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被动接口+路由更新过滤+策略路由(ccn实验)

日期:2010/1/8 18:08:22 来源:本站原创 访问量:
BBR1]
    router ospf 100
    pass f0/0
    使用之前可以看到下面三条路由全部由f0/0学习
    [Copy to clipboard]
    CODE:
    O E2 103.0.0.0/8 [110/20] via 219.146.241.1, 16:30:59, FastEthernet0/0
    O IA 192.168.4.0/24 [110/66] via 219.146.241.1, 16:30:59, FastEthernet0/0
    O 219.146.243.0/24 [110/65] via 219.146.241.1, 16:30:59, FastEthernet0/0
    [验证结果]
    使用之后看到全部由s1/1学习
    [Copy to clipboard]
    CODE:
    O N2 103.0.0.0/8 [110/20] via 219.146.242.2, 00:00:07, Serial1/1
    O IA 192.168.4.0/24 [110/194] via 219.146.242.2, 00:00:07, Serial1/1
    O IA 219.146.243.0/24 [110/129] via 219.146.242.2, 00:00:07, Serial1/1
    注意,实际上两个ospf连接中使用passiveinterface会导致接口down掉,因为hell包被cut
    被动接口的意义在于使某个接口只接收路由更新而不发送更新,一般用于DDR
    但是有些情况下,比如两个wan的ospf或eigrp,被动接口将导致HELLO包和Keepalive的发送导致无法建立邻居关系
    所以被动接口有一定的局限性
    有一个解决方案是使用distribust-list制造一个伪被动接口,举例
    router eigrp 100
    net x.x.x.x
    distri 11 out f0/0
    access-list 11 deny any
    这样的话,hello包还是正常的发送,邻居关系建立,但是任何更新都将被过滤
    [路由更新过滤]
    [BBR1]
    router ospf 100
    distribute-list 11 in s1/0.1
    access-list 11 deny 192.168.2.0 0.0.0.255
    access-list 11 permit any
    实验之前我们可以看到192.168.2.0在BBR2上是通过s1/0.1学习来的,也就是从FR学习来的
    [Copy to clipboard]
    CODE:
    O 192.168.2.0/24 [110/65] via 10.0.0.2, 00:00:04, Serial1/0.1
    我们在BBR1上面实施distribute-list后,通过access-list定义禁止了192.168.2.0的更新
    然后再在BBR1上查看的时候,关于192.168.2.0的路由条目已经消失,说明过滤成功
    在BBR1上面使用 distribute-list 11 out f0/0的时候会得到提示
    [Copy to clipboard]
    CODE:
    BBR1(config-router)#distribute-list 10 out f0/0
    % Interface not allowed with OUT for OSPF
    被动接口的局限性会完全组织端口发送路由更新,有时候我们需要只是抑制些路由的更新,就要用到路由更新列表
    [策略路由]
    [BBR1]
    access-list 19 permit 192.168.4.0 0.0.0.255
    access-list 20 permit 192.168.3.0 0.0.0.255
    route-map ip1 permit 10
    match ip address 19
    set interface s1/1
    route-map ip2 permit 20
    match ip address 20
    set interface f0/0
    int s1/0.1 mu
    ip policy route-map ip1
    ip policy route-map ip2
    定义在BBR1上面让通过FR来自192.168.4.0的数据包,走s1/1的线路
    定义在BBR1上面让通过FR来自192.168.3.0的数据保,走f0/0的线路
    为了查看过程,我们先定义一个方便debug的ACL
    access-list 101 permit icmp any 219.146.242.0 0.0.0.255
    access-list 101 deny icmp any any
    然后在BBR1上面debug ip pac 101
    我们在192.168.4.0上面,ping 219.146.242.2
    查看,结果如下
    [验证结果]
   
[Copy to clipboard]
CODE:
18:53:31: IP: tableid=0, s=192.168.4.1 (Serial1/0.1), d=219.146.242.1
(FastEthernet0/0), routed via RIB
18:53:31: IP: s=192.168.4.1 (Serial1/0.1), d=219.146.242.1 (Serial1/1),
g=219.146.242.1, len 100, forward
18:53:31: IP: tableid=0, s=192.168.4.1 (Serial1/0.1), d=219.146.242.1
(FastEthernet0/0), routed via RIB
18:53:31: IP: s=192.168.4.1 (Serial1/0.1), d=219.146.242.1 (Serial1/1),
g=219.146.242.1, len 100, forward
18:53:31: IP: tableid=0, s=192.168.4.1 (Serial1/0.1), d=219.146.242.1
(FastEthernet0/0), routed via RIB
18:53:31: IP: s=192.168.4.1 (Serial1/0.1), d=219.146.242.1 (Serial1/1),
g=219.146.242.1, len 100, forward
18:53:31: IP: tableid=0, s=192.168.4.1 (Serial1/0.1), d=219.146.242.1
(FastEthernet0/0), routed via RIB
18:53:31: IP: s=192.168.4.1 (Serial1/0.1), d=219.146.242.1 (Serial1/1),
g=219.146.242.1, len 100, forward
18:53:31: IP: tableid=0, s=192.168.4.1 (Serial1/0.1), d=219.146.242.1
(FastEthernet0/0), routed via RIB
18:53:31: IP: s=192.168.4.1 (Serial1/0.1), d=219.146.242.1 (Serial1/1),
g=219.146.242.1, len 100, forward
(Serial1/1), g=219.146.242.1, len 100, forward
    可以看到上面来自4.0段的IP从s1/1出去
   
[Copy to clipboard]
CODE:
19:03:39: IP: tableid=0, s=192.168.3.1 (Serial1/0.1),
d=219.146.242.1 (FastEthernet0/0), routed via RIB
19:03:39: IP: s=192.168.3.1 (Serial1/0.1), d=219.146.242.1
(FastEthernet0/0), g=219.146.241.2, len 100, forward
19:03:39: IP: tableid=0, s=192.168.3.1 (Serial1/0.1),
d=219.146.242.1 (FastEthernet0/0), routed via RIB
19:03:39: IP: s=192.168.3.1 (Serial1/0.1), d=219.146.242.1
(FastEthernet0/0), g=219.146.241.2, len 100, forward
19:03:39: IP: tableid=0, s=192.168.3.1 (Serial1/0.1),
d=219.146.242.1 (FastEthernet0/0), routed via RIB
19:03:39: IP: s=192.168.3.1 (Serial1/0.1), d=219.146.242.1
(FastEthernet0/0), g=219.146.241.2, len 100, forward
19:03:40: IP: tableid=0, s=192.168.3.1 (Serial1/0.1),
d=219.146.242.1 (FastEthernet0/0), routed via RIB
19:03:40: IP: s=192.168.3.1 (Serial1/0.1), d=219.146.242.1
(FastEthernet0/0), g=219.146.241.2, len 100, forward
19:03:40: IP: tableid=0, s=192.168.3.1 (Serial1/0.1),
d=219.146.242.1 (FastEthernet0/0), routed via RIB
19:03:40: IP: s=192.168.3.1 (Serial1/0.1), d=219.146.242.1
(FastEthernet0/0), g=219.146.241.2, len 100, forward
(FastEthernet0/0), g=219.146.241.2, len 100, forward
    可以看到上面来自3.0段的IP从F0/0出去
    要记住策略路由最基本的步骤
    1,定义一个IP范围,Acl
    2,定义一个RouterMAP
    Match ACL范围的IP
    Set 动作
    Action 动作
    3,定义好了以后要在某个接口上应用
    ip policy router-map mapname
    [路由单项重发布以及AD/Metric更改]
    [SW1]
    router ospf 100
    distance 40 [使用Distance 命令修改默认管理距离]
    distance 40 x.x.x.x 255.255.255.255[使用Distance 命令修改默认某条特定路由的管理距离]
    redistribute rip sub metric 30 [修改metric]
    [SR1]
    int lo0
    ip add 105.0.0.1 255.0.0.0
    int lo1
    ip add 106.0.0.1 255.0.0.0
    router rip
    net 105.0.0.0
    net 106.0.0.0
    [SR2]
    int lo0
    ip add 107.0.0.1 255.0.0.0
    int lo1
    ip add 108.0.0.1 255.0.0.0
    router rip
    net 107.0.0.0
    net 108.0.0.0
    增加这两个lo接口地址是为了下一步实验
    举例:
    作为边界路由器经常会学习到到达同一目的地的两条不同协议的路由,比如RIP和EIGRP
    然后这两种协议不具备可比性,一个是跳数,一个是带宽也延迟,那么就要比较管理距离,一个是120一个是90
    肯定要选择EIGRP,那么我们可以通过Distance命令来让它优先选择RIP而不是EIGRP
    他们只对本地有效,另外要注意它的意义所在,例如
    router rip
    distance 40
    router ospf 100
    distance 30
    第一个是只有通过RIP学习到的路由更改AD为40
    第二个是只有通过OSPF 100学习到的路由更改AD为30
    到底什么学习来的,sh ip route的时候看前面的路由标识,R或者O或者其他
    [使用Distance 命令修改默认管理距离]
    修改之前,学习到的外部OSPF路由都是默认的110管理距离
   
[Copy to clipboard]
CODE:
C 102.0.0.0/8 is directly connected, FastEthernet1/3
O N2 103.0.0.0/8 [110/20] via 219.146.244.2, 00:00:02, FastEthernet1/4
C 101.0.0.0/8 is directly connected, FastEthernet1/2
O IA 172.17.0.0/16 [110/129] via 219.146.242.1, 00:00:02, Serial0/1
O IA 172.16.0.0/16 [110/192] via 219.146.242.1, 00:00:02, Serial0/1
O IA 172.19.0.0/16 [110/129] via 219.146.242.1, 00:00:02, Serial0/1
O IA 172.18.0.0/16 [110/193] via 219.146.242.1, 00:00:02, Serial0/1
    ....
    通过distance 40命令修改之后,所有的通过ospf 100学习来的路由AD变为我们指定的40
   
[Copy to clipboard]
CODE:
C 102.0.0.0/8 is directly connected, FastEthernet1/3
O N2 103.0.0.0/8 [40/20] via 219.146.244.2, 00:00:18, FastEthernet1/4
C 101.0.0.0/8 is directly connected, FastEthernet1/2
O IA 172.17.0.0/16 [40/129] via 219.146.242.1, 00:00:18, Serial0/1
O IA 172.16.0.0/16 [40/192] via 219.146.242.1, 00:00:18, Serial0/1
O IA 172.19.0.0/16 [40/129] via 219.146.242.1, 00:00:18, Serial0/1
O IA 172.18.0.0/16 [40/193] via 219.146.242.1, 00:00:18, Serial0/1

    [使用Distance 命令修改默认某条特定路由的管理距离]
    所有的通过ospf 100学习来的路由都将被更改AD,如果我们只是希望更改某一条外部路由的metric
    通过distance 扩展命令就不用根据进程号来进行管理距离的改变,而是根据从哪儿学习来的路由
    这里我们拿RIP来实验
    修改之前我们先再SW1上面查看学习到的RIP路由
    [Copy to clipboard]
    CODE:
    R 106.0.0.0/8 [120/1] via 101.0.0.1, 00:00:11, FastEthernet1/2
    R 105.0.0.0/8 [120/1] via 101.0.0.1, 00:00:12, FastEthernet1/2
    R 108.0.0.0/8 [120/1] via 102.0.0.1, 00:00:16, FastEthernet1/3
    R 107.0.0.0/8 [120/1] via 102.0.0.1, 00:00:22, FastEthernet1/3
    都是从101.0.0.1学习来SR1的RIP路由,从102.0.0.1学习来SR2的RIP路由
    我们现在让从101.0.0.1学习来的RIP路由的AD变为40
    那么执行
    router rip
    distance 40 101.0.0.1 255.255.255.255
    [Copy to clipboard]
    CODE:
    R 106.0.0.0/8 [40/1] via 101.0.0.1, 00:00:02, FastEthernet1/2
    R 105.0.0.0/8 [40/1] via 101.0.0.1, 00:00:14, FastEthernet1/2
    R 108.0.0.0/8 [120/1] via 102.0.0.1, 00:00:06, FastEthernet1/3
    R 107.0.0.0/8 [120/1] via 102.0.0.1, 00:00:12, FastEthernet1/3
    [distribute rip sub metric 30]
    更改我们先查看学习到的RIP路由的Metric
    [Copy to clipboard]
    CODE:
    SW2#sh ip route
    O N2 102.0.0.0/8 [110/20] via 219.146.244.1, 00:00:02, FastEthernet1/4
    O N2 108.0.0.0/8 [110/20] via 219.146.244.1, 00:00:02, FastEthernet1/4
    O N2 106.0.0.0/8 [110/20] via 219.146.244.1, 00:00:03, FastEthernet1/4
    O N2 107.0.0.0/8 [110/20] via 219.146.244.1, 00:00:03, FastEthernet1/4
    O N2 105.0.0.0/8 [110/20] via 219.146.244.1, 00:00:03, FastEthernet1/4
    ...........
    我们在SW1上面redistribute rip sub metric 30以后,再看SW2
    [Copy to clipboard]
    CODE:
    SW2#sh ip route
    CODE:
    C 102.0.0.0/8 is directly connected, FastEthernet1/3
    O N2 103.0.0.0/8 [110/20] via 219.146.244.2, 00:00:02, FastEthernet1/4
    C 101.0.0.0/8 is directly connected, FastEthernet1/2
    O IA 172.17.0.0/16 [110/129] via 219.146.242.1, 00:00:02, Serial0/1
    O IA 172.16.0.0/16 [110/192] via 219.146.242.1, 00:00:02, Serial0/1
    O IA 172.19.0.0/16 [110/129] via 219.146.242.1, 00:00:02, Serial0/1
    O IA 172.18.0.0/16 [110/193] via 219.146.242.1, 00:00:02, Serial0/1
    ....
    通过distance 40命令修改之后,所有的通过ospf 100学习来的路由AD变为我们指定的40
    O N2 102.0.0.0/8 [110/30] via 219.146.244.1, 00:00:02, FastEthernet1/4
    O N2 108.0.0.0/8 [110/30] via 219.146.244.1, 00:00:02, FastEthernet1/4
    O N2 106.0.0.0/8 [110/30] via 219.146.244.1, 00:00:03, FastEthernet1/4
    O N2 107.0.0.0/8 [110/30] via 219.146.244.1, 00:00:03, FastEthernet1/4
    O N2 105.0.0.0/8 [110/30] via 219.146.244.1, 00:00:03, FastEthernet1/4
    .........
    router ospf 100
    redistribute rip sub metric 30
    结果的意思表明是通过ospf 100学习到的RIP路由的metric更改为30,一定要理解含义
    跟前面的distance语法区分开
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