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2.2 Identify the seven layers of the OSI Model and their functions.

OSI Model

Layer	Layer Name	Header	Protocols & Services	Details
7	Application (All)	Protocol Data Unit	Telnet, FTP, SMTP, HTTP, File and Print, E mail, (WWW), EDI, SMB, NCP	User requests network services here. Database and application services but not the applications.
6	Presentation (People)	Protocol Data Unit	ASCII, EBCDIC, TIFF, JPEG, GIF, PICT, MIDI, MPEG, QuickTime	Data representation and translation. Formats data for “presentation” to the layers above and below. Encryption, compression and translation.
5	Session (Seem)	Protocol Data Unit	RPC, ZIP, SCP, SQL, X Window, NetBIOS, NFS, ASP, DNA SCP	Establishes, maintains and manages communication sessions between computers. Think dialog control.
4	Transport (To)	Segments	TCP, NBP, UDP, NCP, SPX, ADP, Windowing, flow control, synchronization	Reliable transmission of data segments. Sets the stage for disassembly and assembly of data before and after transmission. Remember: end-to-end connectivity.
3	Network (Need)	Datagrams or Packets	IP, IPX, RARP, ARP, BootP, DHCP, ICMP, BGP, OSPF, RIP.	If it’s routing, it takes place here. Decides how data will be routed across the network, in addition to the structure and use of logical (IP) addressing. Routers operate here.
2	Data Link Sublayers are MAC and LLC (Data)	Frames	MAC, LLC, Frame Relay, LAPB, PPP, calculating CRC or FCS, controls access to the physical medium	Deals with the links and mechanisms to move data. Topology (Ethernet or Token Ring) is defined here. Switches and Bridges operate here. Remember: Framing.
1	Physical (Processing)	Bits (1s and 0s)	Ethernet, Token Ring, HSSI, 802.3, bit synchronization, physical connector specifications.	The electrical and physical specifications for the network media that carry data bits across a network. Hubs and repeaters operate here.

Yellow=Upper Layers
Blue=Lower Levels

Doing it in Layers Part I: The Beginners Guide to the OSI Model
Doing it in Layers Part II: The beginners Guide to Those “Other” Reference Models
Webopedia’s Breakdown of the OSI Model - great for flash cards ;-)

2.3 Differentiate between the following network protocols in terms of routing, addressing schemes, interoperability, and naming conventions:

TCP/IP
IPX/SPX
NetBEUI
AppleTalk

TCP/IP

Routing
Uses IP address of the sender, the recipient and the next router to determine path. Routers build routing tables using RIP or OSPF. WINS determines a device’s IP address.
Addressing
IP or network addressing. (For example: 131.10.6.2) ARP resolves IP addresses to MAC Addresses. TCP resides at Layer 4 while IP resides at Layer 3.
Interoperability
No protocol is more interoperable than TCP/IP. As the protocol of the Internet, it is easily the most widely use protocol. The protocol is turning up more and more in non-traditional network settings, such as vending machines and household systems.
Naming
Named via DNS conventions, which resolves hostnames to IP addresses. For instance, www.cramsession.com is rendered 63.146.189.41. DNS commonly has at least two parts, the host (or service) name (www) and the domain name (cramsession.com).

IPX/SPX

Routing
Routers that can route TCP/IP usually can route IPX/SPX. Routing protocols are RIP and NLSP.
Addressing
Uses each node’s 12-digit hexadecimal address as it exists on a given segment, which will itself be represented by its own unique 8-digit hexadecimal IPX network address.
Interoperability
Not as flexible as TCP/IP, but the IPX/SPS protocol stack can communicate with a number of clients, including Windows and Linux. However, many versions of Unix and other high-end operating systems, such as OS/400, don’t come with support built in for the IPX/SPX protocol stack or even give you the option for support.
Naming
The only devices that will have names are the servers. Any name may be used, so long as the name includes no “illegal” characters (no periods [.], commas [,], plus signs [+], equal signs [=] or backslashes [\]). and are less than 64 characters (or 47 characters in older versions of NetWare). IPX/SPX names are not case sensitive. Names are resolved using Bindery Services or Novell Directory Services (NDS).