RIP (Routing Information Protocol)

🤔 What is RIP? (Basic Idea)

In a network with many routers:

• Routers must decide which path to use

• They need to share routing information

📌 RIP helps routers learn routes automatically.

🧠 Simple Definition

📌 RIP (Routing Information Protocol) is a distance-vector routing protocol that uses hop count as a metric to determine the best path to a destination.

🧠 Why RIP is Needed?

Without a routing protocol:

• Routes must be added manually

• Network becomes hard to manage

• Errors increase ❌

👉 RIP allows routers to:

• Share routes automatically

• Adapt when network changes

🧠 Real-Life Analogy

🗺️ City Navigation

• Each junction tells you:

  • “Destination X is 3 roads away”

• You choose the route with fewer roads

👉 Roads = hops

👉 RIP works the same way.

🧭 Where Does RIP Work?

• RIP is a Network Layer protocol

• Runs on top of UDP

• Uses port 520

📏 Routing Metric Used by RIP

📌 Hop count = Number of routers a packet must pass through

👉 Lowest hop count = Best path

🚫 Maximum Hop Count Limitation

📌 RIP supports maximum 15 hops only.

❌ Not suitable for:

• Large networks

• Complex topologies

🔄 How RIP Works (Step-by-Step)

1️⃣ Router starts and knows only directly connected networks

2️⃣ Router sends routing table to neighbors

3️⃣ Neighbors update their tables

4️⃣ Tables exchanged every 30 seconds

5️⃣ Network converges

📌 This periodic update keeps routes fresh.

📦 What Information Does RIP Share?

Each routing entry contains:

• Destination network

• Hop count

• Next hop

📌 RIP does not share bandwidth or delay info.

🔁 Distance Vector Routing

RIP follows distance-vector routing:

• Distance → Hop count

• Vector → Direction (next router)

📌 Routers only know:

• Distance to destination

• Next hop

🧠 Problems with RIP

🛡️ Techniques Used to Reduce RIP Problems

🔕 Split Horizon

• Do not advertise route back to where it came from

🔄 Route Poisoning

• Mark failed route as unreachable (16 hops)

⏱️ Hold-Down Timer

• Ignore unstable updates temporarily

🧠 Versions of RIP

⚖️ RIPv1 vs RIPv2

🔐 Security in RIP

• RIPv1 → No security

• RIPv2 → Supports simple authentication

📌 Still weaker than modern protocols.

🧠 RIP vs Modern Routing Protocols

🧠 Memory Tricks

• RIP = Router Information Protocol

• Hop count = Distance

• 15 = Max hops

• 16 = Dead route ☠️

⭐ One-Line Summary

🔹 RIP is a distance-vector routing protocol that selects routes based on minimum hop count, suitable only for small networks.