PROTOCOLS ON LAYERS

PROTOCOLS ON LAYERS:
Protocols on Layers*Application Layer - (ASFAST) AFP SMNP FTP APPC SNMP TELNET and error RECOVERY. Applications, e-mail, into user apps, initiates and accepts requests, higher level protocols live here,*Presentation Layer Layer6 - Protocol conversion. The redirector lives here. Redirector grabs anything meant for network and not local PC, (files, prints anything) and redirects to layers for proccessing to right place. All the different formats from all sources and all kinds are made into like a uniform common format that the rest of the OSI model can understand. *Session layer - Layer5 - Syncs & sessions. Connects two computers and controls, who send when, for how long, how, speeds, and oversees total control of packets. TCP, NWLink, named pipes, netBIOS and remember that DLC lives here. This was one of the questions. Also remember that TCP (microsoft) is like SPX (Novell) and IP (microsoft) is like IPX (Novell). The above 3 layers are the application-level network service users. *Transport layer - (STANN) SPX TCP ATP NWLink NETBEUI "Trains" well I try and remember that the data streams breaks up into what looks like coaches of a train. The transport services layer. The error handling is done here. Different protocols have different requirements for length of data per packet, e.g. Token ring, Ethernet ATM all use different lengths and these are formed and reformed in this layerThe above 4 layers use gateways. There are Qs on which layers use ( i.e) App - Pres - Session - Trans. There are also Qs on Physical = Repeater (or hub) Data link layer = Bridge Network = Router *Network layer = (NINI) NWLink IP NETBEUI IPX Think of a big network, where the traffic is routed to, this being done by adding source and destination addresses, choosing best routes.(and uses routers.) *Data Link Layer layer - Look at the movies on the CD with Net essentials and see that DLL add CRC to other end of the data frames. Bridges work here, and the book is very terse on explanations. Basically the packets use network addresses (source and destination addresses) to get around; they can move around the world using logical addresses and are part of networking software, like Novell or Windows.This whole "network structure" actually sits on top of,( like another thing) ,on top of the LAN. The LAN being the basic underlying network, that's the nitty gritty physical network, where the the actual Network cards talk to each other. The LAN really is only local and the *DATA LINK LAYER controls it. DLL is split into two LOGICAL LINK CONTROL and MEDIA ACCESS CONTROL. This may seem difficult at first but its not too bad. Think that the Media Access Control (MAC) controls the type of media being accessed i.e. media being Token ring, Ethernet etc. also learn the 802.3~"Ethernet", 802.4 ~Arcnet (really only used by GM and obsolete), 802.5~Token ring, and 802.12 Fiber. The LOGICAL LINK CONTROL equates to 802.2 and is the "lowest level" controlling and managing the media. *Physical layer - Layer 1 This is the hardware and physical cables. Repeaters (or hubs) amplify attenuated or weak signal here. (Another gift Q.) It just has to send 0 and 1, hi's and lows, on's and off's. Data frames work at the two bottom layers and only inside the LAN using Physical or MAC addresses (usually factory or hard wired addresses). On page 176 looks like 10 of the gift Qs we got. These bottom 2 layers are called networking services. P179 talks about SAPs. *Protocols - Routable- IP, IPX, OSI, AppleTalk, DECnet, XNS. Non-routable- NetBEUI, LAT. NetBEUI- Microsoft protocol designed for small LANs; Nonroutable. IPX/SPX- Fast protocol for small and large Novell networks; is Routable. Also known in NT as NWLink. *TCP/IP- Internet protocol; is Routable. DECnet- Defines communications over FDDI MANs; is Routable. Appletalk- Apple protocol designed for small LAN file and print sharing. *XNS - Designed by Xerox as an Ethernet protocol. Was replaced by TCP/IP.