EIGRP STUB区域设置了之后，路由器在丢失路由条目的时候不会向 STUB区域发查询消息，在上述top中我们可以把Rc做成 STUB区域，假如Rb的loop0 口down掉了之后，Rb不会向Rc发送查询消息。我们先在这3太路由器上全部启用EIGRP 10 ，所有的接口都参与到EIGRP 10 在没有设置stub的时候，得到路由表如下：
- RA：
- 1.0.0.0/24 is subnetted, 1 subnets
- C 1.1.1.0 is directly connected, Loopback0
- 2.0.0.0/24 is subnetted, 1 subnets
- D 2.2.2.0 [90/2297000] via 12.1.1.2, 00:01:26, Serial2/1
- 3.0.0.0/24 is subnetted, 1 subnets
- D 3.3.3.0 [90/2297000] via 12.1.1.2, 00:00:37, Serial2/1
- 23.0.0.0/30 is subnetted, 1 subnets
- D 23.1.1.0 [90/2297000] via 12.1.1.2, 00:01:26, Serial2/1
- 12.0.0.0/30 is subnetted, 1 subnets
- C 12.1.1.0 is directly connected, Serial2/1
- Rb：
- 1.0.0.0/24 is subnetted, 1 subnets
- D 1.1.1.0 [90/2297000] via 12.1.1.1, 00:02:30, Serial2/1
- 2.0.0.0/24 is subnetted, 1 subnets
- C 2.2.2.0 is directly connected, Loopback0
- 3.0.0.0/24 is subnetted, 1 subnets
- D 3.3.3.0 [90/2297000] via 23.1.1.1, 00:01:41, Serial2/2
- 23.0.0.0/30 is subnetted, 1 subnets
- C 23.1.1.0 is directly connected, Serial2/2
- 12.0.0.0/30 is subnetted, 1 subnets
- C 12.1.1.0 is directly connected, Serial2/1
- Rc:
- 1.0.0.0/24 is subnetted, 1 subnets
- D 1.1.1.0 [90/2297000] via 23.1.1.2, 00:02:06, Serial2/2
- 2.0.0.0/24 is subnetted, 1 subnets
- D 2.2.2.0 [90/2297000] via 23.1.1.2, 00:02:06, Serial2/2
- 3.0.0.0/24 is subnetted, 1 subnets
- C 3.3.3.0 is directly connected, Loopback0
- 23.0.0.0/30 is subnetted, 1 subnets
- C 23.1.1.0 is directly connected, Serial2/2
- 12.0.0.0/30 is subnetted, 1 subnets
- D 12.1.1.0 [90/2297000] via 23.1.1.2, 00:02:06, Serial2/2
下面，我们开始试验，在Rc上没有设置stub的时候，在Rb上打开debug
- RB#debug eigrp packets query
- RB EIGRP Packets debugging is on
- (QUERY)
- RB#config t
- Enter configuration commands, one per line. End with CNTL/Z.
- RB(config)#
- RB(config)#int loopback 0
- RB(config-if)#shu
- *Mar 1 00:16:38.587: EIGRP: Enqueueing QUERY on Serial2/1 iidbQ un/rely 0/1 serno 6-6
- *Mar 1 00:16:38.591: EIGRP: Enqueueing QUERY on Serial2/1 nbr 12.1.1.1 iidbQ un/rely 0/0 peerQ un/rely 0/0 serno 6-6
- *Mar 1 00:16:38.599: EIGRP: Sending QUERY on Serial2/1 nbr 12.1.1.1 （向RA发送查询）
- *Mar 1 00:16:38.603: AS 10, Flags 0x0, Seq 10/3 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 6-6
- *Mar 1 00:16:38.607: EIGRP: Enqueueing QUERY on Serial2/2 iidbQ un/rely 0/1 serno 6-6
- *Mar 1 00:16:38.611: EIGRP: Enqueueing QUERY on Serial2/2 nbr 23.1.1.1 iidbQ un/rely 0/0 peerQ un/rely 0/0 serno 6-6
- *Mar 1 00:16:38.619: EIGRP: Sending QUERY on Serial2/2 nbr 23.1.1.1 （向RC发送查查询）
- *Mar 1 00:16:38.623: AS 10, Flags 0x0, Seq 11/3 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 6-6
可以看到，没有设置stub的时候 Rb会向RA和 Rc发送查询消息。下面我们把Rc做成 STUB区域.
我们先把RB上的loopback 0 打开，让网络回到正常的收敛
- Rb（config-it）# int lo 0
- Rb（config-it）#no sh
然后把RC设置成STUB区域
- RC(config)#router ei 100
- RC(config-router)#eigrp stub receive-only
再关掉RB上的loopback 0
再来看RB的查询情况：
- *Mar 1 00:28:13.139: EIGRP: Enqueueing QUERY on Serial2/2 iidbQ un/rely 0/1 serno 9-9
- *Mar 1 00: 28:13.143: EIGRP: Enqueueing QUERY on Serial2/2 nbr 23.1.1.1 iidbQ un/rely 0/0 peerQ un/rely 0/0 serno 9-9
- *Mar 1 00: 28:13.151: EIGRP: Enqueueing QUERY on Serial2/1 iidbQ un/rely 0/1 serno 9-9
- *Mar 1 00: 28:13.155: EIGRP: Enqueueing QUERY on Serial2/1 nbr 12.1.1.1 iidbQ un/rely 0/0 peerQ un/rely 0/0 serno 9-9
- *Mar 1 00: 28:13.163: EIGRP: Sending QUERY on Serial2/1 nbr 12.1.1.1 （向RA发送查询）
- *Mar 1 00: 28:13.163: AS 10, Flags 0x0, Seq 19/8 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 9-9
- *Mar 1 00: 28:13.351: EIGRP: Received QUERY on Serial2/2 nbr 23.1.1.1
- RB(config-if)#
- *Mar 1 00: 28:13.355: AS 10, Flags 0x0, Seq 11/21 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
自始至终没有发现去往Rc的查询消息，所以，EIGRP的 STUB区域验证成功。
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