Pic. 1 - Topology Diagram.
Task 1
Remove OSPF filtering applied in the previous lab.
Task 2
Configure OSPF filtering on R4, so that 10.0.2.2/32 does not show in its routing table. Use IP ACL as your matching tool.
Questions
Questions
- What other matching tool(s) apart from ip prefix-list and access-list could be used to filter OSPF prefixes?
- What is the difference in the syntax of 'distribute-list' command compared to the previous lab
Lab Solution
Solution configuration below:
Task 1
Remove OSPF filtering applied in the previous lab.
R4 Config:
!
conf t
router ospf 1
no distribute-list prefix BLOCK_R4_L0 in
exit
no ip prefix-list BLOCK_R4_L0
!
Verification:
Pic. 2 - Prefix 10.0.2.2/32 back in R4's Routing Table.
Task 2
R4 Config:
!
ip access-list standard BLOCK_R4_L0
deny 10.0.2.2
permit any
deny 10.0.2.2
permit any
!
router ospf 1
distribute-list BLOCK_R4_L0 in
!
Verification:
Pic. 3 - Prefix 10.0.2.2/32 Removed From R4's Routing Table.
Pic.4 - Remaining Prefixes Remain Intact.
NOTE!
Make sure you check that existing prefixes have not been filtered out. It is easy to forget to allow all other prefixes to be accepted while using filtering.
Study Drill
Consider all remaining alternative methods of filtering OSPF prefixes within an area.
