There are two types of loops that exist in routed networks. These loops are applicable to both IGPs and BGP. Given that IGP loop prevention mechanisms are described in detail in previous chapters, this chapter focuses exclusively on BGP loop prevention. The two types of loops are:
- Routing Information Loops
- Routing Loops
Routing information loops are loops that occur when routing information is both received and accepted by the router that advertised it. Figure 6-20 illustrates a routing information loop: