Networking Concepts. Week-7

Network Protocols Three Major Components:  Application Interface –Connects programs to network  Global Network Transport –Exchange data between remote hosts  Local Network Transport –Exchange data between local hosts

Application Interface System:provides:  TCP/IPTCP or UDP sockets  NovellNetware Shell  MicrosoftNetBIOS port

Global Network Transport System:provides:  TCP/IPIP Layer  NovellIPX  MicrosoftNetBEUI

Host-to-Host Network Transport  Ethernet (local nets spanning ~1Km)  IBM Token Ring (ditto)  Fibre Distributed Data Interface  Frame Relay  Asynchronous Transfer Mode  Others

OSI model Laye r NameExample 7Application Program protocol command 6 Presentatio n eXternal Data Representation 5Session Remote Procedure Call Socket connection 4Transport TCP or UDP, SPX, NetBIOS 3Network IP, IPX, NetBEUI 2 Data Link Ethernet, Token Ring, ATM 1Physical Cables, plugs, microwaves

Network Operating Systems  For the Server-Based and Peer-to-Peer networking environments there needs to be mechanisms that allow communications between workstations and servers  For Example –Netware from Novell –Windows for WorkGroups from Microsoft –TCP/IP from UNIX

Netware Uses Netware Core Protocol requests from the client and responses from the Server  Open(file) >>FileHandle  Read(FileHandle) >>DataBlock  Close(FileHandle) >>FileClosed  …etc…

Microsoft  Uses Server Message Blocks (SMB) for the same purpose

Novell Netware  can use –IPX/SPX or –TCP/IP for client-server communication.

Microsoft Windows Windows XP, 2000, NT, ME, 9X can use NetBEUI, TCP/IP or IPX/SPX for communication

NETBIOS is used to setup links Each computer has a name Resources are given sharenames eg \\tonto\drive_c Before communications can take place a client must broadcast a connection request (get all server info)

Server responds with a Connection number Communications can then commence. A connection must be established for each shared device (drive or printer). NetBIOS requests may be sent native or may be encapsulated in TCP/IP or IPX/SPX.

Network Capabilities provided by Operating Systems

Common Application Interface Networking Issues  Identification of remote system/server  Determining the availability of remote system  Establish authority to communicate  Agreement on encryption mechanism  Authentication of the remote system  Selection of dialog discipline, such as initialisation and release protocol  Agreement on responsibility for error recovery  Identification of constraints on data syntax (character set, data structures, etc)

Windows Server  ASP  COM .NET –Intermediate Language (IL) –P2P technologies, disk groups –Web services for remote execution of code

Novell  CGI  Java  Perl  Cross platform connectivity with MS- Win, Linux, and MacOS.  Web-based access to files and printers.  Support for NDS

CYGWIN  Unix for Wintel  Secure shell (ssh) client  Secure shell daemon (sshd)  Secure FTP (sftp)  Secure copy (scp)  Mirroring tools e.g. rsync

Linux  Standard TCP/IP and Unix like environment  Virtually no licensing costs  Slightly more time consuming to administer  Developments at times lag behind the MS (owing to licensing restrictions)  Ideal for small business environments  Clustering