The BGP topology table, also called the BGP Routing Information Base (RIB), holds the network layer reachability information (NLRI) learned by BGP, as well as the associated PAs. An NLRI is simply an IP prefix and prefix length. This section focuses on the process of how BGP injects NLRI into a router’s BGP table, followed by how routers advertise their associated PAs and NLRI to neighbors. NOTE Technically, BGP does not advertise routes; rather, it advertises PAs plus a..
The first CB Marking example uses the network shown in Figure 14-5. Traffic was generated in the network to make the show commands more meaningful. Two G.711 voice calls were completed between R4 and R1 using Foreign Exchange Station (FXS) cards on these two routers, with Voice Activity Detection (VAD) disabled. Client1 performed an FTP get of a large file from Server1, and downloaded two large HTTP objects, named important.jpg and not-so.jpg. Finally, Client1 and Server1 h..
Building the Backbone Topology
Because you have a basic need for resilience in the backbone, a good starting point for the backbone topology is a ring connecting all distribution networks. This ring could represent the minimum cost of WAN circuits, compromised by an initial estimate of major traffic flows, and possibly some very particular delay requirements (although this is rare, with notable exceptions being high-performance networks). Next, existing links can be fattened, or direct connec..
Sometimes funny things happen when the primary link comes back and the backup link has not yet disconnected. These problems are usually due to poor routing metrics, causing at least one of the routers to prefer the dial path, even if the primary is available. The easiest way to handle these problems is to use bandwidth commands to ensure that the primary is the better path: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router1..
Using the area x range configuration command on your ABRs allows you summarize routes between OSPF areas: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router1(config)#router ospf 55 Router1(config-router)#area 100 range 172.20.0.0 255.255.0.0 Router1(config-router)#area 0 range 172.25.0.0 255.255.0.0 Router1(config-router)#area 2 range 10.0.0.0 255.0.0.0 Router1(config-router)#exit Router1(config)#end Router1# The easiest way..
