- Log on to the system as root.
-
Type /sbin/ifconfig -a to verify:
- Each interface in the network is configured with the correct IP address and netmask
- The network is running
eth0 Link encap:Ethernet HWaddr 24:6E:96:36:49:FC inet addr:39.87.48.4 Bcast:39.87.48.255 Mask:255.255.255.0 inet6 addr: fe80::266e:96ff:fe36:49fc/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1460 errors:0 dropped:0 overruns:0 frame:0 TX packets:475 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:115412 (112.7 Kb) TX bytes:26615 (25.9 Kb) eth1 Link encap:Ethernet HWaddr 24:6E:96:36:49:FD inet addr:39.103.48.4 Bcast:39.111.255.255 Mask:255.240.0.0 inet6 addr: fe80::266e:96ff:fe36:49fd/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1281 errors:0 dropped:0 overruns:0 frame:0 TX packets:450 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:102412 (100.0 Kb) TX bytes:23177 (22.6 Kb) eth2 Link encap:Ethernet HWaddr 24:6E:96:36:49:F8 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) eth3 Link encap:Ethernet HWaddr 24:6E:96:36:49:FA inet addr:10.25.17.104 Bcast:10.25.17.255 Mask:255.255.255.0 inet6 addr: fe80::266e:96ff:fe36:49fa/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:14092 errors:0 dropped:0 overruns:0 frame:0 TX packets:186 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1249099 (1.1 Mb) TX bytes:21484 (20.9 Kb)
The labels eth0, eth1, and eth3 are Ethernet devices and the assigned IP addresses are displayed with the network mask and broadcast address. This indicates that the network is up and running.If there is no output, the network has not started on the node. If there is output, but the node is not communicating over the network, check the network connections and the configuration of the network card.
-
Type route | sort -brk3 to display the routing table.
Output example.
Kernel IP routing table Destination Gateway Genmask Flags Metric Ref UseIface cs3096-18.labs. * 255.255.255.0 U 0 0 eth3 39.87.48.0 * 255.255.0.0 U 0 0 eth0 39.96.0.0 * 255.0.0.0 U 0 0 eth1 default 10.25.17.254 0.0.0.0 UG 0 0 eth3
In the Flags column, U indicates that the routes are up, and G indicates the gateway. -
Type ping -c 3 IP_address
to verify the network connection.
Output example:
# ping -c 3 10.25.17.105 PING 10.25.17.105 (10.25.17.105): 56 (84) bytes of data. 64 bytes from 10.25.17.105: icmp_seq=1 ttl=64 time=0.205 ms 64 bytes from 10.25.17.105: icmp_seq=2 ttl=64 time=0.093 ms 64 bytes from 10.25.17.105: icmp_seq=3 ttl=64 time=0.095 ms --- 10.25.17.105 ping statistics --- 3 packets transmitted, 3 packets received, 0% packet loss, time 1998ms rtt min/avg/max/mdev = 0.093/0.131/0.205/0.052 ms
The results of the ping command in this example indicates a good connection to the network and subnets, and no packet loss. If there was any loss, refer to results from the previous steps to diagnose the problem. If a default router is available, run traceroute IP_address to localize the problem, or ping an external IP address to test connectivity.