| 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 12-1 The ISP Flying Data has recently converted from OSPF to Integrated IS-IS. The migration was relatively painless. The company uses the private network 10.0.0.0 for IP and the private ISO addressing with AFI 49. They created a hierarchical addressing structure. See Figure 12-7 to see this addressing scheme. Figure 12-7. Diagram for Scenario 12-1  The addressing of the network was a large project, with all the pitfalls that accompany such a major exercise. The network is now stable, and it is time to configure the WAN connections using multipoint Frame Relay. | 1: | Issue the commands that will allow Router A to use Integrated IS-IS routing across the NBMA cloud as if the cloud were a broadcast medium. Refer to Figure 12-7 for the addressing scheme. | | 2: | The WAN is a Frame Relay cloud, and Router G has a point-to-point link with Router C. Issue the commands for Router C that configure the link for Integrated IS-IS as a point-to-point link. | | 3: | To reduce bandwidth consumption and to hide some network detail, summarization has been suggested as a solution over the WAN links. Issue the commands for Router A that will summarize the networks behind this router with a prefix of /16 across the WAN. |
Scenario 12-2 Given the configuration of Integrated IS-IS in Example 12-14 and the output screen in Example 12-15, perform the tasks and answer the questions listed. The WAN has light user traffic and has a fully meshed configuration, as shown in Figure 12-8. Figure 12-8. Diagram for Scenario 12-2  Example 12-14. Router B's Configuration File RouterB# show running config Building configuration... Current configuration: ! Version 12.0 Service timestamps debug uptime Service timestamps log uptime no service password-encryption ! hostname B ! ! ip subnet-zero ip tcp synwait-time 5 no ip domain-lookup clns routing ! ! Interface Ethernet0 ip address 140.100.104.1 255.255.255.0 no ip directed-broadcast ip router isis ! Interface Serial0 no ip address no ip directed-broadcast encapsulation frame-relay no ip mroute-cache no fair-queue clockrate 56000 ! Interface Serial0.2 point-to-point ip address 140.100.32.2 255.255.255.0 no ip directed-broadcast ip router isis frame-relay interface-dlci 931 ! Interface Serial0.3 point-to-point ip address 140.100.16.2 255.255.255.0 no ip directed-broadcast ip router isis frame-relay interface-dlci 631 ! Interface Serial1 no ip address no ip directed-broadcast Shutdown ! router isis net 49.0002.0000.0000.000b.00 ! ip classless ! ! alias exec c conf t alias exec s sh run alias exec ii sh ip int brie ! line con 0 exec-timeout 30 0 privilege level 15 logging synchronous transport input none line aux 0 line vty 0 4 ! End Example 12-15. The show clns interface Command from Router B B# show clns interface Ethernet0 is up, line protocol is up Checksums enabled, MTU 1497, Encapsulation SAP ERPDUs enabled, min. interval 10 msec. RDPDUs enabled, min. interval 100 msec., Addr Mask enabled Congestion Experienced bit set at 4 packets CLNS fast switching enabled CLNS SSE switching disabled DEC compatibility mode OFF for this interface Next ESH/ISH in 15 seconds Routing Protocol: IS-IS Circuit Type: level-1-2 Interface number 0x0, local circuit ID 0x1 Level-1 Metric: 10, Priority: 64, Circuit ID: 0000.0000.000B.01 Number of active level-1 adjacencies: 1 Level-2 Metric: 10, Priority: 64, Circuit ID: 0000.0000.000B.01 Number of active level-2 adjacencies: 1 Next IS-IS LAN Level-1 Hello in 678 milliseconds Next IS-IS LAN Level-2 Hello in 1 seconds Serial0 is up, line protocol is up CLNS protocol processing disabled Serial0.1 is up, line protocol is up CLNS protocol processing disabled Serial0.2 is up, line protocol is up Checksums enabled, MTU 1500, Encapsulation FRAME-RELAY ERPDUs enabled, min. interval 10 msec. RDPDUs enabled, min. interval 100 msec., Addr Mask enabled Congestion Experienced bit set at 4 packets CLNS fast switching disabled CLNS SSE switching disabled DEC compatibility mode OFF for this interface Next ESH/ISH in 43 seconds Routing Protocol: IS-IS Circuit Type: level-1-2 Interface number 0x2, local circuit ID 0x101 Level-1 Metric: 10, Priority: 64, Circuit ID: 0000.0000.000B.01 Number of active level-1 adjacencies: 0 Level-2 Metric: 10, Priority: 64, Circuit ID: 0000.0000.000B.01 Number of active level-2 adjacencies: 1 Next IS-IS Hello in 2 seconds Serial0.3 is up, line protocol is up Checksums enabled, MTU 1500, Encapsulation FRAME-RELAY ERPDUs enabled, min. interval 10 msec. RDPDUs enabled, min. interval 100 msec., Addr Mask enabled Congestion Experienced bit set at 4 packets CLNS fast switching disabled CLNS SSE switching disabled DEC compatibility mode OFF for this interface Next ESH/ISH in 11 seconds Routing Protocol: IS-IS Circuit Type: level-1-2 Interface number 0x1, local circuit ID 0x100 Level-1 Metric: 10, Priority: 64, Circuit ID: 0000.0000.000C.01 Number of active level-1 adjacencies: 0 Level-2 Metric: 10, Priority: 64, Circuit ID: 0000.0000.000B.00 Number of active level-2 adjacencies: 1 Next IS-IS Hello in 3 seconds | 1: | Identify the DIS on the Ethernet segment. How was this information apparent? | | 2: | If Router A died, what would the effect be on the network? | | 3: | Is summarization possible only on the routers entering the WAN cloud, or is it possible on the networks not shown in the figure, but on the other side of the routers? Give reasons for your answers. |
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