[Day 7] 4. Drawbacks Of RIP

1. Pinhole Congestion

• Issue: RIP relies on hop count to route traffic, without considering factors like bandwidth or path load. This leads to pinhole congestion.
• Result: Even if there are multiple paths available, RIP might route all traffic through a single path, causing congestion on that path.
• Example:
  • Router A has two paths to Router D: A → B → D and A → C → D.
  • RIP might route all traffic through A → B → D, even though A → C → D is also available and less congested.
  • This causes congestion at Router B, the "pinhole," leading to inefficient traffic distribution.

2. Subnet Mask Issue

• Problem: In RIP v1, subnet masks are not included in routing updates. All entries in the RIP routing table assume the same subnet mask as the first entry.
• Result: This can cause routing issues, especially in networks that use Variable Length Subnet Masking (VLSM) or Classless Inter-Domain Routing (CIDR). Incorrect routing may occur if different subnets or subnet masks are used within the same RIP domain.
• Note: RIP v2 resolves this by including subnet masks in routing updates.

3. Routing Loops and Count to Infinity

• Problem: RIP is vulnerable to routing loops, where data packets endlessly circulate in the network due to incorrect routing table entries.

• Result: When a router updates its routing table with incorrect routes, the data keeps circulating without reaching its destination. This is especially problematic in large networks with multiple paths.

• Example: If Router A and Router B have incorrect routing updates, packets could loop between the two without reaching the destination.

• Count to Infinity: When a routing loop is detected, RIP uses the "infinity" count (16 hops) to indicate an unreachable destination. However, this still leads to network delays and inefficiencies as it takes time for the routers to reach the "infinity" state.

4. Limited Scalability

• Issue: RIP is not suitable for large networks because it is limited to a maximum of 15 hops.
• Result: Networks with more than 15 hops cannot be properly routed using RIP, limiting its scalability in large networks.
• Example: In larger enterprise networks or ISP backbone networks, RIP would not be able to provide effective routing due to its 15-hop limitation.

These drawbacks highlight why RIP is considered less efficient and scalable compared to more advanced routing protocols like OSPF or EIGRP.