BGP路由黑洞基础

BGP路由黑洞实验：

实验拓扑：

实验需求：

• R2,R3,R4属于AS 100,R1属于AS 200,R5属于AS 300,
• AS 100内需要通过loopback口建立邻居关系，AS间用物理接口建立邻居关系，
• R2直接与R4建立IBGP邻居，R3上面不任何BGP的配置。

实验步骤：

• 配置IP地址，ping直连检验连通性（略）

• 配置AS 100内的OSPF(取R3配置):

  [R3]ospf 1 	
  [R3-ospf-1]area 0
  [R3-ospf-1-area-0.0.0.0]network 10.0.23.3 0.0.0.0	
  [R3-ospf-1-area-0.0.0.0]network 10.0.34.3 0.0.0.0
  [R3-ospf-1-area-0.0.0.0]network 3.3.3.3 0.0.0.0
  

• 查看OSPF邻居表：

  [R3]dis ospf peer brief 
  
  	 OSPF Process 1 with Router ID 10.0.23.3
  		  Peer Statistic Information
   ----------------------------------------------------------------------------
   Area Id          Interface                        Neighbor id      State    
   0.0.0.0          GigabitEthernet0/0/0             10.0.23.2        Full        
   0.0.0.0          GigabitEthernet0/0/1             10.0.34.4        Full        
   ----------------------------------------------------------------------------
  [R3]
  
  #状态为full，表明邻接关系建立成功。
  

• 配置BGP:

  [R1]bgp 200	
  [R1-bgp]peer 10.0.12.2 as-number 100	
  [R1-bgp]peer 10.0.12.2 ebgp-max-hop 2
  
  [R2]bgp 100	
  [R2-bgp]peer 4.4.4.4 as-number 100
  [R2-bgp]peer 4.4.4.4 connect-interface LoopBack 0
  [R2-bgp]peer 10.0.12.1 as-number 200
  [R2-bgp]peer 4.4.4.4 next-hop-local 
  
  [R4]bgp 100	
  [R4-bgp]peer 2.2.2.2 as-number 100	
  [R4-bgp]peer 2.2.2.2 connect-interface LoopBack 0
  [R4-bgp]peer 10.0.45.5 as-number 300 
  [R4-bgp]peer 2.2.2.2 next-hop-local  --向邻居转发路由是修改下一跳为本地
  
  [R5]bgp 300
  [R5-bgp]peer 10.0.45.4 as-number 100	
  [R5-bgp]peer 10.0.45.4 ebgp-max-hop 2  --ebgp默认传递报文的ttl值为1，用环回口建立需要修改跳数。
  

• 查看BGP的邻居表：

  [R4]dis bgp peer
  
   BGP local router ID : 10.0.34.4
   Local AS number : 100
   Total number of peers : 2		  Peers in established state : 2
  
    Peer            V          AS  MsgRcvd  MsgSent  OutQ  Up/Down       State Pre
  fRcv
  
    2.2.2.2         4         100       20       20     0 00:18:17 Established    
     0
    10.0.45.5       4         300        2        3     0 00:00:00 Established    
     0
  [R4]
  
  # 当状态为Established就代表建立成功。
  

• 在R1,R5上创建业务网段路由，并宣告进OSPF

  [R1-bgp]network 1.1.1.1 32
  
  [R5-bgp]network 5.5.5.5 32
  

• 在R1上，R5上查看 BGP路由表：

  [R1]dis ip routing-table protocol bgp 
  Route Flags: R - relay, D - download to fib
  ------------------------------------------------------------------------------
  Public routing table : BGP
           Destinations : 1        Routes : 1        
  
  BGP routing table status : 
           Destinations : 1        Routes : 1
  
  Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface
  
          5.5.5.5/32  EBGP    255  0          RD   10.0.12.2       GigabitEthernet
  0/0/0
  
  BGP routing table status : 
           Destinations : 0        Routes : 0
  
  [R1]
  
  [R5]dis ip routing-table protocol bgp 
  Route Flags: R - relay, D - download to fib
  ------------------------------------------------------------------------------
  Public routing table : BGP
           Destinations : 1        Routes : 1        
  
  BGP routing table status : 
           Destinations : 1        Routes : 1
  
  Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface
  
          1.1.1.1/32  EBGP    255  0          RD   10.0.45.4       GigabitEthernet
  0/0/0
  
  BGP routing table status : 
           Destinations : 0        Routes : 0
  
  [R5]
  
  #发现R1,R5上路由表内都存在对方的业务网段路由，
  

• 在R1上tracertR5的业务网段：

  tracert -a 1.1.1.1 5.5.5.5
  
   traceroute to  5.5.5.5(5.5.5.5), max hops: 30 ,packet length: 40,press CTRL_C t
  o break 
  
   1 10.0.12.2 50 ms  20 ms  10 ms 
  
   2  *  *  * 
  
   3  *  *  * 
   
   #访问不了，是为什么呢?发现能到达R1,以此排错，查看本地路由表是否有图中经过的路由
  

• 查看R3的全局路由表：

  dis ip routing-table 
  Route Flags: R - relay, D - download to fib
  ------------------------------------------------------------------------------
  Routing Tables: Public
           Destinations : 13       Routes : 13       
  
  Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface
  
          2.2.2.2/32  OSPF    10   1           D   10.0.23.2       GigabitEthernet
  0/0/0
          3.3.3.3/32  Direct  0    0           D   127.0.0.1       LoopBack0
          4.4.4.4/32  OSPF    10   1           D   10.0.34.4       GigabitEthernet
  0/0/1
        10.0.23.0/24  Direct  0    0           D   10.0.23.3       GigabitEthernet
  0/0/0
        10.0.23.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
  0/0/0
      10.0.23.255/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
  0/0/0
        10.0.34.0/24  Direct  0    0           D   10.0.34.3       GigabitEthernet
  0/0/1
        10.0.34.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
  0/0/1
      10.0.34.255/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
  0/0/1
        127.0.0.0/8   Direct  0    0           D   127.0.0.1       InLoopBack0
        127.0.0.1/32  Direct  0    0           D   127.0.0.1       InLoopBack0
  127.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0
  255.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0
  
  
  
  #发现并没有到达R1,R5业务网段的路由，所以访问就在这里中断了。
  #所以我们需要在R3,R4上将BGP路由重发布到OSPF.
  

• 在R2,R4上将BGP路由重发布到OSPF：

  [R2-ospf-1]import-route bgp 
  
  [R4-ospf-1]import-route bgp 
  

• 再次查看R3路由表：

  [R3]dis ip routing-table 
  Route Flags: R - relay, D - download to fib
  ------------------------------------------------------------------------------
  Routing Tables: Public
           Destinations : 15       Routes : 15       
  
  Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface
  
          1.1.1.1/32  O_ASE   150  1           D   10.0.23.2       GigabitEthernet
  0/0/0
          2.2.2.2/32  OSPF    10   1           D   10.0.23.2       GigabitEthernet
  0/0/0
          3.3.3.3/32  Direct  0    0           D   127.0.0.1       LoopBack0
          4.4.4.4/32  OSPF    10   1           D   10.0.34.4       GigabitEthernet
  0/0/1
          5.5.5.5/32  O_ASE   150  1           D   10.0.34.4       GigabitEthernet
  0/0/1
        10.0.23.0/24  Direct  0    0           D   10.0.23.3       GigabitEthernet
  0/0/0
        10.0.23.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
  0/0/0
      10.0.23.255/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
  0/0/0
        10.0.34.0/24  Direct  0    0           D   10.0.34.3       GigabitEthernet
  0/0/1
        10.0.34.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
  0/0/1
      10.0.34.255/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
  0/0/1
        127.0.0.0/8   Direct  0    0           D   127.0.0.1       InLoopBack0
        127.0.0.1/32  Direct  0    0           D   127.0.0.1       InLoopBack0
  127.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0
  255.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0
  
  [R3]
  
  #发现已经有了业务网段的路由
  

实验结果：

• 在R1上带源地址 1.1.1.1访问5.5.5.5

  [R1]ping -a 1.1.1.1 5.5.5.5
    PING 5.5.5.5: 56  data bytes, press CTRL_C to break
      Reply from 5.5.5.5: bytes=56 Sequence=1 ttl=252 time=70 ms
      Reply from 5.5.5.5: bytes=56 Sequence=2 ttl=252 time=40 ms
      Reply from 5.5.5.5: bytes=56 Sequence=3 ttl=252 time=40 ms
      Reply from 5.5.5.5: bytes=56 Sequence=4 ttl=252 time=40 ms
      Reply from 5.5.5.5: bytes=56 Sequence=5 ttl=252 time=60 ms
  
    --- 5.5.5.5 ping statistics ---
      5 packet(s) transmitted
      5 packet(s) received
      0.00% packet loss
      round-trip min/avg/max = 40/50/70 ms
  
  [R1]
  

总结：

本次BGP黑洞实验，主要查看对BGP路由传递的理解，和对路由器三种协议表的理解，通过分析三种协议表，来实行路由重发布。达到互通