OSPF实验3：OSPF over NBMA下的五种网络类型 （转载）
实验等级：Professional
实验拓扑：
实验基本配置：
1. 首先将R1配置成为帧中继交换机：
frame-relay switching
!
interface Serial1/0
no ip address
encapsulation frame-relay
clock rate 64000
frame-relay lmi-type ansi
frame-relay intf-type dce
frame-relay route 101 interface Serial1/1 102
!
interface Serial1/1
no ip address
encapsulation frame-relay
clock rate 64000
frame-relay lmi-type ansi
frame-relay intf-type dce
frame-relay route 102 interface Serial1/0 101
2. R2和R3的基本配置：
R2：
interface Loopback0
ip address 2.2.2 .2 255.255.255.0
!
interface Serial1/0
ip address 12.1.1 .2 255.255.255.0
encapsulation frame-relay
serial restart-delay 0
frame-relay map ip 12.1.1 .3 101 broadcast
no frame-relay inverse-arp
!
router ospf 10
router-id 2.2.2 .2
log-adjacency-changes
network 2.2.2 .0 0.0.0.255 area 0
network 12.1.1 .0 0.0.0.255 area 0
R3：
interface Loopback0
ip address 3.3.3 .3 255.255.255.0
!
interface Serial1/1
ip address 12.1.1 .3 255.255.255.0
encapsulation frame-relay
serial restart-delay 0
frame-relay map ip 12.1.1 .2 102 broadcast
no frame-relay inverse-arp
!
router ospf 10
router-id 3.3.3 .3
log-adjacency-changes
network 3.3.3 .0 0.0.0.255 area 0
network 12.1.1 .0 0.0.0.255 area 0
Type1----Non_Broadcast（默认）
我们在R2上show ip ospf neighbor，发现没有邻居。说明在这种情况下邻居需要手动配置！配置如下：
R2：
R2(config)#router ospf 10
R2(config-router)#neighbor 12.1.1 .3
R3：
R3(config)#router ospf 10
R3(config-router)#neighbor 12.1.1 .2
此时在R2上查看邻居：
R2#sho ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
发现邻居已经形成并且有DR与BDR的选举！
在R2上查看接口
R2#show ip ospf interface
Serial1/0 is up, line protocol is up
Internet Address 12.1.1 .2/24, Area 0
Process ID 10, Router ID 2.2.2 .2, Network Type NON_BROADCAST, Cost: 64
Transmit Delay is 1 sec, State BDR, Priority 1
Designated Router (ID) 3.3.3 .3, Interface address 12.1.1.3
Backup Designated router (ID) 2.2.2 .2, Interface address 12.1.1.2
Flush timer for old DR LSA due in 00:01:40
Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5
在这种网络类型中，hello的间隔是30s。
打开debug信息，我们可以看到在这种网络类型中，OSPF的数据包是单播传送的。
R2#
*Aug 14 14:52:52.819: OSPF: Send hello to 12.1.1 .3 area 0 on Serial1/0 from 12.1.1.2
R2#
*Aug 14 14:52:57.087: OSPF: Rcv hello from 3.3.3 .3 area 0 from Serial1/0 12.1.1.3
*Aug 14 14:52:57.091: OSPF: End of hello processing
Type2---- Broadcast
首先去掉刚才手动配置的邻居关系：
R2(config)#router ospf 10
R2(config-router)#no neighbor 12.1.1 .3
R3(config)#router ospf 10
R3(config-router)#no neighbor 12.1.1 .2
将R2和R3接口的网络类型改成broadcast
R2(config-router)#int s1/0
R2(config-if)#ip ospf network broadcast
R3(config-router)#int s1/1
R3(config-if)#ip ospf network broadcast
一会我们就看到了如下信息
R3#
*Aug 14 14:59:52.823: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2 .2 on Serial1/1 from LOADING to FULL, Loading Done
这说明了在这种网络类型下是不需要手动配置邻居关系的！
R2#show ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
有DR与BDR的选举。
R2#sho ip ospf int
Serial1/0 is up, line protocol is up
Internet Address 12.1.1 .2/24, Area 0
Process ID 10, Router ID 2.2.2 .2, Network Type BROADCAST, Cost: 64
Transmit Delay is 1 sec, State BDR, Priority 1
Designated Router (ID) 3.3.3 .3, Interface address 12.1.1.3
Backup Designated router (ID) 2.2.2 .2, Interface address 12.1.1.2
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello时间间隔为10s。
R2#
*Aug 14 15:02:20.443: OSPF: Send hello to 224.0.0.5 area 0 on Serial1/0 from 12.1.1 .2
*Aug 14 15:02:20.959: OSPF: Rcv hello from 3.3.3 .3 area 0 from Serial1/0 12.1.1.3
*Aug 14 15:02:20.963: OSPF: End of hello processing
使用224.0.0.5这个组播地址传送数据包。
Type3---- Point-to-Point
将R2，R3接口的网络类型改成Point-to-Point
R2(config-if)#ip ospf net point-to-point
R3(config-if)#ip ospf net point-to-point
很快我们就可以看到如下信息
R3(config-if)#
*Aug 14 15:06:07.559: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2 .2 on Serial1/1 from LOADING to FULL, Loading Done
说明这种网络类型也不需要手动指定邻居
R2#sho ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
没有DR/BDR的选举
R2#sh ip ospf int
Serial1/0 is up, line protocol is up
Internet Address 12.1.1 .2/24, Area 0
Process ID 10, Router ID 2.2.2 .2, Network Type POINT_TO_POINT, Cost: 64
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello时间间隔为10s
R2#
*Aug 14 15:08:25.311: OSPF: Send hello to 224.0.0.5 area 0 on Serial1/0 from 12.1.1 .2
R2#
*Aug 14 15:08:30.259: OSPF: Rcv hello from 3.3.3 .3 area 0 from Serial1/0 12.1.1.3
*Aug 14 15:08:30.263: OSPF: End of hello processing
同样也是使用224.0.0.5这个组播地址传送数据。
Type4---- Point-to-Multipoint
将接口改为Point-to-Multipoint
R2(config-if)#ip ospf network point-to-multipoint
R3(config-if)#ip ospf network point-to-multipoint
*Aug 14 15:10:51.739: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2 .2 on Serial1/1 from LOADING to FULL, Loading Done
同样也不需要手动指定邻居
R2#sho ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
没有DR和BDR的选举
R2#sho ip ospf int
Serial1/0 is up, line protocol is up
Internet Address 12.1.1 .2/24, Area 0
Process ID 10, Router ID 2.2.2 .2, Network Type POINT_TO_MULTIPOINT, Cost: 64
Transmit Delay is 1 sec, State POINT_TO_MULTIPOINT,
Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5
Hello时间间隔为30s
R2#
*Aug 14 15:12:49.759: OSPF: Send hello to 224.0.0.5 area 0 on Serial1/0 from 12.1.1 .2
R2#
*Aug 14 15:12:57.443: OSPF: Rcv hello from 3.3.3 .3 area 0 from Serial1/0 12.1.1.3
*Aug 14 15:12:57.447: OSPF: End of hello processing
以224.0.0.5这个组播地址发送数据
Type5---- Point-to-Multipoint（Non_Broadcast）
改变接口类型为Point-to-Multipoint(Non_Broadcast)
R2(config-if)#ip ospf network point-to-multipoint non-broadcast
R3(config-if)#ip ospf network point-to-multipoint non-broadcast
这个时候邻居没有被自动发现。我们在R2上手动指定邻居
R2(config-if)#router ospf 10
R2(config-router)#neighbor 12.1.1 .3
R2(config-router)#
*Aug 14 15:18:38.955: %OSPF-5-ADJCHG: Process 10, Nbr 3.3.3 .3 on Serial1/0 from LOADING to FULL, Loading Done
邻居只要在一边指定即可。说明在这种网络类型下邻居需要手动指定。
R2#sho ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
同样没有DR和BDR的选取
R2#sho ip ospf int
Serial1/0 is up, line protocol is up
Internet Address 12.1.1 .2/24, Area 0
Process ID 10, Router ID 2.2.2 .2, Network Type POINT_TO_MULTIPOINT, Cost: 64
Transmit Delay is 1 sec, State POINT_TO_MULTIPOINT,
Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5
Hello时间间隔为30s
R2#
*Aug 14 15:21:03.099: OSPF: Send hello to 12.1.1 .3 area 0 on Serial1/0 from 12.1.1.2
*Aug 14 15:21:03.295: OSPF: Rcv hello from 3.3.3 .3 area 0 from Serial1/0 12.1.1.3
*Aug 14 15:21:03.299: OSPF: End of hello processing
使用单播传送OSPF数据。
总结：在NBMA网络下5种网络类型具体情况如下表所示：
|
网络类型 |
邻居自动发现 |
有无DR选举 |
Hello间隔 |
传输方式 |
|
Non_broadcast |
否 |
有 |
30s |
单播 |
|
Broadcast |
是 |
有 |
10s |
组播 |
|
Point-to-Point |
是 |
无 |
10s |
组播 |
|
Point-to-Multipoint |
是 |
无 |
30s |
组播 |
|
Point-to-Multipoint(非广播) |
否 |
无 |
30s |
单播 |
