OSPF creates adjacencies between neighboring routers for the purpose of exchanging routing information. Not every neighbor becomes adjacent in a broadcast environment. The Hello protocol is responsible for establishing and maintaining an adjacency. Hello packets are sent periodically out all router functional interfaces. Two-way communi-cation is established when the router is listed in the neighbor's Hello packet. On broadcast and NBMA networks, Hello packets are used to el..
To modify U.S. routers, configure R2, R3, and R4 as the backbone routers because they are connected to the backbone routers defined in Europe. At this point, it is a good idea to move one of the three U.S. circuits from R1 to R13, so that it has a connection to the United States. If R1 goes down, there is only one connection to the United States left, via R9. The link between R9 and R2 is slow, so losing R1 means that all high-speed links to the United States ar..
Continuing the example from the previous chapters, the fictitious company ABC, Inc., already is correctly classifying and marking all 11 classes of traffic from the QoS Baseline Model within its campus. Such marking is being performed at Layer 3 via DSCP. Furthermore, dual-rate policing is used within the campus so that certain AF classes of traffic can be marked down to a second level of drop preference (for example, AF21 can be marked down to AF22). Additionally, the WAN ag..
Implementing Custom Queuing on a router is a two-step procedure. First, you must define the traffic types that will populate your queues. And then you apply the queuing method to an interface: Router#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#access-list 103 permit ip any any precedence 5 Router(config)#access-list 104 permit ip any any precedence 4 Router(config)#access-list 105 permit ip any any precedence 3 Router(..
You can use the offset-list configuration command to modify the metrics of routes that EIGRP learns through a particular interface: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z.Router1(config)#access-list 22 permit 192.168.30.0Router1(config)#router eigrp 55Router1(config-router)#offset-list 22 in 10000 Serial0.1Router1(config-router)#exitRouter1(config)#endRouter1# This command can also modify the EIGRP metrics of routes as the..
