By Cindy Kvek
There are two basic types of addresses used in Local Area Networking (LAN): logical addresses and physical addresses. Understanding the differences between the two addresses begins with developing an understanding of the following terms.
1. Address Resolution: A support function to assist the network devices to match the correct physical address to a known logical address. The physical address is the final piece of information required to complete the frame to be sent. AppleTalk uses AARP, and TCP/IP uses address resolution protocol (ARP). IPX does not use address resolution.
2. BOOTP: A configuration service used to provide an IP logical address and configuration information to a device over the network. This configuration is static and must be manually entered into the BOOTP server, using the physical address as identification of each device. The server will then send the BOOTP configuration as the device requests it, using the physical address as unique identification.
3. DHCP: A configuration service used to provide an IP logical address and configuration information to a device over the network. The configuration is leased for a specified period of time and, based on server configuration, may require renewal. DHCP and BOOTP services may be provided from the same server.
4. Frame: The combination of Layer 2 headers used to carry the packet from the original source logical address to the final destination. The Layer 2 physical addresses are used to identify the next network device the packet must be passed to toward the destination logical address.
5. IPX: Internetwork Packet Exchange/Sequenced Packet Exchange, usually identified as IPX/SPX. A Layer 3 protocol identified by Novell, Inc., to network Novell servers and clients. This protocol may still be in use, but Novell has updated their servers to support TCP/IP also.
6. LAN: Local Area Network. A LAN is a network and may refer to the entire network or a logical segment of the network. A LAN is the intranet of a business or home network local to the connected network devices.
7. Layer: Layer, used with a number, it identifies a reference layer of the Open System Communication (OSI) model. This model uses Layer 1 - 7 to identify the network functionality for hardware and software, including physical and logical addressing. Layer 2 (data link layer) identifies the functions of physical addressing and Layer 3 (network layer) identifies the functions of logical addressing.
8. Name Server: A service configured to support the matching of known names to logical addresses. This is a support function within a network to assist the devices to get the correct logical address to add to a message.
9. Protocol: A set of rules. Each different protocol uses a different set of rules.
10. Packet: The combination of the headers used to carry the payload or message from the original source to the final destination. A packet must be enveloped in a frame to help the physical network pass the packet.
11. Routed protocol: The set of rules of the Layer 3 protocol used to create the packet of the frame that carries the message.
12. Routing protocol: The set of rules of the router configuration used to choose the best path toward the destination network logical address. The routing protocol creates a routing table within the router to be used for path determination.
13. Routing Table: Each router, following the rules of the routing protocol, builds a table of logical network and logical area address. This table is used to help the router choose the best forwarding path toward the final destination device, based on the best match to the destination logical address identified in the Layer 3 header of the packet.
14. Subnet: A TCP/IP logical group of devices connected to the same network and divided by a router from other logical groups within the network. A broadcast domain is an identified function of a subnet.
15. TCP/IP: Transmission Control Protocol/Internet Protocol is a Layer 3 protocol used on the Internet and most other networks in the world today. There are two versions, IPv4 and IPv6. Each version differs at Layer 3. The need for additional IP addresses prompted the creation of IPv6.
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