BGP route-map cache entries using 0 bytes of memory 0 BGP filter-list cache entries using 0 bytes of memory BGP using 188085279 total bytes of memory Dampening enabled. 850 history paths, 742 dampened paths 182190 received paths for inbound soft reconfiguration BGP activity 192312/9965 prefixes, 4364639/900253 paths, scan interval 60 secs There are 182,347 network entries on this route server. It is reasonable to assume that any router connected to the Internet that is receiving full tables will contain a similar number of network entries. Notice also the fourth line: 182347 network entries using 18417047 bytes of memory Those entries are taking up 18.4 MB of memory in the router. More importantly, any time a change is made to the paths to any of these networks, the entire world of BGP- connected routers must be notified. CIDR comes into play on the Internet because it helps to make these massive tables smaller. It also helps smaller networks (and, more importantly, their administra- tors), by making local routing tables smaller. Smaller routing tables are more logical, easier to understand, and much simpler to troubleshoot during outages. Allocating IP Network Space One of the problems I've seen repeatedly over the years is improper allocation of IP network space. Whether the trouble is the use of public IP addresses that are not rightfully owned, or just a lack of understanding of the benefits of proper IP alloca- tion, a poorly designed IP network can cause daily headaches and increased trouble- shooting time. And because a poorly designed IP scheme can take months to rectify, the problem usually gets worse over time because no one wants to take on the task of renumbering the entire network. Allocating IP Network Space There are some simple rules that can help when designing a network using IP address space. Here is the first one: When allocating IP address space, endeavor to allocate a block that can be referenced with a single access-list entry. Following this simple rule will make everything from server all