Optimize backplane bandwidth

Procedure 6-12: Optimize backplane bandwidth

Overview

Use this procedure to manually optimize the backplane bandwidth between the main packs and the specified LS group(s).

To determine if you need to optimize bandwidth for a particular circuit pack, see Procedure 6-11: Evaluate bandwidth utilization

Defragmentation behaviors

Important!

For Ethernet packs that support VT cross-connections, only the backplane utilization parameters are reported; VT utilization is not reported on the LNW74 pack.

The following behaviors apply when you perform the defragmentation operation:

Rearrangements do not interrupt traffic on cross-connections that are not being rearranged.
No misconnections are caused by rearrangement.
For the LNW70/LNW170 in STS1 mode, rearrangements are not necessary since higher rate cross-connections are not supported.
For the LNW74, the VT vs. STS backplane partitioning is preserved during defragmentation of the backplane bandwidth. When enabled, the first 12 backplane STS1s are reserved for VT-cross connections only. The remaining 36 STS1s are reserved for STS cross-connections only. VT cross-connections are rearranged only within the first 12 STS1s and STS cross-connections will be arranged only within the last 36 STS1s.
Backplane optimization will only affect packs on which the backplane bandwidth is dynamically assigned. During cross-connection provisioning, the NE dynamically assigns the I/O tributaries to the backplane tributaries on the following circuit packs:
- LNW45 and LNW49 that support the VT grooming on the tributary fabrics when the Mains are equipped with non-VLF Mains. If the Mains are equipped with VLF Mains, the LNW45 and LNW49 circuit packs do not support backplane optimization.
- LNW63, LNW70/LNW170, LNW73/LNW73C, LNW74, LNW78, and LNW87 where the number of VCG tributaries exceeds the available backplane bandwidth.
The optimize backplane bandwidth operation removes the fragmentation at the STS1, STS3c and STS12c levels and minimizes the number of STS1s required to transport cross-connected VTs to the main packs. Interruptions will vary from 1 second (OCn) to 3 seconds (Ethernet) in duration on VT1, STS1 and STS3c cross-connections each time they are rearranged.

Excessive fragmentation

You can determine if excessive fragmentation exists in the following ways:

When you provision a new cross-connection and the backplane bandwidth necessary to support the cross-connection is not available, the command will be denied with a SARB (Status All Resources Busy) error response.
You can check the backplane utilization for each transmission pack and the VT fabric utilization for the main pack in the shelf. You can use the CIT to display the information or by view the raw utilization data in the output of the RTRV-ST-EQPT command.

Privilege level

You must login as a Privileged or General user to complete this procedure.

Before you begin

Refer to Before you begin and Required equipment in this chapter.

Steps

NOTICE

Service-disruption hazard

The following conditions apply to traffic interruptions on a rearranged cross-connection:

Protection switching requests may be suspended for up to 25 seconds during rearrangement.
Traffic interruptions due to rearrangement will vary from 1 second (OCn) to 3 seconds (Ethernet with LCAS disabled). A given cross-connection is not be rearranged more than once in response to a single optimization.
Rearrangement of traffic to or from an individual function group completes within 85 seconds. Rearrangement of all function groups completes within 200 seconds.
When LCAS is enabled on an Ethernet pack, the duration of the traffic interruption increases to a maximum of 30 seconds.

Disable LCAS prior to performing a rearrangement operation on an Ethernet/Data interface.

Complete the following steps to optimize backplane bandwidth.


1	From the System View menu, select Configuration → Optimize Backplane Bandwidth. Result: The Equipment Selection screen opens. The Equipment Selection screen will not open under the following conditions: If there are any existing test access sessions in the NE, you will see the following error message: “Optimize Backplane Bandwidth is not allowed when there are test access sessions existing in the NE.” If the NE is in Ring Upgrade mode, you will see the following error message: “Optimize Backplane Bandwidth is not allowed when the NE is in Ring Upgrade mode.”
2	From the Equipment Selection screen, highlight the required functional pack or the shelf. Only the system and function slots equipped with LNW45 (when the Mains are equipped with non-VLF Mains), LNW49 (when the Mains are equipped with non-VLF Mains), LNW63, LNW70/LNW170, LNW73C/LNW73C, LNW74, LNW78, or LNW87 circuit packs will be displayed in the equipment selection screen.
3	Click Select. Important! Defragmentation will not be initiated if one of the following conditions exist: If any test access sessions exist on the NE. If the system is in ring upgrade mode.
4	Important! Optimizing backplane bandwidth for the System (All) may take up to four minutes, and protection switching may be disabled for up to 25 seconds during optimization. A confirmation window opens warning you that execution of this command may affect NE service. Choose one of the following: Yes- to initiate optimization. No - to close the message box, then click Close to return to the NE view. Result: A confirmation message will appear in the Most Recent Command status bar of the CIT System View. End of steps