I have a problem that I can not understand it myself and I need some help. I'm doing a kind of challenge, well network challenge in cisco packet tracer. I have a .pka file that stands for Cisco Packet Tracer Activities. It is a file which has a broken network and we must fix it.

I have done 80% of this troubleshooting network problem and I can't figure why the thing that I'm going to explain now, its not working: enter image description here

So this is my network and router R1 can successfully communicate with R2 network's computers, and R3 can do the same thing with R2 network. Now, R2 can successfully communicate with each network in picture. Now the thing that I don't understand is why R1 can not communicate with R3 even I manually and statically configured each one with next hop interface(R2>ip route ; R2> ip route ; ip addresses are below of each router). Although my computers at network of router1 can communicate with the computers of the network of the router3.....

I'm really trying hard to understand what's is happening here but, since if two router can not communicate with each other, how computers do, and if the computer can communicate why routers won't?




  • 1
    Please don't post text as images, paste it using preformatted text using { and }. Also, please provide configurations.
    – Teun Vink
    Nov 23, 2019 at 22:20
  • Stack Exchange won't allow me to post pictures as they are because it says that I have a low credit(which is true). Also, the links name router1,2,3 display how the routers are configured. I mean only the networks.......
    – RickyLo
    Nov 24, 2019 at 9:14
  • My point is that you shouldn’t post screenshots, post the text instead.
    – Teun Vink
    Nov 24, 2019 at 9:16
  • Ohh I got it, well you are right but my question will be long and hard to read you know... That's why I included pictures for better understating, I guess......
    – RickyLo
    Nov 24, 2019 at 9:32
  • Screenshots can’t be indexed by search engines and are hard to read for visually impaired people. Please include all relevant information in your post.
    – Teun Vink
    Nov 24, 2019 at 9:41

1 Answer 1


When router1 sends a packet to router3, it uses the “closest” interface as the source. That is on subnet

Router3 does not have a route to

I suspect if you do an extended ping and use router1’s Ethernet interface/IP as the source, it would be successful because router3 does have a static route to

Of course, router3 has two IP addresses on it. I’m assuming your ping is destined for router3’s Ethernet IP address. If r1 tried to ping r3’s serial IP that would fail (no route to host error).

This is one reason dynamic routing protocols are more reliable than static routing. Even in your network of 3 routers, you have 5 routes (ignoring type L local routes). Router 1 and router 3 each have 4 non-L routes, so they are each missing one. If you had loopback interfaces you would have 8 routes. This makes static routing, even in the simplest of networks, non-trivial.

Still a critical skill to learn before proceeding to dynamic routing, so rah rah go team go! :-)

Looks like r1 also has an extra static route. Another human error caused by the complexity of static routing :-)

  • Ohh yes you are right I didn't see serial as another network and I being over confused lol. Thanks for your answer I really appreciate it :)
    – RickyLo
    Nov 24, 2019 at 9:12
  • Heyy, if you have a little time for a little question...... In a network, what is Route0?
    – RickyLo
    Nov 24, 2019 at 9:29
  • I don’t know what you are referring to. Feel free to ask a question showing the issue as long as it is on topic (not homework, not home network, etc) Nov 24, 2019 at 16:34

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