OSPF – Troubleshooting Ping Issues Across Network Segments

icmpnetwork accessospfpingvyatta

I'm trying to setup a very simple OSPF network with Vyatta. From the best of my knowledge they let all traffic in by default, and I haven't set any firewall rules. The vyatta instances are launched as virtual instances inside DevStack, and I've allowed ICMP messages to get inside them.

The network looks like this:
Network topology

I'm able to ping from:
* 10.0.1.4 (R1 eth1) to 10.0.1.6 (R2 eth0) and vice versa
* 10.0.2.7 (R3 eth0) to 10.0.2.5 (R2 eth1) and vice versa

However, when I try to ping from R1 to R2 on the address 10.0.2.5 I never get back any reply on R1. When sniffing traffic with tcpdump on R2 I can see the following:

16:31:29.540951 IP 10.0.1.4 > 10.0.2.5: ICMP echo request, id 7301, seq 14, length 64
16:31:29.541297 IP 10.0.2.5 > 10.0.1.4: ICMP echo reply, id 7301, seq 14, length 64
16:31:30.540303 IP 10.0.1.4 > 10.0.2.5: ICMP echo request, id 7301, seq 15, length 64
16:31:30.540536 IP 10.0.2.5 > 10.0.1.4: ICMP echo reply, id 7301, seq 15, length 64
16:31:31.541623 IP 10.0.1.4 > 10.0.2.5: ICMP echo request, id 7301, seq 16, length 64
16:31:31.542315 IP 10.0.2.5 > 10.0.1.4: ICMP echo reply, id 7301, seq 16, length 64

It seems that the request is received and a reply is sent back, but it never gets back to R1. I can verify this by sniffing on eth0 on R0 without seeing any traffic going trough the interface. This is a big confusion for me.

The same thing happens when I try to ping from R3 to 10.0.1.6.

When I try to ping from R1 to R3 and sniff traffic with tcpdump on both R2 and R3 I can see that the requests goes trough R2 but never reaches R3.

Output from tcpdump on R2:

16:38:13.230972 IP 10.0.1.4 > 10.0.2.7: ICMP echo request, id 7302, seq 5, length 64
16:38:14.230283 IP 10.0.1.4 > 10.0.2.7: ICMP echo request, id 7302, seq 6, length 64
16:38:15.232537 IP 10.0.1.4 > 10.0.2.7: ICMP echo request, id 7302, seq 7, length 64
16:38:16.241314 IP 10.0.1.4 > 10.0.2.7: ICMP echo request, id 7302, seq 8, length 64

The routing table on R1 shows that it should send the requests with destination of 10.0.2.0/24 to R2 on ip 10.0.1.6 and routing table on R3 shows that it should send the requests with destinations of 10.0.1.0/24 to R2 on ip 10.0.2.5. This is also confirmed with the output from above.

Below is output from the ip route and configuration from R1, R2, R3

ip route for R1:

vyatta@R1:~$ show ip route

Codes: K - kernel route, C - connected, S - static, R - RIP, O - OSPF,
       I - ISIS, B - BGP, > - selected route, * - FIB route

C>* 10.0.0.0/24 is directly connected, eth0
O   10.0.1.0/24 [110/10] is directly connected, eth1, 17:04:56
C>* 10.0.1.0/24 is directly connected, eth1
O   10.0.1.4/32 [110/10] is directly connected, lo, 16:15:49
C>* 10.0.1.4/32 is directly connected, lo
O>* 10.0.2.0/24 [110/20] via 10.0.1.6, eth1, 17:03:23
C>* 127.0.0.0/8 is directly connected, lo

ip route for R2: 

vyatta@R2:~$ show ip route

Codes: K - kernel route, C - connected, S - static, R - RIP, O - OSPF,
       I - ISIS, B - BGP, > - selected route, * - FIB route

    O   10.0.1.0/24 [110/10] is directly connected, eth0, 01:39:14
C>* 10.0.1.0/24 is directly connected, eth0
O   10.0.1.4/32 [110/20] via 10.0.1.4 inactive, 00:51:29
O   10.0.2.0/24 [110/10] is directly connected, eth1, 01:39:08
C>* 10.0.2.0/24 is directly connected, eth1
C>* 127.0.0.0/8 is directly connected, lo

ip route for R3: 

vyatta@R3:~$ show ip route
Codes: K - kernel route, C - connected, S - static, R - RIP, O - OSPF,
       I - ISIS, B - BGP, > - selected route, * - FIB route

O>* 10.0.1.0/24 [110/20] via 10.0.2.5, eth0, 17:07:20
O>* 10.0.1.4/32 [110/30] via 10.0.2.5, eth0, 16:20:33
O   10.0.2.0/24 [110/10] is directly connected, eth0, 17:08:05
C>* 10.0.2.0/24 is directly connected, eth0
C>* 127.0.0.0/8 is directly connected, lo

R1 configuration 

vyatta@R1:~$ show configuration                                                 
interfaces {
    ethernet eth0 {
        address 10.0.0.5/24
    }
    ethernet eth1 {
        address 10.0.1.4/24
    }
    loopback lo {
        address 10.0.1.4/32
    }
}
protocols {
    ospf {
        area 0.0.0.0 {
            network 10.0.1.0/24
        }
    }
}
service {
    ssh {
    }
}
system {
    config-management {
        commit-revisions 20
    }
    console {
        device ttyS0 {
            speed 9600
        }
    }
    host-name R1
    login {
        user vyatta {
            authentication {
                encrypted-password ****************
            }
            level admin
        }
    }
    ntp {
        server 0.vyatta.pool.ntp.org {
        }
        server 1.vyatta.pool.ntp.org {
        }
        server 2.vyatta.pool.ntp.org {
        }
    }
    package {
        repository community {
            components main
            distribution stable
            url http://packages.vyatta.com/vyatta
        }
    }
    syslog {
        global {
            facility all {
                level notice
            }
            facility protocols {
                level debug
            }
        }

R2 configuration 

vyatta@R2:~$ show configuration                               
interfaces {
    ethernet eth0 {
        address 10.0.1.6/24
        hw-id 00:0c:29:9f:5f:22
    }
    ethernet eth1 {
        address 10.0.2.5/24
        hw-id 00:0c:29:9f:5f:23
    }
    loopback lo {
    }
}
protocols {
    ospf {
        area 0.0.0.0 {
            network 10.0.1.0/24
            network 10.0.2.0/24
        }
    }
}
service {
    ssh {
    }
}
system {
    config-management {
        commit-revisions 20
    }
    console {
        device ttyS0 {
            speed 9600
        }
    }
    host-name R2
    login {
        user vyatta {
            authentication {
                encrypted-password ****************
            }
            level admin
        }
    }
    ntp {
        server 0.vyatta.pool.ntp.org {
        }
        server 1.vyatta.pool.ntp.org {
        }
        server 2.vyatta.pool.ntp.org {
        }
    }
    package {
        repository community {
            components main
            distribution stable
            url http://packages.vyatta.com/vyatta
        }
    }
    syslog {
        global {
            facility all {
                level notice
            }
            facility protocols {
                level debug

Configuration for R3 

vyatta@R3:~$ show configuration                               
interfaces {
    ethernet eth0 {
        address 10.0.2.7/24
    }
    loopback lo {
    }
}
protocols {
    ospf {
        area 0.0.0.0 {
            network 10.0.2.0/24
        }
    }
}
service {
    ssh {
    }
}
system {
    config-management {
        commit-revisions 20
    }
    console {
        device ttyS0 {
            speed 9600
        }
    }
    host-name R3
    login {
        user vyatta {
            authentication {
                encrypted-password ****************
            }
            level admin
        }
    }
    ntp {
        server 0.vyatta.pool.ntp.org {
        }
        server 1.vyatta.pool.ntp.org {
        }
        server 2.vyatta.pool.ntp.org {
        }
    }
    package {
        repository community {
            components main
            distribution stable
            url http://packages.vyatta.com/vyatta
        }
    }
    syslog {
        global {
            facility all {
                level notice
            }
            facility protocols {
                level debug
            }
        }
    }
}

Can someone tell me what I'm missing? It's a really simple configuration but from what I've read it should work.

Thanks,
Muff

Best Answer

On R1, you have :

ethernet eth1   address 10.0.1.4/24
loopback lo address 10.0.1.4/32

Change the loopback IP address, it should be better.

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