1

I created a very simple network in CORE Network Emulator with Host h1, Router R1, Router R2, and Host h2 (screen shot).

I got into the shell for h1, and tried to ping the other devices. I can ping both IP addresses of R1, but attempts to ping anything beyond it, i.e. R2 fails.

When I "log into" R1 I can ping the IP address of R2 that is connected to R1, but not the IP address on the other side (which connects to h2).

What am I missing?

Screen Shot

Here is the config in the CORE/IMUNES format:

node n1 {
    type router
    model router
    network-config {
    hostname R1
    !
    interface eth1
     ip address 10.0.1.1/24
     ipv6 address 2001:1::1/64
    !
    interface eth0
     ip address 10.0.0.1/24
     ipv6 address 2001:0::1/64
    !
    }
    canvas c1
    iconcoords {371.0 308.0}
    labelcoords {371.0 340.0}
    interface-peer {eth0 n3}
    interface-peer {eth1 n2}
}

node n2 {
    type router
    model router
    network-config {
    hostname R2
    !
    interface eth1
     ip address 10.0.2.1/24
     ipv6 address 2001:2::1/64
    !
    interface eth0
     ip address 10.0.1.2/24
     ipv6 address 2001:1::2/64
    !
    }
    canvas c1
    iconcoords {598.0 305.0}
    labelcoords {598.0 337.0}
    interface-peer {eth0 n1}
    interface-peer {eth1 n4}
}

node n3 {
    type router
    model host
    network-config {
    hostname h1
    !
    interface eth0
     ip address 10.0.0.10/24
     ipv6 address 2001:0::10/64
    !
    }
    canvas c1
    iconcoords {201.0 465.0}
    labelcoords {201.0 497.0}
    interface-peer {eth0 n1}
}

node n4 {
    type router
    model host
    network-config {
    hostname h2
    !
    interface eth0
     ip address 10.0.2.10/24
     ipv6 address 2001:2::10/64
    !
    }
    canvas c1
    iconcoords {753.0 460.0}
    labelcoords {753.0 492.0}
    interface-peer {eth0 n2}
}

link l1 {
    nodes {n3 n1}
    bandwidth 0
}

link l2 {
    nodes {n1 n2}
    bandwidth 0
}

link l3 {
    nodes {n2 n4}
    bandwidth 0
}

canvas c1 {
    name {Canvas1}
}

option global {
    interface_names no
    ip_addresses yes
    ipv6_addresses no
    node_labels yes
    link_labels yes
    show_api no
    background_images no
    annotations yes
    grid yes
    traffic_start 0
}

option session {
}
  • You need to edit your question to include the full configurations of the routers. – Ron Maupin Apr 23 '17 at 4:24
  • @RonMaupin I updated my question. Hope this is sufficient. Thanks. – isapir Apr 23 '17 at 4:38
  • I don't see anywhere that you have entered static routes or are running a routing protocol. How does one router know about the network on the other side of the other router? – Ron Maupin Apr 23 '17 at 4:39
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can provide and accept your own answer. – Ron Maupin Feb 19 '18 at 3:45
3

You don't have any type of routing configured. Routers need to know where to send packets, otherwise they will simply drop the packets Routers learn where networks are in three ways:

  1. Directly connected networks
  2. Statically configured routes
  3. Through a dynamic routing protocol

You routers know about the networks that are directly connected to them, but they need to be told about networks that are not directly connected to them. You can either put in static routes to the other networks, or you can run a common routing protocol between the routers.

  • That's what I suspected, but I am using the default settings in CORE and I expected Dynamic Routing Protocol to be in place. Any idea how to set up solutions that you suggested in CORE? – isapir Apr 23 '17 at 7:48
  • I added a static route from R1 to R2's other interface with ip route add 10.0.2.0/24 via 10.0.1.1 and now I can ping that IP from R1, but I still can't ping it from h1. – isapir Apr 23 '17 at 8:14
  • Unfortunately, host configurations are off-topic here, but it looks like you don't have a default gateway set on h1. Hosts need a default gateway, which is the host on the network to which they send traffic destined for a different network. That is usually configured by DHCP, or you must configure it manually if you manually configure the IP addressing on the host. – Ron Maupin Apr 23 '17 at 14:00
  • There are many different dynamic routing protocols, and routers do not default to any one. You must pick one or more and configure that on your routers. RIP is fairly simple, and many people start with it, but it really isn't used much today. The more common one is OSPF. It isn't too hard to set up, is fast, and it is an industry standard. The Internet runs on BGP, but that is really designed for inter-AS communications, and it is probably the most difficult to learn. There are others like IS-IS, which is used by large telcos and ISPs, and there are other less well-known or proprietary ones. – Ron Maupin Apr 23 '17 at 14:08

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