CCIE實驗備考之BGP(2)

彙總設置：
     1.bgp是無類路由協議，支持VLSM，但會要求最長匹配，一般它默認啓動自動彙總的，但我們要求關閉自動彙總，不然就會像EIGRP那樣出現問題，命令：
              no auto-summary
     2.手工彙總方法1：
            1）  network 彙總路由 mask 彙總後的子網掩碼
            2）  ip route 彙總路由 彙總後的子網掩碼 null0
        network命令本身不能彙總路由，它只是把經過igp彙總後的路由發佈出去，然後還要手工指定一條靜態彙總路由，指向null接口，不僅發佈彙總路由，也會把具體的路由發佈出去，如果不想把具體路由發佈出去，需要路由過濾。
     3.手工彙總方法2：
            aggregate-address ip地址 子網掩碼 參數
            參數：
 summary-only：只發送彙總的路由，具體的路由不會發布出去
r2#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
       * - candidate default, U - per-user static route, o - ODR
       P - periodic downloaded static route

Gateway of last resort is not set

B    199.1.3.0/24 [20/0] via 192.1.1.1, 00:00:09     //要彙總的條目
B    199.1.2.0/24 [20/0] via 192.1.1.1, 00:00:09
B    199.1.1.0/24 [20/0] via 192.1.1.1, 00:00:09
C    193.1.1.0/24 is directly connected, Ethernet0
C    192.1.1.0/24 is directly connected, Serial1
B    199.1.4.0/24 [20/0] via 192.1.1.1, 00:00:09
B    199.1.0.0/22 [20/0] via 192.1.1.1, 00:00:09   //這是彙總之後的路由
加入參數後
r2#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
       * - candidate default, U - per-user static route, o - ODR
       P - periodic downloaded static route

Gateway of last resort is not set

C    193.1.1.0/24 is directly connected, Ethernet0
C    192.1.1.0/24 is directly connected, Serial1
B    199.1.0.0/22 [20/0] via 192.1.1.1, 00:00:09

r1#show ip bgp
BGP table version is 18, local router ID is 192.168.194.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*> 192.1.1.0        0.0.0.0                  0         32768 ?
*> 193.1.1.0        0.0.0.0                  2         32768 ?
s> 199.1.2.0        0.0.0.0                  0         32768 ?    //抑制住的路由
*> 192.168.192.0/21 0.0.0.0                            32768 i
s> 199.1.1.0        0.0.0.0                  0         32768 ?
s> 199.1.3.0        0.0.0.0                  0         32768 ?
s> 199.1.4.0        0.0.0.0                  2         32768 ?
   

Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*>i192.168.192.0/21 10.1.1.9                      100      0 {50,200} i
*> 200.200.200.0    0.0.0.0                  0         32768 i
修改加參數：
router bgp 100
 aggregate-address 192.168.192.0 255.255.248.0 as-set summary-only advertise-map cisco
 ......
!
ip as-path access-list 1 permit ^200$
!
route-map cisco permit 10
 match as-path 1
!

r4#show ip bgp
BGP table version is 17, local router ID is 200.200.200.201
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*>i192.168.192.0/21 10.1.1.9                      100      0 200 i
*> 200.200.200.0    0.0.0.0                  0         32768 i

 suppress-map:抑制彙總路由指定的條目
router bgp 100
 aggregate-address 192.168.192.0 255.255.248.0 suppress-map supmap
!
access-list 1 permit 192.168.195.0
access-list 1 permit 192.168.197.0
route-map supmap permit 10
 match ip address 1
!
r3#show ip bgp
BGP table version is 10, local router ID is 3.3.3.3
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*> 192.168.192.0    10.1.1.1                 0             0 50 i
*> 192.168.192.0/21 0.0.0.0                            32768 i
*> 192.168.193.0    10.1.1.1                 0             0 50 i
*> 192.168.194.0    10.1.1.1                 0             0 50 i
*> 192.168.196.0    10.1.1.5                 0             0 200 i
s> 192.168.197.0    10.1.1.5                 0             0 200 i
*> 192.168.198.0    10.1.1.5                 0             0 200 i
*>i200.200.200.0    10.1.1.10                0    100      0 i
----------------------------------------------------------------------------------
路由策略：
1.distribute-list過濾列表
  命令：
      neighbor 鄰居 distribute-list 訪控號 [in | out]
 
  router bgp 100
    neighbor 10.1.1.1 remote-as 50
    neighbor 10.1.1.5 remote-as 200
    neighbor 10.1.1.10 remote-as 100
    neighbor 10.1.1.10 next-hop-self
    neighbor 10.1.1.10 send-community
    neighbor 10.1.1.10 distribute-list 1 out
    ......
  !
  access-list 1 deny   192.168.196.0
  access-list 1 permit any

2.prefix-list前綴列表過濾
  命令：
      ip prefix-list 列表號 [seq 序號] {deny | permit} 網絡號/len匹配長度 [ge 最小匹配值] [le 最大匹配值]
      其中：
          len < ge <= le
          如果存在ge和le，則len匹配長度將會被忽略
  應用：
      neighbor 鄰居 prefix-list 名稱 [in | out]
  注意：prefix-list和distribute-list不能同時應用在同一個鄰居上，但distribute-list可以調用prefix-list定義的列表
  例如：
      router bgp 100
        aggregate-address 192.168.192.0 255.255.248.0 suppress-map supmap
        neighbor 10.1.1.1 remote-as 50
        neighbor 10.1.1.5 remote-as 200
        neighbor 10.1.1.10 remote-as 100
        neighbor 10.1.1.10 next-hop-self
        neighbor 10.1.1.10 send-community
        neighbor 10.1.1.10 prefix-list cisco out
        ......
      !
      ip prefix-list cisco seq 5 permit 192.168.192.0/21 ge 22 le 24

      r3#show ip bgp
      BGP table version is 17, local router ID is 3.3.3.3
      Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
      Origin codes: i - IGP, e - EGP, ? - incomplete

      Network          Next Hop            Metric LocPrf Weight Path
      s> 192.168.192.0    10.1.1.1                 0             0 50 i
      *> 192.168.192.0/21 0.0.0.0                            32768 i
      *> 192.168.193.0    10.1.1.1                 0             0 50 i
      *> 192.168.194.0    10.1.1.1                 0             0 50 i
      *> 192.168.196.0    10.1.1.5                 0             0 200 i
      s> 192.168.197.0    10.1.1.5                 0             0 200 i
      *> 192.168.198.0    10.1.1.5                 0             0 200 i
      *>i200.200.200.0    10.1.1.10                0    100      0 i

3.AS-PATH過濾
 命令：
     ip as-path access-list 編號 { permit | deny } 正則表達式
     其中表達式的原則：
        .                        任何單一字符，包括空格
       []                        在方括號中羅列的任何字符
       [^]                       除了在方括號中所羅列字符外的任何字符（^必須放在字符列表之前）
       -                        （連字符）在由連字符所分配的兩個字符之間的任意字符
       ？                        字符或模式出現 0次或 1次
       *                         字符或模式出現 0次或多次
       +                         字符或模式出現 1次或多次
       ^                         一行的開始
       $                         一行的結束
       |                         由元字符特殊字符分隔的字之一
       _                        （下劃線）一個逗號，行的開始，行的結束或空格
  例如：
     ip as-path access-list 1 permit ^(850|860)*$
     將在AS-PATH中匹配重複多次的AS號爲850或860列表，如（850），（850，850，850），（850，850，888）或（860），（860，860，860）等
  應用：
     neighbor 鄰居 filter-list as-path定義的編號 [ in | out ]
  案例：
     r4#show ip bgp
     BGP table version is 16, local router ID is 200.200.200.201
     Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
     Origin codes: i - IGP, e - EGP, ? - incomplete

        Network          Next Hop            Metric LocPrf Weight Path
     *>i192.168.193.0    10.1.1.9                 0    100      0 50 i
     *>i192.168.194.0    10.1.1.9                 0    100      0 50 i
     *>i192.168.196.0    10.1.1.9                 0    100      0 200 i
     *>i192.168.198.0    10.1.1.9                 0    100      0 200 i
     *> 200.200.200.0    0.0.0.0                  0         32768 i
    
     r3上修改
     router bgp 100
        ......
        neighbor 10.1.1.10 remote-as 100
        neighbor 10.1.1.10 next-hop-self
        neighbor 10.1.1.10 send-community
        neighbor 10.1.1.10 filter-list 1 out
        no auto-summary
     !
     ip as-path access-list 1 permit ^50$  //只允許as號爲50的通過

     r4#show ip bgp
     BGP table version is 22, local router ID is 200.200.200.201
     Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
     Origin codes: i - IGP, e - EGP, ? - incomplete

         Network          Next Hop            Metric LocPrf Weight Path
     *>i192.168.193.0    10.1.1.9                 0    100      0 50 i
     *>i192.168.194.0    10.1.1.9                 0    100      0 50 i
     *> 200.200.200.0    0.0.0.0                  0         32768 i

4.route-map過濾：
  命令：
      route-map 名稱 [permit | deny ] 編號
         match 匹配
  應用：
      neighbor 鄰居 route-map 名稱
  案例：
  router bgp 100
    ......
    neighbor 10.1.1.10 remote-as 100
    neighbor 10.1.1.10 next-hop-self
    neighbor 10.1.1.10 send-community
    neighbor 10.1.1.10 route-map mapcisco out
    no auto-summary
  !
  ip as-path access-list 1 permit ^50$
  access-list 1 permit 192.168.193.0
  access-list 1 permit 192.168.195.0
  route-map mapcisco permit 10
    match ip address 1

 r4#show ip bgp
BGP table version is 22, local router ID is 200.200.200.201
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*>i192.168.193.0    10.1.1.9                 0    100      0 50 i
*>i192.168.194.0    10.1.1.9                 0    100      0 50 i
*> 200.200.200.0    0.0.0.0                  0         32768 i
----------------------------------------------------------------------------------