| The following scenarios and questions are designed to draw together the content of the chapter and to exercise your understanding of the concepts. There is not necessarily a right answer. The thought process and practice in manipulating the concepts are the goals of this section. The answers to the scenario questions are found at the end of this chapter. Scenario 16-1 The company Humugos has successfully implemented iBGP in each country that it operates in, with eBGP connecting the autonomous systems. The company now wants to change the way it connects to the Internet. Currently, it has one connection into the Internet per autonomous system. Figure 16-11 provides the diagram for the network in this scenario. Figure 16-11. Diagram for Scenario 16-1  | 1: | Give reasons to support Humugos's desire to have multiple connections to the Internet. | | 2: | The company has been advised to redistribute static routes into the Internet BGP. It had intended to redistribute dynamic OSPF routes directly into the ISP provider. Explain why the ISP was not in favor of this configuration. | | 3: | Using Figure 16-11, issue the configuration commands that would allow Router B connecting into the Internet to select the path to network 78.9.80.0 via Router G. Use the local preference attribute to select the path . |
NOTE This network scenario is oversimplified for learning purposes. Normally, it would be very difficult to obtain multiple autonomous system numbers from the Internet. Private autonomous system numbers would have to be used, which would make connections into the Internet complex.
Scenario 16-2 The ISP Interconnect Corp. is a startup company that is configuring its network. The company has a well-resourced network and is in the process of configuring the iBGP within the autonomous system. Figure 16-12 provides the diagram for the network in this scenario. Figure 16-12. Diagram for Scenario 16-2  | 1: | The original design required a fully meshed iBGP network. This was calculated to mean 250 connections, which was deemed unacceptable because it would be too great of a drain on resources. Route reflectors are obviously the answer. Configure Router A to run BGP and act as a route reflector to clients B and C. | | 2: | Configure Routers B and C to run BGP as clients to Router A. | | 3: | Having configured the cluster, are any other tasks necessary? | | 4: | The company has decided in its early stages to require organizations connecting into it to use default routes. How would these routes be disseminated without the organization's autonomous system, and how would an interior router running only an IGP determine which path out of the routing domain to take if it had more than one connection? | | 5: | Given that the use of a default route by the client organization gives it the least configuration power to manage and manipulate its traffic flow, how would the network administrator justify this simple approach? |
Scenario 16-3 Review output screens in Examples 16-10 and 16-11, and answer the questions that follow. Example 16-10. Scenario 16-3 Output Screen 1 Router# show ip prefix-list detail tryout ip prefix-list tryout: Description: tryout-list count: 1, range entries: 0, sequences: 5 - 10, refcount: 3 seq 5 permit 130.0.0.0/8 (hit count: 0, refcount: 1) seq 10 permit 44.0.0.0/8 (hit count: 28, refcount: 1) Example 16-11. Scenario 16-3 Output Screen 2 Router# show ip bgp BGP table version is 457017, local router ID is 200.172.136.21 Status codes: s suppressed, d damped, h history, * valid, > best, i internal Origin codes: i - IGP, e - EGP, ? incomplete Network Next Hop Metric LocPrf Weight Path *> 7.2.0.0/16 144.39.228.49 0 100 701 I *> 17.14.96.0/24 144.39.128.7 0 100 99 17I *> 17.4.126.0/24 144.39.228.49 0 100 701 I *> 17.96.91.0/24 144.39.228.49 0 100 701 I *> 33.48.2.0/23 144.39.228.49 0 100 701 I *> 33.48.7.0/24 144.39.228.49 0 100 701 I *> 33.48.8.0/24 144.39.228.49 0 100 701 I *> 33.48.14.0/24 144.39.228.49 0 100 701 I *> 33.48.123.0/24 144.39.228.49 0 100 701 i *> 33.48.124.0/23 144.39.228.49 0 200 701 I *> 33.48.124 0/23 144.39.128.7 0 100 99 17 i *> 33.48.176.0/20 144.39.228.49 0 100 701 i *> 33.49.32.0/23 144.39.228.49 0 100 701 i *> 33.49.35.0/24 144.39.228.49 0 100 701 i *> 33.49.36.0/23 144.39.228.49 0 100 701 i *> 33.96.0.0/18 144.39.228.49 0 100 701 i *> 33.143.24.0/21 144.39.228.49 0 100 701 i *> 33.154.0.0/18 144.39.228.49 0 100 701 i *> 33.216.0.0/24 144.39.228.49 0 100 701 i *> 33.216.0.0/19 144.39.228.49 0 150 701 i | 1: | Using Example 16-10, identify how many times the route 44.0.0.0/8 has been sent in outgoing updates from the router. | | 2: | Which path will be chosen in Example 16-11 to get to 33.48.124.0, and why? | | 3: | What is the most likely reason for the source of a route to be flagged as incomplete? | | 4: | To send packets to network 7.2.0.0/16, the router will direct traffic to a next-hop router. The data frame at Layer 2 will be addressed to this next hop, which will route it on to the next router in the journey to its destination. What is the Layer 3 address of the next logical hop, and why was it selected? |
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