Table of Contents

Chapter 1 System Maintaining and Debugging. 1-1

1.1 System Maintaining and Debugging Overview. 1-1

1.1.1 Introduction to System Maintaining and Debugging. 1-1

1.1.2 Introduction to System Debugging. 1-2

1.2 System Maintaining and Debugging. 1-3

1.2.1 System Maintaining. 1-3

1.2.2 System Debugging. 1-4

1.3 System Maintaining Example. 1-5

 

Chapter 1  System Maintaining and Debugging

When maintaining and debugging the system, go to these sections for information you are interested in:

l           System Maintaining and Debugging Overview

l           System Maintaining and Debugging

l           System Maintaining Example

1.1  System Maintaining and Debugging Overview

1.1.1  Introduction to System Maintaining and Debugging

You can use the ping command and the tracert command to verify the current network connectivity.

I. The ping command

You can use the ping command to verify whether a device with a specified address is reachable, and to examine network connectivity.

The ping command involves the following steps in its execution:

1)         The source device sends an ICMP echo request to the destination device.

2)         If the network is functioning properly, the destination device responds by sending an ICMP echo reply to the source device after receiving the ICMP echo request.

3)         If there is network failure, the source device displays timeout or destination unreachable.

4)         Display related statistics.

Output of the ping command includes:

l           Information on the destination’s responses towards each ICMP echo request, if the source device has received the ICMP echo reply within the timeout time, it displays the number of bytes of the echo reply, the message sequence number, Time to Live (TTL), and the response time.

l           If within the period set by the timeout timer, the destination device has not received the ICMP response, it displays the prompt information.

l           The ping command can apply to the destination’s name or IP address. If the destination’s name is unknown, the prompt information is displayed.

l           The statistics during the ping operation, which include number of packets sent, number of echo reply messages received, percentage of messages not received, the minimum, average, and maximum response time.

II. The tracert command

By using the tracert command, you can trace the switches involved in delivering a packet from source to destination. This is useful for identification of failed node(s) in the event of network failure.

The tracert command involves the following steps in its execution:

1)         The source device sends a packet with a TTL value of 1 to the destination device.

2)         The first hop (the routing device that first receives the packet; the value of TTL decreases by 1 by each hop) responds by sending a TTL-expired ICMP message to the source, with its IP address encapsulated. In this way, the source device can get the address of the first switch.

3)         The source device sends a packet with a TTL value of 2 to the destination device.

4)         The second hop responds with a TTL-expired ICMP message, which gives the source device the address of the second routing device.

5)         The above process continues until the ultimate destination device is reached. In this way, the source device can trace the addresses of all the routing devices that a packet traverses from the source device to the destination device.

1.1.2  Introduction to System Debugging

The device provides various debugging functions. For the majority of protocols and features supported, the system provides corresponding debugging functions to help users diagnose errors.

The following two switches control the display of debugging information:

l           Protocol debugging switch, which controls the output of protocol-specific debugging information

l           Screen output switch, which controls whether to display the debugging information on a certain screen.

Figure 1-1 illustrates the relationship between the protocol debugging switch and the screen output switch. Only when both are turned on can debugging information be output on a terminal.

Figure 1-1 The relationship between the protocol and screen debugging switch

1.2  System Maintaining and Debugging

1.2.1  System Maintaining

To do…	Use the command…	Remarks
Check whether a specified IP address can be reached	ping [ ip ] [ -a source-ip | -c count | -f | -h ttl | -i interface-type interface-number | -m interval | -n | -p pad | -q | -r | -s packet-size | -t timeout | -tos tos | -v | -vpn-instance vpn-instance-name ] * remote-system	Optional Used in IPv4 network Available in any view
	ping [ ipv6 ] [ -a source-ip | -c count | -m interval | -s packet-size | -t timeout ] * remote-system [ -i interface-type interface-number ]	Optional Used in IPv6 network Available in any view
View the routes from the source to the destination	tracert [ -a source-ip | -f first-ttl | -m max-ttl | -p port | -q packet-number | -vpn-instance vpn-instance-name | -w timeout ] * remote-system	Optional Used in IPv4 network Available in any view
	tracert [ ipv6 ] [-f first-ttl | -m max-ttl | -p port | -q packet-number | -w timeout ] * remote-system	Optional Used in IPv6 network Available in any view

 

 

1.2.2  System Debugging

To do…	Use the command…	Remarks
Enable debugging for a specified module	debugging { all [ timeout time ] | module-name [ option ] }	Required Disabled by default Available in user view
Enable the terminal monitoring	terminal monitor	Optional The terminal monitoring on the console is enabled by default and that on the monitoring terminal is disabled by default.
Enable the terminal debugging	terminal debugging	Required Disabled by default Available in user view
Display the enabled debugging functions	display debugging [ interface interface-type interface-number ] [ module-name ]	Optional Available in any view
Display information about the optical modules connected to the optical interfaces on the switch	display lpu fiber-module [ interface-type interface-number ]	Optional Available in any view

 

 

1.3  System Maintaining Example

I. Network requirements

l           The IP address of the destination device is 10.1.1.4.

l           Display the routing devices a packet traverses from the current device to the destination device.

II. Network diagram (omitted here)

III. Configuration procedure

<Sysname> tracert nis.nsf.net

traceroute to nis.nsf.net (10.1.1.4) 30 hops max, 40 bytes packet

1  128.3.112.1  19 ms  19 ms  10 ms

2  128.32.216.1  39 ms  39 ms  19 ms

3  128.32.136.23  39 ms  40 ms  39 ms

4  128.32.168.22  39 ms  39 ms  39 ms

5  128.32.197.4  40 ms  59 ms  59 ms

6  131.119.2.5  59 ms  59 ms  59 ms

7  129.140.70.13  99 ms  99 ms  80 ms

8  129.140.71.6  139 ms  239 ms  319 ms

9  129.140.81.7  220 ms  199 ms  199 ms

10  10.1.1.4  239 ms  239 ms  239 ms

The above output shows that a packet traverses nine routing devices from the source to the destination device.