Specifications

21-58
Cisco BPX 8600 Series Installation and Configuration
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001
Chapter 21 Configuring ATM Connections
Local Management Interface and Integrated Local Management Interface Parameters
It is important to notify the customer premise equipment if a connection is derouted and fails to
transport user data after a specified time interval. However, it is also desirable not to send out Abit = 0,
then Abit =1 when a connection is derouted and rerouted quickly. Such notifictions might prematurely
trigger the CPE backup facilities causing instabilities in an otherwise stable system.
The Early Abit Notification on ILMI/LMI Using Configurable Timer feature allows Abit notifications to be
sent over the LMI/ILMI interface if a connection cannot be rerouted after a user-specified time. Abit = 0 will
not be sent if the connection is rerouted successfully during that time.
The time period is configurable. The configurable time allows you the flexibility to synchronize the
operation of the primary network and backup utilities, such as dialed backup over the ISDN or PSTN
network.
This feature is supported on both the BPX and IGX platforms. A Release 9.2 IGX or BPX node using
this feature is compatible with Release 8.4 and Release 8.5 nodes or Release 9.1 IGX and BPX nodes
so that all existing connection related functions will continue to work. However, the timing in sending
out the Abit notifications at both ends of connections may behave differently, depending on how this
feature is configured.
Configuring Early Abit Notification
You configure the timer delay period by setting cnfnodeparm parameters. You want to choose timer
settings that give you the flexibility to synchronize the operation of the primary network and backup
utilities, such as dialed backup over the ISDN or PSTN network.
Be aware of these guidelines when using the Early Abit feature:
• When you enable this feature by using the cnfnodeparm command, you can specify that Abit
Notification be:
– sent either on deroute
– or a user-configurable time after deroute
• This feature can also be turned off
• It is recommended that this feature be set the same on all nodes. Otherwise, the Abit behavior can
be different on different nodes.
• If this feature is turned off, switch software behaves the same as in previous releases. Existing
functionality continues to function in a mixed release network (releases 8.4, 8.5, or 9.1 IGX or BPX
network).
• If the cnfnodeparm parameter Abit Timer Multiplier M issetto0,thenswitchsoftwarebehaves
the same way as in Release 9.1.07 (which supported the Send Abit on Deroute feature).
• To follow the general Release 9.2 interoperability guideline, it is not recommended that the Early
Abit Notification on ILMI/LMI Using Configurable Timer feature be used when the standby
control processor is in a locked state.
Recommended Settings
You should be aware of the dynamic relation between the two timer parameters:
• Abit Timer Granularity N
The time period is referred to as N, which defines the granularity of the timers. You specify N by
the value of the
cnfnodeparm Abit Timer Granularity N parameter.
The default value for N is 3sec.