BGP2

1) 按照拓扑搭建网络，在所有AS间使用直连接口建立EBGP邻居关系；

2) 在公司总部AS400中，R4与R5，R5与R7，R7与R6，R6与R4间使用环回接口建立IBGP邻居关系，IGP协议使用OSPF；

3) 所有业务网段，与所有设备上的Loopback 0所在网段都能通过BGP路由实现互相访问；

4) 为了使网络资源能充分得到利用，要求业务网段A的流量通过运营商设备转发，业务网段B的流量通过专线转发；

5) 网络管理员进行定期线路检查，现通过适当调整IGP的链路开销值，使得所有经过总部AS的流量都沿着R4-R5-R7-R6路径转发；

6) 网络管理员在检查中发现业务网段B的流量非常大，决定将业务网段B的流量单独沿着R4-R6路径转发（要求BGP路由选路与实际转发路径一致）；

7) 公司总部网络将进行改造，在不改变原有配置的基础上，通过增加少量配置实现，R5与R7不参与BGP路径选择。

1) 按照拓扑搭建网络，在所有AS间使用直连接口建立EBGP邻居关系；

R1:（为例）R1R2R3R4R6都做

bgp 100
 peer 12.1.1.2 as-number 200
 peer 14.1.1.4 as-number 400

2) 在公司总部AS400中，R4与R5，R5与R7，R7与R6，R6与R4间使用环回接口建立IBGP邻居关系，IGP协议使用OSPF；

R4为例（R4R5R6R7都做）bgp 400

 peer 5.5.5.5 as-number 400
 peer 5.5.5.5 connect-interface LoopBack0
 peer 6.6.6.6 as-number 400
 peer 6.6.6.6 connect-interface LoopBack0
 peer 7.7.7.7 as-number 400
 peer 7.7.7.7 connect-interface LoopBack0
 peer 14.1.1.1 as-number 100
  import-route ospf 1
  
ospf 1 router-id 4.4.4.4
 area 0.0.0.0
  network 4.4.4.0 0.0.0.255
  network 5.5.5.0 0.0.0.255
  network 45.1.1.0 0.0.0.255
  network 46.1.1.0 0.0.0.255

3) 所有业务网段，与所有设备上的Loopback 0所在网段都能通过BGP路由实现互相访问；

前3问之前R1到R7的所有命令：

R1: 

interface GigabitEthernet0/0/0
 ip address 12.1.1.1 255.255.255.0
#
interface GigabitEthernet0/0/1
 ip address 14.1.1.1 255.255.255.0
#
interface GigabitEthernet0/0/2
#
interface NULL0
#
interface LoopBack0
 ip address 1.1.1.1 255.255.255.0
#
interface LoopBack1
 ip address 11.11.11.11 255.255.255.0
#
bgp 100
 peer 12.1.1.2 as-number 200
 peer 14.1.1.4 as-number 400
 #
 ipv4-family unicast
  undo synchronization
  network 1.1.1.0 255.255.255.0
  network 11.11.11.0 255.255.255.0
  peer 12.1.1.2 enable
  peer 14.1.1.4 enable
#
ip route-static 2.2.2.0 255.255.255.0 12.1.1.2
ip route-static 4.4.4.0 255.255.255.0 14.1.1.4
#
user-interface con 0
 authentication-mode password
user-interface vty 0 4
user-interface vty 16 20
#
wlan ac
#
return

R2:

interface GigabitEthernet0/0/0
 ip address 12.1.1.2 255.255.255.0
#
interface GigabitEthernet0/0/1
 ip address 23.1.1.2 255.255.255.0
#
interface GigabitEthernet0/0/2
#
interface NULL0
#
interface LoopBack0
 ip address 2.2.2.2 255.255.255.0
#
interface LoopBack1
 ip address 22.22.22.22 255.255.255.0
#
bgp 200
 peer 12.1.1.1 as-number 100
 peer 23.1.1.3 as-number 300
 #
 ipv4-family unicast
  undo synchronization
  network 2.2.2.0 255.255.255.0
  network 22.22.22.0 255.255.255.0
  peer 12.1.1.1 enable
  peer 23.1.1.3 enable
#
ip route-static 1.1.1.0 255.255.255.0 12.1.1.1
ip route-static 3.3.3.0 255.255.255.0 23.1.1.3
#
user-interface con 0
 authentication-mode password
user-interface vty 0 4
user-interface vty 16 20
#
wlan ac
#
return

R3:

interface GigabitEthernet0/0/0
 ip address 23.1.1.3 255.255.255.0
#
interface GigabitEthernet0/0/1
 ip address 36.1.1.3 255.255.255.0
#
interface GigabitEthernet0/0/2
#
interface NULL0
#
interface LoopBack0
 ip address 3.3.3.3 255.255.255.0
#
interface LoopBack1
 ip address 33.33.33.33 255.255.255.0
#
bgp 300
 peer 23.1.1.2 as-number 200
 peer 36.1.1.6 as-number 400
 #
 ipv4-family unicast
  undo synchronization
  network 3.3.3.0 255.255.255.0
  network 33.33.33.0 255.255.255.0
  peer 23.1.1.2 enable
  peer 36.1.1.6 enable
#
ip route-static 2.2.2.0 255.255.255.0 23.1.1.2
ip route-static 6.6.6.0 255.255.255.0 36.1.1.6
#
user-interface con 0
 authentication-mode password
user-interface vty 0 4
user-interface vty 16 20
#
wlan ac
#

R4:

interface GigabitEthernet0/0/0
 ip address 14.1.1.4 255.255.255.0
#
interface GigabitEthernet0/0/1
 ip address 46.1.1.4 255.255.255.0
#
interface GigabitEthernet0/0/2
 ip address 45.1.1.4 255.255.255.0
#
interface NULL0
#
interface LoopBack0
 ip address 4.4.4.4 255.255.255.0
#
interface LoopBack1
 ip address 44.44.44.44 255.255.255.0
#
bgp 400
 peer 5.5.5.5 as-number 400
 peer 5.5.5.5 connect-interface LoopBack0
 peer 6.6.6.6 as-number 400
 peer 6.6.6.6 connect-interface LoopBack0
 peer 7.7.7.7 as-number 400
 peer 7.7.7.7 connect-interface LoopBack0
 peer 14.1.1.1 as-number 100
 #
 ipv4-family unicast
  undo synchronization
  network 4.4.4.0 255.255.255.0
  network 44.44.44.0 255.255.255.0
  import-route ospf 1
  peer 5.5.5.5 enable
  peer 5.5.5.5 next-hop-local
  peer 6.6.6.6 enable
  peer 6.6.6.6 next-hop-local
  peer 7.7.7.7 enable
  peer 7.7.7.7 next-hop-local
  peer 14.1.1.1 enable
#
ospf 1 router-id 4.4.4.4
 area 0.0.0.0
  network 4.4.4.0 0.0.0.255
  network 5.5.5.0 0.0.0.255
  network 45.1.1.0 0.0.0.255
  network 46.1.1.0 0.0.0.255
#
ip route-static 1.1.1.0 255.255.255.0 14.1.1.1
#
user-interface con 0
 authentication-mode password
user-interface vty 0 4
user-interface vty 16 20
#
wlan ac
#

R5:

interface GigabitEthernet0/0/0
 ip address 45.1.1.5 255.255.255.0
#
interface GigabitEthernet0/0/1
 ip address 57.1.1.5 255.255.255.0
#
interface GigabitEthernet0/0/2
#
interface NULL0
#
interface LoopBack0
 ip address 5.5.5.5 255.255.255.0
#
bgp 400
 peer 4.4.4.4 as-number 400
 peer 4.4.4.4 connect-interface LoopBack0
 peer 6.6.6.6 as-number 400
 peer 6.6.6.6 connect-interface LoopBack0
 peer 7.7.7.7 as-number 400
 peer 7.7.7.7 connect-interface LoopBack0
 #
 ipv4-family unicast
  undo synchronization
  peer 4.4.4.4 enable
  peer 4.4.4.4 next-hop-local
  peer 6.6.6.6 enable
  peer 6.6.6.6 next-hop-local
  peer 7.7.7.7 enable
  peer 7.7.7.7 next-hop-local
#
ospf 1 router-id 5.5.5.5
 area 0.0.0.0
  network 4.4.4.0 0.0.0.255
  network 5.5.5.0 0.0.0.255
  network 7.7.7.0 0.0.0.255
  network 45.1.1.0 0.0.0.255
  network 57.1.1.0 0.0.0.255
#
user-interface con 0
 authentication-mode password
user-interface vty 0 4
user-interface vty 16 20
#
wlan ac

R6:

interface GigabitEthernet0/0/0
 ip address 36.1.1.6 255.255.255.0
#
interface GigabitEthernet0/0/1
 ip address 46.1.1.6 255.255.255.0
#
interface GigabitEthernet0/0/2
 ip address 67.1.1.6 255.255.255.0
#
interface NULL0
#
interface LoopBack0
 ip address 6.6.6.6 255.255.255.0
#
interface LoopBack1
 ip address 66.66.66.66 255.255.255.0
#
bgp 400
 peer 4.4.4.4 as-number 400
 peer 4.4.4.4 connect-interface LoopBack0
 peer 5.5.5.5 as-number 400
 peer 5.5.5.5 connect-interface LoopBack0
 peer 7.7.7.7 as-number 400
 peer 7.7.7.7 connect-interface LoopBack0
 peer 36.1.1.3 as-number 300
 #
 ipv4-family unicast
  undo synchronization
  network 6.6.6.0 255.255.255.0
  network 66.66.66.0 255.255.255.0
  import-route ospf 1
  peer 4.4.4.4 enable
  peer 4.4.4.4 next-hop-local
  peer 5.5.5.5 enable
  peer 5.5.5.5 next-hop-local
  peer 7.7.7.7 enable
  peer 7.7.7.7 next-hop-local
  peer 36.1.1.3 enable
#
ospf 1 router-id 6.6.6.6
 area 0.0.0.0
  network 6.6.6.0 0.0.0.255
  network 7.7.7.0 0.0.0.255
  network 46.1.1.0 0.0.0.255
  network 67.1.1.0 0.0.0.255
#
ip route-static 3.3.3.0 255.255.255.0 36.1.1.3
#
user-interface con 0
 authentication-mode password
user-interface vty 0 4
user-interface vty 16 20
#
wlan ac
#
return

R7:

#
interface GigabitEthernet0/0/0
 ip address 57.1.1.7 255.255.255.0
#
interface GigabitEthernet0/0/1
 ip address 67.1.1.7 255.255.255.0
#
interface GigabitEthernet0/0/2
#
interface NULL0
#
interface LoopBack0
 ip address 7.7.7.7 255.255.255.0
#
bgp 400
 peer 4.4.4.4 as-number 400
 peer 4.4.4.4 connect-interface LoopBack0
 peer 5.5.5.5 as-number 400
 peer 5.5.5.5 connect-interface LoopBack0
 peer 6.6.6.6 as-number 400
 peer 6.6.6.6 connect-interface LoopBack0
 #
 ipv4-family unicast
  undo synchronization
  peer 4.4.4.4 enable
  peer 4.4.4.4 next-hop-local
  peer 5.5.5.5 enable
  peer 5.5.5.5 next-hop-local
  peer 6.6.6.6 enable
  peer 6.6.6.6 next-hop-local
#
ospf 1 router-id 7.7.7.7
 area 0.0.0.0
  network 5.5.5.0 0.0.0.255
  network 6.6.6.0 0.0.0.255
  network 7.7.7.0 0.0.0.255
  network 57.1.1.0 0.0.0.255
  network 67.1.1.0 0.0.0.255
#
user-interface con 0
 authentication-mode password
user-interface vty 0 4
user-interface vty 16 20
#
wlan ac

注意：用物理口做EBGP时，不用做静态

4) 为了使网络资源能充分得到利用，要求业务网段A的流量通过运营商设备转发，业务网段B的流量通过专线转发；

都在R2上做，在192.168.20.0和172.16.20.0增加一条as-path路径

acl number 2000 
 rule 5 permit source 172.16.20.0 0
acl number 2001 
 rule 5 permit source 192.168.20.0 0

route-policy 1 permit node 5
 if-match acl 2000
 apply as-path 500 additive
#
route-policy 1 permit node 10
#
route-policy 2 permit node 15
 if-match acl 2001
 apply as-path 600 additive
#
route-policy 2 permit node 20

 peer 12.1.1.1 enable
  peer 12.1.1.1 route-policy 1 export
  peer 23.1.1.3 enable
  peer 23.1.1.3 route-policy 2 export

在R1:

在R3:

方法二(有可能还是不对)：

修改MED值：

在R2做，修改MED值。

在R3写入强制引入才可生效：

[Huawei-bgp]compare-different-as-med

5. 网络管理员进行定期线路检查，现通过适当调整IGP的链路开销值，使得所有经过总部AS的流量都沿着R4-R5-R7-R6路径转发

注意：注入时，不要把bgp注入到ospf中，在第6步有影响

让192.168.20.0/24和172.16.20.0/24沿着R4-R5-R7-R6路径转发

原本都是走R4 R6

修改R4和R6的cost值，不用acl列表，进端口配置就可以

在R4:

interface GigabitEthernet0/0/1

 ospf cost 200

在R6:

interface GigabitEthernet0/0/1

 ospf cost 200

在R1:

在R3:

 

6. 网络管理员在检查中发现业务网段B的流量非常大，决定将业务网段B的流量单独沿着R4-R6路径转发（要求BGP路由选路与实际转发路径一致）

方法一：

R4: 

acl number 2001 
 rule 5 permit source 192.168.20.0 0.0.0.255

  peer 6.6.6.6 route-policy local export

route-policy local permit node 10
 if-match acl 2001
 apply ip-address next-hop 46.1.1.4
#
route-policy local permit node 20

R6:

acl number 2001 
 rule 5 permit source 172.16.20.0 0.0.0.255
#

  peer 4.4.4.4 route-policy local export

route-policy local permit node 15
 if-match acl 2001
 apply ip-address next-hop 46.1.1.6
#
route-policy local permit node 20

方法二（此方法貌似不太可行）：

R4和R6都做

bgp 400

preference 100 100 100

 

7. 公司总部网络将进行改造，在不改变原有配置的基础上，通过增加少量配置实现，R5与R7不参与BGP路径选择

在R4和R6上配置：

R4:

[Huawei-bgp]peer 5.5.5.5 ignore

R6:

[Huawei-bgp]peer 7.7.7.7 ignore

9. 假设172.16.10.0/24该业务网段状态不稳定，时而出现网络中断现象，通过适当配置以减小其对整网的影响

R3做：

bgp 300

 dampening route-policy damp

10. 为了提高BGP网络安全性，在EBGP邻居间配置认证

simple是明文认证

cipher是MD5认证

R1和R2做MD5认证：

R1:

[Huawei]bgp 100

[Huawei-bgp]peer 12.1.1.2 password cipher 123

R2:

bgp 200

[Huawei-bgp]peer 12.1.1.1 password cipher 123

11. 修改R2上BGP的存活时间为30s，同时适当调整保持时间

BGP的保持激活时间Keepalive默认是60s一次，而保持时间Ｈoldtime则是3倍的激活时间。

在R2:

[Huawei-bgp]timer keepalive 30 hold 90

在R1上：

<Huawei>display bgp peer 12.1.1.2 verbose

 BGP Peer is 12.1.1.2,  remote AS 200 
 Type: EBGP link
 BGP version 4, Remote router ID 12.1.1.2
 Update-group ID: 1 
 BGP current state: Established, Up for 00h04m38s
 BGP current event: KATimerExpired
 BGP last state: OpenConfirm
 BGP Peer Up count: 2
 Received total routes: 6
 Received active routes total: 5
 Advertised total routes: 22
 Port:  Local - 49458 Remote - 179
 Configured: Connect-retry Time: 32 sec
 Configured: Active Hold Time: 180 sec Keepalive Time:60 sec
 Received  : Active Hold Time: 90 sec
 Negotiated: Active Hold Time: 90 sec Keepalive Time:30 sec
 Peer optional capabilities:
 Peer supports bgp multi-protocol extension
 Peer supports bgp route refresh capability
 Peer supports bgp 4-byte-as capability
 Address family IPv4 Unicast: advertised and received