【实验说明】
在AS2上配置汇聚路由，使得AS1上的路由器只学习到（
10.0.0.0/16, 10.1.0.0/16, 10.2.0.0/16, and 10.3.0.0/16
网络）的汇聚路由，而不包括被汇聚的源明细路由。
【实验拓扑】
【实验配置步骤】
- 按照上图配置各个设备的接口地址
- 在 R1, R3, R4, R5 上配置BGP
- R1 与 R3 and R4 建立邻居对等体
- R5 与 R3 and R4 建立邻居对等体
- 通告 R5与R4上的loopback0 地址到BGP
- 通告R1 上的Loopback地址 BGP
- 通告R2 上的Loopback地址 BGP
- 在R1与R3上配置BGP 汇聚路由，汇聚R1与R3的loopback地址，并且使用summary-only参数
【实验分析】
使用aggregate-address对路由进行汇聚时，如果不加入summary-only参数，邻居路由器不仅仅收到汇聚后的路由，而且会收到被汇聚的源明细路由，本实验正是验证加入summary-only之后，邻居将不会学习到被汇聚的源明细路由。
【实验基本配置】
|
R1：
interface Loopback0
ip address 10.0.0.1 255.255.0.0
!
interface Loopback1
ip address 10.1.0.1 255.255.0.0
!
interface FastEthernet0/0
ip address 155.1.146.1 255.255.255.0
duplex auto
speed auto
!
interface Serial0/0
ip address 155.1.13.1 255.255.255.0
clock rate 2000000
!
router bgp 2
network 10.0.0.0 mask 255.255.0.0
network 10.1.0.0 mask 255.255.0.0
aggregate-address 10.0.0.0 255.252.0.0 summary-only
neighbor 155.1.13.3 remote-as 2
neighbor 155.1.13.3 next-hop-self
neighbor 155.1.146.4 remote-as 1
R3：
interface Loopback0
ip address 10.2.0.1 255.255.0.0
!
interface Loopback1
ip address 10.3.0.1 255.255.0.0
!
interface Serial0/0
ip address 155.1.0.3 255.255.255.0
encapsulation frame-relay
clock rate 2000000
frame-relay map ip 155.1.0.5 305 broadcast
no frame-relay inverse-arp
!
interface Serial0/1
ip address 155.1.13.3 255.255.255.0
clock rate 64000
!
router bgp 2
network 10.2.0.0 mask 255.255.0.0
network 10.3.0.0 mask 255.255.0.0
aggregate-address 10.0.0.0 255.252.0.0 summary-only
neighbor 155.1.13.1 remote-as 2
neighbor 155.1.13.1 next-hop-self
neighbor 155.1.0.5 remote-as 1
|
R4：
interface Loopback0
ip address 204.12.1.4 255.255.255.0
!
interface FastEthernet0/0
ip address 155.1.146.4 255.255.255.0
duplex auto
speed auto
!
interface Serial0/0
ip address 155.1.45.4 255.255.255.0
clock rate 2000000
!
router bgp 1
network 204.12.1.0
neighbor 155.1.45.5 remote-as 1
neighbor 155.1.146.1 remote-as 2
neighbor 155.1.45.5 next-hop-self
R5：
interface Loopback0
ip address 155.1.5.5 255.255.255.0
!
interface Serial0/1
ip address 155.1.45.5 255.255.255.0
clock rate 64000
!
interface Serial0/0
ip address 155.1.0.5 255.255.255.0
encapsulation frame-relay
clock rate 2000000
frame-relay map ip 155.1.0.3 503 broadcast
no frame-relay inverse-arp
!
router bgp 1
network 155.1.5.0 mask 255.255.255.0
neighbor 155.1.45.4 remote-as 1
neighbor 155.1.0.3 remote-as 2
neighbor 155.1.45.4 next-hop-self
|
【实验验证】
在R1与R3上未配置 aggregate-address 10.0.0.0 255.252.0.0 summary-only 之前，我们发现R4与R5上学习到的路由中包括所有明细路由，正如下面输出结果
-----------------------------------------------------------------------------------------------------
R4#show ip bgp
<隐藏部分输出结果>
Network Next Hop Metric LocPrf Weight Path
*> 10.0.0.0/16 155.1.146.1 0 0 2 i
*> 10.1.0.0/16 155.1.146.1 0 0 2 i
*> 10.2.0.0/16 155.1.146.1 0 2 i
*> 10.3.0.0/16 155.1.146.1 0 2 i
*>i155.1.5.0/24 155.1.45.5 0 100 0 i
*> 204.12.1.0 0.0.0.0 0 32768 i
R5#show ip bgp
<隐藏部分输出结果>
Network Next Hop Metric LocPrf Weight Path
* i10.0.0.0/16 155.1.146.1 0 100 0 2 i
* i10.1.0.0/16 155.1.146.1 0 100 0 2 i
* i10.2.0.0/16 155.1.146.1 0 100 0 2 i
* i10.3.0.0/16 155.1.146.1 0 100 0 2 i
*> 155.1.5.0/24 0.0.0.0 0 32768 i
*>i204.12.1.0 155.1.45.4 0 100 0 i
R1(config-router)#do show ip bgp
<隐藏部分输出结果>
Network Next Hop Metric LocPrf Weight Path
*> 10.0.0.0/16 0.0.0.0 0 32768 i
*> 10.1.0.0/16 0.0.0.0 0 32768 i
*>i10.2.0.0/16 155.1.13.3 0 100 0 i
*>i10.3.0.0/16 155.1.13.3 0 100 0 i
*> 155.1.5.0/24 155.1.146.4 0 1 i
*> 204.12.1.0 155.1.146.4 0 0 1 i
R3(config-router)#do show ip bgp
<隐藏部分输出结果>
Network Next Hop Metric LocPrf Weight Path
*>i10.0.0.0/16 155.1.13.1 0 100 0 i
*>i10.1.0.0/16 155.1.13.1 0 100 0 i
*> 10.2.0.0/16 0.0.0.0 0 32768 i
*> 10.3.0.0/16 0.0.0.0 0 32768 i
* i155.1.5.0/24 155.1.146.4 0 100 0 1 i
* i204.12.1.0 155.1.146.4 0 100 0 1 i
在R1与R3上配置 aggregate-address 10.0.0.0 255.252.0.0 但是不加如 summary-only 参数之后，我们看到所有路由器不仅学习到了汇聚路由，而且学习到了明细路由，如下面输出结果：
-------------------------------------------------------------------------------------------------------------------------
R4#show ip bgp
<隐藏部分输出结果>
Network Next Hop Metric LocPrf Weight Path
*> 10.0.0.0/16 155.1.146.1 0 0 2 i
*> 10.0.0.0/14 155.1.146.1 0 0 2 i
*> 10.1.0.0/16 155.1.146.1 0 0 2 i
*> 10.2.0.0/16 155.1.146.1 0 2 i
*> 10.3.0.0/16 155.1.146.1 0 2 i
*>i155.1.5.0/24 155.1.45.5 0 100 0 i
*> 204.12.1.0 0.0.0.0 0 32768 i
R5#show ip bgp
<隐藏部分输出结果>
Network Next Hop Metric LocPrf Weight Path
*
>
i10.0.0.0/16 155.1.146.1 0 100 0 2 i
*
>
i10.0.0.0/14 155.1.146.1 0 100 0 2 i
*
>
i10.1.0.0/16 155.1.146.1 0 100 0 2 i
*
>
i10.2.0.0/16 155.1.146.1 0 100 0 2 i
*
>
i10.3.0.0/16 155.1.146.1 0 100 0 2 i
*> 155.1.5.0/24 0.0.0.0 0 32768 i
*>i204.12.1.0 155.1.45.4 0 100 0 i
R1(config-router)#do show ip bgp
<隐藏部分输出结果>
Network Next Hop Metric LocPrf Weight Path
*> 10.0.0.0/16 0.0.0.0 0 32768 i
*>i10.0.0.0/14 155.1.13.3 0 100 0 i
*> 0.0.0.0 32768 i
*> 10.1.0.0/16 0.0.0.0 0 32768 i
*>i10.2.0.0/16 155.1.13.3 0 100 0 i
*>i10.3.0.0/16 155.1.13.3 0 100 0 i
*> 155.1.5.0/24 155.1.146.4 0 1 i
*> 204.12.1.0 155.1.146.4 0 0 1 i
R3(config-router)#do show ip bgp
<隐藏部分输出结果>
Network Next Hop Metric LocPrf Weight Path
*>i10.0.0.0/16 155.1.13.1 0 100 0 i
*> 10.0.0.0/14 0.0.0.0 32768 i
* i 155.1.13.1 0 100 0 i
*>i10.1.0.0/16 155.1.13.1 0 100 0 i
*> 10.2.0.0/16 0.0.0.0 0 32768 i
*> 10.3.0.0/16 0.0.0.0 0 32768 i
* i155.1.5.0/24 155.1.146.4 0 100 0 1 i
* i204.12.1.0 155.1.146.4 0 100 0 1 i
在R1与R3上配置 aggregate-address 10.0.0.0 255.252.0.0 summary-only 之后，我们看到所有路由器学习到的仅仅是汇聚路由，不包括明细路由，如下面输出结果
-----------------------------------------------------------------------------------------------------
R4#show ip bgp
<隐藏部分输出结果>
Network Next Hop Metric LocPrf Weight Path
*> 10.0.0.0/14 155.1.146.1 0 0 2 i
*>i155.1.5.0/24 155.1.45.5 0 100 0 i
*> 204.12.1.0 0.0.0.0 0 32768 i
R5#show ip bgp
BGP table version is 3, local router ID is 155.1.5.5
Status codes: s suppressed, d damped, h history, * valid, > best, i - inter
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
* i10.0.0.0/14 155.1.146.1 0 100 0 2 i
*> 155.1.5.0/24 0.0.0.0 0 32768 i
*>i204.12.1.0 155.1.45.4 0 100 0 i
R1(config-router)#do show ip bgp
BGP table version is 29, local router ID is 155.1.146.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
s> 10.0.0.0/16 0.0.0.0 0 32768 i
* i10.0.0.0/14 155.1.13.3 0 100 0 i
*> 0.0.0.0 32768 i
s> 10.1.0.0/16 0.0.0.0 0 32768 i
*> 155.1.5.0/24 155.1.146.4 0 1 i
*> 204.12.1.0 155.1.146.4 0 0 1 i
R3(config-router)#do show ip bgp
<隐藏部分输出结果>
Network Next Hop Metric LocPrf Weight Path
*> 10.0.0.0/14 0.0.0.0 32768 i
* i 155.1.13.1 0 100 0 i
s> 10.2.0.0/16 0.0.0.0 0 32768 i
s> 10.3.0.0/16 0.0.0.0 0 32768 i
* i155.1.5.0/24 155.1.146.4 0 100 0 1 i
* i204.12.1.0 155.1.146.4 0 100 0 1 i
【实验总结】
下面我们将R4上的路由输出进行对比，对比结果很明显，如果aggregate-address 命令中加如 summary-only 参数，将不通告明细路由，否则将通告明细路由
| R1与R3上未配置任何汇聚路由，R4的BGP路由包含邻居通告的所有路由 |
|
R4#show ip bgp
<隐藏部分输出结果>
Network Next Hop Metric LocPrf Weight Path
*> 10.0.0.0/16 155.1.146.1 0 0 2 i
*> 10.1.0.0/16 155.1.146.1 0 0 2 i
*> 10.2.0.0/16 155.1.146.1 0 2 i
*> 10.3.0.0/16 155.1.146.1 0 2 i
*>i155.1.5.0/24 155.1.45.5 0 100 0 i
*> 204.12.1.0 0.0.0.0 0 32768 i
|
| R1与R3上配置 aggregate-address 10.0.0.0 255.252.0.0，R4上的BGP路由中不仅包含了汇聚路由，而且包含了被汇聚的源明细路由 |
|
R4#show ip bgp
<隐藏部分输出结果>
Network Next Hop Metric LocPrf Weight Path
*> 10.0.0.0/16 155.1.146.1 0 0 2 i
*> 10.0.0.0/14 155.1.146.1 0 0 2 i
*> 10.1.0.0/16 155.1.146.1 0 0 2 i
*> 10.2.0.0/16 155.1.146.1 0 2 i
*> 10.3.0.0/16 155.1.146.1 0 2 i
*>i155.1.5.0/24 155.1.45.5 0 100 0 i
*> 204.12.1.0 0.0.0.0 0 32768 i
|
| R1与R3上配置 aggregate-address 10.0.0.0 255.252.0.0 summary-only，R4上的BGP路由中只包含了汇聚路由，不包含被汇聚的源明细路由 |
|
R4#show ip bgp
<隐藏部分输出结果>
Network Next Hop Metric LocPrf Weight Path
*> 10.0.0.0/14 155.1.146.1 0 0 2 i
*>i155.1.5.0/24 155.1.45.5 0 100 0 i
*> 204.12.1.0 0.0.0.0 0 32768 i本文转自zcm8483 51CTO博客，原文链接:http://blog.51cto.com/haolun/992258 |
