without Zeroconf or something similar, a knowledgeable user must either set up special servers, like DHCP and DNS, or set up each computer by hand.
#Networks
A Local Area Network (LAN) is a computer network covering a small local area, like a home, office, or small group of buildings such as a home, office, or college. Current LANs are most likely to be based on switched Ethernet or Wi-Fi technology running at 10, 100 or 1,000 Mbit/s.The defining characteristics of LANs in contrast to WANs (wide area networks) are: their much higher data rates; smaller geographic range; and that they do not require leased telecommunication lines.
A Personal Area Network (PAN) is a computer network used for communication among computer devices (including telephones and personal digital assistants) close to one person. The reach of a PAN is typically a few metres and may use Bluetooth, wireless or USB for connection.
A Wide Area Network (WAN) is a computer network covering a wide geographical area, involving a vast array of computers. This is different from personal area networks (PANs), metropolitan area networks (MANs) or local area networks (LANs) that are usually limited to a room, building or campus. The most well-known example of a WAN is the Internet. WANs are used to connect local area networks (LANs) together, so that users and computers in one location can communicate with users and computers in other locations.
A protocol (TCP/IP IPX/SPX, APPLE TALK) is a convention or standard that controls or enables the connection, communication, and data transfer between two computing endpoints. Sending and receiving systems need to use the same protocol unless a gateway service sits between networks and translates from one to the other.
Most protocols specify one or more of the following properties:
*Detection of the underlying physical connection (wired or wireless), or the existence of the other endpoint or node
*Handshaking
*Negotiation of various connection characteristics
*How to start and end a message
*How to format a message
*What to do with corrupted or improperly formatted messages (error correction)
*How to detect unexpected loss of the connection, and what to do next
*Termination of the session or connectio
#NetBIOS
NetBIOS is an acronym for Network Basic Input/Output System. The NetBIOS API allows applications on separate computers to communicate over a local area network. NetBIOS must be enabled for Windows File and Print Sharing to work.
NetBIOS provides three distinct services:
*Name service for name registration and resolution
*Session service for connection-oriented communication
*Datagram distribution service for connectionless communication.
Name service In order to start Sessions or distribute Datagrams, an application must register its NetBIOS name using the Name service. NetBIOS names are 16 bytes in length.
Session service Session mode lets two computers establish a connection for a “conversation,” allows larger messages to be handled, and provides error detection and recovery. In NBT, the session service runs on TCP port 139.
Datagram distribution service Datagram mode is “connectionless”. Since each message is sent independently, they must be smaller; the application becomes responsible for error detection and recovery. In NBT, the datagram service runs on UDP port 138.
IPX/SPX (NWLINK)
Internetwork Packet Exchange (IPX) is the OSI-model Network layer protocol in the IPX/SPX protocol stack. The IPX/SPX protocol stack is supported by Novell’s NetWare network operating system. Because of Netware’s popularity through the late 1980s into the mid 1990s, IPX became a popular internetworking protocol. Novell derived IPX from Xerox Network Services’ IDP protocol. IPX usage is in general decline as the boom of the Internet has made TCP/IP nearly universal.
Computers and networks can run multiple network protocols, so almost all IPX sites will be running TCP/IP as well to allow for Internet connectivity. It is also now possible to run Novell products without IPX, as they have supported both IPX and TCP/IP since NetWare reached version 5.
Sequenced Packet Exchange (SPX) is a transport layer protocol (layer 4 of the OSI Model) used in Novell Netware networks. The SPX layer sits on top of the IPX layer (layer 3 – the network layer) and provides connection-oriented services between two nodes on the network. SPX is used primarily by client/ server applications.
NWLink is a IPX/SPX-compatible protocol developed by Microsoft and used in its Windows NT product line.NWLink is Microsoft’s version of Novell’s IPX/SPX Protocol. The Microsoft version of NWLink includes the same level of functionality as the Novell Protocol. NWLink includes a tool for resolving NetBIOS names.NWLink packages data to be compatible with client/server services on NetWare Networks. However, NWLink does not provide access to NetWare File and Print Services. To access the File and Print Services the Client Service for NetWare needs to be installed.
AppleTalk
AppleTalk is a suite of protocols developed by Apple Computer for computer networking. It was included in the original Macintosh (1984) and is now used less by Apple in favour of TCP/IP networking.
AppleTalk contains two protocols aimed at making the system completely self- configuring. The AppleTalk address resolution protocol (AARP) allowed AppleTalk hosts to automatically generate their own network addresses, and the Name Binding Protocol (NBP) was essentially a dynamic DNS system which mapped network addresses to user-readable names.
For interoperability Microsoft maintains the file services for Macintosh and the print services for Macintosh
TCP/IP
The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. It is sometimes called the TCP/IP protocol suite, after the two most important protocols in it: the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were also the first two defined.The Internet protocol suite like many protocol suites can be viewed as a set of layers, each layer solves a set of problems involving the transmission of data, and provides a well-defined service to the upper layer protocols based on using services from some lower layers. Upper layers are logically closer to the user and deal with more abstract data, relying on lower layer protocols to translate data into forms that can eventually be physically transmitted.The OSI model describes a fixed, seven layer stack for networking protocols.
Comparisons between the OSI model and TCP/IP can give further insight into the significance of the components of the IP suite, but can also cause confusion, as TCP/IP consists of only 4 layers.
The four layers in the DoD model, from bottom to top, are:
*The Network Access Layer is responsible for delivering data over the particular hardware media in use. Different protocols are selected from this layer, depending on the type of physical network.
*The Internet Layer is responsible for delivering data across a series of different physical networks that interconnect a source and destination machine. Routing protocols are most closely associated with this layer, as is the IP Protocol, the Internet’s fundamental protocol.
*The Host-to-Host Layer handles connection rendezvous, flow control, retransmission of lost data, and other generic data flow management. The mutually exclusive TCP and UDP protocols are this layer’s most important members.
*The Process Layer contains protocols that implement user-level functions, such as mail delivery, file transfer and remote login.
Network Services
DNS (Domain Naming System)
The Domain Name System (DNS) stores and associates many types of information with domain names, but most importantly, it translates domain names (computer hostnames) to IP addresses. It also lists mail exchange servers accepting e-mail for each domain. In providing a worldwide keyword- based redirection service, DNS is an essential component of contemporary Internet use.
The DNS pre-eminently makes it possible to attach easy-to-remember domain names (such as “es-net.co.uk”) to hard-to-remember IP addresses (such as 270.146.131.206). People take advantage of this when they recite URLs and e-mail addresses.
WINS (Windows Internet Naming Service)
Windows Internet Naming Service (WINS) is Microsoft’s implementation of NetBIOS Name Server (NBNS) on Windows, a name server and service for NetBIOS computer names. Effectively, it is to NetBIOS names what DNS is to domain names – a central mapping of host names to network addresses. However, the mappings have always been dynamically updated (e.g. at workstation boot) so that when a client needs to contact another computer on the network it can get its up-to-date DHCP allocated address. Networks normally have more than one WINS server and each WINS server should be in push pull replication; the favoured replication model is the hub and spoke, thus the WINS design is not central but distributed. Each WINS server holds a full copy of every other related WINS system’s records.
There is no hierarchy in WINS (unlike DNS), but like DNS its database can be queried for the address to contact rather than broadcasting a request for which address to contact. The system therefore reduces broadcast traffic on the network, however replication traffic can add to WAN / LAN traffic.
DHCP (Dynamic Host Configuration Protocol)
The Dynamic Host Configuration Protocol (DHCP) automates the assignment of IP addresses, subnet masks, default routers, and other IP parameters. The assignment usually occurs when the DHCP configured machine boots up or regains connectivity to the network. The DHCP client sends out a query requesting a response from a DHCP server on the locally attached network. The DHCP server then replies to the client with its assigned IP address, subnet mask, DNS server and default gateway information.The assignment of the IP address usually expires after a predetermined period of time, at which point the DHCP client and server renegotiate a new IP address from the server’s predefined pool of addresses. Configuring firewall rules to accommodate access from machines who receive their IP addresses via DHCP is therefore more difficult because the remote IP address will vary from time to time.
Administrators must usually allow access to the entire remote DHCP subnet for a particular TCP/UDP port. Most home routers and firewalls are configured in the factory to be DHCP servers for a home network. ISPs (Internet Service Providers) generally use DHCP to assign clients individual IP addresses.DHCP is a broadcast-based protocol. As with other types of broadcast traffic, it does not
cross a router.
APIPA (Automatic Private IP Addressing)
If computers are unable to pick an address up from a DHCP server they use Automatic Private IP Addressing (APIPA). This means the computer will assign itself a random address between 169.254.0.1 – 169.254.254.254/16, allowing it to communicate with other clients who are also using
APIPA.
Automatic Private IP Addressing (APIPA), this allows unknowledgeable users to connect computers, networked printers, and other items together and expectthem to work. Without Zeroconf or something similar, a knowledgeable user must either set up special servers, like DHCP and DNS, or set up each computer by hand.
#Networks
A Local Area Network (LAN) is a computer network covering a small local area, like a home, office, or small group of buildings such as a home, office, or college. Current LANs are most likely to be based on switched Ethernet or Wi-Fi technology running at 10, 100 or 1,000 Mbit/s.The defining characteristics of LANs in contrast to WANs (wide area networks) are: their much higher data rates; smaller geographic range; and that they do not require leased telecommunication lines.
A Personal Area Network (PAN) is a computer network used for communication among computer devices (including telephones and personal digital assistants) close to one person. The reach of a PAN is typically a few metres and may use Bluetooth, wireless or USB for connection.
A Wide Area Network (WAN) is a computer network covering a wide geographical area, involving a vast array of computers. This is different from personal area networks (PANs), metropolitan area networks (MANs) or local area networks (LANs) that are usually limited to a room, building or campus. The most well-known example of a WAN is the Internet. WANs are used to connect local area networks (LANs) together, so that users and computers in one location can communicate with users and computers in other locations.
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