Layer 3 - Network Layer
The network layer is responsible for moving data through a set of networks (internetwork). The destination of data as it moves through the networks is determined by its addressing scheme.198
Protocols of this layer use a hierarchical addressing scheme that allows for unique addresses across the network with a method for finding a path for data to travel between networks, while MAC addresses use a flat addressing scheme that makes it difficult to locate devices on other networks.
Routers are the primary internetworking devices that operate at Layer 3. They interconnect network segments or entire networks and pass data packets between networks based on Layer 3 information. Routers make logical decisions regarding the best path for the delivery of data on an internetwork and then direct packets to the appropriate output port and segment. Routers take packets from LAN devices (usually Ethernet interface) and forward them through the network (usually Serial synchronous interface)
Path determination is what enables a router to evaluate the available paths to a destination, and to establish the preferred handling of a packet. Routing services use network topology information when evaluating network paths. Path determination is the process that the router uses to choose the next hop in the path for the packet to travel to its destination (routing the packet).
Home - Table Of Contents - Contact Us
CertiGuide to A+ (A+ 4 Real) (http://www.CertiGuide.com/apfr/) on CertiGuide.com
Version 1.0 - Version Date: March 29, 2005
Adapted with permission from a work created by Tcat Houser et al.
CertiGuide.com Version © Copyright 2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.