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In addition to the standard IPX routing software for wired LANs and WANs, Novell Internet Access Server 4.1 routing software provides wireless connectivity for portable NetWare workstations through NetWare Mobile IPXTM software.
NetWare Mobile IPX consists of router and mobile client software that work in concert to shield network users from the protocol and Network-layer interruptions that occur when a user changes network interfaces or locations during a network session.
This topic contains the following sections:
Configuring the NetWare Mobile IPX Home Router and client software is straightforward and simple. The only decision you need to make before you get started is where to locate the Home Router on your network. The next section helps you determine the best location.
The Home Router serves as the central connection point between mobile clients and NetWare servers. To enable mobile clients to establish and maintain network connections, the Home Router allocates an address from the server's IPX internal network for use by the mobile clients.
To configure a Home Router, complete the following steps:
Load NIASCFG, then select the following parameter path:
Select Configure NIAS > Protocols and Routing > Protocols > IPX
Select Mobile IPX Support , then select Enabled .
NOTE: Selecting Enabled automatically causes client validation on remote access servers to be disabled. Remote access systems check whether packets received from a WAN client have the same source IPX node address that was assigned to the client during the IPXWANTM negotiation phase. Because NetWare Mobile IPX uses a different filtering method, client validation is turned off to prevent NetWare Mobile IPX packets being discarded by remote access servers.
Select Mobile IPX Configuration and configure the Home Router parameters.
Select Time To Live Override and enter a value, in minutes, from 1 to 10080.
Time To Live Override overrides the mobile client's HR Time To Live parameter, which defines how long the Home Router serves the mobile client without receiving a response from the client. Each time the Home Router receives information from the mobile client, the Time To Live Override counter is reset to the value you enter here. A value of 0, the default, disables the override.
A mobile client cannot obtain a Time To Live value longer than the one you specify here.
The Watchdog Spoofing parameter is enabled by default; to disable watchdog spoofing on the Home Router, select Disabled .
Watchdog Spoofing controls whether the Home Router answers NetWare Core ProtocolTM (NCPTM ) watchdog packets on behalf of a mobile client. If Watchdog Spoofing is enabled, users do not lose their connections to file servers as they roam out of wireless range.
Configure the Broadcast to Virtual Network parameter.
Broadcast to Virtual Network directs the Home Router to forward or discard broadcast packets destined for the virtual network that the router uses to communicate with its mobile clients.
If a large number of broadcast packets are being directed at mobile clients, or if a mobile client's application does not require broadcast, select Discard . By directing the Home Router to discard broadcast packets, you reduce the amount of bandwidth used on the network.
Press Esc to return to the Internetworking Configuration menu; save your changes when prompted.
If you want these changes to take effect immediately, select Reinitialize System .
If you want to configure other parameters, do so now, then reinitialize the system when you are finished.
To configure a mobile client, you modify the client's STARTNET.BAT and NET.CFG files. The changes you make to STARTNET.BAT are required for NetWare Mobile IPX connectivity. Changes to NET.CFG are optional; they are required only if you want to customize the client's NetWare Mobile IPX configuration.
Before you begin, you must complete the following tasks:
To configure a mobile client, complete the following steps:
Open the client's STARTNET.BAT file using a text editor.
A typical STARTNET.BAT file looks something like this:
@ECHO OFFSET NWLANGUAGE=ENGLISHCD NWCLIENTLSLdriverIPXODIVLM /ps=server_nameCD \Add the following changes, indicated in bold, in the order shown:
@ECHO OFFSET NWLANGUAGE=ENGLISHCD NWCLIENTLSLNESLdriverIPXODI /MVLM /ps=server_nameCD \
NESL must be loaded for the mobile client to be activated. NetWare Mobile IPX reacts to changes in the system, such as location and the client's adapter board. The MAC driver is the system module that knows of these events (for example, out of range of access point coverage, card insertion or removal, and so on) and notifies IPX of such changes through NESL.
The IPXODI /M switch enables the NetWare Mobile IPX client software.
A STARTNET.BAT file configured for NetWare Mobile IPX operation looks something like this:
@ECHO OFFCD C:\NWCLIENTSET NWLANGUAGE=ENGLISHLH C:\NWCLIENT\LSL.COMLH C:\NWCLIENT\NESL.COMLH C:\NWCLIENT\NE2000.COMLH C:\NWCLIENT\IPXODI.COM /MC:\NWCLIENT\VLM.EXE /ps=MY_SERVERRestart the client.
This section describes the optional parameters you can add to the Mobile IPX section of a mobile client's NET.CFG file. The parameters enable you to customize your NetWare Mobile IPX configuration.
An example of how these parameters are used is provided in Example NET.CFG File.
The following parameters enable you to customize the interaction between a mobile client and its Home Router:
This command causes IPXODI to attempt to attach to the specified Home Router (HR). If the router does not exist or is not specified, the Home Router closest to the client is used.
This command enables some level of routing optimization to be achieved. Specifying a Home Router that is the user's preferred server, or specifying one in an inline routing path between the mobile client and most of its logged-in servers, causes packets sent back to the client to take a more direct path because all packets being sent to the client go through the Home Router first.
HR Time To Live specifies the time-to-live interval, in minutes, that the IPXODI module attempts to use with the Home Router. It defines how long the Home Router serves the mobile client before the router requires an update from the mobile client. If this is not defined, IPXODI uses a default value of 30 minutes. NOTE: HR Time To Live can be overridden by the Home Router's Time To Live Override parameter.
If the client does not update the Home Router after the HR Time To Live value runs out, the Home Router stops serving the mobile client. Note that only NCP watchdog packets, not Sequenced Packet ExchangeTM (SPXTM ) watchdog packets, are handled by the Home Router. If the mobile client roams out of range and comes back within the amount of time set by HR Time To Live , the timer is reset automatically; otherwise, if the client is not back within range when the timer runs out, the mobile client is dropped. It is especially important to set HR Time To Live to a large value if the mobile client is out of network range for a long time. While the time-to-live value is still active in the Home Router, the router responds to server NCP watchdogs on behalf of the client so that client sessions do not time out while network connectivity is lost. If this value is too small, the Home Router stops serving the mobile client before it returns within network range, and all server connections are lost. The only reasons the Home Router might not see a NetWare Mobile IPX watchdog packet from a mobile client are that the client is off, in sleep mode, or out of range.
This command determines what IPXODI does when the current Home Router is no longer reachable. If you set Allow HR Change to On , IPXODI tries to sign on with the first available Home Router, even if it is not the same as the current one. If you set Allow HR Change to Off , IPXODI continues trying to reestablish a connection to the Home Router to which the client is currently attached. If Allow HR Change is not defined, IPXODI assumes Allow HR Change is set to Off ; if it is set to On , and the current Home Router stops operating, IPXODI obtains a different virtual address while signing on with a different router. Most applications available today cannot operate gracefully through the address change; as a result, connections might be terminated.
The NET.CFG parameters described in this section enable you to specify an alternate board to be used in the portable computer. Alternate board parameters enable IPXODI to use a second board for mobile communications if the primary board loses connectivity. The driver for the alternate board must be specified in the Mobile IPX section of NET.CFG. Note that the equal sign (=) is optional; however, it can be used to quickly find the parameter values.
IMPORTANT: The first three parameters (Alt Name , Alt Board Number , and Alt Frame ) must all be specified; if one is missing, no alternate board setting is used. Additionally, the frame type specified by the Alt Frame parameter must be set under the Link Driver Heading for the desired alternate board.
Alt Name specifies the name of the driver supporting the alternate board.
Alt Board Number specifies the Link Support LayerTM (LSLTM ) board number of the alternate board displayed when the driver loads. The board number of a driver changes if there is a change in the order of MAC driver load commands. Therefore, it is important to always load the primary driver first, followed by the alternate driver, to ensure that the Alt Board Number parameter always refers to the alternate board. After the MAC drivers have been loaded, you can get board numbers and other information by entering the following command: MAC_Driver_Name /s
This command displays information about all Open Data-Link InterfaceTM (ODITM ) drivers currently loaded. The information you see is similar to the following example:The following LAN drivers are loaded in memory:MAC driver name and version informationIRQ 5, Port 300, Mem D0000, Node Address 4096003F53 LMax Frame 1514 bytes, Line Speed 2 MbpsBoard 1, Frame ETHERNET_II, LSB Mode
Alt Frame specifies the frame type for the alternate board (for example, ETHERNET_802.2). The driver loaded first in STARTNET.BAT becomes the primary driver. If IPXODI cannot locate the alternate driver during initialization, an error is issued and only the primary board is used. If there is no primary board either, IPXODI issues an error and fails to load. The drivers for both the primary and alternate boards must be loaded before IPXODI. The driver load order is not important; however, it is harder to determine the LSL board numbers to enter for the IPX BIND statement or alternate board configurations if the primary driver is not loaded first. If PCMCIA adapters are used and the card vendor's drivers are written to support card in/card out events, or driver initialization without the PCMCIA card inserted, the PCMCIA cards need not be inserted into the system until network connectivity is needed. Here is an example STARTNET.BAT file that shows the load order of the primary driver, alternate driver, and IPXODI:@ECHO OFFSET NWLANGUAGE=ENGLISHCD NWCLIENTLSLNESLprimary driveralternate driverIPXODI /MVLM /ps=server_nameCD \
The NET.CFG file allows you to specify whether the SPX Watchdog protocol will be run to validate SPX connections periodically. The one-line entry to specify the SPX Watchdog protocol behavior follows the Heading PROTOCOL IPX and has the following format:
SPX WATCHDOGS = ON|OFF
where ON specifies that the Watchdog protocol will be run to validate SPX connections periodically and OFF specifies that it will not. For more information on the use of the Watchdog protocol, refer to Watchdog Packet Spoofing.
This section provides an example NET.CFG file that shows the format of mobile client customization parameters.
LINK DRIVER Wireless FRAME = ETHERNET_802.2LINK DRIVER Wireless2 FRAME = ETHERNET_802.2NETWARE DOS REQUESTER NETWARE PROTOCOL = NDS BIND FIRST NETWORK DRIVE = F SHOW DOTS = ON USE DEFAULTS = ON VLM = AUTO.VLMMOBILE IPX PREFERRED HR = Home_Router_Name ALT NAME = Wireless2 ALT BOARD NUMBER = 2 ALT FRAME = ETHERNET_802.2PROTOCOL IPX SPX WATCHDOGS = OFF| |