WB1 RIP 4.11 Access-List ODD v.s EVEN

BB1一共送出四筆路由給R6

Rack1R6#show ip route rip | i Serial0/0
R    212.18.0.0/24 [120/1] via 54.1.1.254, 00:00:15, Serial0/0
R    212.18.1.0/24 [120/1] via 54.1.1.254, 00:00:15, Serial0/0
R    212.18.2.0/24 [120/1] via 54.1.1.254, 00:00:15, Serial0/0
R    212.18.3.0/24 [120/1] via 54.1.1.254, 00:00:15, Serial0/0
         
Rack1R6#

--------------------------------------------------------------------------------

Configure a one line standard access-list on R6 to filter out all routes
coming from BB1 that have an even number in the third octet.

過濾第三位為even(偶數)的路由 ---> 那就是允許第三位為單數(odd)的路由

router rip
 version 2
 network 54.0.0.0
 network 150.1.0.0
 network 155.1.0.0
 distribute-list 1 in Serial0/0
 no auto-summary
!
access-list 1 permit 0.0.1.0 255.255.254.255
!

Rack1R6#show ip route rip | include Serial0/0
R    212.18.1.0/24 [120/1] via 54.1.1.254, 00:00:02, Serial0/0
R    212.18.3.0/24 [120/1] via 54.1.1.254, 00:00:02, Serial0/0
Rack1R6#

--------------------------------------------------------------------------------

Configure a one line standard access-list on R6 to filter out all routes
coming from BB1 that have an odd number in the third octet.

過濾第三位為odd(單數)的路由 ---> 那就是允許第三位為偶數(even)的路由

router rip
 version 2
 network 54.0.0.0
 network 150.1.0.0
 network 155.1.0.0
 distribute-list 2 in Serial0/0
 no auto-summary
!
access-list 2 permit 0.0.0.0 255.255.254.255
!

Rack1R6#show ip route rip | include Serial0/0
R    212.18.0.0/24 [120/1] via 54.1.1.254, 00:00:02, Serial0/0
R    212.18.2.0/24 [120/1] via 54.1.1.254, 00:00:02, Serial0/0
Rack1R6#