NE80/NE40系列路由器BGP Local-preference属性的配置

NE80/NE40系列路由器BGP Local-preference

属性的配置

一、  组网需求：

如图所示，通过配置路由器BGP的Local-preference属性，控制从RT4到10.6.1.1的数据包选择路由器RT2做为下一跳（默认选择RT1作为下一跳）。

二、  组网图：

 

 

三、  配置步骤：

1.      如图所示配置路由器的各接口地址；

2.      配置AS2的IGP协议，使得AS内部互通；本例IGP选择ISIS路由协议；

3.      配置BGP的邻居关系，使相互之间的邻接关系能正常建立（以RT1为例）；

#                                                                               

bgp 2                                                                          

 group 2-1 external                                                            

 peer 2-1 as-number 1                                                           

 peer 2-1 ebgp-max-hop 255                                                     

 peer 2-1 connect-interface LoopBack0                                          

 peer 3.3.3.3 as-number 1                                                       

 peer 3.3.3.3 group 2-1                                                        

 group 2-2 internal                                                            

 peer 2-2 connect-interface LoopBack0                                           

 peer 4.4.4.4 as-number 2                                                      

 peer 4.4.4.4 group 2-2                                                        

 #                                                                              

 ipv4-family unicast                                                           

  undo synchronization                                                                                                         

  import-route direct                                                          

  peer 2-1 enable                                                              

  peer 2-1 next-hop-local                                                      

  peer 3.3.3.3 enable                                                          

  peer 3.3.3.3 group 2-1                                                       

  peer 2-2 enable                                                               

  peer 2-2 next-hop-local                                                      

  peer 4.4.4.4 enable                                                          

  peer 4.4.4.4 group 2-2                                                        

#                                                                              

4.      配置RT1的local-preference值，使其小于RT2的local-preference

#                                                                             

 ipv4-family unicast                                                                                                                         

  default local-preference 50

#

 

四、  配置关键点：

因为BGP的local-preference默认为100，而BGP默认选择local-preference较大的值作为下一跳 ，所以在该例中将RT1的local-preference改为50后，从RT4到10.6.1.1的数据包下一跳选择RT2.