Mirrored Server Link (MSL) Driver

26 May 1994
Software Version 1.10


SKFM_MSL.MSL is a driver for Netware SFTIII v4.10. The driver corresponds
to the MSL Specification Version 1.00 from February 5, 1993.
On Netware 4.10 the driver can be loaded multiple times.

We do our Mirrored Server Link not on dedicated point to point connection
but on a standard FDDI LAN. Due to this it is possible to mirror more than
one server pair on one FDDI ring, or to put a third standby server in the
LAN (which is only powered on when one of the two mirrored servers is down).
So the configuration with the SKFM_MSL.MSL is very flexible (you have only
the limitations of FDDI).

Note: before you start disk accesses on the server (for example when
	copying Public and System Files during installation) you have
	to set the timeout time to a greater value. Therefor enter the
	following command:
	set Mirrored Server Comm ACK Wait Time Out = 2.0
	(default: 0.8)

	If you set the parameter 'Maximum Physical Receive Packet Size'
	to a higher value (default: 1514), you possibly may have to increase
	the memory given to the IOEngine. Therefor use the parameter
	'New Start Address For Unclaimed Memory Block'. Refer to the
	SFT III manual to get more information about this.

Due to features listed above the driver knows some specific keywords.
-MIRROREDSERVER (optional)
     specifies the MAC address of the other server.
     (default: Broadcst) Because the number of Broadcast packets on a LAN
     should not be very high, you should specify the address of the other
     server.
     example: load SKFM_MSL.MSL MIRROREDSERVER=00005a400764

-ConID (optional)
     specifies the connection ID of the MSL. (default: 0)
     If you specify a Connection ID, they have to be the same on the two
     mirrored servers. If you mirror more than one server pair on the same
     FDDI ring and have not defined MIRROREDSREVER you must use this keyword.
     Each server pair must have a different connection ID.
     The Connection ID is a two byte hex value.
     example: load SKFM_MSL.MSL ConID=0808

-MSLRetry (optional)
     specifies the number of retries if no acknowledge is received
     (default 0). Due to the fact that we are on a LAN, it is possible
     that packets are lost because of RingOpChanges or other trouble on the
     Medium. If this happens the MSL is down and SFTIII will restart the
     secondary server to reestablish the connection. If you specify a number
     of MSLRetries the driver itsself will do a retry if an acknowledge is
     missing, so SFTIII does not need to restart the secondary server if a
     packet was lost (the restart of the scondary server is a critical
     process because during the restart and synchronisation you have no
     mirrored servers). You will not need to specify retries if you have only
     the servers in the FDDI ring.
     The maximum value for MSLRetry is 5.
     example: load SKFE_MSL MSLRetry=1

-WindowSize (optional)
     specifies the size of the window for data transmission. On the MSL
     you have to send an acknowledge for each packet. With this parameter
     you can specify how much packets are send, without receiving an
     acknowledge (burst mode). If there is heavy load on the MSL with big
     packets it is desirable to have a great windowsize. You will see this
     scenario during memory synchronisation or if there are many write
     accesses to the disk (the data have to be put over the MSL to the
     secondary server). If you have many read accesses to the disk there
     will be a lot of small packets on the MSL. If now the windowsize is
     smaller, it is possible to queue many small messages (24bytes) into
     one packet. This mechanism reduces the overhead for transmitting
     many packets.
     The maximum value for WindowSize is 8.
     example: load SKFE_MSL WindowSize=1
     default: 4


Additional you can specify the following SMT parametres as on a SKFDDIFE
LAN driver (they are all optional):

-PMFPASSWD
     This keyword defines the password that all remote PMF (Parameter
     Management Frame) requests must provide to change FDDI attributes
     within the adapter.
     The value for PMFPASSWD is 8 ASCII characters long and not
     case sensitive since lower case letters will be converted to upper cases.
     Password protection can be disabled by setting this keyword
     to all zeros (default), or by not specifying a PMFPASSWD.

-USERDATA
     This keyword provides local write access to the User Data
     attribute, registered as fddiSMT 17 in the SMT Standard.
     The User Data must be an ASCII string for compliance
     with the FDDI SMT Standard.

-LERCUTOFFA
     This keyword provides local write access to the LER Cutoff
     attributes, registered as fddiPORT 58 in the SMT Standard.
     This attributes indentifies the excessive Link Error Rate that
     removes Port A/B (or Port S).
     This keyword is specified as absolute value of the base 10 logarithm
     of the LER Cufoff value.
     The valid range reaches from 1E-4 to 1E-15. If a value
     is specified which lies outside the limits, the upper/lower
     limit will be taken. If no value is specified,
     the default value for LERCUTOFFA/LERCUTOFFB (1E-7) will be used.

-LERCUTOFFB
     This keyword provides local write access to the LER Cutoff
     attributes, registered as fddiPORT 58 in the SMT Standard.
     This attributes indentifies the excessive Link Error Rate that
     removes Port A/B (or Port S).
     This keyword is specified as absolute value of the base 10 logarithm
     of the LER Cufoff value.
     The valid range reaches from 1E-4 to 1E-15. If a value
     is specified which lies outside the limits, the upper/lower
     limit will be taken. If no value is specified,
     the default value for LERCUTOFFA/LERCUTOFFB (1E-7) will be used.

-LERALARMA
     This keyword provides local write access to the LER
     Alarm attributes, registered as fddiPORT 59 in the SMT Standard.
     This attributes identifies the excessive Link Error Rate
     that siganls an alarm at Port A/B (or Port S).
     This keywords are specified as absolute values of the base 10 logarithm
     of the LER Alarm value.
     The valid range reaches from 1E-4 to 1E-15 for both keywords. If a value
     is specified which lies outside the limits, the upper/lower
     limit will be taken. If no value is specified,
     the default value for LERALARMA/LERALARMB (1E-8) will be used.

-LERALARMB
     This keyword provides local write access to the LER
     Alarm attribute, registered as fddiPORT 59 in the SMT Standard.
     This attribute identifies the excessive Link Error Rate
     that siganls an alarm at Port A/B (or Port S).
     This keyword is specified as absolute value of the base 10 logarithm
     of the LER Alarm value.
     The valid range reaches from 1E-4 to 1E-15. If a value
     is specified which lies outside the limits, the upper/lower
     limit will be taken. If no value is specified,
     the default value for LERALARMA/LERALARMB (1E-8) will be used.

-TMIN
     This keyword provides local write access to the 2's complement T-Min
     attribute, registered as fddiMAC 55 in the SMT Standard.
     The value for TMIN is specified in milliseconds.
     The valid range reaches from 5 ms to 165 ms. If a value
     is specified which lies outside the limits, the upper/lower
     limit will be taken. If no value is specified,
     the default value for TMIN (5 ms) will be used.

-TMAX
     This keyword provides local write access to the 2's complement T-Max
     attribute, registered as fddiMAC 53 in the SMT Standard.
     The value for TMAX is specified in milliseconds.
     The valid range reaches from 5 ms to 165 ms. If a value
     is specified which lies outside the limits, the upper/lower
     limit will be taken. If no value is specified,
     the default value for TMAX (165 ms) will be used.

-TREQ
     This keyword provides local write access to the 2's complement T-Req
     attribute, registered as fddiMAC 51 in the SMT Standard.
     The value for TREQ is specified in milliseconds.
     The valid range reaches from 5 ms to 165 ms. If a value
     is specified which lies outside the limits, the upper/lower
     limit will be taken. If no value is specified,
     the default value for TREQ (165 ms) will be used.

-TVX
     This keyword provides local write access to the TVX attribute,
     registered as fddiMAC 54 in the SMT Standard.
     This attribute provides local control of the recovery time
     from transient ring errors.
     The value for TVX is specified in microseconds.
     The valid range reaches from 2500 us to 10000 us. If a value
     is specified which lies outside the limits, the upper/lower
     limit will be taken. If no value is specified,
     the default value for TVX (2700 us) will be used.
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