Microsoft Networking Model
Microsoft network model
Microsoft networking is modular to make it flexible. NT components work through interfaces that are called boundary layers. These boundary layers provide a way for the network component layers to communicate. The boundary layers (interfaces) are software specifications. Microsoft's model uses component layers different than the OSI network model. Components and boundary layers are.
- User mode applications is a component used by applications.
- Programming interfaces is a boundary layer which interface to User mode applications above and file system drivers below. Supports NetBIOS, Windows Sockets, RPC, and NetDDE.
- File system driver component (session and presentation layers). This is the layer where the redirector works to direct access to a remote computer when required. Named pipes, server service, workstation service, and mailslots.
- Transport driver interface (TDI) is a boundary layer making transport protocols look the same to the upper layers.
- Transport protocol component (Transport and network layers). TCP/IP, AppleTalk, NetBEUI, IPX/SPX
- Network Driver Interface Specification (NDIS) is a boundary layer running on top of the network drivers, deciding which protocol to use.
- Adapter driver component (data link layer)
The layers are:
- File System Driver - This component supports the inter process communication mechanisms talked about in the next section. It is also called the redirector layer since the I/O manager redirects the resource request in this layer. The remote resource request is directed to the NT network redirector (RDR.SYS). This service, called a workstation service automatically runs on NT.
Since the resource request may be for a resource on a server that supports a different protocol, various redirectors may be installed to allow redirection to support the various services. The Client Services for NetWare (CSNW) redirector performs file and print sharing for Netware computers at the file system layer. It will locate the correct binding to send the message to NetWare based computers.
- Network Protocol Layer (Transport protocol) - Creates the packets of data which are sent from one computer to another on a network. NT supports:
The first three protocols may be used by NetBIOS (Network Basic Input Output system) for the data transport layer support.
- NetBEUI - NetBIOS Extended User Interface works at the transport layer and provides data transportation. It is not a routable transport protocol.
- TCP/IP - When NetBIOS uses TCP/IP for the transport protocol, it is called NBT (NetBIOS over TCP/IP) and is generally used on large networks.
- NWLink - Microsoft’s 32-bit implementation of IPX/SPX and is normally used on medium sized networks. The Client Services for NetWare (CSNW) redirector performs file and print sharing for Netware computers at the file system layer.
- Data Link Control (DLC) - The protocol for SNA mainframes and does not support higher level protocols but can be uset to allow migration to NT.
- Network Adapter (NIC) Layer (Adapter driver) - Microsoft requires an NDIS-4.0 compatible driver
The user mode interface determines the file system the user is requesting
It is a specification which makes all transport methods look the same to redirectors and filesystems. It interfaces the redirector layer (file system driver layer) and the transport protocol layer. Any director can bind the proper protocol using this interface to access the correct resources whether the protocol be accessed over NetBEUI, NWLink, or TCP/IP. This layer makes the redirector independent of the installed protocols.
Network Driver Interface specification (NDIS) current version 4.0. It provides the interface between card drivers and the transport protocol and allows several adapter drivers to use any number of transport protocols.