Expand Configuration and Management Manual (G06.24+)
Expand Modifiers
Expand Configuration and Management Manual—523347-008
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L2DISCARDONRESET_OFF/L2DISCARDONRESE
T_ON
L2DISCARDONRESET_OFF/L2DISCARDONRESET_ON
Default: L2DISCARDONRESET_ON
Units: Not applicable
Range: ON or OFF
These Layer 2 modifiers are applicable to direct-connect and satellite-connect line-
handler processes only. The L2DISCARDONRESET_ON modifier causes
unacknowledged High-Level Data Link Control (HDLC) frames to be discarded at the
transmitting node and causes recovery to take place at Layer 4 when either the
transmitting or the receiving node initiates a link reset (SABM-UA exchange).
The L2DISCARDONRESET_ON modifier should be enabled on direct-connect and
satellite-connect lines in paths that contain multiple high-speed lines that are prone to
outages or significant variances in transmission delay.
L2RETRIES n
Default: 20 for Expand-over-IP and Expand-over-ATM
10 for all other line types
Units: Not applicable
Range: 1 through 255
This Layer 2 modifier is applicable to all Expand line types. This modifier specifies the
number of times that the Expand line-handler process will retry a request at Layer 2
before reporting an error. A minimum value of 3 is recommended for the L2RETRIES
modifier.
The purpose of the L2RETRIES modifier is to bridge common failures without
unnecessarily rerouting traffic. A correct value for the L2RETRIES modifier depends on
a thorough knowledge of the network and the application. In general, the L2RETRIES
modifier should be selected so that the result of the following algorithm is greater than
the characteristic short-term failure mode of the network and 15 seconds less than the
delay tolerance of the application:
L2RETRIES * L2TIMEOUT * 3
The result of this algorithm is the point at which the Expand line-handler process will
declare the line unusable and begin rerouting. For most networks the result will be a
value that allows you to bridge 10-second to 30-second network outages.
Note. The L2TIMEOUT modifier is the time interval that the Expand line-handler process will
wait for a response to a request at Layer 2 before retrying. You can modify the Layer 2 timeout
using the L2TIMEOUT modifier.