案例精解：BGP路由黑洞
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案例精解：BGP路由黑洞
什么是路由黑洞？简单的说，它会默默的将数据包丢弃，使所有数据包有去无回，下面来看一个案
如图所示：
R1和R2建立EBGP邻居关系
R2和R5建立IBGP邻居关系
R5和R7建立EBGP邻居关系
R2、R3、R5之间运行RIPv2
首先看配置：
sysname route-1
#
router id 1.1.1.1
#
interface Ethernet0/0
ip address 192.168.12.1 255.255.255.252
#
interface Ethernet0/1
ip address dhcp-alloc
#
interface LoopBack0
ip address 1.1.1.1 255.255.255.255
#
bgp 100
undo synchronization
group 1 external
peer 192.168.12.2 group 1 as-number 200
#
ip route-static 2.2.2.2 255.255.255.255 192.168.12.2 preference 60
#
sysname route-2
#
router id 2.2.2.2
#
interface Ethernet0/0
ip address 192.168.12.2 255.255.255.252
#
interface Ethernet0/1
ip address 192.168.23.1 255.255.255.252
#
interface LoopBack0
ip address 2.2.2.2 255.255.255.255
#
bgp 200
undo synchronization
group 1 external
peer 192.168.12.1 group 1 as-number 100
group 2 internal
peer 192.168.35.2 group 2
#
ospf 1
import-route direct
import-route static
area 0.0.0.0
network 2.2.2.2 0.0.0.0
network 192.168.23.0 0.0.0.3
#
ip route-static 1.1.1.1 255.255.255.255 192.168.12.1 preference 60 #
sysname route-3
#
router id 3.3.3.3
#
interface Ethernet0/0
ip address 192.168.35.1 255.255.255.252
#
interface Ethernet0/1
ip address 192.168.23.2 255.255.255.252
#
interface LoopBack0
ip address 3.3.3.3 255.255.255.255
#
ospf 1
import-route direct
import-route static
area 0.0.0.0
network 3.3.3.3 0.0.0.0
network 192.168.23.0 0.0.0.3
network 192.168.35.0 0.0.0.3
#
sysname route-5
#
router id 5.5.5.5
#
interface Ethernet0/0
ip address 192.168.35.2 255.255.255.252
#
interface Ethernet0/1
ip address 192.168.57.1 255.255.255.252
#
interface LoopBack0
ip address 5.5.5.5 255.255.255.255
#
bgp 200
undo synchronization
group 2 internal
peer 192.168.23.1 group 2
group 1 external
peer 192.168.57.2 group 1 as-number 300
#
ospf 1
import-route direct
import-route static
area 0.0.0.0
network 5.5.5.5 0.0.0.0
network 192.168.35.0 0.0.0.3
#
ip route-static 7.7.7.7 255.255.255.255 192.168.57.2 preference 60
sysname route-7
#
router id 7.7.7.7
#
interface Ethernet0/0
ip address dhcp-alloc
#
interface Ethernet0/1
ip address 192.168.57.2 255.255.255.252
#
interface LoopBack0
ip address 7.7.7.7 255.255.255.255
#
bgp 300
undo synchronization
group 1 external
peer 192.168.57.1 group 1 as-number 200
#
ip route-static 1.1.1.1 255.255.255.255 192.168.57.1 preference 60
ip route-static 5.5.5.5 255.255.255.255 192.168.57.1 preference 60
现在查看R7的路由表
Routing Table: public net
Destination/Mask Protocol Pre Cost Nexthop Interface
1.1.1.1/32 STA TIC 60 0 19
2.168.57.1 Ethernet0/1
5.5.5.5/32 STA TIC 60 0 192.168.57.1 Ethernet0/1
7.7.7.7/32 DIRECT 0 0 127.0.0.1 InLoopBack0
127.0.0.0/8 DIRECT 0 0 127.0.0.1 InLoopBack0
127.0.0.1/32 DIRECT 0 0 127.0.0.1 InLoopBack0
192.168.57.0/30 DIRECT 0 0 192.168.57.2 Ethernet0/1
192.168.57.2/32 DIRECT 0 0 127.0.0.1 InLoopBack0
可见R7学到了R1的路由，从表面上看这个实验很完美，达了目的，然而这时问题出现了，