某局点SR6608 bgp和ospf路由引入异常的经验案例

现场2台路由器互联是跑的bgp，路由器上联交换机都是跑的ospf area 2。传递的路由都在YW-VPN的vpn实例里面。（T5000是RBM二层部署，可忽略），路由器A和B通过mpibgp建立邻居关系，骨干接入交换机引入了一条外部路由1.1.1.0，现在需要在路由器上路由互引，目前在路由器A上bgp区域引入了ospf路由，在路由器B上将BGP路由引入ospf，ospf路由引入到了bgp区域

SR6608B要实现从bgp邻居SR6608A学习到这条路由引入的路由1.1.1.0，但现场情况是路由器B通过上行直连交换机10.X.X.69学习到了这条路由：

1，查看主要配置如下：

路由器A：

ospf 1 router-id 10.X.X.233 vpn-instance YW-VPN

  import-route static type 1

  import-route bgp 100 route-policy YW-BGP-TO-OSPF

  preference 195

  preference ase 195

  vpn-instance-capability simple

  area 0.0.0.2

     network 10.X.Y.0 0.0.0.7

     network 10.X.Y.0 0.0.0.7

#

  address-family l2vpn

#

 address-family l2vpn evpn

    peer rr enable

    peer rr reflect-client

    peer rr advertise encap-type srv6

    peer FD00:X:X:X::Y enable

    peer FD00:X:X:X::Y advertise encap-type srv6

#

 ip vpn-instance MGT-VPN

#

   address-family ipv4 unicast

      default local-preference 200

      segment-routing ipv6 best-effort evpn

      segment-routing ipv6 locator MGT evpn

      import-route static

#

  address-family ipv6 unicast

   default local-preference 200

   segment-routing ipv6 best-effort evpn

   segment-routing ipv6 locator MGT-ipv6 evpn

   import-route static

#

ip vpn-instance YW-VPN

#

  address-family ipv4 unicast

    default local-preference 200

    preference 20 200 200

    segment-routing ipv6 best-effort evpn

    segment-routing ipv6 locator YW evpn

    import-route ospf 1 route-policy YW-OSPF-TO-BGP-TAG

  #

  address-family ipv6 unicast

     default local-preference 200

     segment-routing ipv6 best-effort evpn

     segment-routing ipv6 locator YW-ipv6 evpn

路由器B：

ospf 1 router-id 10.X.X.234 vpn-instance YW-VPN

  import-route static type 1

  import-route bgp route-policy YW-BGP-TO-OSPF

  silent-interface Ten-GigabitEthernet2/3/0

  silent-interface Ten-GigabitEthernet2/3/1

  preference 215

  preference ase 220

  vpn-instance-capability simple

  area 0.0.0.2

address-family l2vpn evpn

  peer rr enable

  peer rr reflect-client

  peer rr advertise encap-type srv6

  peer FD00:X:X:X::Y enable

  peer FD00:X:X:X::Y advertise encap-type srv6

ip vpn-instance YW-VPN

  #

  address-family ipv4 unicast

   preference 20 200 205

   segment-routing ipv6 best-effort evpn

   segment-routing ipv6 locator YW evpn

   import-route ospf 1 route-policy YW-OSPF-TO-BGP-TAG

   network 10.X.X.X 255.255.255.248

   network 10.X.X.Y 255.255.255.248

  #

  address-family ipv6 unicast

   segment-routing ipv6 best-effort evpn

   segment-routing ipv6 locator YW-ipv6 evpn 

2，查看两个设备上有效的bgp路由信息没有引入的这条路由：

3，后来建议现场直接network发布路由，还是没有1.1.1.0的路由：

[BJBJ-GGRT-SR6608_A]bgp 100

[BJBJ-GGRT-SR6608_A-bgp-default]ip vpn-instance YW-VPN

[BJBJ-GGRT-SR6608_A-bgp-default-YW-VPN]add ipv4

[BJBJ-GGRT-SR6608_A-bgp-default-ipv4-YW-VPN]network 1.1.1.1 30

<BJBJ-GGRT-SR6608_A>  dis ip routing-table vpn-instance YW-VPN protocol bgp inactive

BGP Routing table status : <Inactive>

Summary count : 4

Destination/Mask   Proto   Pre Cost        NextHop         Interface

10.X.X.0/29      BGP     200 5           FDXX:X:X:X:5::  RAGG3

10.X.Y.0/29      BGP     200 0           FDXX:X:X:X:5::  RAGG3

10.X.Y.60/30    BGP     200 4           FDXX:X:X:X:5::  RAGG3

10.X.Y.0/25     BGP     200 5           FDXX:X:X:X:5::  RAGG3

<BJBJ-GGRT-SR6608_B>dis ip routing-table vpn-instance YW-VPN protocol bgp inactive

BGP Routing table status : <Inactive>

Summary count : 1

Destination/Mask   Proto   Pre Cost        NextHop         Interface

10.X.X.68/30    BGP     200 103         FDXX:X:X:X:1::  RAGG3

发现即使发布路由在生效路由中也不存在

经确认，设备实现就是这样的，因为路由器B的bgp里也引入了ospf路由，所以在bgp路由表里，从路由器A学到的路由与本地路由相比，优选了本地路由；然后bgp路由和ospf路由相比，因为ospf是原始路由，无论怎么调整优先级，派生路由都不会取代原始路由，所以B这台的路由肯定是从ospf学到的