In Chapter 1, we learned that split horizon is a Distance Vector protocol feature that mandates that routing information cannot be sent back out of the same interface through which it was received. This prevents the re-advertising of information back to the source from which it was learned. While this characteristic is a great loop prevention mechanism, however, it is also a significant drawback, especially in hub-and-spoke networks. To better understand the drawbacks of this feature, we will refer to the EIGRP hub-and-spoke network in Figure 2-14: