This is my topology.topology

And I can send a package to every router and PC within the colored area, how can I ping from a PC on EIGRP area to a PC on the OSPF area? I heard about default route but I saw it with another router in the middle of both areas and I'm not really sure how does that work with this kind of topology.

I'd appreciate any help! Thank you!

EDIT: show ip route from RD and R4,

RD: https://pastebin.com/3pdWp6gT S0/1/0

R4: https://pastebin.com/0YsMpwHa S0/1/0


  • 1
    You need to post sanitized configs for both RD and R4 so we can see how they are connected.
    – Jesse P.
    Commented Sep 24, 2019 at 1:12
  • @JesseP. I just edited the post.
    – George C.
    Commented Sep 24, 2019 at 1:50

2 Answers 2


Like Eric stated, you need to add routes on both sides. You can do that by either having default routes pointing to each other via the /30 you're already using, or you can add routes for each host/subnet separately to go over the /30. You could add more dynamic routing over that serial connection, too, if you don't want to maintain static routes or use default routes.

For example, on R4, you could add: ip route and on RD you could add: ip route

As for whether all of the routers could reach each other (not just RD to/from R4), that depends on how your other routers route their traffic. If RD has valid paths to the other routers in the EIGRP AS and visa-versa, and R4 has valid paths to the other routers in the OSPF area(s) and visa-versa, and all of their subnets/hosts are part of the route statements that you set to traverse the serial interfaces via that /30 segment, then it should all work.

Edit 1: On RA, RB, and RC, you need to have RD be their next hop (which you can do as a static default route on each, if you just want the easiest way for now); on R1, R2, and R3 you need to have R4 be their next hop, which you can again add as a static default route on each if you want the easiest solution.

  • Now I can ping from RD to R4 and visa-versa, but still can't ping from RA to R1, should I add to RA this ip route Or I'm totally wrong? I added a picture with the addresses I'm using.
    – George C.
    Commented Sep 24, 2019 at 2:30

You need to redistribute routes between RD and R4 and vice-versa. That way both routing domains have a route/path to the other side

  • Yes! But how can I accomplish that? And will all the routers be able to ping each other for example RA to R1?
    – George C.
    Commented Sep 24, 2019 at 1:44

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