TSHOOT 300-135 Ticket #11

TSHOOT 300-135 Ticket 11 on OSPF to EIGRP

Hi ! everyone on today we are going to learn about troubleshooting on OSPF to EIGRP as explained in screenshot by given below topology.

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
!
router ospf 1
  network 10.1.1.8 0.0.0.0 area 34
  redistribute eigrp 10 subnets
!

route-map OSPF_to_EIGRP
  match ip address 1

Ans 1: R4
Ans 2: IPv4 Route Redistribution
Ans 3: Under the EIGRP process, delete the redistribute ospf 1 route-map OSPF->EIGRP command and enter the 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_to_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_to_EIGRP by denying any routes with tag 90 set.

Therefore in this ticket, typing a wrong route-map (which does not exist) may cause problem in this given configuration for troubleshooting and on our next session we will learn on dhcp helper address.