Page 145 - Handout Computer Network.

Computer Network 2026

Figure 6-16 shown a Distance Vector Routing Metric Components

6.7.1.1 Routing Updates Explained

Each router receives a routing table from its directly connected neighboring routers.

For example, Router B receives information from Router A. Router B adds a distance
vector number (such as a number of hops), which increases the distance vector and passes this
new routing table to its another neighbor router. This same step-by-step process occurs in all
directions between direct-neighbor routers.
A distance vector is comparable to the signs along a highway. Highway signs direct drivers
toward a destination and indicate the distance to that destination. Farther down the highway,
additional signs point toward the same destination, but now the distance is shorter. As long as
the distance continues to become shorter, the traffic is on the right path.

6.7.2 Link-State Routing Basics

The second basic algorithm used for routing is the link-state algorithm.

Link-state algorithms are also known as Dijkstras algorithm or as shortest path first (SPF)
algorithms. They maintain a complex database of topology information. Whereas the distance
vector algorithm has nonspecific information about distant networks and no knowledge of
distant routers, a link-state routing algorithm maintains full knowledge of distant routers and
how they interconnect.

Link-state routing uses the following:

• Link-state advertisements (LSAs)—Small packets of routing information that are
sent between routers

• Topological database—A collection of information gathered from LSAs

165