RIP
Course Description
RIP (Routing Information Protocol) is an old distance vector routing protocol. It uses hop count as its metric, and a network that is more than 15 hops away is unreachable. Both versions send their full routing table every 30 seconds. Version 1 is classful and uses broadcast; version 2 is classless, uses multicast, and supports authentication and manual summarization. RIP converges slowly compared to other IGPs (Interior Gateway Protocols) like OSPF, EIGRP, and IS-IS, so you won’t find it in many networks anymore. It’s still a great protocol to start with if you are new to routing protocols, because it shows you how distance vector routing works and why it needs loop prevention. We start with the basics of RIP and then cover some more advanced topics.
Course Highlights
In this course you will learn:
- How distance vector routing protocols work, and how RIP uses hop count as its metric.
- How to configure RIP version 1 and 2, and the difference between classful and classless updates.
- How split horizon, route poisoning, poison reverse, and holddown prevent routing loops.
- How the RIP update, invalid, holddown, and flush timers work together.
- How to use passive interfaces, equal cost load balancing, and offset lists.
- How to advertise a default route, and how to make it reliable with IP SLA.
- How to summarize RIP routes and troubleshoot missing routes.
- How to redistribute between RIP, OSPF, and EIGRP.
- How RIP behaves as a PE-CE protocol in MPLS VPNs and on DMVPN.
Presented to you by instructor Rene Molenaar, CCIE #41726
Course at a glance
- 15 lessons in 5 units.
- Format: self-paced lessons with Cisco IOS configurations, debug output, and video.
- Last updated: October 2026.
Requirements
- No RIP knowledge required; we start from the beginning.
- Basic knowledge of IP addressing, subnetting, and how routers forward packets.
Course Schedule
What is RIP?
RIP (Routing Information Protocol) is a distance vector routing protocol. Distance means the metric: how far away a network is. Vector means the direction: which interface and next hop to use. RIP uses hop count as its metric, which is simply the number of routers you have to pass to reach a destination. Every 30 seconds, each RIP router sends a copy of its routing table to its neighbors, and they add one hop to everything they learn.
A RIP router only knows what its neighbors tell it; it has no map of the network like OSPF has. That makes RIP vulnerable to routing loops and the counting to infinity problem. RIP deals with this through a maximum hop count of 15 (16 means unreachable), split horizon, route poisoning, poison reverse, and holddown timers. These mechanisms work, but they also make RIP slow to converge: with the default timers, it can take minutes before a failed route disappears from the routing table.
Who uses RIP? Not many networks anymore. You might still find it in small or old networks, sometimes as the routing protocol between a customer and a service provider, or in a network that needs to be migrated to OSPF or EIGRP. RIP is still valuable to learn: it’s simple to configure, and it teaches you the distance vector concepts that you’ll need to understand EIGRP and BGP.
RIP Learning Roadmap
This roadmap follows the course units. Each topic has a short explanation and links to the lessons where we cover it in detail.
RIP Fundamentals
We start with how distance vector routing works and how RIP builds its routing table from the updates of its neighbors. You configure RIP with the network command, which decides both which networks are advertised and on which interfaces RIP sends updates; a passive interface stops those updates where you don’t need them. RIP version 1 is classful and doesn’t send a subnet mask, so you’ll see why you want version 2 with no auto-summary. When RIP has multiple paths with the same hop count, it load balances over them, by default over a maximum of 4 paths.
RIP Timers and Troubleshooting
RIP uses four timers: update (30 seconds), invalid (180 seconds), holddown (180 seconds), and flush (240 seconds). Because the invalid and flush timers start at the same time, a route that is in holddown is removed after only 60 seconds. RIP doesn’t form a neighbor adjacency like OSPF or EIGRP, so most RIP problems are about missing routes: wrong network commands, passive interfaces, version mismatches, authentication, split horizon, and auto-summarization. You’ll learn how to troubleshoot RIP step by step, and why RIP packets have a TTL of 2.
Default Routes, Summarization and Metrics
If your network has a single exit point, RIP can advertise a default route with the default-information originate command. With IP SLA and object tracking, you can make sure RIP only advertises that default route when the next hop is reachable. Summarization reduces the number of routes you advertise, and in RIP you configure it per interface. Since hop count is the only metric, the offset list is the tool to make one path look worse than another.
RIP Redistribution
Old networks that still run RIP often need to exchange routes with OSPF or EIGRP, for example during a migration. That’s what redistribution is for, and we configure it between OSPF and RIP and between EIGRP and RIP. When you redistribute into RIP, the default seed metric is infinity, so you have to set a hop count yourself or your redistributed routes won’t show up.
RIP over MPLS VPN and DMVPN
RIP can be the routing protocol between a customer (CE) and a service provider (PE) router in an MPLS VPN. The PE routers redistribute RIP into BGP, and BGP carries the hop count in its MED so it can be restored on the other side. On DMVPN phase 1, split horizon on the hub stops spoke routes from reaching the other spokes, so you’ll see how to fix that, or simply advertise a default route from the hub.
Frequently Asked Questions
RIP (Routing Information Protocol) is one of the oldest routing protocols. It’s a distance vector protocol that uses hop count as its metric and sends its routing table to its neighbors every 30 seconds. It’s simple to configure, but slow to converge compared to OSPF or EIGRP. Read our introduction to RIP.
Each RIP router starts with only its directly connected networks. Every 30 seconds, it sends its routing table to its neighbors, who add one hop to every network they learn and install the best routes in their own routing table. After a few rounds, every router knows how to reach every network and how many hops away it is.
The maximum hop count in RIP is 15. A network with a hop count of 16 is considered unreachable. This limit stops the counting to infinity problem, but it also means RIP can’t be used in networks where a destination is more than 15 routers away.
RIP version 1 is classful: it doesn’t include the subnet mask in its updates, and it uses broadcast. RIP version 2 is classless, sends the subnet mask, uses multicast address 224.0.0.9, and supports authentication and manual summaries. Version 2 still summarizes automatically at classful boundaries until you configure no auto-summary. Learn how to configure RIP version 2.
RIP uses four timers: update (30 seconds), invalid (180 seconds), holddown (180 seconds), and flush (240 seconds). When a router stops receiving updates for a route, the route becomes invalid after 180 seconds and is removed when the flush timer expires at 240 seconds. See the RIP timers in action.
Split horizon is a loop prevention rule for distance vector protocols: a router doesn’t advertise a route back out of the interface where it learned it. RIP also uses route poisoning, which advertises a failed network with a metric of 16, and poison reverse, where the neighbor sends that poisoned route back. Route poisoning overrules split horizon.
Rarely. Most networks use OSPF, EIGRP, or IS-IS internally, because they converge faster and scale better. You may still find RIP in small or old networks, or between a customer and a service provider, and it’s still a good protocol to learn how distance vector routing works.
RIP is a distance vector protocol that uses hop count and only knows what its neighbors tell it. OSPF is a link-state protocol: every router has a complete map of its area and calculates the lowest cost path based on bandwidth. OSPF converges much faster, scales to large networks with areas, and has replaced RIP in most networks. Learn more about OSPF.
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