Lab 7 Task 4.11

 

Can anybody explain why the " Distance ospf External  171 " command is on OSPF config on R2 and R4 under OSPF ?

I knwo this means the OSPF E2 routes will have higher cost that External EIGRP routes but what is purpose of the command applied in task 4.11 ? 

Comments

  • Otherwise R2 and R4 will prefer the prefixes originating from RIP via OSPF instead of EIGRP since EIGRP external distance is higher than OSPF.

  • Yes.

    Alternatively, I think we can make use of Route-Tagging to filter the EIGRP routes distributed into OSPF to be added in the OSPF ASBR routers' routing table.

    I always like to use route-tagging way, although it is somewhat more tedious to configure compared to AD...

    Cheers.

     

  • I agree...tagging should have been sufficient for this task....eliminating route feedback on the distribution points!

     

     

  • I don't have the work book with me right now. But routing loop caused by AD cannot be solved with tagging alone. Brian mentioned this in ATCv4.5 redistribution section.

  • yes, agree, but I tested and all connectivity achieved..... this one had a couple of ways to solve the issues....

     

    important to test thorough!

     

  • I don't have the work book with me right now. But routing loop caused by AD cannot be solved with tagging alone. Brian mentioned this in ATCv4.5 redistribution section.

    Thats correct, if only tagging is used on R4 not AD then on R4 rip routes will always be prefered via ospf due to less AD value, if this happens then R4 does not have any rip routes via eigrp in its routing table hence R4 will not be able to advertise these rip route via eigrp to R6 that means right side routers running eigrp will not able to install rip route at all. Therefore we have to use AD on R2 anfd R4 to get loop free ip reachability.

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