Expand Configuration and Management Manual (G06.24+)

Expand Modifiers
Expand Configuration and Management Manual—523347-008
17-13
L2TIMEOUT n
L2TIMEOUT n
Default: 100 (1.00 second) for direct-connect lines
200 (2.00 seconds) for satellite-connect lines
Units: 0.01 seconds
Range: 20 through 32767
This Layer 2 modifier is applicable to direct-connect and satellite-connect line-handler
processes only. This modifier specifies the length of time, in one-hundredth of a
second increments, that the Expand line-handler process will wait for a response to a
request at Layer 2 before retrying. (The number of retries is determined by the
L2RETRIES modifier.)
You can calculate the value of the L2TIMEOUT modifier using the following algorithm:
((txw + 1) * fsz * 16) / (lspd / 100)) + (2 * dl) + 10
where txw is the TXWINDOW modifier value, fsz is the FRAMESIZE modifier value,
lspd is the line speed in bits per second (actual, not configured), and dl is the DELAY
modifier value. The result of this algorithm should be the worst-case possible delay for
a successful transmission. However, you should keep in mind that a limit less than 0.5
seconds can be affected by vendor rerouting over alternate facilities, and a limit greater
than 0.5 seconds can seriously affect recovery times in case of actual failure.
When the multipacket frame feature or variable packet size feature is used, the value
specified for the L2TIMEOUT modifier should be based on the transmission time
required for the larger configured PATHBLOCKBYTES or PATHPACKETBYTES
modifier value rather than on the configured FRAMESIZE modifier value.
When the multipacket frame feature is used, you can calculate the value of the
L2TIMEOUT modifier using the following algorithm:
(((txw + 1) * pathblockbytes * 8) / (lspd / 100)) + (2 * dl) + 10
When the variable packet size feature is used, you can calculate the value of the
L2TIMEOUT modifier using the following algorithm:
(((txw + 1) * pathpacketbytes * 8) / (lspd / 100)) + (2 * dl) + 10
The result of these algorithms is a one-hundredth of a second value.
For more information about the multipacket frame and variable packet size features,
refer to Section 18, Subsystem Description.
Note. If you use the Expand subsystem SCF ALTER LINE command to set the L2TIMEOUT
modifier, you must convert the result of this algorithm to a time interval. For example, if the
result was 300 (3 seconds), you would enter the following command:
ALTER LINE $device_name, L2TIMEOUT 3.00.