[ Pobierz całość w formacie PDF ]
.Being connected to two areas makes Dallas an ABR (Line 4).Dallas has two interfaces in area 0 (Line 11) and one interface in area 1 (Line 21).We also see the number of times that the SPF algorithm has been run for each of the areas (Lines 13 and 23).This is good statistic to monitor.If it starts increasing rapidly, we probably have an unstable network somewhere.The OSPF neighbor table contains the RID’s for all of the routers that the local router has discovered as neighbors.Figure 7-84 shows the neighbor table displayed on Dallas after issuing the show ip ospf neighbor command.lDallas#show ip ospf neighborNeighbor ID Pri State Dead Time Address Interface192.168.3.2 1 FULL/ - 00:00:31 192.168.2.2 Serial0192.168.3.1 1 FULL/ - 00:00:35 172.16.11.2 Serial1Dallas#<<<Figure 7-84 Show IP OSPF Neighbor Output>>>Dallas’ two neighbor routers are Austin (Line 4) and FortWorth (Line 5).The Neighbor ID column shows the RID’s for the routers, not the addresses of their directly-connected interfaces.The neighbors’ directly-connected interface addresses are given in the Address column, and the interface to which the neighbor is connected is shown in the Interface column.The State column shows the status of the neighbor relationship.A full state indicates that an adjacency has been established with a neighbor.The Dead Time column indicates the amount of time left in the dead interval either to receive a Hello packet from a neighbor or to remove the neighbor from the table.lDallas#show ip ospf interfaceBRI0 is administratively down, line protocol is downOSPF not enabled on this interfaceBRI0:1 is administratively down, line protocol is downOSPF not enabled on this interfaceBRI0:2 is administratively down, line protocol is downOSPF not enabled on this interfaceEthernet0 is up, line protocol is upInternet Address 172.16.10.1/24, Area 0Process ID 100, Router ID 192.168.2.1, Network Type BROADCAST, Cost: 10Transmit Delay is 1 sec, State DR, Priority 1Designated Router (ID) 192.168.2.1, Interface address 172.16.10.1No backup designated router on this networkTimer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5Hello due in 00:00:01Neighbor Count is 0, Adjacent neighbor count is 0Suppress hello for 0 neighbor(s)Serial0 is up, line protocol is upInternet Address 192.168.2.1/24, Area 1Process ID 100, Router ID 192.168.2.1, Network Type POINT_TO_POINT, Cost: 390Transmit Delay is 1 sec, State POINT_TO_POINT,Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5Hello due in 00:00:08Neighbor Count is 1, Adjacent neighbor count is 1Adjacent with neighbor 192.168.3.2Suppress hello for 0 neighbor(s)Serial1 is up, line protocol is upInternet Address 172.16.11.1/24, Area 0Process ID 100, Router ID 192.168.2.1, Network Type POINT_TO_POINT, Cost: 64Transmit Delay is 1 sec, State POINT_TO_POINT,Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5Hello due in 00:00:05Neighbor Count is 1, Adjacent neighbor count is 1Adjacent with neighbor 192.168.3.1Suppress hello for 0 neighbor(s)Serial2 is administratively down, line protocol is downOSPF not enabled on this interfaceSerial3 is administratively down, line protocol is downOSPF not enabled on this interfaceDallas#<<<Figure 7-85 Show IP OSPF Interface Output>>>Figure 7-85 shows the output of the show ip ospf interface command on Dallas.The show ip ospf interface command shows the status of OSPF on a router’s interfaces.Figure 7-85 shows that Dallas has OSPF enabled on interfaces Ethernet0, Serial0, and Serial1 (Lines 9, 19, and 28).We will look at some of the information given for the Serial1 interface (starting on Line 27).The Serial1 interface is connected to area 0 (Line 28) for Dallas’s OSPF PID 100 (Line 29).Dallas’ RID is 192.168.2.1 (Line 29).The network to which Serial1 is connected is a point-to-point network with a cost of 64.The cost of 64 is based on the bandwidth of the Serial1 interface being set to the fast-serial interface default value of 1544.That is 1544 kbps, or 1,544,000 bps, to plug into the formula for calculating OSPF cost.The OSPF timers are given on Line 31.Dallas has one neighbor out its Serial1 interface (Line 33), and an adjacency has been established with that neighbor (Line33).The neighbor’s RID (192.168.3.1) is given on Line 34; the neighbor is Austin.The link state database is another useful item to examine when verifying the operation of OSPF.Figure 7-86 shows the output of the show ip ospf database command on Dallas.lDallas#show ip ospf databaseOSPF Router with ID (192.168.2.1) (Process ID 100)Router Link States (Area 0)Link ID ADV Router Age Seq# Checksum Link count192.168.2.1 192.168.2.1 280 0x80000003 0x36B3 3192.168.3.1 192.168.3.1 279 0x80000002 0x7668 3Summary Net Link States (Area 0)Link ID ADV Router Age Seq# Checksum192.168.1.0 192.168.2.1 222 0x80000001 0x5B79192.168.1.0 192.168.3.1 224 0x80000001 0x358192.168.2.0 192.168.2.1 232 0x80000001 0xEBF1192.168.2.0 192.168.3.1 225 0x80000001 0xDDFE192.168.3.0 192.168.2.1 222 0x80000001 0xD903192.168.3.0 192.168.3.1 235 0x80000001 0x89D9Router Link States (Area 1)Link ID ADV Router Age Seq# Checksum Link count192.168.2.1 192.168.2.1 232 0x80000003 0x668D 2192.168.3.1 192.168.3.1 237 0x80000003 0x3FB 2192.168.3.2 192.168.3.2 229 0x80000003 0xCB3B 5Summary Net Link States (Area 1)Link ID ADV Router Age Seq# Checksum172.16.10.0 192.168.2.1 323 0x80000001 0xD926172.16.10.0 192.168.3.1 276 0x80000001 0x5569172.16.11.0 192.168.2.1 281 0x80000001 0xECDB172.16.11.0 192.168.3.1 277 0x80000001 0xE5E1172.16.20.0 192.168.2.1 272 0x80000001 0xEDC7172.16.20.0 192.168.3.1 277 0x80000001 0x6490Dallas#<<<Figure 7-86 Show IP OSPF Database Output>>>Since Dallas is an ABR with connections to both area 0 and area 1, there are two sets of link state information in the database.There are two routers with connections to area 0; therefore, there must be two router link states for area 0: one for Dallas (Line 9) and one for FortWorth (Line 10).There are two ABR’s between area 0 and area 1; therefore, each of them generated summary LSA’s into area 0 indicating the routes in area 1 (Lines 15 through 20).There are three routers with connections to area 1 so there must be three router link states for area 1: one for Dallas (Line 25), one for FortWorth (Line 26), and one for Austin (Line 27).The two ABR’s each generated summary LSA’s into area 1 indicating the routes in area 0 (Lines 32 through 37).OSPF Stub Area ConfigurationStub areas were covered in Section 7.7.4.1
[ Pobierz całość w formacie PDF ]