静态路由依赖下一跳ARP生效典型配置及应用场景举例

静态路由的track通常通过探测下一跳IP是否可达来决定是否生效。在某些场景下，可以配置静态路由依赖下一跳接口ARP来替代track的配置，既能简化配置，又可以提高敏感性，多用于HA场景。

如下图，两个VSR堆叠，每台VSR上联一台Service Leaf。多租户场景下，VSR上创建为每个租户创建两个子接口，将这两个子接口加入到一个冗余口中，冗余口绑定租户的VRF。

两台Service Leaf上都需要配置静态路由，下一跳指向VSR上对应的冗余口地址。要实现正常状态下，访问VSR的流量都会通过Service Leaf1来到VSR的主slot；当主slot故障时，流量都会通过Service Leaf2来到备slot。

【Service Leaf的有关配置】

#vpn配置

ip vpn-instance vpna                                                             

 route-distinguisher 1:2211111                                                  

 description SDN_VRF_6317e6c9-ef55-42fe-bf5e-4f8efb38c287                      

 #                                                                             

 address-family ipv4                                                           

  vpn-target 0:2211111 1:2211111 import-extcommunity                           

  vpn-target 1:2211111 export-extcommunity                                     

 #                                                                             

 address-family evpn                                                           

  vpn-target 0:2211111 1:2211111 import-extcommunity                           

  vpn-target 1:2211111 export-extcommunity  

#VSI配置

vsi SDN_VSI_2211119 

 gateway vsi-interface 11119                                                   

 statistics enable                                                              

 vxlan 2211119                                                                 

 evpn encapsulation vxlan                                                      

  mac-advertising disable                                                       

  arp mac-learning disable                                                     

  route-distinguisher auto                                                     

  vpn-target auto export-extcommunity                                           

  vpn-target auto import-extcommunity

#L2VNI配置

interface Vsi-interface11119                                                                                   

 ip binding vpn-instance    vpna                                                

 ip address 121.1.1.41 255.255.255.248 sub                                     

 mac-address 0056-5656-5656                                                    

 local-proxy-arp enable      

 arp route-direct advertise -------开启ARP直连路由通告

 distributed-gateway local

#AC口配置

interface Bridge-Aggregation3                                                                                                                  

 port link-type trunk      

undo port trunk permit vlan 1                                                     

 port trunk permit 2 to 500       

 port trunk pvid vlan 2                                  

 link-aggregation mode dynamic                                                 

 stp edged-port 

#

service-instance 201                                                          

  encapsulation s-vid 201                                                      

  xconnect vsi SDN_VSI_2211119

#

bgp 65203 instance SDN_INSTANCE_BGP  

 #                                                                                                                                                      

 ip vpn-instance vpna                                                          

  #                                                                            

  address-family ipv4 unicast                                                  

   balance 4                                                                    

   import-route static---引入静态路由                                                          

# 

ip route-static vpn-instance vpna 104.78.0.0 16 121.1.1.42 recursive-lookup host-route---------------------指定静态路由只能迭代到直连主机路由

【VSR的有关配置】

#冗余口配置

interface Reth211                                                            

 ip binding vpn-instance 30_mgtgw_1                                          

 ip address 121.1.1.42 255.255.255.248                                      

 member interface Route-Aggregation3.200 priority 100                        

 member interface Route-Aggregation4.200 priority 50

#路由子接口配置

interface Route-Aggregation3.200                                            

 vlan-type dot1q vid 200

interface Route-Aggregation4.200                                             

 vlan-type dot1q vid 2010                            

VSR部分也可以为其他设备，例如防火墙，LB等

配置关键点在于静态路由配置时添加recursive-lookup参数，并在对应的接口下使能ARP直连路由通告