79 NETWORK C ONNECTIVITY TESTNetwork ConnectivityTestping You can use the ping command to check the network connectivity and thereachability of a host.This command can output the following results:■ Response status for each ping packet. If no response packet is received withinthe timeout time, the message “Request time out” is displayed. Otherwise, thenumber of data bytes, packet serial number, TTL (time to live) and responsetime of the response packet are displayed.■ Final statistics, including the numbers of sent packets and received responsepackets, the unresponsive packet percentage, and the minimum, average andmaximum values of response time.tracert You can use the tracert command to trace the gateways a packet passes duringits journey from the source to the destination. This command is mainly used tocheck the network connectivity. It can help you locate the trouble spot of thenetwork.The executing procedure of the tracert command is as follows: First, the sourcehost sends a data packet with the TTL of 1, and the first hop device returns anICMP error message indicating that it cannot forward this packet because of TTLtimeout. Then, the source host resends the packet with the TTL of 2, and thesecond hop device also returns an ICMP TTL timeout message. This proceduregoes on and on until the packet gets to the destination. During the procedure, thesystem records the source address of each ICMP TTL timeout message in order tooffer the path that the packet passed through to the destination.Table 672 The ping commandOperation CommandSupport IP protocol ping [ -a ip-address | -c count | -d | -f | -httl | -i interface-type interface-number | -n |- p pattern | -q | -r | -s packetsize | -ttimeout | -tos tos | -v | ip ]* host-ipSupport IPX protocol ping ipx ipx-address [ -c count | -spacketsize | -t timeout ]*Support CLNS protocol ping clns nsap-address
