Ticket 11 – Redistribution Route-map (a & b)
On R4:
router eigrp 10
redistribute ospf 1 route-map OSPF->EIGRP
network 10.1.4.0 0.0.0.255
network 10.1.10.0 0.0.0.255
network 10.1.21.128 0.0.0.3
default-metric 100000 100 100 1 1500
no auto-summary
!
……
route-map OSPF_to_EIGRP deny 10
match tag 90
route-map OSPF_to_EIGRP permit 20
set tag 110
Ans1) R4
Ans2) IPv4 Route Redistribution
Ans3) Under the EIGRP process, delete the ‘redistribute ospf 1 route-map OSPF->EIGRP’ command and enter ‘redistribute ospf 1 route-map OSPF_to_EIGRP’ command.
Explanation for this ticket:
In this topology, we are doing mutual redistribution at multiple points (between OSPF and EIGRP on R4, DSW1 & DSW2), which is a very common cause of network problems, especially routing loops so you should use route-map to prevent redistributed routes from redistributing again into the original domain.
In this ticket, route-map is also used for this purpose. For example, the route-map “EIGRP->OSPF” is used to prevent any routes that have been redistributed into OSPF from redistributed again into EIGRP domain by tagging these routes with tag 90. These routes are prevented from redistributed again by route-map OSPF->EIGRP by denying any routes with tag 90 set.