home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Black Box 4
/
BlackBox.cdr
/
lan
/
tb250.arj
/
TB291.TXT
< prev
next >
Wrap
Text File
|
1991-08-06
|
8KB
|
157 lines
NOVELL TECHNICAL BULLETIN
TITLE: IBM Token Ring and Novell NetWare
DOCUMENT ID#: TB.P.291
DATE: 04/06/91
PRODUCT: NetWare 286, 386
PRODUCT REVISION: all versions
SUPERSEDES: NA
SYMPTOM: NA
ISSUE/PROBLEM
Several Novell customers and third-party vendors have experienced
problems with IBM Token Ring stations while using IBM LAN Support Program
and Novell NetWare. Symptoms typically are that the workstation will
simply "hang." Most of these problems have been with TIC (Token Ring
Interconnect Option) connected 3270 gateways.
Tracking these problems down turned out to be extremely difficult. With
the help of our customers, third-party vendors, and IBM we now believe we
understand the nature of the problem. These problems are not due to a
single cause. We believe we have identified a total of three issues
which individually could cause problems and together are likely to cause
a network station to fail.
The exact combination of hardware and software which has been shown to
have problems is the IBM Token Ring Adapter (any vintage or bus type),
IBM LAN Support Program version 1.0 through 1.1, NetWare Token Ring
drivers versions 2.60 and earlier, MS-DOS or PC-DOS 3.3x or 4.0x, and a
3270 gateway such as DCA's Irmalan product. It must be emphasized these
problems are not properly "bugs" as all the components of a system
showing these symptoms are functioning as designed. Furthermore, the
circumstances which can cause a failure are extremely unusual and always
involve very heavy LAN traffic, particularly connection attempts.
SOLUTION
PROBLEM #1
Certain characteristics of the IBM LAN Support Program DXMC0MOD.SYS
driver were interacting with NetWare's IPX program causing IPX and
DXMC0MOD to enter infinite loops waiting for a reply. The DXMC0MOD
driver, for performance reasons related to RS232C communications through
serial ports using single character buffer UARTs (such as National
Semiconductor's INS8250 or equivalent) will re-enable interrupts after
400 µseconds to avoid dropping characters during high speed
communications. This behavior can be disabled with a switch on the
CONFIG.SYS line which loads the driver, "q" for "quiet." This switch is
not case sensitive. This "Q" switch is not currently documented in the
IBM LAN Support Program documentation.
The syntax to use the "q" switch is given below.
DEVICE=<PATH>DXMC0MOD.SYS Q
This interrupt disabling behavior of DXMC0MOD can allow IPX and DXMC0MOD
to enter an endless wait. When two protocols are using DXMC0MOD, such as
802.2 3270 protocols from a gateway to the System 370 Controller and
IPX/SPX between the gateway station and network stations connecting to
the gateway, problems can occur. The scenario of events is as follows:
An 802.2 TRANSMIT begins. Before the TRANSMIT can complete interrupts
are re-enabled. While interrupts are re-enabled an SPX CONNECT request
arrives. If the SPX CONNECT request has passed through a NetWare Router
(sometimes erroneously called a NetWare Bridge) SPX issues an
IPXGetLocalTarget request to determine the Time To Target. Because the
previous 802.2 TRANSMIT is still pending the IPX TRANSMIT is queued. IPX
assumes that only two things can EVER happen to a packet transmit
request: it will either FAIL or SUCCEED. Thus IPX waits for a reply from
the card indicating the packet transmit has either failed or succeeded
but because the packet has NOT been transmitted, only queued up, IPX
NEVER receives this required response from the card. Meanwhile the
DXMC0MOD driver is patiently waiting for control to return to it so it
can process the two pending transmits. Both IPX and DXMC0MOD thus wait
for each other forever. This failure is most likely to occur in an
environment where very large numbers of connect requests are being
presented to the gateway.
PROBLEM #2
The combination of the IBM LAN Support Program, IPX, SPX, the gateway
software, and DOS use a large amount of DOS STACK space. The default
STACKS of DOS 3.3x/4.0x in 286/386 machines of 9 stack frames of 128
bytes each may be insufficient in some cases. To prevent internal stack
failure or stack overruns we suggest increasing the size and number of
these dynamic stacks. Add the following line to CONFIG.SYS in the
gateway station:
STACKS=16,256
This allocates 16 stack frames of 256 bytes each and should prevent any
stack related problems.
PROBLEM #3
The combination of an IBM 4/16 Token Ring Adapter with 1990 firmware,
version 1.1 LAN Support Program, and NetWare 2.60 or earlier Token Ring
drivers has been shown to cause the Token Ring Adapter to lockup. In
most instances this has been resolved with the 1.20 or 1.21 LAN Support
Program and 2.62 NetWare Token Ring drivers when used together with the
"Q" switch for the DXMC0MOD.SYS driver. If these problems persist in a
station using these latest drivers, the IBM Token Ring Adapter
Diagnostics diskette provided with the adapter should be run to determine
the revision level of the adapter's microcode. If the ISA adapter
microcode revision level is C24550 an Authorized IBM Dealer or Support
Representative should be contacted to arrange for an upgrade of the
adapter microcode. This applies ONLY to stations being used as a gateway
and does not apply to other network stations including file servers.
To use the IBM Token Ring Adapter Diagnostic diskette to check your
firmware level:
FOR MCA ADAPTERS -
Place the Token Ring Adapter diskette in the boot diskette drive of the
computer being tested and power the computer on.
Press 0
After the Ring Adapter Open completes, press <F1>
The next screen will show the Adapter Code Level number.
Press <F3>, Press <F3>, remove the Adapter Diagnostic diskette and press
any key to re-boot the computer.
FOR ISA ADAPTERS -
Place the Token Ring Adapter diskette in the boot diskette drive ofthe
computer being tested and power the computer on.
Press 1 (Ring Diagnostics) then Press Enter
Press 0
After the Ring Adapter Open completes, press <F1>
The next screen will show the Adapter Code Level number.
Press <F3>, Press <F3>, remove the Adapter Diagnostic diskette and press
any key to re-boot the computer.
Novell Technical Services has reports of another Token Ring Adapter Code
Level which has produced similar symptoms, 8A78064. This has not been
completely confirmed by both IBM and Novell Technical Services. If the
symptoms described above are experienced and the solutions described
above do not resolve the problems please contact Novell Technical
Services (1-800-NETWARE) and/or IBM.
PLEASE NOTE: AT THIS TIME WE ARE NOT RECOMMENDING REQUESTING
REPLACEMENT FOR THIS ADAPTER CODE LEVEL. IF PROBLEMS ARE
EXPERIENCED, REPORT THEM AND IBM AND NOVELL WILL
INVESTIGATE FURTHER.