Routing TCP[s]IP (Vol. 11998)

2017-07-07 02:10:07

Figure 6.31 shows the routing table of RTA in Figure 6.32. Although there are no reachability problems in this internetwork, RTA's routing table contains an unexpected entry: Network 192.168.3.0 is reachable via the less-desirable serial links. In Figures 6.33 through 6.36, debugging is used to observe the IGRP updates on the four routers. Although the cause of the problem cannot be determined from these debug messages, the router from which the problem originates can be discovered . Based on the information given, create a hypothesis that explains the most likely cause of the problem.

Figure 6.31. The routing table of RTA in Figure 6.32.

Figure 6.32. The internetwork for Troubleshooting Exercise 1.

Figure 6.33. The IGRP updates sent and received by RTA in Figure 6.32.

Figure 6.34. The IGRP updates sent and received by RTB in Figure 6.32.

Figure 6.35. The IGRP updates sent and received by RTC in Figure 6.32.

Figure 6.36. The IGRP updates sent and received by RTD in Figure 6.32.

Users on subnets 172.16.1.8/29 and 172.16.2.16/29 in Figure 6.37 are reporting that they cannot connect to servers on sub net 172.17.1.8/29. Figures 6.38 through 6.41 show analyzer captures of the IGRP updates on the two Ethernet links. Part of the IP header is also shown in each screen. Determine which router originated each update and then find the problem.

Figure 6.37. The internetwork for Troubleshooting Exercise 2.

Figure 6.38. An analyzer capture of an 1GRP update from the internetwork in Figure 6.37.

Figure 6.39. An analyzer capture of an 1GRP update from the internetwork in Figure 6.37.

Figure 6.40. An analyzer capture of an 1GRP update from the internetwork in Figure 6.37.

Figure 6.41. An analyzer capture of an 1GRP update from the internetwork in Figure 6.37.