在Nexus交換機上配置路由重分發

簡介

本文檔介紹如何在基於Cisco Nexus NXOS®的交換機上配置路由重分發。

必要條件

需求

思科建議您瞭解以下主題：

•  Nexus NX-OS軟體。
• 路由協定：開放最短路徑優先(OSPF)、邊界網關協定(BGP)、增強型內部網關路由協定(EIGRP)。

採用元件

本文檔中的資訊基於NXOS版本10.2.5.M的Cisco Nexus 9000。

本文中的資訊是根據特定實驗室環境內的裝置所建立。文中使用到的所有裝置皆從已清除（預設）的組態來啟動。如果您的網路運作中，請確保您瞭解任何指令可能造成的影響。

設定

網路圖表

• NEXUS A正在通告OSPF進程中的環回21

loopback0 192.168.1.1/32

• NEXUS B正在通告OSPF進程21中的環回

loopback0 192.168.2.1/32

• NEXUS C通告EIGRP進程19中的環回

loopback10 172.16.9.1/32

• NEXUS D正在通告EIGRP進程19中的環回:

loopback10 172.16.21.1/32

組態

在這種情況下，Nexus交換機已使用OSPF、iBGP和EIGRP會話建立鄰居會話。

注意：當在單個路由器的兩個或多個路由協定之間重分發時，重分發不可傳遞。簡而言之，如果路由器將協定1重新分發到協定2，然後協定2重新分發到協定3，則來自協定1的路由不會重新分發到協定3。

重新分發到OSPF。

NEXUS B:

步驟 1.使用需要重新分發的字首配置字首清單。

Nexus-B(config)# ip prefix-list REDISTRIBUTION seq 5 permit 0.0.0.0/0 le 32

注意：通過在步驟2上配置空白路由對映可以跳過此步驟，0.0.0.0/0 le 32 inside prefix-list允許所有路由，本文中字首清單配置的意圖旨在說明您可以選擇/過濾重新分發的路由。

步驟 2.建立與字首清單中指定的條件匹配的路由對映。

Nexus-B(config)# route-map BGP-TO-OSPF permit 10
Nexus-B(config-route-map)# match ip address prefix-list REDISTRIBUTION
Nexus-B(config-route-map)# match route-type internal

注意:match route-type internal命令是重分發iBGP路由的要求，預設情況下，僅重分發eBGP路由。

步驟 3.將來自其他協定（本例中為iBGP）的路由重分發到OSPF。

Nexus-B(config)# router ospf 21
Nexus-B(config-router)# router-id 2.2.2.2
Nexus-B(config-router)# redistribute bgp 6500 route-map BGP-TO-OSPF

重新分發到BGP。

NEXUS B:

步驟 1. 使用需要重新分發的字首配置字首清單。

Nexus-B(config)# ip prefix-list REDISTRIBUTION seq 5 permit 0.0.0.0/0 le 32

步驟 2. 建立與字首清單中指定的條件匹配的路由對映。

Nexus-B(config)# route-map OSPF-TO-BGP permit 10
Nexus-B(config-route-map)# match ip address prefix-list REDISTRIBUTION

步驟 3. 將路由重分佈到來自另一個協定（本例中為OSPF）的BGP中。

Nexus-B(config)# router bgp 6500
Nexus-B(config-router)# address-family ipv4 unicast
Nexus-B(config-router-af)# redistribute ospf 21 route-map OSPF-TO-BGP  
Nexus-B(config-router-af)# neighbor 10.24.1.2
Nexus-B(config-router-neighbor)# remote-as 6500
Nexus-B(config-router-neighbor)# address-family ipv4 unicast

NEXUS C:

步驟 1. 使用需要重新分發的字首配置字首清單。

Nexus-C(config)# ip prefix-list REDISTRIBUTION seq 5 permit 0.0.0.0/0 le 32

步驟 2. 建立與字首清單中指定的條件匹配的路由對映。

Nexus-C(config)# route-map EIGRP-TO-BGP permit 10
Nexus-C(config-route-map)# match ip address prefix-list REDISTRIBUTION 

步驟 3. 將路由重分佈到來自另一個協定（本例中為EIGRP）的BGP中。

Nexus-C(config)# router bgp 6500
Nexus-C(config-router)# address-family ipv4 unicast
Nexus-C(config-router-af)# redistribute eigrp 19 route-map EIGRP-TO-BGP
Nexus-C(config-router-af)# neighbor 10.24.1.1
Nexus-C(config-router-neighbor)# remote-as 6500
Nexus-C(config-router-neighbor)# address-family ipv4 unicast

重新分發到EIGRP。

NEXUS C:

步驟 1. 使用需要重新分發的字首配置字首清單。

Nexus-C(config)# ip prefix-list REDISTRIBUTION seq 5 permit 0.0.0.0/0 le 32

步驟 2. 建立與字首清單中指定的條件匹配的路由對映。

Nexus-C(config)# route-map BGP-TO-EIGRP permit 10
Nexus-C(config-route-map)# match ip address prefix-list REDISTRIBUTION
Nexus-C(config-route-map)# match route-type internal

步驟 3. 將路由重分佈到來自另一個協定（本例中為OSPF）的EIGRP中。

Nexus-C(config)# router eigrp 19
Nexus-C(config-router)# address-family ipv4 unicast
Nexus-C(config-router-af)# autonomous-system 17
Nexus-C(config-router-af)# router-id 11.11.11.11
Nexus-C(config-router-af)# redistribute bgp 6500 route-map BGP-TO-EIGRP

驗證

配置重分發後，Nexus裝置開始接收來自其他協定的路由，這些路由顯示為外部路由。

Nexus-A路由表：

Nexus-A# show ip route ospf-21 
IP Route Table for VRF "default"
'*' denotes best ucast next-hop
'**' denotes best mcast next-hop
'[x/y]' denotes [preference/metric]
'%
    
    
      ' in via output denotes VRF 
     
       172.16.21.1/32, ubest/mbest: 1/0 *via 10.12.1.2, Eth1/36, [110/1], 00:00:57, ospf-21, type-2, tag 6500 <<< <<< this prefix is external to OSPF as it is coming from redistribution, originated from Nexus-B, the original route comes from Nexus-D. 192.168.2.1/32, ubest/mbest: 1/0 *via 10.12.1.2, Eth1/36, [110/2], 00:00:57, ospf-21, intra Nexus-A# show ip route direct IP Route Table for VRF "default" '*' denotes best ucast next-hop '**' denotes best mcast next-hop '[x/y]' denotes [preference/metric] '% 
      
        ' in via output denotes VRF 
       
         10.12.1.0/24, ubest/mbest: 1/0, attached *via 10.12.1.1, Eth1/36, [0/0], 01:37:21, direct 192.168.1.1/32, ubest/mbest: 2/0, attached *via 192.168.1.1, Lo0, [0/0], 23:42:19, direct 
        
       
      
    

Nexus-B路由表：

Nexus-B# show ip route ospf-21 
IP Route Table for VRF "default"
'*' denotes best ucast next-hop
'**' denotes best mcast next-hop
'[x/y]' denotes [preference/metric]
'%
    
    
      ' in via output denotes VRF 
     
       192.168.1.1/32, ubest/mbest: 1/0 *via 10.12.1.1, Eth1/49, [110/2], 00:15:08, ospf-21, intra Nexus-B# show ip route bgp-6500 IP Route Table for VRF "default" '*' denotes best ucast next-hop '**' denotes best mcast next-hop '[x/y]' denotes [preference/metric] '% 
      
        ' in via output denotes VRF 
       
         172.16.21.1/32, ubest/mbest: 1/0 *via 10.24.1.2, [200/128576], 00:19:49, bgp-6500, internal, tag 6500 <<< This prefix is learned by iBGP from Nexus-C, the original route is coming from the EIGRP redistribution, originated from NexusD. 
        
       
      
    

Nexus-C路由表：

Nexus-C# show ip route bgp-6500 
IP Route Table for VRF "default"
'*' denotes best ucast next-hop
'**' denotes best mcast next-hop
'[x/y]' denotes [preference/metric]
'%
    
    
      ' in via output denotes VRF 
     
       192.168.1.1/32, ubest/mbest: 1/0 *via 10.24.1.1, [200/2], 00:15:59, bgp-6500, internal, tag 6500 <<< This prefix is coming from iBGP, the route was originated from Nexus-A. Nexus-C# show ip route eigrp-19 IP Route Table for VRF "default" '*' denotes best ucast next-hop '**' denotes best mcast next-hop '[x/y]' denotes [preference/metric] '% 
      
        ' in via output denotes VRF 
       
         172.16.21.1/32, ubest/mbest: 1/0 *via 10.36.1.2, Eth1/49, [90/128576], 00:26:03, eigrp-19, internal 
        
       
      
    

重分發統計資訊，僅用於EIGRP:

Nexus-C# show ip eigrp 19 route-map statistics redistribute bgp 6500
IP-EIGRP Route-map Traffic Statistics for AS 17 VRF default
C: No. of comparisions, M: No. of matches

route-map BGP-TO-EIGRP permit 10
  match ip address prefix-list REDISTRIBUTION                C: 2      M: 2     
  match route-type internal                                  C: 2      M: 2     

Total accept count for policy: 2     
Total reject count for policy: 0  

Nexus-D路由表：

Nexus-D# show ip route eigrp-19 
IP Route Table for VRF "default"
'*' denotes best ucast next-hop
'**' denotes best mcast next-hop
'[x/y]' denotes [preference/metric]
'%
    
    
      ' in via output denotes VRF 
     
       172.16.9.1/32, ubest/mbest: 1/0 *via 10.36.1.1, Eth1/2, [90/128576], 00:29:14, eigrp-19, internal 192.168.1.1/32, ubest/mbest: 1/0 *via 10.36.1.1, Eth1/2, [170/51456], 00:12:49, eigrp-19, external, tag 6500 <<< This prefix is external to EIGRP as it is coming from redistribution, it comes from BGP but it was originated on Nexus-A. Nexus-D# sh ip route direct IP Route Table for VRF "default" '*' denotes best ucast next-hop '**' denotes best mcast next-hop '[x/y]' denotes [preference/metric] '% 
      
        ' in via output denotes VRF 
       
         10.36.1.0/24, ubest/mbest: 1/0, attached *via 10.36.1.2, Eth1/2, [0/0], 1d00h, direct 172.16.21.1/32, ubest/mbest: 2/0, attached *via 172.16.21.1, Lo10, [0/0], 01:47:30, direct 
        
       
      
    

Nexus-B(config)# router bgp 6500
Nexus-B(config-router)# address-family ipv4 unicast
Nexus-B(config-router-af)# redistribute ospf 21 route-map OSPF-TO-BGP  
Nexus-B(config-router-af)# neighbor 10.24.1.2
Nexus-B(config-router-neighbor)# remote-as 6500
Nexus-B(config-router-neighbor)# address-family ipv4 unicast