BGP双平面实验架构

架构如图

1.问题描述：

此为某大型企业的网，中间为骨干网，后缀为A的是电信网，后缀为B的是联通网。骨干网分布在北京、深圳、广州、天津。两侧为公司分部- - -西安和东莞

其中 XA(西安)和DG(东莞)通信有两种流量
业务：主走A面，A面故障走B面
办公：主走B面，B面故障走A面
两者通过不同的线路接入到不同的城市- - -可靠性高

2.规划：

双平面上层为AS1

双平面下层为AS2

XA为AS3

DG为AS4

正常业务流量走A面(电信网)，办公流量走B面(联通网)

当正常连接双平面网的线路出现问题，则要切换到另一条线，经相反面的路由器再切换回原平面

3.在进行后期干涉选路前，首先先了解选路的条件

4.走向分析

以XA到DG为例

1.正常时XA到DG走A面

2.非正常时
1）当连接AS1和AS3的线路出现问题，XA到DG会切换到下面的线路，到达SZ-B，但是SZ-B并不会沿着IDC机房的线切换到本来该走的电信面，而是继续走联通面，因为联通面到达DG的AS-PATH比切换到电信面的AS-PATH短

解决：在连接电信网的每个联通路由器上加大DG给过来的业务流量的weight值，这样根据weight>AS-PATH,故会切换到原面(电信面)继续走

结果：

不选local-pre是因为local-pre会传递给邻居，这样邻居切换回原面要绕路

2）DG返回XA时，流量走到原面(电信面)并不会沿着该面回去，而是会沿着IDC机房的线切换到联通面，因为EBGP>IBGP

解决：在原面上加大bgp邻居传过来的目的ip的weight值，这样就不会切换到联通面去了

结果：

不选metric是因为一个AS内的设备都设置metric的话，因为metric可以传递，IBGP邻居间会metric抵消，不会起控制选路的作用

注意：

在抓取打标签的流量时，抓取的是所有，包括所有分支打标签的流量，我们做策略也是针对于所有流量，做策略之后，会引起路径混乱

解决方法：

我们在抓取打标签的流量时，在骨干网中某城市节点应该去掉与自身建邻EBGP邻居的打标签分支流量,这样在一个面中就不会因为weight值被修改而导致的选weight而不选EBGP>IBGP而导致的绕路，致使数据层面和路由层面tracroute不一样
比如：
XA->BJ-A,我们需在BJ-A上剔除XA的业务流量，在BJ-B上剔除XA的办公流量，也就是不针对与XA的100.10.1.1/32和100.10.2.2/32路由做任何策略
BJ-A(config)#ip community-list 100 deny 1:10
BJ-A(config)#ip community-list 100 permit 1:*
BJ-B(config)#ip community-list 101 deny 2:10
BJ-B(config)#ip community-list 101 permit 2:*
抓取打标签的流量就是为了通过route-map来控制其流量走向

---

版权声明：本文为CSDN博主「飞儿呀」的原创文章，遵循CC 4.0 by-sa版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/weixin_43726831/article/details/98634984

5.配置：

XA(西安分支节点)

*定义业务流量和办公流量
interface Loopback0
ip address 100.10.1.1 255.255.255.255
interface Loopback1
ip address 100.10.2.2 255.255.255.255      
interface Serial2/0
ip address 100.1.1.1 255.255.255.0
interface Serial2/1
ip address 100.1.2.1 255.255.255.0
router bgp 3
bgp router-id 99.1.1.1
network 100.10.1.1 mask 255.255.255.255
network 100.10.2.2 mask 255.255.255.255
neighbor 100.1.1.2 remote-as 1
*开启传递团期属性，尽量选both
neighbor 100.1.1.2 send-community both //开启传递团期属性，尽量选both
neighbor 100.1.1.2 route-map A in
neighbor 100.1.1.2 route-map tag out
neighbor 100.1.2.2 remote-as 2
*开启传递团期属性，尽量选both
neighbor 100.1.2.2 send-community both
neighbor 100.1.2.2 route-map B in
neighbor 100.1.2.2 route-map tag out
*显示团体属性设置
ip bgp-community new-format
*匹配团体属性值
ip community-list expanded A permit ^1:*
ip community-list expanded B permit ^2:*
ip prefix-list A seq 5 permit 100.10.1.1/32 
ip prefix-list B seq 5 permit 100.10.2.2/32      
route-map A permit 10
match community A
set weight 100   
route-map A permit 20     
route-map B permit 10
match community B
set weight 100
route-map B permit 20    
route-map tag permit 10
match ip address prefix-list A
set community 1:10      
route-map tag permit 20
match ip address prefix-list B
set community 2:10

DG(东莞分支节点)

*定义业务流量和办公流量
interface Loopback0
ip address 100.20.1.1 255.255.255.255    
interface Loopback1
ip address 100.20.2.2 255.255.255.255       
interface Serial2/0
ip address 100.1.3.1 255.255.255.0
interface Serial2/1
ip address 100.1.4.1 255.255.255.0    
router bgp 4
bgp router-id 99.2.2.2
network 100.20.1.1 mask 255.255.255.255
network 100.20.2.2 mask 255.255.255.255
neighbor 100.1.3.2 remote-as 1
*开启团体属性值 尽量选both
neighbor 100.1.3.2 send-community both
neighbor 100.1.3.2 route-map A in
neighbor 100.1.3.2 route-map tag out
neighbor 100.1.4.2 remote-as 2
*开启团体属性值 尽量选both
neighbor 100.1.4.2 send-community both
neighbor 100.1.4.2 route-map B in
neighbor 100.1.4.2 route-map tag out 
ip bgp-community new-format
ip community-list expanded A permit ^1:*
ip community-list expanded B permit ^2:* 
ip prefix-list A seq 5 permit 100.20.1.1/32        
ip prefix-list B seq 5 permit 100.20.2.2/32         
route-map A permit 10
match community A
set weight 100     
route-map A permit 20        
route-map B permit 10
match community B
set weight 100        
route-map B permit 20         
route-map tag permit 10
match ip address prefix-list A
set community 1:20         
route-map tag permit 20
match ip address prefix-list B
set community 2:20

BJ-A(北京电信骨干网)

interface Loopback0
ip address 1.1.1.1 255.255.255.255       
interface Ethernet0/0
ip address 10.12.1.1 255.255.255.0        
interface Serial1/0
ip address 10.17.1.1 255.255.255.0
interface Serial1/1
ip address 10.13.1.1 255.255.255.0
interface Serial2/0
ip address 100.1.1.2 255.255.255.0
router eigrp 90
network 1.1.1.1 0.0.0.0
network 10.13.1.0 0.0.0.255
network 10.17.1.0 0.0.0.255     
router bgp 1
bgp router-id 1.1.1.1
neighbor k peer-group
neighbor k remote-as 1
neighbor k update-source Loopback0
neighbor k next-hop-self
neighbor k send-community both
neighbor k route-map comm1 in
neighbor 3.3.3.3 peer-group k
neighbor 5.5.5.5 peer-group k
neighbor 7.7.7.7 peer-group k
neighbor 10.12.1.2 remote-as 2
neighbor 10.12.1.2 send-community both
neighbor 10.12.1.2 route-map comm in
neighbor 100.1.1.1 remote-as 3
neighbor 100.1.1.1 send-community both  
ip bgp-community new-format
*此处为
ip community-list expanded A permit ^2:*
ip community-list expanded B deny 1:10
ip community-list expanded B permit ^1:*
*重点
route-map comm permit 10
match community A
set weight 100
route-map comm permit 20         
route-map comm1 permit 10
match community B
set weight 100         
route-map comm1 permit 20

BJ-B(北京联通骨干网)

interface Loopback0
ip address 2.2.2.2 255.255.255.255      
interface Ethernet0/0
ip address 10.12.1.2 255.255.255.0        
interface Serial1/0
ip address 10.28.1.1 255.255.255.0      
interface Serial1/1
ip address 10.24.1.1 255.255.255.0    
router eigrp 90
network 2.2.2.2 0.0.0.0
network 10.24.1.0 0.0.0.255
network 10.28.1.0 0.0.0.255       
router bgp 2
bgp router-id 2.2.2.2
neighbor k peer-group
neighbor k remote-as 2
neighbor k update-source Loopback0
neighbor k next-hop-self
neighbor k send-community both
neighbor k route-map comm1 in
neighbor 4.4.4.4 peer-group k
neighbor 6.6.6.6 peer-group k
neighbor 8.8.8.8 peer-group k
neighbor 10.12.1.1 remote-as 1
neighbor 10.12.1.1 send-community both
neighbor 10.12.1.1 route-map comm in        
ip bgp-community new-format
ip community-list expanded B deny 2:10
ip community-list expanded B permit ^2:*
ip community-list expanded A permit ^1:*
route-map comm permit 10
match community A
set weight 100       
route-map comm permit 20      
route-map comm1 permit 10
match community B
set weight 100      
route-map comm1 permit 20

GZ-A(广州电信骨干网)

interface Loopback0
ip address 3.3.3.3 255.255.255.255         
interface Ethernet0/0
ip address 10.34.1.1 255.255.255.0     
interface Serial1/0
ip address 10.35.1.1 255.255.255.0   
interface Serial1/1
ip address 10.13.1.2 255.255.255.0
router eigrp 90
network 3.3.3.3 0.0.0.0
network 10.13.1.0 0.0.0.255
network 10.35.1.0 0.0.0.255        
router bgp 1
bgp router-id 3.3.3.3
neighbor k peer-group
neighbor k remote-as 1
neighbor k update-source Loopback0
neighbor k next-hop-self
neighbor k send-community both
neighbor k route-map comm1 in
neighbor 1.1.1.1 peer-group k
neighbor 5.5.5.5 peer-group k
neighbor 7.7.7.7 peer-group k
neighbor 10.34.1.2 remote-as 2
neighbor 10.34.1.2 send-community both
neighbor 10.34.1.2 route-map comm in  
ip bgp-community new-format
ip community-list expanded A permit ^2:*
ip community-list expanded B deny 1:20
ip community-list expanded B permit ^1:*
route-map comm permit 10
match community A
set weight 100        
route-map comm permit 20       
route-map comm1 permit 10
match community B
set weight 100      
route-map comm1 permit 20

GZ-B(广州联通骨干网)

interface Loopback0
ip address 4.4.4.4 255.255.255.255        
interface Ethernet0/0
ip address 10.34.1.2 255.255.255.0        
interface Serial1/0
ip address 10.46.1.1 255.255.255.0    
interface Serial1/1
ip address 10.24.1.2 255.255.255.0  
interface Serial2/0
ip address 100.1.4.2 255.255.255.0
router eigrp 90
network 4.4.4.4 0.0.0.0
network 10.24.1.0 0.0.0.255
network 10.46.1.0 0.0.0.255        
router bgp 2
bgp router-id 4.4.4.4
neighbor k peer-group
neighbor k remote-as 2
neighbor k update-source Loopback0
neighbor k next-hop-self
neighbor k send-community both
neighbor k route-map comm1 in
neighbor 2.2.2.2 peer-group k
neighbor 6.6.6.6 peer-group k
neighbor 8.8.8.8 peer-group k
neighbor 10.34.1.1 remote-as 1
neighbor 10.34.1.1 send-community both
neighbor 10.34.1.1 route-map comm in
neighbor 100.1.4.1 remote-as 4
neighbor 100.1.4.1 send-community both  
ip bgp-community new-format
ip community-list expanded A permit ^1:*
ip community-list expanded B deny 2:20
ip community-list expanded B permit ^2:*
route-map comm permit 10
match community A
set weight 100        
route-map comm permit 20        
route-map comm1 permit 10
match community B
set weight 100         
route-map comm1 permit 20

SZ-A(深圳电信骨干网)

interface Loopback0
ip address 7.7.7.7 255.255.255.255        
interface Ethernet0/0
ip address 10.78.1.1 255.255.255.0     
interface Serial1/1
ip address 10.57.1.1 255.255.255.0
router eigrp 90
network 7.7.7.7 0.0.0.0
network 10.17.1.0 0.0.0.255
network 10.57.1.0 0.0.0.255        
router bgp 1
bgp router-id 7.7.7.7
neighbor k peer-group
neighbor k remote-as 1
neighbor k update-source Loopback0
neighbor k next-hop-self
neighbor k send-community both
neighbor k route-map comm1 in
neighbor 1.1.1.1 peer-group k
neighbor 3.3.3.3 peer-group k
neighbor 5.5.5.5 peer-group k
neighbor 10.78.1.2 remote-as 2
neighbor 10.78.1.2 send-community both
neighbor 10.78.1.2 route-map comm in   
ip bgp-community new-format
ip community-list expanded A permit ^2:*
ip community-list expanded B deny 1:10
ip community-list expanded B permit ^1:*   
route-map comm permit 10
match community A
set weight 100      
route-map comm permit 20         
route-map comm1 permit 10
match community B
set weight 100        
route-map comm1 permit 20

SZ-B(深圳联通骨干网)

interface Loopback0
ip address 8.8.8.8 255.255.255.255       
interface Ethernet0/0
ip address 10.78.1.2 255.255.255.0
interface Serial1/0
ip address 10.28.1.2 255.255.255.0 
interface Serial1/1
ip address 10.68.1.1 255.255.255.0
interface Serial2/0
ip address 100.1.2.2 255.255.255.0
router eigrp 90
network 8.8.8.8 0.0.0.0
network 10.28.1.0 0.0.0.255
network 10.68.1.0 0.0.0.255       
router bgp 2
bgp router-id 8.8.8.8
neighbor k peer-group
neighbor k remote-as 2
neighbor k update-source Loopback0
neighbor k next-hop-self
neighbor k send-community both
neighbor k route-map comm1 in
neighbor 2.2.2.2 peer-group k
neighbor 4.4.4.4 peer-group k
neighbor 6.6.6.6 peer-group k
neighbor 10.78.1.1 remote-as 1
neighbor 10.78.1.1 send-community both
neighbor 10.78.1.1 route-map comm in
neighbor 100.1.2.1 remote-as 3
neighbor 100.1.2.1 send-community both
ip bgp-community new-format
ip community-list expanded A permit ^1:*
ip community-list expanded B deny 2:10
ip community-list expanded B permit ^2:*   
route-map comm permit 10
match community A
set weight 100        
route-map comm permit 20        
route-map comm1 permit 10
match community B
set weight 100        
route-map comm1 permit 20

TJ-A(天津电信骨干网)

interface Loopback0
ip address 5.5.5.5 255.255.255.255        
interface Ethernet0/0
ip address 10.56.1.1 255.255.255.0        
interface Serial1/0
ip address 10.57.1.2 255.255.255.0
interface Serial1/1
ip address 10.35.1.2 255.255.255.0
interface Serial2/0
ip address 100.1.3.2 255.255.255.0
router eigrp 90
network 5.5.5.5 0.0.0.0
network 10.35.1.0 0.0.0.255
network 10.57.1.0 0.0.0.255       
router bgp 1
bgp router-id 5.5.5.5
neighbor k peer-group
neighbor k remote-as 1
neighbor k update-source Loopback0
neighbor k next-hop-self
neighbor k send-community both
neighbor k route-map comm1 in
neighbor 1.1.1.1 peer-group k
neighbor 3.3.3.3 peer-group k
neighbor 7.7.7.7 peer-group k
neighbor 10.56.1.2 remote-as 2
neighbor 10.56.1.2 send-community both
neighbor 10.56.1.2 route-map comm in
neighbor 100.1.3.1 remote-as 4
neighbor 100.1.3.1 send-community both
ip bgp-community new-format
ip community-list expanded A permit ^2:*
ip community-list expanded B deny 1:20
ip community-list expanded B permit ^1:*
route-map comm permit 10
match community A
set weight 100        
route-map comm permit 20        
route-map comm1 permit 10
match community B
set weight 100       
route-map comm1 permit 20

TJ-B(天津联通骨干网)

interface Loopback0
ip address 6.6.6.6 255.255.255.255      
interface Ethernet0/0
ip address 10.56.1.2 255.255.255.0        
interface Serial1/0
ip address 10.68.1.2 255.255.255.0 
interface Serial1/1
ip address 10.46.1.2 255.255.255.0
router eigrp 90
network 6.6.6.6 0.0.0.0
network 10.46.1.0 0.0.0.255
network 10.68.1.0 0.0.0.255        
router bgp 2
bgp router-id 6.6.6.6
neighbor k peer-group
neighbor k remote-as 2
neighbor k update-source Loopback0
neighbor k next-hop-self
neighbor k send-community both
neighbor k route-map comm1 in
neighbor 2.2.2.2 peer-group k
neighbor 4.4.4.4 peer-group k
neighbor 8.8.8.8 peer-group k
neighbor 10.56.1.1 remote-as 1
neighbor 10.56.1.1 send-community both
neighbor 10.56.1.1 route-map comm in   
ip bgp-community new-format
ip community-list expanded A permit ^1:*
ip community-list expanded B deny 2:20
ip community-list expanded B permit ^2:*
route-map comm permit 10
match community A 
weight 100       
route-map comm permit 20         
route-map comm1 permit 10
match community B
set weight 100        
route-map comm1 permit 20

注意：

1.传送团体属性时，因为所传递的值是扩展标记，需要用neighbor 10.56.1.1 send-community both
每一台路由器都需要ip bgp-community new-format，这样可以使团体值显示为正常所打的标记值