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Cracker 之 OSPF 案例专题七篇（配图）+ 详细验证过程

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发表于 2007-10-16 12:15:15 | 显示全部楼层 |阅读模式
一、OSPF的规则、存根、完全存根以及NSSA区域案例（配图）+详细验证过程




Cisco路由器支持多种区域类型（规则、存根、完全存根以及NSSA区域），区域类型之间的不同表现在区域允许的LSA类型的不同。

在规则区域中，允许所有类型的LSA。其好处就是所有的路由器都有所有的路由信息，因此具有到达目的地的最佳路径。缺点就是，任何区域外的链路失效将引起局部的SPF计算。

在存根区域中（Stub）中，不允许外部的LSA。因此，ABR不产生任何更新。外部LSA用于描述OSPF区域外的目的地。例如，从其他路由协议接收到的路由，比如RIP，以及重分布到OSPF中的路由将被认为是外部的，并将在一个外部LSA中被通告。

虽然存根区域可以防止外部区域对区域的影响，但它们并不阻止区域内对区域的影响。因为仍然允许汇总LSA，所以，其他区域将仍然影响到存根区域。

完全存根区域（Totally Stub）区域同存根区域类似，将阻止外部LSA。但是，同存根区域不同的是，完全存根区域不允许汇总LSA。这样其他区域将不影响完全存根区域。

NSSA区域同存根区域类似，但是，它可以将外部路由导入到区域中。区域间的路由为类型7的LSA，并被ABR转换为类型5的LSA。例如，如果你需要阻止外部LSA进入该区域，但仍需要向区域外部发送外部LSA（例如，如果区域中的某个路由器为ASBR），就需要使用NSSA区域。

基本配置如下：
// R1 //
int e0/0
  ip ad 192.1.1.1 255.255.255.252

router os 1
  network 192.1.1.1 0.0.0.0 area 1


// R2 //
int e0/0
  ip ad 192.1.1.2 255.255.255.252

int lo0
  ip ad 193.1.1.129 255.255.255.192
  ip ospf network point-to-point    //变主机路由为网段路由

int e1/0
  ip ad 193.1.1.2 255.255.255.128

router os 1
  network 192.1.1.2 0.0.0.0 area 1
  network 193.1.1.129 0.0.0.0 area 0
  network 193.1.1.2 0.0.0.0 area 0
  area 0 range 193.1.1.0 255.255.255.0    //区域汇总


// R3 //
int e1/0
  ip ad 193.1.1.3 255.255.255.128

int lo0
  ip ad 193.1.1.193 255.255.255.192
  ip ospf network point-to-point    //变主机路由为网段路由

int e0/0
  ip ad 194.1.1.1 255.255.255.252

router os 1
  network 193.1.1.3 0.0.0.0 area 0
  network 193.1.1.193 0.0.0.0 area 0
  network 194.1.1.1 0.0.0.0 area 2
  area 0 range 193.1.1.0 255.255.255.0    //区域汇总


// R4 //
int e0/0
  ip ad 194.1.1.2 255.255.255.252

int e1/0
  ip ad 130.1.4.4 255.255.255.0

rotuer os 1
  netw 194.1.1.2 0.0.0.0 area 2
  summary-address 130.1.0.0 255.255.248.0    //外部路由汇总

router rip
  netw 130.1.0.0


// R5 //
int e1/0
  ip ad 130.1.4.5 255.255.255.0

int lo1
  ip ad 130.1.1.1 255.255.255.0

int lo2
  ip ad 130.1.2.1 255.255.255.0

int lo3
  ip ad 130.1.3.1 255.255.255.0

int lo5
  ip ad 130.1.5.1 255.255.255.0

int lo6
  ip ad 130.1.6.1 255.255.255.0

int lo7
  ip ad 130.1.7.1 255.255.255.0

router rip
  network 130.1.0.0



基本配置完成后，先进行验证：
r1#sh ip ro
     130.1.0.0/21 is subnetted, 1 subnets
O E2    130.1.0.0 [110/10] via 192.1.1.2, 00:00:02, Ethernet0/0
O IA 193.1.1.0/24 [110/11] via 192.1.1.2, 00:00:02, Ethernet0/0
     192.1.1.0/30 is subnetted, 1 subnets
C       192.1.1.0 is directly connected, Ethernet0/0
     194.1.1.0/30 is subnetted, 1 subnets
O IA    194.1.1.0 [110/30] via 192.1.1.2, 00:00:02, Ethernet0/0
我们观察到了区域间路由以及外部路由。这时候其它区域的路由波动会引起本地区域的路由重新计算。外部路由同样也会引起内部路由计算。


第一个实验，我们要进行区域设置，按图例将各区域分别设置为stub,nssa。只需在各区域边界路由器上加一条命令即可。观察设置区域前后的不同。

// R1 //
  area 1 stub

// R2 //
  area 1 stub

// R3 //
area 2 nssa

// R4 //
area 2 nssa


配置完成后我们比较一下结果：
r1#sh ip ro
O IA 193.1.1.0/24 [110/11] via 192.1.1.2, 00:00:13, Ethernet0/0
     192.1.1.0/30 is subnetted, 1 subnets
C       192.1.1.0 is directly connected, Ethernet0/0
     194.1.1.0/30 is subnetted, 1 subnets
O IA    194.1.1.0 [110/30] via 192.1.1.2, 00:00:13, Ethernet0/0
O*IA 0.0.0.0/0 [110/11] via 192.1.1.2, 00:00:13, Ethernet0/0
注意，R1中不再有到130.1.0.0的OSPF外部路由，相反，添加了一个缺省路由。但是，仍然存在两个内部路由，因为stub区域并不阻止内部区域更新。


下面我们说明一下如何配置区域，以阻止外部LSA的扩散。为了阻止其他区域的汇总LSA影响到本地区域，该区域必须配置为完全存根区域。可以以OSPF进程下添加下列命令：
// R1 //
  area 1 stub no-summary

// R2 //
  area 1 stub no-summary

验证结果如下：
r1#sh ip ro
     192.1.1.0/30 is subnetted, 1 subnets
C       192.1.1.0 is directly connected, Ethernet0/0
O*IA 0.0.0.0/0 [110/11] via 192.1.1.2, 00:00:48, Ethernet0/0
在R1上只出现了一条缺省路由。


注意R3上显示路由表时，只观察到一条N2路由，即外部路由。
r3#sh ip ro
     130.1.0.0/21 is subnetted, 1 subnets
O N2    130.1.0.0 [110/10] via 194.1.1.2, 00:17:57, Ethernet0/0
     193.1.1.0/24 is variably subnetted, 4 subnets, 3 masks
C       193.1.1.192/26 is directly connected, Loopback0
O       193.1.1.128/26 [110/11] via 193.1.1.2, 00:17:57, Ethernet1/0
O       193.1.1.0/24 is a summary, 00:17:57, Null0
C       193.1.1.0/25 is directly connected, Ethernet1/0
     192.1.1.0/30 is subnetted, 1 subnets
O IA    192.1.1.0 [110/20] via 193.1.1.2, 00:01:32, Ethernet1/0
     194.1.1.0/30 is subnetted, 1 subnets
C       194.1.1.0 is directly connected, Ethernet0/0
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 楼主| 发表于 2007-10-16 12:15:28 | 显示全部楼层
二、OSPF区域间、外部路由汇总（配图）+详细验证过程





Cisco允许对地址进行汇总，以通过限制区域间通告的路由来达到节省资源的目的。Cisco路由器支持两种类型的地址汇总：区域间汇总和外部路由汇总。区域间汇总用于在区域间汇总地址，而外部汇总用于收集到某个域中的一系列外部路由的汇总。

// R1 //
int e0/0
  ip ad 192.1.1.1 255.255.255.252

router os 1
  network 192.1.1.1 0.0.0.0 area 1


// R2 //
int e0/0
  ip ad 192.1.1.2 255.255.255.252

int e1/0
  ip ad 193.1.1.2 255.255.255.128

int lo0
  ip ad 193.1.1.129 255.255.255.192
router os 1
  network 192.1.1.2 0.0.0.0 area 1
  network 193.1.1.2 0.0.0.0 area 0
  network 193.1.1.129 0.0.0.0 area 0


// R3 //
int e1/0
  ip ad 193.1.1.3 255.255.255.128

int e0/0
  ip ad 194.1.1.1 255.255.255.252

int lo0
  ip ad 193.1.1.193 255.255.255.192

router os 1
  network 193.1.1.193 0.0.0.0 area 0
  network 193.1.1.3 0.0.0.0 area 0
  network 194.1.1.1 0.0.0.0 area 2


// R4 //
int e0/0
  ip ad 194.1.1.2 255.255.255.252

int e1/0
  ip ad 130.1.4.4 255.255.255.0

router os 1
  network 194.1.1.2 0.0.0.0 area 2

router rip
  network 130.1.0.0


// R5 //
int e1/0
  ip ad 130.1.4.5 255.255.255.0

int lo1
  ip ad 130.1.1.1 255.255.255.0

int lo2
  ip ad 130.1.2.1 255.255.255.0

int lo3
  ip ad 130.1.3.1 255.255.255.0

int lo5
  ip ad 130.1.5.1 255.255.255.0

int lo6
  ip ad 130.1.6.1 255.255.255.0

int lo7
  ip ad 130.1.7.1 255.255.255.0

router rip
  network 130.1.0.0


基本配置完成后，我们首选来验证一下。

r1#sh ip ro
     130.1.0.0/24 is subnetted, 7 subnets
O E2    130.1.3.0 [110/10] via 192.1.1.2, 00:00:03, Ethernet0/0
O E2    130.1.2.0 [110/10] via 192.1.1.2, 00:00:03, Ethernet0/0
O E2    130.1.1.0 [110/10] via 192.1.1.2, 00:00:03, Ethernet0/0
O E2    130.1.7.0 [110/10] via 192.1.1.2, 00:00:03, Ethernet0/0
O E2    130.1.6.0 [110/10] via 192.1.1.2, 00:00:03, Ethernet0/0
O E2    130.1.5.0 [110/10] via 192.1.1.2, 00:00:03, Ethernet0/0
O E2    130.1.4.0 [110/10] via 192.1.1.2, 00:00:03, Ethernet0/0
     193.1.1.0/24 is variably subnetted, 3 subnets, 2 masks
O IA    193.1.1.192/26 [110/21] via 192.1.1.2, 00:00:48, Ethernet0/0
O IA    193.1.1.128/26 [110/11] via 192.1.1.2, 00:00:48, Ethernet0/0
O IA    193.1.1.0/25 [110/20] via 192.1.1.2, 00:00:48, Ethernet0/0
     192.1.1.0/30 is subnetted, 1 subnets
C       192.1.1.0 is directly connected, Ethernet0/0
     194.1.1.0/30 is subnetted, 1 subnets
O IA    194.1.1.0 [110/30] via 192.1.1.2, 00:39:39, Ethernet0/0


在我们汇总完成后，上述结果里，红、蓝色显示部分将会被取代。方法如下：

区域间汇总：
// R2 //
router os 1
area 0 range 193.1.1.0 255.255.255.0

// R3 //
router os 1
  area 0 range 193.1.1.0 255.255.255.0

外部路由汇总：
// R4 //
router os 1
  summary-address 130.1.0.0 255.255.248.0


验证如下：
r1#sh ip ro
     130.1.0.0/21 is subnetted, 1 subnets
O E2    130.1.0.0 [110/10] via 192.1.1.2, 00:00:02, Ethernet0/0
O IA 193.1.1.0/24 [110/11] via 192.1.1.2, 00:00:13, Ethernet0/0
     192.1.1.0/30 is subnetted, 1 subnets
C       192.1.1.0 is directly connected, Ethernet0/0
     194.1.1.0/30 is subnetted, 1 subnets
O IA    194.1.1.0 [110/30] via 192.1.1.2, 00:47:19, Ethernet0/0
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 楼主| 发表于 2007-10-16 12:15:41 | 显示全部楼层
三、OSPF邻居认证实际案例（配图）＋详细验证过程


邻居认证使得路由器确认每次所收到的路由更新的源。如果关键字不匹配，就会拒绝路由更新。

Cisco使用两种类型的邻居认证：纯文本和MD5。

纯文本认证发一个关键字，这个关键字是明文传输，可被非法用户所窃取，所以不推荐使用。

MD5认证发一个报文摘要，而不是关键字。MD5被用来生成一个关键字的散列。这个散列是被发送的对象。MD5方式不易被非法用户所窃取。

这个案例中，我们在R1与R2之间使用明文认证，在R2与R3之间使用MD5认证。


// R1 //
int e0/0
  ip ad 192.1.1.1 255.255.255.0
  ip ospf authentication-key cisco    //明文认证，关键字为cisco

router os 1
  network 192.1.1.1 0.0.0.0 area 0
  area 0 authentication


// R2 //
int e0/0
  ip ad 192.1.1.2 255.255.255.0
  ip ospf authentication-key cisco    //明文认证，关键字为cisco

int e1/0
  ip ad 193.1.1.2 255.255.255.0
  ip ospf message-digest-key 1 md5 cracker

router os 1
  network 192.1.1.2 0.0.0.0 area 0
  network 193.1.1.2 0.0.0.0 area 1
  area 0 authentication
  area 1 authentication message-digest


// R3 //
int e1/0
  ip ad 193.1.1.3 255.255.255.0
  ip ospf message-digest-key 1 md5 cracker

router os 1
  network 193.1.1.3 0.0.0.0 a 1
  area 1 authentication message-digest



验证过程：
r1#sh ip os int e0/0
Ethernet0/0 is up, line protocol is up
  Internet Address 192.1.1.1/24, Area 0
  Process ID 1, Router ID 192.1.1.1, Network Type BROADCAST, Cost: 10
  Transmit Delay is 1 sec, State BDR, Priority 1
  Designated Router (ID) 193.1.1.2, Interface address 192.1.1.2
  Backup Designated router (ID) 192.1.1.1, Interface address 192.1.1.1
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:06
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 193.1.1.2  (Designated Router)
  Suppress hello for 0 neighbor(s)
  Simple password authentication enabled

r2#sh ip os int e0/0
Ethernet0/0 is up, line protocol is up
  Internet Address 192.1.1.2/24, Area 0
  Process ID 1, Router ID 193.1.1.2, Network Type BROADCAST, Cost: 10
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 193.1.1.2, Interface address 192.1.1.2
  Backup Designated router (ID) 192.1.1.1, Interface address 192.1.1.1
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:04
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 2
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 192.1.1.1  (Backup Designated Router)
  Suppress hello for 0 neighbor(s)
  Simple password authentication enabled

r2#sh ip os int e1/0
Ethernet1/0 is up, line protocol is up
  Internet Address 193.1.1.2/24, Area 1
  Process ID 1, Router ID 193.1.1.2, Network Type BROADCAST, Cost: 10
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 193.1.1.2, Interface address 193.1.1.2
  Backup Designated router (ID) 193.1.1.3, Interface address 193.1.1.3
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:03
  Index 1/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 2, maximum is 2
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 193.1.1.3  (Backup Designated Router)
  Suppress hello for 0 neighbor(s)
  Message digest authentication enabled
    Youngest key id is 1

r3#sh ip os int e1/0
Ethernet1/0 is up, line protocol is up
  Internet Address 193.1.1.3/24, Area 1
  Process ID 1, Router ID 193.1.1.3, Network Type BROADCAST, Cost: 10
  Transmit Delay is 1 sec, State BDR, Priority 1
  Designated Router (ID) 193.1.1.2, Interface address 193.1.1.2
  Backup Designated router (ID) 193.1.1.3, Interface address 193.1.1.3
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:04
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 2
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 193.1.1.2  (Designated Router)
  Suppress hello for 0 neighbor(s)
  Message digest authentication enabled
    Youngest key id is 1



为了更进一步理解认证过程，我们可以打开DEBUG，并将R3的MD5认证key改为5：
// R3 //
debug ip ospf adj

int e1/0
  ip ospf message-digest-key 5 md5 cracker

r3#
01:16:03: OSPF: Rcv pkt from 193.1.1.2, Ethernet1/0 : Mismatch Authentication Key - No message digest key 1 on interface
01:16:09: OSPF: Send with youngest Key 5


r3#show ip ospf neighbor    //观察结果无法发现邻居。

//认证未通过，无法与R2建立起邻居关系。

当我们把MD5认证KEY改回1后，认证通过。


第二步实验，我们把关键字进行修改：
// R3 //
debug ip ospf adj

int e1/0
  ip ospf message-digest-key 1 md5 cuijian

01:21:33: OSPF: Rcv pkt from 193.1.1.2, Ethernet1/0 : Mismatch Authentication Key - Message Digest Key 1
01:21:40: OSPF: Send with youngest Key 1

我们要在实际工作中学会使用debug这个思科排错的利器。
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 楼主| 发表于 2007-10-16 12:16:08 | 显示全部楼层
四、OSPF虚链路（virtual-link）配置实例 + 详细验证过程




这个配置将验证一个OSPF虚电路（Virtual-Link）的过程，重点在观察虚链路连接的临时网络与正常区域间路由有何区别。上图中区域4（area 4）没有和area 0直接相连。在R2与R3之间配置了一条虚链路。

// R1 //
int lo0
  ip ad 1.1.1.1 255.255.255.0

int e0
  ip ad 192.1.1.1 255.255.255.0

router os 1
  network 192.1.1.0 0.0.0.255 area 0


// R2 //
int lo0
  ip ad 2.2.2.2 255.255.255.0

int e0
  ip ad 192.1.1.2 255.255.255.0

int e1
  ip ad 193.1.1.2 255.255.255.0

router os 1
  network 192.1.1.0 0.0.0.255 area 0
  network 193.1.1.0 0.0.0.255 area 1


// R3 //
int lo0
  ip ad 3.3.3.3 255.255.255.0

int e1
  ip ad 193.1.1.3 255.255.255.0

int e0
  ip ad 194.1.1.3 255.255.255.0

router os 1
  network 193.1.1.0 0.0.0.255 area 1
  network 194.1.1.0 0.0.0.255 area 4


// R4 //
int lo0
  ip ad 4.4.4.4 255.255.255.0

int e0
  ip ad 194.1.1.4 255.255.255.0

router os 1
  network 194.1.1.0 0.0.0.255 area 4



基本配置完成后，我们在每台路由器上分别来验证一下：
r1#sh ip os nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
2.2.2.2           1   FULL/BDR        00:00:33    192.1.1.2       Ethernet0/0
r1#
r1#sh ip ro
     1.0.0.0/24 is subnetted, 1 subnets
C       1.1.1.0 is directly connected, Loopback0
O IA 193.1.1.0/24 [110/20] via 192.1.1.2, 00:00:19, Ethernet0/0
C    192.1.1.0/24 is directly connected, Ethernet0/0
//注意R1上有关于193.1.1.0的路由条目，是属于IA类型（域间路由）

r2#sh ip os nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
1.1.1.1           1   FULL/DR         00:00:35    192.1.1.1       Ethernet0/0
3.3.3.3           1   FULL/BDR        00:00:35    193.1.1.3       Ethernet1/0
r2#
r2#
r2#sh ip ro
     2.0.0.0/24 is subnetted, 1 subnets
C       2.2.2.0 is directly connected, Loopback0
C    193.1.1.0/24 is directly connected, Ethernet1/0
C    192.1.1.0/24 is directly connected, Ethernet0/0


r3#sh ip os nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
2.2.2.2           1   FULL/DR         00:00:32    193.1.1.2       Ethernet1/0
4.4.4.4           1   FULL/DR         00:00:34    194.1.1.4       Ethernet0/0
r3#sh ip ro
     3.0.0.0/24 is subnetted, 1 subnets
C       3.3.3.0 is directly connected, Loopback0
C    193.1.1.0/24 is directly connected, Ethernet1/0
O IA 192.1.1.0/24 [110/20] via 193.1.1.2, 00:02:49, Ethernet1/0
C    194.1.1.0/24 is directly connected, Ethernet0/0
//注意R3中有关于192.1.1.0的路由是属于IA类型（域间路由）

r4#sh ip os nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           1   FULL/BDR        00:00:33    194.1.1.3       Ethernet0/0
r4#sh ip ro
     4.0.0.0/24 is subnetted, 1 subnets
C       4.4.4.0 is directly connected, Loopback0
C    194.1.1.0/24 is directly connected, Ethernet0/0
//R4上没有关于AREA 0内的任何路由信息





我们下面在R2、R3上添加Virtual-link的配置：
R2：
router os 1
  area 1 virtual-link 3.3.3.3

R3:
router os 1
  area 1 virtual-link 2.2.2.2




对比之前的路由信息，看有何区别：
r1#sh ip ro
     1.0.0.0/24 is subnetted, 1 subnets
C       1.1.1.0 is directly connected, Loopback0
O IA 193.1.1.0/24 [110/20] via 192.1.1.2, 00:00:01, Ethernet0/0
C    192.1.1.0/24 is directly connected, Ethernet0/0
O IA 194.1.1.0/24 [110/30] via 192.1.1.2, 00:00:01, Ethernet0/0
//多了一条194网段的路由，类型IA（区域间）


r2#sh ip ro
     2.0.0.0/24 is subnetted, 1 subnets
C       2.2.2.0 is directly connected, Loopback0
C    193.1.1.0/24 is directly connected, Ethernet1/0
C    192.1.1.0/24 is directly connected, Ethernet0/0
O IA 194.1.1.0/24 [110/20] via 193.1.1.3, 00:00:06, Ethernet1/0
//多了一条194网段路由，类型为IA（区域间）

r3#sh ip ro
     3.0.0.0/24 is subnetted, 1 subnets
C       3.3.3.0 is directly connected, Loopback0
C    193.1.1.0/24 is directly connected, Ethernet1/0
O    192.1.1.0/24 [110/20] via 193.1.1.2, 00:02:56, Ethernet1/0
C    194.1.1.0/24 is directly connected, Ethernet0/0
//R3的192路由原本为IA类型（区域间），现在转为O类型（区域内），说明R3认为自已与192网段是直连的。虚链路相当于将R3直接连接了AREA 0 与 AREA 4区域


r4#sh ip ro
     4.0.0.0/24 is subnetted, 1 subnets
C       4.4.4.0 is directly connected, Loopback0
O IA 193.1.1.0/24 [110/20] via 194.1.1.3, 00:03:40, Ethernet0/0
O IA 192.1.1.0/24 [110/30] via 194.1.1.3, 00:03:25, Ethernet0/0
C    194.1.1.0/24 is directly connected, Ethernet0/0
//R4上192路由类型IA（区域间）


最后我们将虚链路效果再与正常连接方式进行一下比对，如下图：





验证如下：
r1#sh ip ro
     1.0.0.0/24 is subnetted, 1 subnets
C       1.1.1.0 is directly connected, Loopback0
O IA 193.1.1.0/24 [110/20] via 192.1.1.2, 00:00:41, Ethernet0/0
C    192.1.1.0/24 is directly connected, Ethernet0/0
C    192.2.2.0/24 is directly connected, Ethernet1/0
O IA 194.1.1.0/24 [110/20] via 192.2.2.4, 00:00:39, Ethernet1/0



r2#sh ip ro
     2.0.0.0/24 is subnetted, 1 subnets
C       2.2.2.0 is directly connected, Loopback0
C    193.1.1.0/24 is directly connected, Ethernet1/0
C    192.1.1.0/24 is directly connected, Ethernet0/0
O    192.2.2.0/24 [110/20] via 192.1.1.1, 00:01:04, Ethernet0/0
O IA 194.1.1.0/24 [110/30] via 192.1.1.1, 00:00:03, Ethernet0/0
r2#


r3#sh ip ro
     3.0.0.0/24 is subnetted, 1 subnets
C       3.3.3.0 is directly connected, Loopback0
C    193.1.1.0/24 is directly connected, Ethernet1/0
O IA 192.1.1.0/24 [110/20] via 193.1.1.2, 00:01:31, Ethernet1/0
O IA 192.2.2.0/24 [110/30] via 193.1.1.2, 00:01:15, Ethernet1/0
O IA 194.1.1.0/24 [110/40] via 193.1.1.2, 00:00:15, Ethernet1/0


r4#sh ip ro
     4.0.0.0/24 is subnetted, 1 subnets
C       4.4.4.0 is directly connected, Loopback0
O IA 193.1.1.0/24 [110/30] via 192.2.2.1, 00:00:39, Ethernet1/0
O    192.1.1.0/24 [110/20] via 192.2.2.1, 00:01:37, Ethernet1/0
C    192.2.2.0/24 is directly connected, Ethernet1/0
C    194.1.1.0/24 is directly connected, Ethernet0/0


r5#sh ip ro
     5.0.0.0/24 is subnetted, 1 subnets
C       5.5.5.0 is directly connected, Loopback0
O IA 193.1.1.0/24 [110/40] via 194.1.1.4, 00:00:52, Ethernet0/0
O IA 192.1.1.0/24 [110/30] via 194.1.1.4, 00:00:52, Ethernet0/0
O IA 192.2.2.0/24 [110/20] via 194.1.1.4, 00:00:52, Ethernet0/0
C    194.1.1.0/24 is directly connected, Ethernet0/0




如果上述方式还不容易理解，你也可以将virtual-link可以想象成：将R2与R3合并成一台路由器，如下图：





r1#sh ip ro
     1.0.0.0/24 is subnetted, 1 subnets
C       1.1.1.0 is directly connected, Loopback0
O IA 193.1.1.0/24 [110/20] via 192.1.1.2, 00:00:57, Ethernet0/0
C    192.1.1.0/24 is directly connected, Ethernet0/0
O IA 194.1.1.0/24 [110/74] via 192.1.1.2, 00:00:24, Ethernet0/0


r2#sh ip ro
     2.0.0.0/24 is subnetted, 1 subnets
C       2.2.2.0 is directly connected, Loopback0
C    193.1.1.0/24 is directly connected, Ethernet1/0
C    192.1.1.0/24 is directly connected, Ethernet0/0
C    194.1.1.0/24 is directly connected, Serial2/0



r3#sh ip ro
     3.0.0.0/24 is subnetted, 1 subnets
C       3.3.3.0 is directly connected, Loopback0
C    193.1.1.0/24 is directly connected, Ethernet1/0
O IA 192.1.1.0/24 [110/20] via 193.1.1.2, 00:01:06, Ethernet1/0
O IA 194.1.1.0/24 [110/74] via 193.1.1.2, 00:00:37, Ethernet1/0


r4#sh ip ro
     4.0.0.0/24 is subnetted, 1 subnets
C       4.4.4.0 is directly connected, Loopback0
O IA 193.1.1.0/24 [110/74] via 194.1.1.2, 00:00:17, Serial2/0
O IA 192.1.1.0/24 [110/74] via 194.1.1.2, 00:00:17, Serial2/0
C    194.1.1.0/24 is directly connected, Serial2/0
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 楼主| 发表于 2007-10-16 12:16:23 | 显示全部楼层
五、在NBMA网络广播模式下配置OSPF实际案例（配图）＋详细验证过程




广播式网络是一个渐进的操作过程,它可以定义所有邻居。当给一个接口配置广播时，这个接口就好像是连入了LAN中，网络中仍要选出DR和BDR，需特别保证路由器选出的DR/BDR与网络中所有路由器都有物理连接。

使用接口命令ip ospf network broadcast可以向所有路由器上设置网络类型。R2、R4的串行接口被配置成OSPF PRIORITY为0，这将保证R3成为DR。

// 帧交换机
frame-relay switching

int s2/0
  encapsulation frame-relay
  clock rate 64000
  frame-relay intf-type dce
  frame-relay route 200 int s3/0 300

int s3/0
  encapsulation frame-relay
  clock rate 64000
  frame-relay intf-type dce
  frame-relay route 300 int s2/0 200
  frame-relay route 399 int s4/0 400

int s4/0
  encapsulation frame-relay
  clock rate 64000
  frame-relay intf-type dce
  frame-relay route 400 int s2/0 399


// R2 //
int lo0
  ip ad 2.2.2.2 255.255.255.0


int s2/0
  encapsulation frame-relay
  ip ospf network broadcast    //将OSPF网络类型设置为广播模式
  ip ospf priority 0    //优先级为0，不参与DR选举
  ip ad 192.1.1.2 255.255.255.0
  frame-relay map ip 192.1.1.3 200 broadcast
  frame-relay map ip 192.1.1.4 200 broadcast

router os 1
  network 2.2.2.2 0.0.0.0 area 0
  network 192.1.1.2 0.0.0.0 area 0


// R3 //
int lo0
  ip ad 3.3.3.3 255.255.255.0

int s3/0
  encapsulation frame-relay
  ip ospf network broadcast    //将OSPF网络类型设置为广播模式
  ip address 192.1.1.3 255.255.255.0
  frame-relay map ip 192.1.1.2 300 broadcast
  frame-relay map ip 192.1.1.4 399 broadcast

router os 1
  network 3.3.3.3 0.0.0.0 area 0
  network 192.1.1.3 0.0.0.0 area 0

// R4 //
int lo0
  ip ad 4.4.4.4 255.255.255.0

int s4/0
  encapsulation frame-relay
  ip ad 192.1.1.4 255.255.255.0
  ip ospf network broadcast    //将OSPF网络类型设置为广播模式
  ip ospf priority 0    //优先级为0，不参与DR选举
  frame-relay map ip 192.1.1.2 400 broadcast
  frame-relay map ip 192.1.1.3 400 broadcast

router os 1
  network 4.4.4.4 0.0.0.0 area 0
  network 192.1.1.4 0.0.0.0 area 0




验证过程：
一、首先来检查DR选举是否按我们的设计，R3被选举为DR，R2、R4不参与选举，同时注意网络类型是否为NBMA，hello时间间隔是否为30秒。。。。。。

r3#sh ip os int s3/0
Serial3/0 is up, line protocol is up
  Internet Address 192.1.1.3/24, Area 0
  Process ID 1, Router ID 3.3.3.3, Network Type BROADCAST, Cost: 64
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 3.3.3.3, Interface address 192.1.1.3
  No backup designated router on this network
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:27
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 2, maximum is 2
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 2, Adjacent neighbor count is 2
    Adjacent with neighbor 4.4.4.4
    Adjacent with neighbor 2.2.2.2
  Suppress hello for 0 neighbor(s)


r2#sh ip os int s2/0
Serial2/0 is up, line protocol is up
  Internet Address 192.1.1.2/24, Area 0
  Process ID 1, Router ID 2.2.2.2, Network Type BROADCAST, Cost: 64
  Transmit Delay is 1 sec, State DROTHER, Priority 0
  Designated Router (ID) 3.3.3.3, Interface address 192.1.1.3
  No backup designated router on this network
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:06
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 3.3.3.3  (Designated Router)
  Suppress hello for 0 neighbor(s)


r4#sh ip ospf int s4/0
Serial4/0 is up, line protocol is up
  Internet Address 192.1.1.4/24, Area 0
  Process ID 1, Router ID 4.4.4.4, Network Type BROADCAST, Cost: 64
  Transmit Delay is 1 sec, State DROTHER, Priority 0
  Designated Router (ID) 3.3.3.3, Interface address 192.1.1.3
  No backup designated router on this network
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:05
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 3.3.3.3  (Designated Router)
  Suppress hello for 0 neighbor(s)


二、接下来观察各路由器邻居建立情况：
r2#sh ip os nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           1   FULL/DR         00:01:50    192.1.1.3       Serial2/0

r3#sh ip os nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
4.4.4.4           0   FULL/DROTHER    00:01:41    192.1.1.4       Serial3/0
2.2.2.2           0   FULL/DROTHER    00:01:30    192.1.1.2       Serial3/0

r3#sh ip os nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           1   FULL/DR         00:01:48    192.1.1.3       Serial4/0


三、最后验证路由：
r2#sh ip ro   
     2.0.0.0/24 is subnetted, 1 subnets
C       2.2.2.0 is directly connected, Loopback0
     3.0.0.0/32 is subnetted, 1 subnets
O       3.3.3.3 [110/65] via 192.1.1.3, 00:00:17, Serial2/0
     4.0.0.0/32 is subnetted, 1 subnets
O       4.4.4.4 [110/65] via 192.1.1.4, 00:00:17, Serial2/0
C    192.1.1.0/24 is directly connected, Serial2/0



r3#sh ip ro
     2.0.0.0/32 is subnetted, 1 subnets
O       2.2.2.2 [110/65] via 192.1.1.2, 00:00:38, Serial3/0
     3.0.0.0/24 is subnetted, 1 subnets
C       3.3.3.0 is directly connected, Loopback0
     4.0.0.0/32 is subnetted, 1 subnets
O       4.4.4.4 [110/65] via 192.1.1.4, 00:00:38, Serial3/0
C    192.1.1.0/24 is directly connected, Serial3/0



r4#sh ip ro
     2.0.0.0/32 is subnetted, 1 subnets
O       2.2.2.2 [110/65] via 192.1.1.2, 00:01:04, Serial4/0
     3.0.0.0/32 is subnetted, 1 subnets
O       3.3.3.3 [110/65] via 192.1.1.3, 00:01:04, Serial4/0
     4.0.0.0/24 is subnetted, 1 subnets
C       4.4.4.0 is directly connected, Loopback0
C    192.1.1.0/24 is directly connected, Serial4/0
r4#



如果我们将R2路由器的优先级调整为10，重启后R2将成为DR，R3作为BDR，R4作为DROTHER，这样的结果会导致R4无法收到R2、R3的路由更新，原因如下：

r4#sh ip ospf database
            OSPF Router with ID (4.4.4.4) (Process ID 1)
                Router Link States (Area 0)
Link ID         ADV Router      Age         Seq#       Checksum Link count
2.2.2.2         2.2.2.2         99          0x80000009 0xCF69   2
3.3.3.3         3.3.3.3         109         0x8000000B 0xDF4A   2
4.4.4.4         4.4.4.4         107         0x8000000C 0xFB1F   2
                Net Link States (Area 0)
Link ID         ADV Router      Age         Seq#       Checksum
192.1.1.2       2.2.2.2         108         0x80000001 0x4910

r4#sh ip os database router
            OSPF Router with ID (4.4.4.4) (Process ID 1)
                Router Link States (Area 0)
  Adv Router is not-reachable
  LS age: 124
  Options: (No TOS-capability, DC)
  LS Type: Router Links
  Link State ID: 2.2.2.2
  Advertising Router: 2.2.2.2
  LS Seq Number: 80000009
  Checksum: 0xCF69
  Length: 48
  Number of Links: 2
    Link connected to: a Transit Network
     (Link ID) Designated Router address: 192.1.1.2
     (Link Data) Router Interface address: 192.1.1.2
      Number of TOS metrics: 0
       TOS 0 Metrics: 64
    Link connected to: a Stub Network
     (Link ID) Network/subnet number: 2.2.2.2
     (Link Data) Network Mask: 255.255.255.255
      Number of TOS metrics: 0
       TOS 0 Metrics: 1

  Adv Router is not-reachable
  LS age: 198
  Options: (No TOS-capability, DC)
  LS Type: Router Links
  Link State ID: 3.3.3.3
  Advertising Router: 3.3.3.3
  LS Seq Number: 8000000B
  Checksum: 0xDF4A
  Length: 48
  Number of Links: 2
    Link connected to: a Transit Network
     (Link ID) Designated Router address: 192.1.1.2
     (Link Data) Router Interface address: 192.1.1.3
      Number of TOS metrics: 0
       TOS 0 Metrics: 64
    Link connected to: a Stub Network
     (Link ID) Network/subnet number: 3.3.3.3
     (Link Data) Network Mask: 255.255.255.255
      Number of TOS metrics: 0
       TOS 0 Metrics: 1
         
  LS age: 215
  Options: (No TOS-capability, DC)
  LS Type: Router Links
  Link State ID: 4.4.4.4
  Advertising Router: 4.4.4.4
  LS Seq Number: 8000000C
  Checksum: 0xFB1F
  Length: 48
  Number of Links: 2
    Link connected to: a Transit Network
     (Link ID) Designated Router address: 192.1.1.3
     (Link Data) Router Interface address: 192.1.1.4
      Number of TOS metrics: 0
       TOS 0 Metrics: 64
    Link connected to: a Stub Network
     (Link ID) Network/subnet number: 4.4.4.4
     (Link Data) Network Mask: 255.255.255.255
      Number of TOS metrics: 0
       TOS 0 Metrics: 1
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 楼主| 发表于 2007-10-16 12:16:36 | 显示全部楼层
六、在NBMA网络点到多点模式下配置OSPF实际案例（配图）＋详细验证过程




一个点到多点网络被看作若干具有一个或多个邻居的点到点接口。当一个接口被配置给点到多点网络，就不需要DR/BDR，不需要定义邻居，这大大简化了给NBMA网络配置OSPF。

使用端口命令 ip ospa network point-to-multioint可以给所有路由器设置网络类型。既不需要定义邻居，也不需要设置优先级，因为网络中没有DR/BDR。

// 帧交换机
frame-relay switching

int s2/0
  encapsulation frame-relay
  clock rate 64000
  frame-relay intf-type dce
  frame-relay route 200 int s3/0 300

int s3/0
  encapsulation frame-relay
  clock rate 64000
  frame-relay intf-type dce
  frame-relay route 300 int s2/0 200
  frame-relay route 399 int s4/0 400

int s4/0
  encapsulation frame-relay
  clock rate 64000
  frame-relay intf-type dce
  frame-relay route 400 int s2/0 399


// R2 //
int lo0
  ip ad 2.2.2.2 255.255.255.0


int s2/0
  encapsulation frame-relay
  ip ad 192.1.1.2 255.255.255.0
  ip ospf network point-to-multipoint    //改变接口模式为点到多点
  frame-relay map ip 192.1.1.3 200 broadcast
  frame-relay map ip 192.1.1.4 200 broadcast

router os 1
  network 2.2.2.2 0.0.0.0 area 0
  network 192.1.1.2 0.0.0.0 area 0


// R3 //
int lo0
  ip ad 3.3.3.3 255.255.255.0

int s3/0
  encapsulation frame-relay
  ip address 192.1.1.3 255.255.255.0
  ip ospf network point-to-multipoint    //改变接口模式为点到多点
  frame-relay map ip 192.1.1.2 300 broadcast
  frame-relay map ip 192.1.1.4 399 broadcast

router os 1
  network 3.3.3.3 0.0.0.0 area 0
  network 192.1.1.3 0.0.0.0 area 0



// R4 //
int lo0
  ip ad 4.4.4.4 255.255.255.0

int s4/0
  encapsulation frame-relay
  ip ad 192.1.1.4 255.255.255.0
  ip ospf network point-to-multipoint    //改变接口模式为点到多点
  frame-relay map ip 192.1.1.2 400 broadcast
  frame-relay map ip 192.1.1.3 400 broadcast

router os 1
  network 4.4.4.4 0.0.0.0 area 0
  network 192.1.1.4 0.0.0.0 area 0

注意上述配置中没有任何特别操作，比如使用neighbor命令指明邻居，设置OSPF优先级等等，这就是点到多点模式下的特点。


验证过程：
一、首先来检查DR选举是否按我们的设计，R3被选举为DR，R2、R4不参与选举，同时注意网络类型是否为NBMA，hello时间间隔是否为30秒。。。。。。

r3#sh ip os int s3/0
Serial3/0 is up, line protocol is up
  Internet Address 192.1.1.3/24, Area 0
  Process ID 1, Router ID 3.3.3.3, 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 due in 00:00:18
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 2
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 2, Adjacent neighbor count is 2
    Adjacent with neighbor 4.4.4.4
    Adjacent with neighbor 2.2.2.2
  Suppress hello for 0 neighbor(s)


r2#sh ip os int s2/0
Serial2/0 is up, line protocol is up
  Internet Address 192.1.1.2/24, Area 0
  Process ID 1, 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 due in 00:00:01
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 2
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 3.3.3.3
  Suppress hello for 0 neighbor(s)


r4#sh ip ospf int s4/0
Serial4/0 is up, line protocol is up
  Internet Address 192.1.1.4/24, Area 0
  Process ID 1, Router ID 4.4.4.4, 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 due in 00:00:02
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 3.3.3.3
  Suppress hello for 0 neighbor(s)


二、接下来观察各路由器邻居建立情况：
r2#sh ip os nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           1   FULL/  -        00:01:33    192.1.1.3       Serial2/0

r3#sh ip os nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
4.4.4.4           1   FULL/  -        00:01:56    192.1.1.4       Serial3/0
2.2.2.2           1   FULL/  -        00:01:36    192.1.1.2       Serial3/0


r4#sh ip os nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           1   FULL/  -        00:01:37    192.1.1.3       Serial4/0


三、最后验证路由：
r2#sh ip ro   
     2.0.0.0/24 is subnetted, 1 subnets
C       2.2.2.0 is directly connected, Loopback0
     3.0.0.0/32 is subnetted, 1 subnets
O       3.3.3.3 [110/65] via 192.1.1.3, 00:08:30, Serial2/0
     4.0.0.0/32 is subnetted, 1 subnets
O       4.4.4.4 [110/129] via 192.1.1.3, 00:08:30, Serial2/0
     192.1.1.0/24 is variably subnetted, 3 subnets, 2 masks
C       192.1.1.0/24 is directly connected, Serial2/0
O       192.1.1.3/32 [110/64] via 192.1.1.3, 00:08:30, Serial2/0
O       192.1.1.4/32 [110/128] via 192.1.1.3, 00:08:30, Serial2/0



r3#sh ip ro

     2.0.0.0/32 is subnetted, 1 subnets
O       2.2.2.2 [110/65] via 192.1.1.2, 00:08:54, Serial3/0
     3.0.0.0/24 is subnetted, 1 subnets
C       3.3.3.0 is directly connected, Loopback0
     4.0.0.0/32 is subnetted, 1 subnets
O       4.4.4.4 [110/65] via 192.1.1.4, 00:08:54, Serial3/0
     192.1.1.0/24 is variably subnetted, 3 subnets, 2 masks
C       192.1.1.0/24 is directly connected, Serial3/0
O       192.1.1.2/32 [110/64] via 192.1.1.2, 00:08:54, Serial3/0
O       192.1.1.4/32 [110/64] via 192.1.1.4, 00:08:54, Serial3/0



r4#sh ip ro
     2.0.0.0/32 is subnetted, 1 subnets
O       2.2.2.2 [110/129] via 192.1.1.3, 00:09:20, Serial4/0
     3.0.0.0/32 is subnetted, 1 subnets
O       3.3.3.3 [110/65] via 192.1.1.3, 00:09:20, Serial4/0
     4.0.0.0/24 is subnetted, 1 subnets
C       4.4.4.0 is directly connected, Loopback0
     192.1.1.0/24 is variably subnetted, 3 subnets, 2 masks
C       192.1.1.0/24 is directly connected, Serial4/0
O       192.1.1.2/32 [110/128] via 192.1.1.3, 00:09:20, Serial4/0
O       192.1.1.3/32 [110/64] via 192.1.1.3, 00:09:20, Serial4/0


注意，在点到多点或点到点模式下，路由表中会自动生成32位主机路由。
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 楼主| 发表于 2007-10-16 12:16:59 | 显示全部楼层
七、在NBMA网络非广播模式下配置OSPF实际案例（配图）＋详细验证过程



当在NBMA网络（如帧中继、ATM）中配置OSPF，必须注意哪个路由器是网络的DR和BDR，DR和BDR要求与网络中的所有路由器都有完全的逻辑连接。

同时，根据所使用的是四种网络类型中的哪一种（广播式、非广播式、点到点、点到多点），有必要使用额外的配置。

这个实验是在非广播的NBMA帧中继网络中使用了OSPF。这种类型是帧中继网络中物理接口的缺省类型。在非广播式网络中，存在一个DR或BDR，这要根据网络的性能，这要根据网络的性能，这个DR和BDR必须有一个包含所有处于帧中继的路由器的静态表，在OSPF进程中使用邻居命令可以完成这个任务。

对于这个实验，DR是路由器3，因为它具有与网络上其它所有路由器的完整的物理连接。如上图表示。

// 帧交换机
frame-relay switching

int s2/0
  encapsulation frame-relay
  clock rate 64000
  frame-relay intf-type dce
  frame-relay route 200 int s3/0 300

int s3/0
  encapsulation frame-relay
  clock rate 64000
  frame-relay intf-type dce
  frame-relay route 300 int s2/0 200
  frame-relay route 399 int s4/0 400

int s4/0
  encapsulation frame-relay
  clock rate 64000
  frame-relay intf-type dce
  frame-relay route 400 int s2/0 399


// R2 //
int lo0
  ip ad 2.2.2.2 255.255.255.0


int s2/0
  encapsulation frame-relay
  ip ospf priority 0    //优先级为0，不参与DR选举
  ip ad 192.1.1.2 255.255.255.0
  frame-relay map ip 192.1.1.3 200 broadcast
  frame-relay map ip 192.1.1.4 200 broadcast

router os 1
  network 2.2.2.2 0.0.0.0 area 0
  network 192.1.1.2 0.0.0.0 area 0


// R3 //
int lo0
  ip ad 3.3.3.3 255.255.255.0

int s3/0
  encapsulation frame-relay
  ip address 192.1.1.3 255.255.255.0
  frame-relay map ip 192.1.1.2 300 broadcast
  frame-relay map ip 192.1.1.4 399 broadcast

router os 1
  network 3.3.3.3 0.0.0.0 area 0
  network 192.1.1.3 0.0.0.0 area 0
  neighbor 192.1.1.2    //NBMA模式下OSPF必须手动指定邻居
  neighbor 192.1.1.4    //NBMA模式下OSPF必须手动指定邻居


// R4 //
int lo0
  ip ad 4.4.4.4 255.255.255.0

int s4/0
  encapsulation frame-relay
  ip ad 192.1.1.4 255.255.255.0
  ip ospf priority 0    //优先级为0，不参与DR选举
  frame-relay map ip 192.1.1.2 400 broadcast
  frame-relay map ip 192.1.1.3 400 broadcast

router os 1
  network 4.4.4.4 0.0.0.0 area 0
  network 192.1.1.4 0.0.0.0 area 0




验证过程：
一、首先来检查DR选举是否按我们的设计，R3被选举为DR，R2、R4不参与选举，同时注意网络类型是否为NBMA，hello时间间隔是否为30秒。。。。。。

r3#sh ip os int s3/0
Serial3/0 is up, line protocol is up
  Internet Address 192.1.1.3/24, Area 0
  Process ID 1, Router ID 3.3.3.3, Network Type NON_BROADCAST, Cost: 64
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 3.3.3.3, Interface address 192.1.1.3
  No backup designated router on this network
  Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5
    Hello due in 00:00:27
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 2, maximum is 2
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 2, Adjacent neighbor count is 2
    Adjacent with neighbor 4.4.4.4
    Adjacent with neighbor 2.2.2.2
  Suppress hello for 0 neighbor(s)


r2#sh ip os int s2/0
Serial2/0 is up, line protocol is up
  Internet Address 192.1.1.2/24, Area 0
  Process ID 1, Router ID 2.2.2.2, Network Type NON_BROADCAST, Cost: 64
  Transmit Delay is 1 sec, State DROTHER, Priority 0
  Designated Router (ID) 3.3.3.3, Interface address 192.1.1.3
  No backup designated router on this network
  Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5
    Hello due in 00:00:20
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 3.3.3.3  (Designated Router)
  Suppress hello for 0 neighbor(s)


r4#sh ip ospf int s4/0
Serial4/0 is up, line protocol is up
  Internet Address 192.1.1.4/24, Area 0
  Process ID 1, Router ID 4.4.4.4, Network Type NON_BROADCAST, Cost: 64
  Transmit Delay is 1 sec, State DROTHER, Priority 0
  Designated Router (ID) 3.3.3.3, Interface address 192.1.1.3
  No backup designated router on this network
  Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5
    Hello due in 00:00:05
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 3.3.3.3  (Designated Router)
  Suppress hello for 0 neighbor(s)


二、接下来观察各路由器邻居建立情况：
r2#sh ip os nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           1   FULL/DR         00:01:50    192.1.1.3       Serial2/0

r3#sh ip os nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
4.4.4.4           0   FULL/DROTHER    00:01:41    192.1.1.4       Serial3/0
2.2.2.2           0   FULL/DROTHER    00:01:30    192.1.1.2       Serial3/0

r3#sh ip os nei
Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           1   FULL/DR         00:01:48    192.1.1.3       Serial4/0


三、最后验证路由：
r2#sh ip ro   
     2.0.0.0/24 is subnetted, 1 subnets
C       2.2.2.0 is directly connected, Loopback0
     3.0.0.0/32 is subnetted, 1 subnets
O       3.3.3.3 [110/65] via 192.1.1.3, 00:00:17, Serial2/0
     4.0.0.0/32 is subnetted, 1 subnets
O       4.4.4.4 [110/65] via 192.1.1.4, 00:00:17, Serial2/0
C    192.1.1.0/24 is directly connected, Serial2/0



r3#sh ip ro
     2.0.0.0/32 is subnetted, 1 subnets
O       2.2.2.2 [110/65] via 192.1.1.2, 00:00:38, Serial3/0
     3.0.0.0/24 is subnetted, 1 subnets
C       3.3.3.0 is directly connected, Loopback0
     4.0.0.0/32 is subnetted, 1 subnets
O       4.4.4.4 [110/65] via 192.1.1.4, 00:00:38, Serial3/0
C    192.1.1.0/24 is directly connected, Serial3/0



r4#sh ip ro
     2.0.0.0/32 is subnetted, 1 subnets
O       2.2.2.2 [110/65] via 192.1.1.2, 00:01:04, Serial4/0
     3.0.0.0/32 is subnetted, 1 subnets
O       3.3.3.3 [110/65] via 192.1.1.3, 00:01:04, Serial4/0
     4.0.0.0/24 is subnetted, 1 subnets
C       4.4.4.0 is directly connected, Loopback0
C    192.1.1.0/24 is directly connected, Serial4/0
r4#
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