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Routing and need of routing protocol

Short answer

Routing selects the best path for packets. Dynamic routing protocols automatically build routing tables, adapt to topology changes, select optimal paths using metrics, scale to large networks, avoid loops, and enable load balancing without manual configuration.

What is routing? Why is a routing protocol necessary?

Routing

Routing is the process of selecting the best path along which a packet travels from the source network to the destination network across an internetwork. It is the main function of the network layer and is done by routers using routing tables.

Why a routing protocol is necessary

  1. Automatic building of routing tables: in a large network, entering routes by hand (static routing) is not practical. A routing protocol lets routers exchange information and learn routes themselves.
  2. Adapting to changes: if a link fails or a new network is added, the protocol updates the tables (dynamic routing), giving fault tolerance.
  3. Best path selection: it uses metrics such as hop count, bandwidth, delay and cost to select the optimal route.
  4. Scalability: the Internet has millions of networks, which no administrator can configure by hand.
  5. Load balancing and reliability through alternative routes.
  6. Loop avoidance and consistent view of the network by all routers.

Examples: RIP, OSPF (interior); BGP (exterior).

✓ Answer checked by Claude Opus 5.5 (high effort)

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