RIP Explained: The Original Routing Protocol
RIP (Routing Information Protocol) is the oldest and simplest dynamic routing protocol — a distance-vector protocol that picks routes purely by hop count (fewest routers to cross). Its simplicity made it historically popular, but its limitations made it obsolete for anything but the smallest networks.
How RIP works
Each RIP router periodically broadcasts its entire routing table to neighbours. Routes are rated by hop count — a route crossing 3 routers has metric 3. The lowest hop count wins, with a hard maximum of 15 hops (16 = unreachable), which caps the size of any RIP network.
Why it fell out of use
- Hop count ignores bandwidth — RIP prefers a 3-hop path over slow links to a 4-hop path over fast ones
- 15-hop limit — unusable in large networks
- Slow convergence — periodic full-table updates and slow reaction to failures
Link-state protocols like OSPF and advanced distance-vector EIGRP replaced it by using better metrics and faster convergence.
Why it's still taught
RIP is the simplest illustration of distance-vector routing, making it a useful teaching tool for concepts like split horizon and route poisoning — still occasionally appearing in CCNA. RIPv2 added subnet-mask support (classless) and multicast updates, but the fundamental limitations remain.
Frequently asked questions
Why is RIP considered obsolete?
Its hop-count metric ignores bandwidth, the 15-hop limit caps network size, and its convergence is slow — modern protocols like OSPF and EIGRP are far superior.
What is RIP's maximum hop count?
15 — a route requiring 16 hops is considered unreachable, which strictly limits how large a RIP network can be.
What is the difference between RIPv1 and RIPv2?
RIPv2 is classless (carries subnet masks), uses multicast instead of broadcast for updates, and supports authentication — RIPv1 lacked all of these.
Is RIP still used anywhere?
Rarely — only in very small or legacy networks. It's mostly retained as a teaching example of distance-vector routing.
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