Page 109 - Handout Computer Network.

Figure 5-2 shown a Routing Protocol Metrics

The metrics of hop count, bandwidth, delay, reliability, load, and cost are calculated in various
combinations to determine the best path through an internetwork. Routers interconnect network
segments or entire networks. They pass data frames 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 to be encapsulated for transmission.
The encapsulation/ de-encapsulation process occurs each time a packet passes through a
router and data is sent from one device to another.

Encapsulation breaks the data stream into segments, adds the appropriate headers and
trailers, and transmits the data.
The de-encapsulation process is the opposite, removing the headers and trailers and then
recombining the data into a seamless stream. Routers take frames from LAN devices (for example,
workstations) and, based on Layer 3 information, forward them through the network.
A routing protocol operates as the following:

• It provides processes for sharing routing information.

• It allows routers to communicate with other routers to update and maintain the routing
tables.
Examples of routing protocols that support IP routed protocols include RIP, IGRP, OSPF, Border
Gateway Protocol (BGP), and EIGRP.