Comment on the restrictions of the RIP Protocol

Although r I P has a long history, it still has its own limitations. It is very suitable for the early Internet computing routing; however, technological advances have greatly changed the way the Internet is built and used. Therefore, r I P will soon be eliminated by today's interconnected networks.

The maximum limits of r I P are:

A path longer than 1 5 hops is not supported.

Routing is calculated based on fixed metrics.

A strong response to route updates.

Relatively slow convergence.

Lack of dynamic and negative balancing support.

Hop count limit
R I P is designed for relatively small autonomous systems. In this way, it sets a strict Number of hops to 1 to 5. When a packet is forwarded by a routing device, its hop count counter will add the cost of the link to be forwarded. If the packet still fails to reach its addressing destination after the hop count reaches 1 5, the destination is considered inaccessible and the packet is discarded.

This effectively fixes the maximum network diameter of 1 5 hops. Relying on How to intelligently design the network, this value is large enough to build a fairly large network, but r I P is still strictly restricted compared with other more modern routing protocols. Therefore, if the network you want to build has many features but is not very small, r I P may not be the right choice.

Fixed measurement
The discussion of the number of hops paves the way for examining the next basic limitation of r I P, which is a fixed consumption measurement. Although the consumption metrics can be configured by the Administrator, they are static in nature. R I P cannot update them in real time to adapt to changes in the network. The consumption metrics defined by the Administrator remain unchanged until they are manually updated.

This means that r I P is particularly unsuitable for highly dynamic networks. In such an environment, routes must be calculated in real time to reflect changes in network conditions. For example, if the network supports time-sensitive applications, it is reasonable to use a protocol that can calculate routes based on measurable Transmission Line latency or load conditions on a given line. R I P uses a fixed metric, so it cannot support real-time route computing.

Strong response to route table updates
The r I P node does not broadcast its route table to the ground every 3 0 seconds. In a large network with many nodes, this consumes a considerable amount of bandwidth.

Slow convergence
From the perspective of people, it is not inconvenient to wait 3 0 seconds for an update. However, routers and computers run at a much faster speed than humans. You have to wait for 3 to 0 seconds for an update to produce obvious negative results. This can be seen in section 1 2. 3 of this chapter.

It is more destructive than simply waiting for 3 0 seconds for an update, but you have to wait for 1 8 0 seconds to invalidate a route. This is only the amount of time required for a router to begin convergence. The number of interconnected routers and their topology may need to be updated to completely converge to the new topology. The slow convergence speed of the r I P router creates many opportunities to broadcast invalid routes incorrectly as valid routes. Obviously, this will reduce network performance.

This chapter should fully show the risks caused by the slow convergence of r I P.

Lack of Load Balancing
Another obvious disadvantage of r I P is its lack of dynamic load balancing capabilities. Figure 1 9 shows a serial link between two routers. Ideally, the routers in the figure allocate traffic to the two serial links as equal as possible. This minimizes the congestion on the two links and optimizes the performance.

Figure vro with redundant serial links

Unfortunately, r I P cannot perform such dynamic load balancing. It uses a first known physical link. It forwards all packets on this link, even if the second link is available. The only way to change this is that the vro in Figure 1 receives a route update to notify it of a metric change to any destination. If the update indicates that the second link to the destination has the lowest cost, it will stop using the first link and use the second link.

R I P lacks the capability of Server Load balancer to restrict its use in small networks. A simple network usually features almost no redundant routing. Therefore, Server Load balancer is not a design requirement and is not supported.

Summary
The ease of configuration, flexibility, and ease of use of r I P makes it a very successful routing protocol. Since the development of r I P, it has made great strides in computing, networking and interconnection technologies. The accumulation effect of these advances makes r I P a popular protocol. In fact, many routing protocols in use today are more advanced than r I P. Although these protocols are successful, r I P is still a very useful routing protocol, provided that you understand the actual meaning of its shortcomings and can use it correctly.

Related Articles]

• Getting Started: RIP route protocol Quick Start

• Implementation of collaboration between r1_1 and r1_2

• Overview of route selection protocols, RIP, and IGRP