Easy question on prefix-list

Answered Question
Feb 25th, 2010
User Badges:

Hi, imagine I need to allow only traffic from the following networks:

10.1.0.0 /16 
10.175.206.0 255.255.255.0
10.175.207.0 255.255.255.0


between (OSPFDepartmentRouterBGP 100)--------------CorporateRouter (BGP 200)



That said, can you please give me a hint if the following prefix-lists correctly represent the networks above. I know how to get this working with route-map and access-lists but I am new to prefix-lists. Thanks!



DepartmentRouter
router bgp 100
neighbor 10.1.47.193 remote-as 200
redistribute ospf 1 route-map RM_ENG
!
ip prefix-list LIST_ENG seq 5 permit 10.0.0.0/8
ip prefix-list LIST_ENG seq 10 permit 10.175.206.0/24
ip prefix-list LIST_ENG seq 15 permit 10.175.207.0/24
!
route-map RM_ENG permit 10
match ip address prefix-list LIST_ENG
set local-preference 200
!
router ospf 1
router-id 10.1.1.15
redistribute bgp 100 metric 10 subnets route-map RM_ENG
redistribute static metric 50 metric-type 1 subnets
(...)

Correct Answer by Jerry Ye about 7 years 5 months ago

I think you want to said to accept the routes from these networks? And you have


ip prefix-list LIST_ENG seq 5 permit 10.0.0.0/8


it should be


ip prefix-list LIST_ENG seq 5 permit 10.1.0.0/16


The end result is only the following 3 routes that will be accept to your routing table


10.1.0.0/16

10.175.206.0/24

10.175.207.0/24


If the remote is sending your a route of 10.1.1.0/24, it will be blocked.


Regards,

jerry

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Loading.
Correct Answer
Jerry Ye Thu, 02/25/2010 - 16:18
User Badges:
  • Cisco Employee,

I think you want to said to accept the routes from these networks? And you have


ip prefix-list LIST_ENG seq 5 permit 10.0.0.0/8


it should be


ip prefix-list LIST_ENG seq 5 permit 10.1.0.0/16


The end result is only the following 3 routes that will be accept to your routing table


10.1.0.0/16

10.175.206.0/24

10.175.207.0/24


If the remote is sending your a route of 10.1.1.0/24, it will be blocked.


Regards,

jerry

Actions

This Discussion