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HP 5500 Ei 5500 Si Switch Series Configuration Guide

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1 
Using ping, tracert, and system debugging 
Use the ping, tracert, and system debugging utilitie s to test network connectivity and identify network 
problems. 
Ping 
The ping utility sends ICMP echo requests (ECHO-REQUEST) to the destination device. Upon receiving 
the requests, the destination device responds with ICMP echo replies (ECHO-REPLY) to the source device. 
The source device outputs statistics about the ping operation, including the number of packets sent, 
number of echo replies received, and the round-trip time. You can measure the network performance by 
analyzing these statistics.  
Using a ping command to test network connectivity  
Task Command Remarks 
Check whether a specified 
address in an IP network is 
reachable. 
•  For an IPv4 net work: 
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  ] * host
 
• For an IPv6 net work: 
ping ipv6  [ -a source-ipv6  | -c count  | -m  
interval  | -s  packet-size  | -t timeout  |-tos  
tos | -vpn-instance  vpn-instance-name  ] * 
host  [ -i interface-type interface-number  ]  Use one of the commands. 
Available in any view. 
Only the HP 5500 EI Switch 
Series supports the 
vpn-instance 
keyword. 
 
  IMPORTANT: 
When you configure the 
ping command for a low-speed network, HP recommends that you set a larger 
value for the timeout timer (indicated by the  -t keyword in the command).  
Ping example 
Network requirements 
Test the network connectivity between Device A and Device C in  Figure 1. If the y can reach each other, 
get detailed information about routes from Device A to Device C.
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Figure 1  Network diagram 
 
 
Test procedure 
# Use the ping command on Device A to test connectivity to Device C. 
 ping 1.1.2.2 
  PING 1.1.2.2: 56  data bytes, press CTRL_C to break 
    Reply from 1.1.2.2: bytes=56 Sequence=1 ttl=254 time=205 ms 
    Reply from 1.1.2.2: bytes=56 Sequence=2 ttl=254 time=1 ms 
    Reply from 1.1.2.2: bytes=56 Sequence=3 ttl=254 time=1 ms 
    Reply from 1.1.2.2: bytes=56 Sequence=4 ttl=254 time=1 ms 
    Reply from 1.1.2.2: bytes=56 Sequence=5 ttl=254 time=1 ms 
 
  --- 1.1.2.2 ping statistics --- 
    5 packet(s) transmitted 
    5 packet(s) received 
    0.00% packet loss 
round-trip min/avg/max = 1/41/205 ms 
# Get detailed information about routes from Device A to Device C. 
 ping -r 1.1.2.2 
  PING 1.1.2.2: 56  data bytes, press CTRL_C to break 
    Reply from 1.1.2.2: bytes=56 Sequence=1 ttl=254 time=53 ms 
      Record Route: 
         1.1.2.1 
         1.1.2.2 
         1.1.1.2 
         1.1.1.1 
    Reply from 1.1.2.2: bytes=56 Sequence=2 ttl=254 time=1 ms 
      Record Route: 
         1.1.2.1 
         1.1.2.2 
         1.1.1.2 
         1.1.1.1 
    Reply from 1.1.2.2: bytes=56 Sequence=3 ttl=254 time=1 ms 
      Record Route: 
         1.1.2.1 
         1.1.2.2 
         1.1.1.2
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         1.1.1.1 
    Reply from 1.1.2.2: bytes=56 Sequence=4 ttl=254 time=1 ms 
      Record Route: 
         1.1.2.1 
         1.1.2.2 
         1.1.1.2 
         1.1.1.1 
    Reply from 1.1.2.2: bytes=56 Sequence=5 ttl=254 time=1 ms 
      Record Route: 
         1.1.2.1 
         1.1.2.2 
         1.1.1.2 
         1.1.1.1 
  --- 1.1.2.2 ping statistics --- 
    5 packet(s) transmitted 
    5 packet(s) received 
    0.00% packet loss 
round-trip min/avg/max = 1/11/53 ms 
The test procedure with the  ping –r command (see Figure 1) is a s follows: 
1. The source (Device A) sends an ICMP echo request with the RR option being empty to the 
destination (Device C). 
2. The intermediate device (Device B) adds the IP addr ess of its outbound interface (1.1.2.1) to the RR 
option of the ICMP echo requ est, and forwards the packet. 
3. Upon receiving the request, the destination device copies the RR option in the request and adds the 
IP address of its outbound interface (1.1.2.2) to  the RR option. Then the destination device sends 
an ICMP echo reply. 
4.  The intermediate device adds the IP address of its ou tbound interface (1.1.1.2) to the RR option in 
the ICMP echo reply, and then forwards the reply. 
5.  Upon receiving the reply, the so urce device adds the IP address of  its inbound interface (1.1.1.1) 
to the RR option. Finally, you can ge t detailed information about routes from Device A to Device C: 
1.1.1.1  {1.1.1.2; 1.1.2.1}  1.1.2.2. 
Tracert 
Tracert (also called Traceroute) enables you to get the IP addresses of Layer 3 devices in the path to a 
specific destination. You can use tracert to test network connectivity and identify failed nodes.
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Figure 2  Network diagram 
 
 
Tracert uses received ICMP error messages to get the IP addresses of devices. As shown in Figure 2, 
tr
acert works as follows: 
1.  The source device (Device A) sends a UDP packet with a TTL value of 1 to the destination device 
(Device D). The destination UDP port is not used  by any application on the destination device. 
2. The first hop (Device B, the first Layer 3 device  that receives the packet) responds by sending a 
TTL-expired ICMP error message to the source, with  its IP address encapsulated. In this way, the 
source device can get the address of  the first Layer 3 device (1.1.1.2). 
3. The source device sends a packet with a TTL  value of 2 to the destination device. 
4. The second hop (Device C) responds with a TTL-expired ICMP error message, which gives the 
source device the address of the se cond Layer 3 device (1.1.2.2). 
5. The process continues until the packet sent by the source device reaches the ultimate destination 
device. Because no application uses the destination  port specified in the packet, so the destination 
device responds with a port-unreachable ICMP me ssage to the source device, with its IP address 
1.1.3.2 encapsulated. This way, the source device  gets the IP address of the destination device 
(1.1.3.2). 
6.  The source device thinks that the packet has re ached the destination device after receiving the 
port-unreachable ICMP message, and the path to th e destination device is 1.1.1.2 to 1.1.2.2 to 
1.1.3.2. 
Prerequisites 
Before you use a tracert command, perform the tasks in this section.  
For an IPv4 net work: 
•   Enable sending of ICMP timeout packets on the  intermediate devices (the devices between the 
source and destination devices). If the interm ediate devices are HP devices, execute the ip 
ttl-expires enable  command on the devices. For more  information about this command, see  Layer 
3—IP Services Command Reference . 
•   Enable sending of ICMP destination unreachabl e packets on the destination device. If the 
destination device is an HP device, execute the  ip unreachables enable command. For more 
information about this command, see  Layer 3—IP Services Command Reference . 
For an IPv6 net work: 
•   Enable sending of ICMPv6 timeout packets on th e intermediate devices (the devices between the 
source and destination devices). If the intermediate devices are HP devices, execute the  ipv6
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hoplimit-expires enable  command on the devices. For more information about this command, see 
Layer 3—IP Services Command Reference . 
•   Enable sending of ICMPv6 destination unreacha ble packets on the destination device. If the 
destination device is an HP device, execute the  ipv6 unreachables enable command. For more 
information about this command, see  Layer 3—IP Services Command Reference . 
Using a tracert command to identify failed or all nodes in a 
path 
 
Task Command Remarks 
Display the routes from 
source to destination. 
• For an IPv4 net work: 
tracert  [ -a source-ip  | -f first-ttl  | -m  max-ttl |  
-p  port  | -q packet-number  | -tos  tos | 
-vpn-instance  vpn-instance-name  | -w  
timeout  ] * host
 
• For an IPv6 net work: 
tracert ipv6  [ -f first-ttl  | -m max-ttl  | -p port  | 
-q  packet-number  | -tos  tos  | -vpn-instance  
vpn-instance-name  | -w timeout  ] * host  Use one of the commands. 
Available in any view. 
Only the HP 5500 EI Switch 
Series supports the 
vpn-instance 
keyword. 
 
System debugging 
The device supports various debugging for the majo rity of protocols and features and provides 
debugging information to help users diagnose errors. 
Debugging information control switches 
The following two switches control the display of debugging information: 
•   Protocol debugging switch —Controls protocol-specific debugging information. 
•   Screen output switch —Controls whether to display the debugging information on a certain screen. 
As shown in  Figure 3, a
ssume that the device can provide debugging for the three modules 1, 2, and 3. 
The debugging information can be output on a termin al only when both the protocol debugging switch 
and the screen output switch are turned on. 
Output of debugging information depends on the configurations of the information center and the 
debugging commands of each protocol and function al module. Debugging information is typically 
displayed on a terminal (including console or  VTY) for display. You can also send debugging 
information to other destinations. For more information, see  Configuring the information center.
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Figure 3  Relationship between the protocol and screen output switch 
 
 
Debugging a feature module 
Output of debugging commands is memory intensive. To guarantee system performance, enable 
debugging only for modules that are in an exceptio nal condition. When debugging is complete, use the 
undo debugging all  command to disable all the debugging functions. 
Configure the  debugging, terminal debugging , and terminal monitor commands before you can display 
detailed debugging information on the te rminal. For more information about the terminal debugging 
and terminal monitor  commands, see Network Management and Monitoring Command Reference . 
To debug a feature module and display th e debugging information on a terminal: 
 
Step Command Remarks 
1.  Enable the terminal 
monitoring of system 
information.  terminal monitor  Optional. 
The terminal monitoring on the 
console is enabled by default and 
the terminal monitoring on the 
monitoring terminal is disabled by 
default. 
Available in user view. 
2.
  Enable the terminal display of 
debugging information.  terminal debugging  Disabled by default. 
Available in user view. 
3.
  Enable debugging for a 
specified module.  debugging
  module-name  [ option ] Disabled by default. 
Available in user view. 
4.  Display the enabled 
debugging functions.  display
 debugging  [ interface 
interface-type interface-number  ] 
[  module-name  ] [ | { begin  | 
exclude  | include  } 
regular-expression  ] Optional. 
Available in any view.
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7 
Ping and tracert example 
Network requirements 
As shown in  Figure 4, Device A failed to Telnet Device C. Determine whether Device A and Device C can 
reach each other. If they cannot reach each other, locate the failed nodes in the network. 
Figure 4  Network diagram 
 
 
Test procedure 
1. Use the  ping command to test connectivity between Device A and Device C. 
 ping 1.1.2.2 
  PING 1.1.2.2: 56  data bytes, press CTRL_C to break 
    Request time out 
    Request time out 
    Request time out 
    Request time out 
    Request time out 
 
  --- 1.1.2.2 ping statistics --- 
    5 packet(s) transmitted 
    0 packet(s) received 
100.00% packet loss 
The output shows that Device A and Device C cannot reach each other. 
2. Use the  tracert command to identify failed nodes. 
 system-view 
[DeviceA] ip ttl-expires enable 
[DeviceA] ip unreachables enable 
[DeviceA] tracert 1.1.2.2 
 traceroute to 1.1.2.2(1.1.2.2) 30 hops max,40 bytes packet, press CTR\
L_C to bre 
ak 
 1  1.1.1.2 14 ms 10 ms 20 ms 
 2  * * * 
 3  * * * 
 4  * * * 
 5 
 
The output shows that Device A and Device C  cannot reach other, Device A and Device B can 
reach each other, and an error has occurred on  the connection between Device B and Device C.  
3. Use the  debugging ip icmp  command on Device A and Device C to verify that they can send and 
receive the specific ICMP packets, or use the  display ip routing-table command to verify the 
availability of active routes  between Device A and Device C.
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    							 8 
Configuring NTP 
The term Layer 3 Ethernet port  refers to route-mode (or Layer 3) Ethernet ports. You can set an Ethernet 
port to operate in route mode by using the  port link-mode  route  command (see  Layer 2—LAN Switching 
Configuration Guide ). 
Overview 
NTP is typically used in large networks to dynamically synchronize time among network devices. It 
guarantees higher clock accuracy than manual system  clock setting. In a small network that does not 
require high clock accuracy, you can keep time synchronized among devices by changing their system 
clocks one by one.  
NTP runs over UDP and uses UDP port 123. 
NTP application 
An administrator is unable to keep time synchronized among all devices within a network by changing 
the system clock on each station, because this is  a huge work and does not guarantee clock precision. 
NTP, however, allows quick clock synchronization within the entire network and ensures high clock 
precision. 
NTP is used when all devices within the network must keep consistent time. For example: 
•   In analyzing log and debugging information collected from different devices in network 
management, time must be used as a reference basis. 
•   All devices must use the same reference clock in a charging system. 
•   To implement certain functions, such as a scheduled restart of all devices within the network, all 
devices must keep consistent time. 
•   If multiple systems process a complex event in cooperation, these systems must use the same 
reference clock to ensure the correct execution sequence. 
•   For incremental backup between a backup server and clients, timekeeping must be synchronized 
between the backup server and all clients. 
NTP advantages 
•  NTP uses a stratum to describe clock accuracy. The stratum ranges from 1 to 16. Clock accuracy 
decreases as the stratum number increases. The stratum of a reference clock ranges from 1 to 15. A 
stratum 16 clock is in unsynchronized state. 
•   The local clock of this Switch Series cannot operate as a reference clock. It can serve as an NTP 
server only after it is synchronized. 
•   NTP supports access control and MD5 authentication. 
•   NTP can unicast, multicast, or broadcast protocol messages.
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How NTP works 
Figure 5 shows the basic workflow of NTP. Device A and Device B are connected over a network. They 
have their own independent system clocks, which need to be automatically synchronized through NTP. 
Assume that: 
•   Prior to system clock synchronization between Device A and Device B, the clock of Device A is set 
to 10:00:00 am while that of Device B is set to 1 1:00:00 am. 
•   Device B is used as the NTP time server, so Device A synchronizes to Device B. 
•   It takes 1 second for an NTP message to travel from one device to the other. 
Figure 5  Basic workflow of NTP 
 
 
The synchronization process is as follows: 
•  Device A sends Device B an NTP message, which  is timestamped when it leaves Device A. The 
timestamp is 10:00:00 am (T1). 
•   When this NTP message arrives at Device B, it is timestamped by Device B. The timestamp is 
11:00:01 am (T2). 
•   When the NTP message leaves Device B, De vice B timestamps it. The timestamp is 11:00:02 am 
(T3). 
•   When Device A receives the NTP message, the local time of Device A is 10:00:03 am (T4). 
Up to now, Device A can calculate the following parameters based on the timestamps: 
•   The roundtrip delay of NTP message: Delay = (T4–T1) – (T3-T2) = 2 seconds. 
•   Time difference between Device A and Device B: Offset = ((T2-T1) + (T3-T4))/2 = 1 hour. 
Based on these parameters, Device A can synchronize its own clock to the clock of Device B. 
This is a rough description of how NTP works. For more information, see RFC 1305.
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