Using PicLan with RAS and PPTP

January 20, 1998

A number of PicLan customers have asked for assistance in configuring PicLan for use with dial-up network environments. This article discusses two test configurations that were assembled at Modular Software.

The Test Configuration

Test System Configuration

The test configuration consisted of a production Windows NT server with the following software loaded:

The test client was a Windows 95 system running:

All of the upgrade packs are available from Microsoft on the Web or CD.

Modems and Internet Connections

For RAS testing, the Windows NT server had an internal Boca 28.8 modem installed on COM3 using IRQ5. The Windows 95 client had an Eiger PCMCIA 28.8 modem installed using vendor supplied modem drivers.

For PPTP testing, the Windows NT server had a permanent routed internet connection via an ISDN modem to a local ISP. The Windows 95 client dialed up a standard ISP account using PPP and dial-up networking.

General Network Configuration

Configuring Network Addresses and Frame Types

In order to use RAS with PicLan, you must configure the Pick host system and the RAS server's network interface to use IPX routers. This means that you must assign a specific IPX network address to the Pick host system and to the Windows NT network adapter.

On the Windows NT RAS system, you must configure the IPX protocol to use the same frame type and network address that you configured on the Pick host system. You enter these values in Control Panel | Network | Protocols | IPX/SPX | Properties for the network adapter that is connected to your Pick host system.

Configuring Timeouts

RAS connnections are inherently slower than local network connections and because of this you should lengthen the timeout values that PicLan uses.

On the client workstation, you set timeouts in the PL-CFG.INI file. Again, you should set the timeout to 3000 milliseconds. The PL_SETUP program will set this value for you if you select "dial up connection" on the first page.

If you do not setup the timeout values to a longer value, PicLan will still operate, but may generate an excessive number of retries. This does not generally hurt operation, but may degrage performance.

Configuring RAS

In order for the Windows NT system to act as a RAS (Remove Access Services) server, you must install the "Routing and RAS" upgrade package from Microsoft. The existing RAS server that is included in Windows NT 4.0 Server also functions, but is more difficult to install and configure. The existing RAS server that is included in Windows NT 4.0 Workstation may or may not provide PicLan access.

Windows NT Workstation does not include the RIP for IPX/SPX service. RIP is the routing protocol that IPX uses to interconnect networks. Without RIP, it is unknown whether RAS will route IPX packets from the dial-up circuit to the local network. This paper does not imply that this configuration does not work, only that it has not been tested at Modular Software. After you install RAS (the Routing and RAS accessory pack), you must configure the following elements:

Adding Modems

Before you configure RAS, you must install and configure the Modem drivers for your modems. You do this in Control Panel | Modems.

Routing and RAS Properties

In Control Panel | Network | Services | Routing and Remote Access Services | Properties you must configure each modem that RAS is to use. Use the ADD button to add each modem that is to be used by RAS. This single screen is used to configure both dial-in and dial-out modems. This example configures dial-in (receive calls) modems.

For each modem uses as a RAS Server, you should check "Receive calls as a RAS server" under configure port usage. After you have configured each modem, you then must configure the overall network setup for RAS services. This is done by selecting the "Network" button, which brings up the "Network Configuration" dialog box. For PicLan use, you must check the "Server Settings" IPX box. After checking this box, click on "Configure" for IPX networks and select "Allow remote IPX clients to access entire network", and "Allocate nework numbers automatically". You should not check "Assign same network number to all clients" or "Allow client to request a network address".

You can also configure TCP/IP and NETBEUI access over RAS, but this is not necessary for PicLan access.

Setting up a Dial-Up Account

Once RAS is setup to accept calls, you must configure a Windows NT login account with dial-up priviledges. You should always assign a passwork to dial-up accounts. It is this dial-up account name and passwork that the Windows 95 client uses to gain access to the network.

Configuring Windows 95 Dial-Up Networking

You configure Windows 95 dial-up networking by installing a modem and by clicking on "Add New Connection" in dial-up networking. You then enter a connection name and phone number. Under network settings, you must specify that you wish to use IPX as a protocol on dial-up. The Windows 95 dial-up networking then proceeds normally.

When You Connect using Dial-Up Networking into RAS

When the Windows 95 system dials the RAS telephone number, the Windows NT Server will answer the call and request a user name and password over PPP (Point to Point Protocol). After the user is authenticated (the account name and password is verified), the Windows 95 client system will be assigned an IPX network address. At this point the Windows 95 system should be able to run standard PicLan client programs like PLTW, PL-STATW, etc. and access any Pick host system on the network.

Configuring PPTP

Configuring PPTP allows you to "tunnel" IPX over IP connections. This can be used to access local IPX services from a remote system connected to the internet.

Adding PPTP to Windows NT

You must first add the PPTP protocol to the Windows NT network layer. You do this with Control Panel | Network | Protocols | Add. When you add PPTP to the Windows NT network layer, you specify the number of virtual circuits that you wish to support. Each client that will simultaniously access your network over PPTP requires a virtual circuit.

Adding PPTP to Windows 95

In order to dial-up the PPTP connection from Windows 95, the Windows 95 system must have an existing internet account and dial-up software installed. After the internet software is installed, dial-up network is used to make a new connection using a Virtual Private Network. Instead of supplying a phone number, you supply the IP address of your PPTP server.

It can be confusing deciding which IP address to use with the PPTP server. In our test case at Modular Software, the PPTP server was running on the same system as our ISDN internet connection was connected to. In this case, you use the IP address that is associated with the ISDN connection and not one of the IP addresses associated with the LAN adapters installed in the same system. Microsoft is very unclear in this area, so some experimentation may be required. When you configure PPTP in dial-up networking, you must specify IPX as a requested protocol. After the PPTP connection is established, you should be able to access IPX network resources including PicLan servers.

RAS Performance

PicLan performance over a RAS connection will always be worse (and better) than a direct modem connection would be into the Pick host system. In general, you should get good overall throughput equal to at least half of the dial-up baud rate unless your telephone connection is particularily bad. The one area that you will notice perforance problems is in echo delay. You should expect 1/3 to 2/3 of a second delay in seeing echo characters from the Pick host. There is little that can be done about this delay which is caused by latency in building packets over the modem.

PPTP Performance

PPTP performance over the internet is at the mercy of your internet connections and internet packet path. If you have a short path from your client to your host network (such as exists when you use the same ISP for both sites), then the performance for PPTP will be only a slight amount worse than a direct RAS connection. If your internet path is longer and/or the connections and internet is busy then you may start to experience 3 to 10 second echo delays.

Our testing of PPTP performance involved our local internet connection through Pursuit Internet | PacBell Internet | IBM Global Internet Services on the server end and AT&T Worldnet dial-up access via AT&T's 800 number POP on the client side. In this environment there were about 15 internet hops between the client and the server and response times varied from 2 to 8 seconds for echo delay. While this is "poor" from a performance point of view, it is amazing that it works at all and overall the connections were quite reliable. Our PPTP tests also had us mapping a number of NetWare drives over the internet as well. NetWare directory operation usually took 20 to 40 seconds and file copies could take several minutes for 100K files. It should be noted that Windows NT file system access took about the same amount of time.

Send Us Your Experiences

There are many other possible configurations that should work with PicLan. We have heard that the following configurations can also work:

Windows NT workstation RAS
Windows 95 "Plus Pack" dial-up server
NetWare Connect
Shiva NetModems

If you have tried these configurations, email your experiences to support@modsoft.com so that we can pass them on to others.