The BGP decision process uses some of the PAs listed in Table 13-7, as well as several others. This section focuses on the decision process as an end to itself, with only brief explanations of new features or PAs. Following that, the text explains the details of some of the PAs that have not yet been covered in the book, as well as some other details that affect the BGP decision process. When a BGP router learns multiple routes to the same NLRI, it must choose a single best r..
CIDR, Private Addresses, and NAT
The sky was falling in the early 1990s in that the commercialization of the Internet was rapidly depleting the IP Version 4 address space. Also, Internet routers’ routing tables were doubling annually (at least). Without some changes, the incredible growth of the Internet in the 1990s would have been stifled. To solve the problems associated with this rapid growth, several short-term solutions were created, as well as an ultimate long-term solution. The short-term solution..
Legacy Layer 3 Queuing Mechanisms
There is a long history of queuing algorithms in Cisco IOS Software, not all of which are covered in this chapter because they are not applicable to QoS deployment for converged networks. Newer queuing and scheduling algorithms are simply combinations and enhancements of older queuing algorithms. For a historical perspective and an understanding of why these mechanisms are insufficient for today's converged networks, it is helpful to review some of these legacy queuing techni..
NTP is used for accurate time-keeping and can, for example, reference atomic clocks that are present on the Internet. NTP is capable of synchronizing clocks within milliseconds and is a useful protocol when reporting error logs (for instance, from Cisco routers). NTP is useful for security/incident event correlation across multiple security devices and helps to determine the exact time of the event. For NTP, the defined ports are UDP port 123 and TCP port 123. NTP can ..
For this recipe, we must configure Multicast capabilities on all of the different types of routers: C, CE, P, and PE. Router-C-An#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router-C-An(config)#ip multicast-routing Router-C-An(config)#interface FastEthernet0/0 Router-C-An(config-if)#ip address 192.168.5.12 255.255.255.0 Router-C-An(config-if)#ip pim sparse-dense-mode Router-C-An(config-if)#exit Router-C-An(config)#end Router..
