TCP/IP Transport for DOSUtilitiesPart 3/3 |
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This chapter explains how to run the DIALUP, LWPCON, and PING utilities.
DIALUP is a Hayes* Smartmodem (or compatible) control program. It provides service to dial, redial, answer, hang up, or set line format to establish a modem connection in either batch mode or conversational mode for the asynchronous NCOMX and NWREMOTE drivers.
DIALUP operates in batch mode (dial only) when a hostname is specified. The hostname is a name entry in the file DIALUP.TXT in the \NET\HSTACC directory. The DIALUP.TXT file has a phone number paired with each hostname. DIALUP looks up the hostname in DIALUP.TXT and dials its associated phone number. The format for entries in the DIALUP.TXT file is as follows:
hostname1 phone_number1 hostname2 phone_number2 . . . . hostnamen phone_numbern
The result of the batch dialing can be interrogated using the DOS batch file command ERRORLEVEL.
For example:
LSL NESL.COM NCOMX.COM NWREMOTE.COM DIALUP ENGINEERING-ROUTER IF ERRORLEVEL 1 GOTO NOCONNECTION TCPIP TELAPI :NOCONNECTION
DIALUP operates in conversational mode when a hostname is not specified, either through a menu or as a dumb terminal emulator.
The DIALUP syntax is as follows:
DIALUP [ -? | -H ] [ -n ] [ -Snnnnn ] [ -A | -E | -T | hostname ]
The following table describes the DIALUP options.
DIALUP Options
| Option | Description |
|---|---|
| -? or -H | Displays DIALUP usage help. |
| -n | Specifies the resident NCOMX to use; n is the board number returned when NCOMX is loaded. |
| -Snnnnn | Sets the baud rate to nnnnn to start modem initialization. If not selected, modem initialization starts with the current baud rate setting in the Link Driver NCOMX section of the NET.CFG file. |
| -A | Puts the modem in blind answer mode and returns. |
| -E | Hangs up the line and ends the session. |
| -T | Requests dumb terminal emulator. |
A dumb terminal emulator is enabled with the -T command line option. AT commands can be entered directly to control the modem, and pressing <Ctrl>+<L> lets you change the baud rate at any time. Pressing <Ctrl>+<X> lets you establish the connection and exit.
Menu driven control is enabled when the -T command line option is omitted.
DIALUP Menu Options
| Menu Option | Description |
|---|---|
| L | Line settings |
| D | Dial a phone number |
| R | Redial the last phone number |
| A | Answer incoming calls |
| H | Hang up |
| Q | Quit |
DIALUP requires the asynchronous NCOMX and NWREMOTE drivers to be loaded to operate, and its sole purpose is to establish or tear down modem connections for SLIP/PPP. Although dumb terminal mode is supported, it should only be used to set modem parameters and establish modem connections.
The LAN WorkPlace Console (LWPCON) utility is a DOS menu-based application that lets you display TCP/IP configuration, statistics, and service information for your workstation and remote hosts on your network. You can do the following tasks with LWPCON:
In addition to these capabilities, LWPCON provides several statistical displays that network administrators can use to monitor network traffic and isolate problems.
You start LWPCON by double-clicking the LWPCON icon while using MS Windows or entering the LWPCON command at the DOS prompt. From MS Windows, LWPCON runs in a DOS window. In either case, LWPCON displays the following initial screen and menu:
The top line of the LWPCON screen identifies the program, LAN WorkPlace Console, followed by the current date and time. The bottom line is a reverse-video display of the special keys and function keys available for that particular screen. Above the last line is a two-line message area for help information about a particular screen or highlighted item.
To exit from the initial LWPCON screen and return to DOS, press <Esc>.
LWPCON menus have a title followed by a list of options. You can select a menu option using the up or down arrow keys, then pressing <Enter>. You cannot use a mouse to make LWPCON selections. In some cases, information about the highlighted option is displayed in the message area. Pressing <F1> provides additional help.
LWPCON can also display lists or tables containing a varying number of items. You can highlight and select list items as you do menu items. In some cases, you can make insertions (using <Insert>), deletions (using <Delete>), and modifications (using <Enter>).
To let you enter new information, LWPCON includes various forms. An LWPCON form contains data fields. You can edit and change the information in some fields, while others are used only for display. After you type new information in a field, press <Esc> to exit the field and continue the operation.
Table 3-3 describes the control keys used by LWPCON.
LWPCON Control Keys
| Key | Description |
|---|---|
| <up arrow>, <down arrow> | Moves the highlight bar through menu or list items. |
| <Delete> | Removes an existing entry from a list, if the entry can be removed, or clears a field, if the field can be changed. |
| <Enter> | Selects the currently highlighted menu or list item or selects a hostname from a list. Selecting an entry from a list of statistics causes the application to list additional information about the entry. |
| <Esc> | Returns you to the previous menu level or ends a field selection. |
| <F1> | Accesses online help for the current display or, in some cases, list selections. |
| <Insert> | Adds a new entry to a list that can be changed. |
| <PgUp>, <PgDn> | Scrolls through long lists, one screen at a time. |
| <Tab> | Toggles between the hostname and the IP address display. |
| <Ctrl>+<PgUp>, <Ctrl>+<PgDn> | Displays the first and last page of a list. |
The LWPCON application displays your workstation or remote host configuration information on a general overview screen like the following screen:
Follow these steps to check the TCP/IP configuration settings for your workstation or a remote host on your network:
If you selected Local Workstation from the Available Options menu, the Local Workstation Options menu appears.
If you select Remote Host, LWPCON prompts you to enter the remote hostname.
The remote host must be running a server program, such as TCPIP.NLM for a NetWare® server or SNMP.EXE for a PC workstation.
After you enter a valid remote hostname or IP address, the Remote Host Options menu opens.
An overview screen opens and displays the following information:
The other choices on the options menus (Interfaces, Protocols, Tables, and SNMP) provide statistical displays that are of interest to the network administrator.
Occasionally a TCP connection might not be closed properly (for example, when a remote connection is severed unexpectedly). This can result in a shortage of TCP resources (sockets) on your workstation.
You can list and close your TCP connections using the following screen:
Follow these steps to display this screen and close your TCP connections:
The Local Workstation Options menu opens.
The TCP/IP Tables menu opens.
The LWPCON utility displays the workstation (Local Host) address and port, remote host address and port, and status for each of your workstation's connections.
Use caution in deleting established connections. When you delete a connection that is in use, you can lose data that has not been saved by the user who is communicating on that connection.
The utility prompts you to confirm that you want to delete the connection.
The utility closes the connection and deletes it from the table.
When a remote host is running and available on your network, the Host Up field on the remote host status table contains a Yes.
Follow these steps to display this status table and determine the status of a remote host:
The utility prompts you for a hostname.
The utility displays the status table for the remote host.
You can display the network route between your workstation and a remote host by displaying the following route table.
You can use this table to verify the connections between your workstation and a remote host. This information can be useful if you are having difficulty connecting to a host or the response from the host is slow.
Follow these steps to display a network route table:
The utility prompts you for a hostname:
The utility displays the Services Options menu.
The utility displays a route table that lists the name and IP address of each intermediate host through which your connection is routed, starting with your router (hop 1) and ending with the remote host you specified. The route table also lists the amount of time in milliseconds required to make each intermediate connection. A time of 0 indicates that less than 55 milliseconds was required to connect, as is often the case for a LAN connection.
If a host in the route does not respond to LWPCON within its time limit, the table displays the message "Not Available." You can use these messages to determine where a problem is occurring in reaching a remote host. For example, if both hop 6 and hop 7 are part of the same network and both are not available, you might suspect that their network is down.
You can determine what network services a remote host makes available and check the current availability of each service by displaying and using the following List of TCP Services.
Follow these steps to display this list and check the availability of remote host services:
The utility prompts you for a hostname.
The utility displays the Services Options menu.
LWPCON displays the list of TCP services.
This listing includes a service number with each well-known TCP port number. For example, the File Transfer Protocol service, usually service (port) 21, provides services used by Rapid FilerTM and FTP. The Terminal Connection service, usually service 23 (the Telnet port), is used by Host PresenterTM and TNVT220.
If a service is available, LWPCON replies with the following message:
servicename is active.
If the service is inactive, a problem exists on the remote host. The server program that supports this service might not be running on the remote host. The remote host administrator can check and activate the service.
The utility prompts you to enter a TCP port number:
The utility replies with a message indicating whether the service is active, as in Step 4.2.
You can determine whether a remote host is known to your network DNS name servers, and if so, display information about the remote host. You display this information on the Name Service Information screen.
Follow these steps to display DNS information for a remote host:
The utility prompts you for a hostname.
The utility displays the Services Options menu.
The utility lists the available DNS information for the remote host.
The PING utility is a diagnostic aid you use to test your workstation's network connections. This utility sends ICMP echo packets (ICMP ECHO_REQUEST) to the remote host you specify and records the time it takes the host to respond to the packets. The utility uses the ICMP protocol's mandatory ECHO_REQUEST datagram to get an echo response from the specified host or network router.
This utility lets you specify the number of packets that PING sends to the remote host as well as the size of the packets and the time interval between packet transmissions. You can specify one size for all packets or vary the size incrementally beginning with one size that you specify. You can also specify that the utility display the IP addresses and hostnames of the IP routers along the path of the packet between your workstation and the destination host.
You use the following syntax to specify PING command options.
PING hostname [ /R[N] ] [ /Tn ] [ /Nn] [ /Pn ] [ /Ln | /Sn [ /In ] ]
The following table describes each of these options.
PING Command Parameters
| Parameter | Description | Default Value |
|---|---|---|
| hostname | Destination of the ICMP echo packets. Type a hostname or IP address for this parameter. | --- |
| /R[N] | Enables the trace route function so that PING displays the IP addresses and hostnames of the IP routers in the path taken by the ICMP echo packets.
Include N to display the IP addresses without displaying the hostnames. | --- |
| /Tn | Modifies the destination response timeout value. Type the time in seconds. | 2 |
| /Nn | Modifies the number of packets you send to the destination host. | 1 |
| /Pn | Modifies the amount of time (seconds) that PING waits before sending a packet to the destination host. PING begins waiting once it receives a response from the destination host for the previous packet. You can type a 0 for a continuous stream of packets. | 0 |
| /Ln | Modifies the fixed size of ICMP echo packets. The minimum size of a packet is 12 bytes; the maximum size is 8192 bytes. | 12 |
| /Sn | Specifies the starting packet size for variable-sized ICMP echo packets. The minimum size of a packet is 12 bytes; the maximum size is 8192 byte | 12 |
| /In | Modifies the number of bytes that PING uses as an increment between variable-sized ICMP echo packets. | 1 |
If you type a hostname that PING cannot resolve with DNS or with the host file, PING displays the following message:
PING: hostname could not be resolved
If an error occurs in any of the socket functions used by PING, then PING displays the error and exits.
Some of the parameters have default values. When you do not specify these parameters with the PING command, the PING utility uses their default values. For example, when you type the following PING command,
PING DEV.ACME.COM<Enter>
the PING utility uses the default values of the parameters you do not include as though you typed the following command:
PING DEV.ACME.COM /T2 /N1 /P0 /L12 <Enter>
When you send one packet with the PING utility, the utility displays response statistics for the one packet. For example, after you send a packet to the DEV.ACME.COM host, the PING utility displays transmission statistics in the following format:
Packet: 1 Length: 12 Response: 54 ms. DEV.ACME.COM (129.45.6.7) responded in 54 milliseconds
You can send multiple packets to a remote host and specify the amount of time that PING waits before sending each packet by including the /N and /P parameters with the PING command. For example, the following command sends nine packets and has PING wait five seconds after it receives a response from the remote host before it sends the next packet:
PING DEV.ACME.COM /N9 /P5 <Enter>
When you send multiple packets with the PING utility, the utility displays response statistics for the multiple packets. These statistics include information on the number of packets you sent and received as well as the minimum, average, and maximum response times for the packets.
Packet: 9 Length: 12 Response: 54 ms. DEV.ACME.COM (129.45.6.7) response statistics: 9 packets sent, 9 responses received Minimum response time: 54 milliseconds Average response time: 54 milliseconds Maximum response time: 54 milliseconds
You can test your network to see how it performs with a packet of a specific size by specifying the packet size with the /L parameter. For example, you can send a 100-byte packet size by typing the following command:
PING DEV.ACME.COM /L100 <Enter>
You can send multiple packets of a specific size by including the /L and /N parameters with the PING command. For example, you can send nine 100-byte packets by typing the following command:
PING DEV.ACME.COM /L100 /N9 <Enter>
You can determine the maximum size of packets transported by your network by varying the size of the packets. You vary the size of the packets by including the /N, /S, and /I parameters with the PING command. For example, to send 10 packets, the first of which contains 100 bytes and each of the following packets is 10 bytes longer than the previous packet, type the following command:
PING DEV.ACME.COM /N10 /S100 /I10 <Enter>
You can trace the route or network path of hosts and routers that your packets follow by including the /R parameter with the PING command. For example, the following command traces the route to the DEV.ACME.COM host:
PING DEV.ACME.COM /R <Enter>
The PING utility displays this route in a message similar to the following message:
Packet: 1 Length: 12 Response: 109 ms. DEV.ACME.COM (129.45.6.7) responded in 109 milliseconds HOP IP Address Host Name Time 1 155.66.6.6 sysdev.acme.COM 0 2 155.66.7.167 wan-2.acme.COM 0 3 155.66.7.168 wan-3.acme.COM 0 4 155.77.8.99 sys.acme.COM 0 5 123.45.6.7 DEV.ACME.COM 109
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