This chapter contains a description and configuration information for the SONET Automatic Protection System (APS) which may be used to provide line and card redundancy for BXM OC-3 and OC-12 cards. Refer to the Cisco WAN Switch Command Reference for further information on configuration and monitoring commands.

This chapter contains the following:

Introduction

Automatic Protection Switching provides a standards based line-redundancy for BXM OC-3 and OC-12 cards. With Release 9.2, the BXM OC-3 and BXM OC-12 cards support the SONET APS 1+1 and APS 1:1 standards for line redundancy which is provided by switching from the working line to the protection line. The working line is normally the active line, and the protection line is normally the standby line.

The APS 1+1 and APS 1:1 protocols that are supported by the BXM are listed in Table 9-1 and shown in Figure 9-1 and Figure 9-2, respectively. APS 1+1 Annex B has the same general layout as shown in Figure 9-1, except that the active line is called the primary, and the standby line is referred to as the secondary.

Table 9-1: BXM SONET APS

APS 1+1	The APS 1+1 redundancy provides card and line redundancy, using the same numbered ports on adjacent BXM backcards.
APS 1:1	The APS 1:1 redundancy provides line redundancy, using adjacent lines on the same BXM backcard.
APS 1+1 Annex B	The APS 1+1 Annex B redundancy provides 1+1 high-speed protection, which can be configured only for bi-directional, non-revertive protection switching. For Annex B, the active line is referred to as the "primary section" and the standby line is referred to as the "secondary section". Manual switching (switchapsln) is not allowed in the APS 1+1 Annex B implementation.

Automatic Operation

SONET Automatic Protection Switching configures a pair of SONET lines for line redundancy so that the interface hardware automatically switches from a working line to the protection line or vice versa within a specified period after an active line failure.

Upon detection of a signal fail condition (i.e., LOS, LOF, Line AIS, or Bit Error Rate in excess of a configured limit) or a signal degradation condition (i.e., BER exceeding a configured limit), the hardware switches from the working line to the protection line. This case assumes that the working line was the active line and the protection line was not in alarm.

If the "Revertive" option is enabled, (cnfapsln command), the hardware switches back to the working line from the protection line after a configured time period called "Wait to Restore" (cnfapsln command) has elapsed. The working line must be in a clear state for this to occur. The revertive option is the default for APS 1:1 but not for APS 1+1.

Coordination between the interfaces on the two ends of the lines is provided via an in-band protocol.

Manual Operation

The switchapsln command may be used to control switching manually. The last user switch request (switchapsln) per line pair is saved by switch software so that the APS can be configured correctly in the event of a node rebuild.

Figure 9-1: APS 1+1 Redundancy

Figure 9-2: APS 1:1 Redundancy

Operation Criteria

APS cards provide both front and backcard LED displays providing line and card status active and standby status.

APS Front Card Displays

The front card LED functions are listed in Table 9-2.

Table 9-2: BXM Front Card LED Display

LED	Description
Card LED, Green	Active
Card LED, Yellow	Inactive
Port LED, Green	Line is active
Port LED, Yellow	Line is standby

APS 1+1 LED Displays

The backcards used for APS 1+1 with front card redundancy have an LED which indicates whether the backcard can be pulled out for service replacement.

For example, all the lines on the card except one may be working properly and therefore the card needs to be replaced. The backcard LED functions are listed in Table 9-3.

Note In the APS 1+1 configuration, when the primary card is active and the protection line is active, LEDs on both backcards are green. The LED of the secondary is green because that backcard is carrying traffic. The LED of the primary backcard is green, because that is in the physical path of the front card in receiving traffic from the protection line. When the backcard LED is green do not pull out the backcard, because it will disrupt traffic. When the LED is yellow it is OK to pull out the backcard, but it should be put back as soon as possible, because the card will be needed in the event of a switchover.

Table 9-3: BXM Back Card for APS 1+1 LED Display

LED	Description
Green	The card has at least one active line and may not be removed without affecting service.
Yellow	The card has no active lines and my be removed.
Red	Not used and not applicable.

APS 1+1 (Card and Line Redundancy)

The APS 1+1 feature requires two BXM front cards, an APS redundant frame assembly, and two redundant type BXM backcards. The two redundant BXM backcards are plugged into the APS redundant frame assembly as shown in Figure 9-3. The types of available backcards are:

The types of redundant backcard and backplane sets required are:

BPX-RDNT-LR-155-8 (8 port, long reach, SMF, SC connector)
BPX-RDNT-LR-622 (single port, long reach, SMF, FC connector)
BPX-RDNT-SM-155-4 (4 port, medium reach, SMF, SC connector)
BPX-RDNT-SM-155-8 (8 port, medium reach, SMF, SC connector)
BPX-RDNT-SM-622 (single port, medium reach, SMF, FC connector)
BPX-RDNT-SM-622-2 (2 port, medium reach, SMF, FC connector)

Each of the listed model numbers includes two single backcards and one mini-backplane (providing cross coupling of two backcards).

The single backcards and mini-backplane can be ordered as spares. Their model numbers are:

BPX-RDNT-BP= (common backplane for all redundant APS backcards)
BPX-LR-155-8R-BC= (for BPX-RDNT-LR-155-8)
BPX-LR-622-R-BC= (for BPX-RDNT-LR-622
BPX-SMF-155-4R-BC= (for BPX-RDNT-SM-155-4)
BPX-SMF-155-8R-BC= (for BPX-RDNT-SM-155-8)
BPX-SMF-622-R-BC= (for BPX-RDNT-SM-622)
BPX-SMF-622-2R-BC= (for BPX-RDNT-SM-622-2)

Figure 9-3: APS 1+1 Redundancy, Installing APS Backcards in APS Redundant Backplane

Traffic protected by APS 1+1 redundancy is carried via the working line and the protection line simultaneously (see Figure 9-4). Bridging is implemented such that the same payloads are transmitted identically over the working line as the protection line.

The receiver terminating the APS 1+1 has to select cells from either the working or protection line and be able to forward one consistent traffic stream. Since both working and protection line transport identical information, the receiving ends can switch from one to the other without the need for coordinating with the transmit end.

Figure 9-4: SONET APS 1+1 Detail

To set up APS, the addapsln command is used.

The addapsln command defines which line is working and which is protection.
Before you can execute the addapsln command for a line pair, the protection line must be in the standby state.
If the addapsln command is executed, the working line is always initially selected.

When no port on a BXM is configured for APS, each backcard of the pair may be used independently by independent front cards. The switch software disallows configuration of APS if independent usage is detected. There must be no active lines on the card that is selected to be the secondary card.

With previous card cages, because of the positioning of mechanical dividers, the APS card pairs can only be inserted in certain slots. These are slots 2 through 5 and 10 through 13. The mechanical dividers are located at slots 1 and 2, 5 and 6, 9 and 10, and 13 and 14.

With current card cages, this limitation is removed, and the APS card pairs can be located anywhere, except BCC cards slots 7 and 8, and ASM card slot 15.

An APS 1+1 redundant card pair must be in adjacent slots (2,3 or 4,5 etc.).

APS +1 Redundancy Criteria

The APS 1+1 redundancy is implemented by first setting up Y-redundancy, then adding APS.

When card redundancy is implemented, the two BXM front cards must reside in the same two adjacent slots as the APS backcards which must be inserted into the APS redundant backplane assembly. The working lines on the backcard must be connected to the same slot as the primary front card and the protection lines connected to the same slot as the secondary front card.

The switching of the front cards is controlled by switch software under the Y-redundancy protocol. The switch software performs switching between the two cards in the event of a front card failure, front card downed, front card failing self-test, etc.

The user may add APS at any time after Y-redundancy is configured as long as the protection line is in the standby state. The user may add APS even if lines and trunks are upped and the card is passing traffic.

Note Normally when APS and card redundancy are implemented together, the term YRED really means card redundancy, as in this case there is no Y-cabling involved. An exception exists when the BXM is attached to a MGX 8220 (feeder shelf) or other device which does not support APS. In that case, Y-cables or straight cables may be used with APS.

When APS is configured on a card pair, switch software checks to ensure that both cards match and support APS.

For APS 1+1 redundancy, the same numbered ports on adjacent BXM backcards are used. The maximum number of connections supported does not change, as the complete connection capability of the cards is available.

Note Using only one front card and two backcards is not a valid configuration when adding APS capability, and the APS alarm capability is reduced when the standby card is not available.

Application Notes for APS 1+1

Using switchcdred/switchyred command

Note Entering switchcdred or switchyred execute the same command. The newer name is switchcdred which replaces switchyred, but switchyred may still be used for those familiar with that command.

The switchcdred (switchyred) command can be used to switch between an active and standby front card in an APS 1+1 configuration. For example, you might want to do this to test the standby front card.

Following a switchcdred (switchyred), or active card reset, the BXM card is sent a message from switch software to have it perform an APS switch to align itself with the last user switchapsln switch request. If the last user request is "clear", full automatic APS switching is in effect with the working line in the active state by default. When there is no last user switch request to switch any particular line (i.e., protection line), the working line becomes active.

Note In the APS 1+1 configuration, if the protection line is active and the last user request is "clear", a switchdred will cause the working line to be active if there is no line condition on working line. When APS 1+1 comes up, it will come up on the working line if the working line is clear. When a switchcdred is issued, the active card also comes up on the working line if the working line is clear and there is no user request. In the case where the working line is in alarm or there is a user request to switch to the protection line (switchapsln), the card will first come up on the working line. Then the card will detect the alarm or the user request and switch to the protection line.

Other Notes:

Note In the APS 1+1 configuration, if the last user request was a W->P switch, then dsplog will log a W->P switching event when a switchcdred is issued. On a switchcdred, the newly active card comes up on working line first. Then it responds to a user request to switch from working to protection by switching to the protection line and sending an event notification to that effect. The event notification can be seen in the event log by using the dsplog command.

Note It may be necessary to perform a switchcdred (switchyred) command after performing a service switch with the switchapsln command so that the backcard that the service switch selects has its associated front card active.

Some switchapsln Notes

With APS 1+1, when repetitive switchapsln commands are issued, up to two in a row can be executed sequentially, when alternating between options 3 and 4 (forced switch), or 5 and 6 (manual switch), but no more. Attempts to execute a third switchapsnln will not succeed, and the following error message is displayed:

"Cannot request manual W->P when manual P->W switch in progress"

If users desire to perform repetitive switchapsln commands, they need to issue a clear switch between each W-P, P-W pair of commands, for example:

switchapsln 2.1  1

Configuration Procedure, APS 1+1

The following is an example of configuring APS 1+1 redundancy:

Step 1 Verify that appropriate front and back cards are installed along with APS two-card daughterboard.

Step 2 Ensure that lines are connected, for example on port 1 of BXM card in slot 2 and port 1 of BXM card in slot 3.

Step 3 Execute the following commands and verify chan half= no, and standard= GR-253 (default)

cnfcdaps 2.1 N 1

cnfcdaps 3.1 N 1

Step 4 Execute the following command, for example, for redundant line on port 1 for BXM OC-3 cards and APS backcards in slots 2 and 3 of the BPX:

addcdred 2 3

Step 5 addapsln 2.1 3.1 1 {addapsln<slot.port> <slot.port> <1|2|3|..>

Note The last entry, "1", in the addapsln command specifies the type of APS, in this example APS 1+1.

Step 6 cnfapsln 2.1

Step 7 upln 2.1 {or uptrk, as applicable

APS 1:1 (Line Redundancy)

The APS 1:1 feature provides port and line redundancy for a single BXM front card and associated OC-3 or OC-12 redundant backcard.

There is no new hardware required to support APS 1:1. A single front card with a standard backcard is used.

Two adjacent lines on the same card are used. The maximum number of connections supported by a non-enhanced BXM card is reduced by half for APS 1:1 operation. Using enhanced BXM cards, the number of available connections is not decreased.

Similarly to APS 1+1, Sonet APS 1:1 requires that for every working line, there must exist a redundant protection line (see Figure 9-5). However, unlike the 1+1 case, traffic protected by the redundancy must be carried on the protection line only when a failure occurs on the working line. In the case of no failure, the protection line can transport idle traffic, `same' traffic as working line, or extra traffic. Since the protection line is not guaranteed to carry real traffic until the transmit end is informed of the failure and switches, this coordination between the equipments at both ends and thus is more complex.

Figure 9-5: SONET APS 1:1 Detail

To set up APS, the addapsln command is used.

Before the addapsln is used, the switch software will not attempt to use or monitor the protection line; only the working line is used.
If the addapsln command is used with a working line in place, the working line is always initially selected.

General Criteria

APS 1:1 cannot be configured on cards already configured for YRED. They cannot be configured concurrently. Use APS 1 + 1 instead.

APS 1:1 configuration requires that the user add the APS configuration to a line before upping the line.

APS 1:1 configuration requires that the user down a line prior to deleting the APS configuration on the line.

APS 1:1 can only be configured for bi-directional operation and revertive switching.

Configuration Criteria

The redundant lines must be adjacent. In addition, the lines which may be paired are:

1 and 2
3 and 4
5 and 6
7 and 8

Either of the two lines may be designated as working line and the other as the protection line.

The switching of the working and protection lines is controlled by BXM firmware/hardware under the APS protocol.

The BPX firmware/hardware performs switching between the protection and working lines in the event of a line or port failure.

The user may add APS as long as the working and protection line are in the standby state. Lines and trunks can only be upped after APS 1:1 is added.

Configuration Procedure, APS 1:1

The following is an example of configuring APS 1:1 redundancy:

Note Before configuring for APS 1:1 redundancy, all card connections must be deleted using the delcon command

Step 1 Ensure that lines are connected, for example on ports 1 and 2 of a BXM in slot 3.

Note The last entry, "2", in the addapsln command specifies the type of APS, in this example APS 1:1.

Step 2 Execute cnfcdaps and verify chan half= yes (not default), and standard= GR-253 (default)

cnfcdaps 3.1 Y 1

Step 3 addapsln 3.1 3.2 2 {addapsln<slot.port> <slot.port> <1|2|3|4|5>

Step 4 upln 3.1 {or uptrk, as applicable

APS 1 +1 Annex B Card and Line Redundancy

The APS 1 +1 Annex B feature is similar to the APS 1+1 feature, with the main difference being that APS 1+1 Annex B redundancy only can be configured for bi-directional operation and non-revertive switching.

General Criteria

APS 1 + 1 Annex B can only be configured for bidirectional operation and nonrevertive switching on a line.

Note In non-revertive switching, to avoid data loss, a line is not automatically switched back to active after a failure is corrected.

Configuration Procedure, APS 1+1 Annex B

The following is an example of configuring APS 1+1 redundancy:

Step 1 Verify that appropriate front and back cards are installed along with APS two-card daughterboard.

Step 2 Ensure that lines are connected, for example port 1 on BXM in slot 1 and port 1 on BXM in slot 2.

Step 3 Execute the following commands and verify chan half= no, and standard= GR-253 (default)

cnfcdaps 1.1 N 1

cnfcdaps 2.1 N 1

Step 4 Execute the following command, for example, for redundant line on port 1 for BXM OC-3 cards and APS backcards in slots 1 and 2 of the BPX:

addcdred 1 2

Step 5 addapsln 1.1 2.1 3 {addapsln<slot.port> <slot.port> <1|2|3|..>

Note The last entry, "3", in the addapsln specifies the type of APS, in this example APS 1 + 1, Annex B.

Step 6 cnfapsln 1.1

Step 7 upln 1.1 {or uptrunk, as applicable

Test Loops

The test commands addlnloclp and addlnrmtlp are service affecting even when APS is configured. In all APS configurations if the working line is looped, both lines will be looped and traffic disrupted.

Notes on APS Messages

When adding an APS 1+1 line or trunk using addapsln, if the working slot's paired redundant slot is not a legal protection slot, or if firmware can't determine what the paired slot is, an invalid slot pairing exists and one of the following two messages will be displayed:

"Protection card specified by user does not match HW."

"Working card specified by user does not match HW."

The redundant card information can be displayed with the dspcd command under the "Backcard Installed" heading. For example, if a redundant pair is configured with a primary slot of 2 and a secondary slot of 3, the dspcd 2 command should display "RedSlot: 3", and the dspcd 3 command should display "RedSlot: 2". The following example is of dspcd 2:

swwye     TN       silves        BPX8620      9.2.20       Aug. 9  1999
 
Detailed Card Display for BXM-155 in slot 2
 
Status:          Active 
Revision:        DDA                 Backcard Installed
Serial Number    652774                Type:          LM-BXM
Fab Number       28-2158-02            Revision       EW
Queue Size       228300                Serial Number  1..1...
Support: 4 Pts, OC-3, FST,  VcShp       Supp: 4 Pts, OC-3, SMF, RedSlot:3
Support: VT, ChStLv 2, VSIlvl 2        
Support: APS (FW, HW1+1)
Support: OAMLp, TrfcGen
#Ch: 8128, PG[1] :8123
#Sched_Ch:16284
 
Last Command: dspcd 2

APS Alarms

The APS alarms are listed in Table 9-4. The listing includes the class or state of the alarm, minor, major, info, or clear.

Statistical Alarms

Statistical alarms are not cleared when a YRED switch occurs. The user can clear these stats as appropriate.

Note On the active line/trunk, alarms (e.g., LOS and LOF) and statistics (e.g., error counters) are supported. On the standby line/trunk, alarms are supported but not statistics.

Summary statistics are not supported on a standby line/trunk.

Table 9-4: APS Alarms

Class	Name	Description
Minor	APS Standard Mismatch	In a 2 card APS 1+1 configuration, one card is programmed for GR-253 and the other card is programmed for ITUT.
Minor	APS Card Missing	Indicates that either a BXM frontcard or backcard supporting this APS line is detected as missing by a BXM.
Clear	APS OK	APS line is up with no alarms.
Clear	APS Deactivated	APS line is down.
Minor	APS Lines looped	APS line is looped.
Minor	APS Remote Signal Failure	A remote signal failure indicates that there is a problem with the far end signalling information in the K1K2 bytes.
Minor	APS Channel Mismatch	Can only happen in bidirectional mode and indicates that there is a problem with the underlying APS channel protocol. The receive K2 channel number does not equal the transmit K1 channel number.
Minor	APS Protection Switch Byte Failure	Protection Switch Byte failure or PSB. In bidirectional mode indicates that there is an invalid K1 byte. The receive K1 request does not match the reverse request and is less than the transmit K1 request. In all modes a PSB alarm indicates that K1/K2 protocol is not stable.
Minor	APS Far End Protection Failure	Far end protection failure indicates that the far end's protection line is failing. When there is Signal Failure on the protection channel, the remote end sees Far End Protection Fail.
Minor	APS Architecture Mismatch	Architecture mismatch means that the APS configuration on one end of the line does not match the APS configuration at the other side of the line. Specifically GR-253 at one end and ITUT at the other or 1+1 at one end and 1:1 at the other.
Info	APS Init/Clear/Revert	A BXM APS event indicating that the BXM APS has been initialize or a clear switch has occurred or a revert switch has occurred.
Info	Cannot perform a Clear/Revert switch	A BXM APS event indicating that the BXM APS was unable to perform a clear or revertive switch.
Info	APS Manual switch	A BXM APS event indicating that the BXM APS has performed a user requested manual switch.
Info	Cannot perform a Manual switch	A BXM APS event indicating that the BXM APS was unable to perform a user requested manual switch.
Info	APS Signal Degrade LoPri switch	A BXM APS event indicating that the BXM APS performed a switch due to a low priority signal degrade condition. An automatically initiated switch due to a "soft failure" condition resulting from the line BER exceeding a pre-selected threshold (cnfapsln).
Info	Cannot perform a Signal Degrade LoPri switch	A BXM APS event indicating that the BXM APS was unable to perform a switch due to a low priority signal degrade condition.
Info	APS Signal Degrade HiPri switch	A BXM APS event indicating that the BXM APS performed a switch due to a high priority signal degrade condition. An automatically initiated switch due to a "soft failure" condition resulting from the line BER exceeding a pre-selected threshold (cnfapsln).
Info	Cannot perform a Signal Degrade HiPri switch	A BXM APS event indicating that the BXM APS was unable to perform a switch due to a high priority signal degrade condition.
Info	APS Signal Failure LoPri switch	A BXM APS event indicating that the BXM APS performed a switch due to a low priority signal failure condition. An automatically initiated switch due to a signal failure condition on the incoming OC-N line including loss of signal, loss of frame, AIS-L defects, and a line BER exceeding 10-3.
Info	Cannot perform a Signal Failure LoPri switch	A BXM APS event indicating that the BXM APS was unable to perform a switch due to a low priority signal failure condition.
Info	APS Signal Failure HiPri switch	A BXM APS event indicating that the BXM APS performed a switch due to a high priority signal failure condition. An automatically initiated switch due to a signal failure condition on the incoming OC-N line including loss of signal, loss of frame, AIS-L defects, and a line BER exceeding 10-3.
Info	Cannot perform a Signal Failure HiPri switch	A BXM APS event indicating that the BXM APS was unable to perform a switch due to a high priority signal failure condition.
Info	APS Forced switch	A BXM APS event indicating that the BXM APS has performed a user requested forced switch.
Info	Cannot perform a Forced switch	A BXM APS event indicating that the BXM APS was unable to perform a user requested forced switch.
Info	APS Lockout switch	A BXM APS event indicating that the BXM APS has performed a user requested switch which prevents switching from working line to protection line from taking place.
Info	Cannot perform a Lockout switch	A BXM APS event indicating that the BXM APS was unable to perform a user requested lockout of protection switch.
Info	WTR switch	A BXM APS event indicating that the BXM APS performed a switch due to a Wait to Restore timeout. A state request switch due to the a revertive switch back to the working line because the wait-to-restore timer has expired.
Info	Cannot perform a WTR switch	A BXM APS event indicating that the BXM APS was unable to perform a switch due to a WTR condition.
Info	Exercise switch	Not supported.
Info	Cannot perform a Exercise switch	Not supported.
Info	Reverse switch	A BXM APS event indicating that the BXM APS performed a switch due to a reverse request. A state request switch due to the other end of an APS bi-directional line performing an APS switch.
Info	Cannot perform a Reverse switch	A BXM APS event indicating that the BXM APS was unable to perform a switch due to a reverse switch request.
Info	No Revert switch	A BXM APS event indicating that the BXM APS performed a switch due to a Do not Revert. A state request due to the external user request being cleared (such as a forced switch) while using non-revertive switching.
Info	Cannot perform a No Revert switch	A BXM APS event indicating that the BXM APS was unable to perform a switch due to a Do not Revert switch request.
Minor	Standby Line Section Trace	APS standby line alarm.
Minor	Standby Line Path Trace	APS standby line alarm.
Minor	Standby Line path yellow alarm	APS standby line alarm.
Minor	Standby Line path AIS	APS standby line alarm.
Minor	Standby Line loss of pointer	APS standby line alarm.
Minor	Standby Line loss of cell	APS standby line alarm.
Minor	Standby Line plcp yellow alarm	APS standby line alarm.
Minor	Standby Line plcp out of frame alarm	APS standby line alarm.
Minor	Standby Line yellow alarm	APS standby line alarm.
Minor	Standby Line alarm indication signal (AIS)	APS standby line alarm.
Minor	Standby Line out of frame alarm (LOF)	APS standby line alarm.
Minor	Standby Line loss of signal alarm (LOS)	APS standby line alarm.

Architecture Mismatch means that 1 side supports 1+1 and other end of line is configured for 1:1, or the directional or revertive parameter does not match. FW cannot bring the two ends into compliance on the fly; the user must correct the configuration error.

APS K1 Command Precedence

The possible conditions which may cause/prevent a switch are listed in Table 9-5. The list is arranged starting from highest precedence and ending with lowest precedence. Refer to the Cisco WAN Switching Command Reference for further description and information.

Table 9-5: K1 Switching Conditions

APS K1 Command Precedence
Lock out of Protection
Forced Switch
Signal Fail
Signal Degrade
Manual Switch
Wait To Restore
Reverse Request
Do not Revert
No Request

Command Reference

APS Command Summary

A number of commands have been added and modified to support APS. These are listed in Table 9-6, and defined in more detail in the following pages. Refer to the Cisco WAN Command Reference for information on commands not described here and for additional detailed information on commands.

Table 9-6: APS Commands

Command	Description
New Commands Added for Management of APS
cnfcdaps slot	Sets APS options on the card.
addapsln slot1.port1 slot2.port2 protocol	Adds APS.
delapsln slot.port	Deletes APS.
dspapsln	Displays status of APS line pairs.
switchapsln slot.port (option 1...6, S)	Controls the APS user switching interface.
cnfapsln slot.port	Configures the APS parameters on a line.
New Commands for Card Redundancy for APS 1+1
addcdred	Adds redundancy across two cards.
dpscdred	Display redundant cards.
delcdred	Deletes redundancy configuration for cards.
switchcdred	Switches active and redundant cards.
Commands modified for use with APS
cnfbkcd	Modified to APS options.
dspalms	Added row for "APS Alarms" which lists Minor and Major APS alarms.
dspcd	Displays front and backcard APS attributes. For the front card, displays that card supports APS 1+1 and APS 1:1. For the back card, displays if backcard is a redundant backcard, and if so, the slot number of the redundant backcard. Also, displays APS mismatch conditions.
dspsv3	Modified to display APS alarms pending.
dsplog	Displays APS alarms.
addyred	Modified to prevent invalid configurations when combined with APS.
delyred	Modified to prevent invalid configurations when combined with APS.

addapsln/delapsln

The addapsln command adds APS for BXM OC-3 or OC-12 lines. The user specifies the desired APS Protocol when adding a new APS line pair. The delapsln command deletes APS for the lines.

Syntax

addapsln <slot.port1> < slot.port2> <protocol>

Parameter

Description

slot.port1

The desired working line number.

slot.port2

The desired protection line number.

protocol

1: 1+1

2: 1:1

3: 1+1 Annex B

4: 1+1 Ignore K1K2 bytes

When the command is exercised, the switch software does the following:

Verifies that the slot.port arguments support APS.
Verifies that the appropriate backcard is installed.
Verifies that the protection port is not already active.
If card redundancy is already configured for the 2 slot case (APS 1+1), verifies that the primary card is the same type as the working line card.

Example:

The user is required to enter the slot.port pair and the protocol option. If the user does not enter the protocol option a menu listing the options is displayed.

Example:
 
alexa       TRM    genre    BPX 15        9.2         Sep. 9 1998           16:08 PDT 
 
                            Actv     Current Line      Current APS          Last User
Work/Protect    Protocol    Line     Alarm Stat        Alarm StatCard       Switch Req
2.1 3.1         1+1         WORK     OK                APS OK               Clear
 
Command: addapsln 2.1 3.1 1

addcdred

Note Entering addcdred or addyred executes the same command. The newer name is addcdred which replaces addyred, but addyred may still be used for those familiar with that command.

The addcdred command enables card and line redundancy for the cards on the IGX and BPX. It lets you add card and line redundancy for APS 1+1 across two BXM OC-3 or OC-12 cards. You also use it before enabling APS 1:1 line redundancy. It works similarly to the addyred command.

Syntax

addcdred <primary slot> <secondary slot>

Example 1

addcdred 2 3

Related Commands

delcdred, dspcdred, prtcdred, switchcdred

Attributes

Privilege	Jobs	Log	Node	Lock
1-4	No	Yes	BPX	Yes

Table 9-7: addcdred-Parameters

Parameter	Description
primary slot	Specifies the slot number of the primary card set.
secondary slot	Specifies the slot number of the secondary card set.

Description

Add redundant line on port 1 for BXM OC-3 card and APS backcards in slots 2 and 3 of the BPX.

Use the addcdred command to specify the slots of the primary and secondary (standby) cards that form the redundant pair.

When configuring APS 1+1 card and line redundancy, you must execute the addcdred command before using addapsln.

Redundant card sets must have the following characteristics:

The primary and secondary card sets must be identical.
For APS 1+1 card redundancy only, the primary and secondary card sets must reside in adjacent slots. (This restriction only applies to APS 1+1 Card and Line Redundancy.) APS 1+1 is not supported on a single-card option.
Secondary card sets must not currently be active.
Neither the primary nor secondary card set may already be part of a redundant set.
Redundancy applies to the entire card and not specific trunks or lines.

In both the single and multi-port card sets, if the secondary card set becomes active, the primary card set serves as its backup (assuming the primary card set is complete and not failed). You cannot use the addcdred command on empty card slots. If one or both of the card slots is empty, and you use the addcdred command, the command will fail.

Note When SONET Automatic Protection Switching (APS) is configured in release 9.2, you will not be able to use the addyred or delyred commands on a card configured for APS 1:1 architecture. That is, you will not be able to execute the addyred command, then configure the APS 1:1 architecture. Similarly, you will not be able to configure APS 1:1, then execute the addyred command. You will be blocked from executing these commands at the command line interface.

In Release 9.2, to ensure that only cards with the Idle Code Suppression feature enabled on them are allowed to be a Y-redundancy pair, addcdred blocks cards that have different idle code suppression capability.

cnfapsln

The cnfapsln command allows the user to configure various APS line parameters.

Syntax

cnfapsln <slot.port> <SFBER> < SDBER> <Revertive_mode> <WTR> <Direction>

Parameter	Description	Range
slot.port	Slot and port of the line to be configured.	-
SFBER	Signal Fail Bit Error Rate threshold which will cause an APS switch.	Default 3, range 3 - 12
SDBER	Signal Degrade Bit Error Rate for line degradation.	Default 5, range 5 - 12
Revertive mode	Revert to Working line after WTR interval expires. User enters numeral 0 or 1. This only applies to automatic switches. Revertive switching does not take place as a result of user-initiated switching.	Default 1, range 0, 1 0 = revertive 1 = non-revertive
WTR	Wait to restore interval. After a switch from a Working to a Protection line, this is the interval in minutes to wait before attempting to switch back to the Working line. This is not applicable if the Revertive Mode option is set to N (Non-revertive).	Default 5: range 1 - 12 minutes
Direction	Direction of switching. Uni-directional is switching in only one direction. With Bidirectional, after one side switches, then the other side also switches.	Default is 0, unidirectional, range 0/1 where 0 is unidirectional and 1 is bidirectional.

Example:
 
alexa       TRM    genre         BPX 8620      9.2         Sep. 9 1998    16:15 PDT 
 
APS Configuration parameters for Working, Protection lines 1.1, 1.2 
 
APS Protocol:                                        1+1
 
Signal Fail BER threshold (10 to the -n):            3
Signal Detect BER threshold (10 to the -n):          5
Revertive Switching:                                 Yes
Wait to Restore Timer:                               5 minutes
Uni/Bi Directional Switching:                        Unidirectional
 
Command:cnfapsln 1.1

cnfcdaps

The cnfcdaps command sets the APS 1:1 channels option and the APS standard option on the card.

Syntax

cnfcdaps <slot> <Y/N> < 0/1>

Parameter	Description
slot	Specifies the desired BXM APS slot number.
Y/N	Disable/Enable the channels option on the card.
0/1	0 = ITUT, 1 = GR253

When the command is exercised, the switch software does the following:

Checks that the slot is a BXM OC-3 or OC-12 card.
Verifies that the BXM card version supports APS.
Issues a warning if any trunks or lines are upped on the card, and if so, issues a warning that a card mismatch may occur.
Issues a warning if this card is Y redundant and its redundant card has a different APS standard configured.

bpx1           TN    StrataCom       BPX 8620  9.2    May  11 1999 09:38 PDT 
>
>APS Card Configuration parameters for card 6
>
>Channels Halved for APS operation:              Yes
>APS Standard for Card:                          GR-253
>
>
>
>
>
>
>
>
>
>
>
>                                                                                
>This Command:cnfcdaps 6  
>
>
>Enter channels halved option (Y or N):
>

dspapsln

The dspapsln command displays the currently configured APS lines and their status.

Syntax

dspapsln

>bpx1           TN    StrataCom       BPX 8620  9.2    May  11 1999 09:37 PDT 
>
>             Actv Active Line      Standby Line     Current APS      Last User
>Work/Protect Line Alarm Status     Alarm Status     Alarm Status     Switch Req
> 6.3  6.4    WORK OK               OK               APS OK           Clear
> 6.5  6.6    WORK OK               OK               APS OK           Clear
> 6.7  6.8    PROT OK               Loss of Sig(RED) Loss of Sig(RED) Clear
>10.1 11.1    WORK OK               OK               APS OK           Clear
>10.2 11.2    WORK OK               OK               APS OK           Clear
>10.3 11.3    NONE Deactivated      APS Deactivated  APS Deactivated  Clear
>10.4 11.4    NONE Deactivated      APS Deactivated  APS Deactivated  Clear
>10.5 11.5    NONE Deactivated      APS Deactivated  APS Deactivated  Clear
>10.6 11.6    NONE Deactivated      APS Deactivated  APS Deactivated  Clear
>10.7 11.7    WORK OK               OK               APS OK           Clear
>10.8 11.8    WORK OK               OK               APS OK           Clear
>
>                                                                                
>Last Command:dspapsln

dsplog/dspalms

Syntax

dsplog

dspalms

APS alarms are displayed with the dsplog command, and propagated to the Cisco WAN Manager. Refer to Notes on APS Messages, in the preceding paragraphs, for a listing that includes the Class and dsplog text of each APS alarm.

Also, the dspalms command includes a row for APS alarms.

Example:
 
alexa       TRM    genre         BPX 15      9.2       May. 9 1998           16:35 PDT
 
 
Alarm summary   (Configured alarm slots: None)
Connections Failed:                                    None
TRK Alarms:                                                None
Line Alarms:                                               None
Cards Failed:                                              None
Slots Alarmed:                                             1 Major
Missing Cards:                                             1
Remote Node Alarms:                                        1 Minor
Remote Domain Alarms:                                      None
APS Alarms:                                   1 Major, 1 Minor
 
Interface Shelf Alarms:                                    None
ASM Alarms:                                                None
 
 
 
                                                                                
Last Command: dspalms

switchapsln

The switchapsln command controls the APS user switching interface.

Syntax

switchapsln<slot.port> <switchoption> [S]

Parameter	Description
slot.port	The desired working line number
switch option	1. Clear	Clears last user request.
	2. Lockout	Prevents specified APS pair from being switched to protection line. If protection line is already active, switch is made back to the working line.
	3. Forced switch (Working to Protection line)	Forced Working to Protection line switch. If Working line is active, switch is made to Protection line unless the Protection line is locked out or in the SF condition or Forced Switch is already in effect. Forces hardware to switch to the Protection line even if it is in alarm.
	4.Forced switch (Protection to Working line)	Protection line is active, switch is made to Working line unless a request of equal or higher priority is in effect. This Protection to Working line switch only applies to APS 1+1.
	5. Manual switch (Working to Protection Line)	Switch from Working to Protection line unless a request of equal or higher priority is in effect. Note Not applicable to APS 1+1, Annex B.
	6. Manual switch (Protection to Working line)	This Protection to Working line switch only applies to APS 1+1. Note Not applicable to APS 1+1, Annex B.
S	If S is entered as an additional parameter, a service switch is performed for all ports on the card such that all lines are forcibly switched to one backcard so that the other card of the pair can be removed for service. Be sure that the associated frontcard is active for the backcard that is to remain in the rack. You may have to perform a switchcdred command so that the backcard that the service switch changes to has its associated front card active.

switchcdred/switchyred

Switches active and redundant cards used for SONET APS (Automatic Protection Switching). The switchcdred command is the same as the switchyred command, and you can use it on any Y-cable redundancy card pair. You typically only would use the switchcdred command to perform diagnostics or maintenance, and you need to remove and service the active card.

Syntax

switchcdred <slot.port> <slotport>

Example 1

switchcdred

Note When implementing two-card APS 1+1, it must be implemented with card redundancy (may also be referred to as "Y-redundancy", because the new card redundancy commands you use to configure APS 1+1 are based on Y-redundancy commands used in releases previous to release 9.2 APS commands.)

When there is a front card failure, front card downed, or the front card fails a self-test, the card switchover should happen automatically (that is, you should not need to execute the switchcdred command for the card switchover to happen.) An automatic switchover typically occurs when the switch software determines that the card is in a worse condition than the redundant pair (that is, a card is in a failed state due to a condition such as self-test, background test, fatal errors.) If a standby card is not available, the switchcdred command will not be executed.

Typically, when APS and card redundancy are implemented together, the term Y-redundancy actually refers to card redundancy because there is no Y cable connecting two backcards to one line. With SONET APS 1+1 card redundancy, there is a primary and a secondary front card/back card pair. The redundant front card must be in Hot Standby state before a switchover can occur. When a front card failure is detected, the switchover should happen automatically (when card redundancy has been implemented). However, for the APS application, the active line is not switched if the line status is good. If the line has Loss of Signal (or other defects), it will be switched to the redundant line. (The line refers to the physical cable attached to the output of the backcard.)

For APS 1+1, a front card can switch and become the standby card while its associated back card still has the active lines. The APS line will not switch during a card redundancy switch, unless the APS firmware detects that an APS switch is needed.

Following a switchcdred, or active card reset, the BXM card is sent a message from switch software to have it perform an APS switch to align itself with the last user switchapsln switch request. If the last user request is "clear", full automatic APS switching is in effect with the working line in the active state by default. When there is no last user switch request to switch any particular line (i.e., protection line), the working line becomes active.

Note In the APS 1+1 configuration, if the protection line is active and the last user request is "clear", a switchcdred will cause the working line to be active if there is no line condition on the working line. When APS 1+1 comes up, it will come up on the working line if the working line is clear. When a switchcdred is issued, the active card also comes up on the working line if the working line is clear and there is no user request. In the case where the working line is in alarm or there is a user request to switch to the protection line, the card will first come up on the working line. Then the card will detect the alarm or the user request and switch to the protection line.

Other Notes:

Note In the APS 1+1 configuration, if the last user request was a W->P switch, then dsplog will log a W->P switching event when a switchcdred is issued. On a switchcdred, the newly active card comes up on working line first. Then it responds to a user request to switch from working to protection by switching to the protection line and sending an event notification to that effect. The event notification can be seen in the event log by using the dsplog command.

Note It may be necessary to perform a switchcdred command after performing a service switch with the switchapsln command so that the backcard that the service switch selects has its associated front card active.

Troubleshooting Notes

Introduction

Automatic Protection Switching (APS) is the ability to configure a pair of SONET lines for line redundancy so that hardware automatically switches from a Working line to a Protection line when the Working line fails, and vice versa. Each redundant line pair consists of a Working Line and a Protection Line. The concept of Working and Protection Lines is similar to the concept of Primary and Secondary Y Redundant cards. That is, the Working line is the logical line which the user refers to.

Left undisturbed, hardware performs line switching automatically. Upon detection of a Signal Fail condition (LOS, LOF, Line AIS or Bit Error Rate exceeding a configured limit) or a Signal Degrade condition (BER exceeding a configured limit), hardware switches from the Working Line to the Protection Line (assuming the Working line was the Active line and the Protection line is not in alarm). If the Revertive option is Enabled, hardware switches back to the Working line automatically after a configured time period called Wait to Restore has elapsed (assuming the Working line is now OK). Coordination between the two ends of the line is accomplished using the in-band protocol.

During setup, the commands addapsln, cnfcdaps, and cnfapsln are used to create the line-redundant pair. Also, appropriate front cards, back cards, and a special RDNT-BP daughter backplane are required for APS 1+1 configurations.

During operation, signal failure or signal degradation can cause APS "switchovers". A switchover is when the line that was active gives up control to its partner line. This partner line now becomes the "active" line, while the original active line becomes the "standby" line.

For APS line redundancy, the following problems can occur:

APS Configuration Problems
- Not Able to Correctly Set Up APS 1+1 Line Redundancy Configuration

The following sections describe possible APS configuration problems.

Not Able to Correctly Set Up APS 1+1 Line Redundancy Configuration

Description

The addapsln user interface command fails to execute correctly for APS 1+1 line addition.

Initial Investigation

The addapsln command is used to setup the APS line redundancy configuration. For APS 1+1 configurations, BPX software supporting APS and BXM firmware supporting APS must be used. Also the following hardware requirements must be met:

BXM-Enhanced OC-3 or OC-12 front cards. BXM -155-4 or BXM-155-8 frontcard of revision C or higher. BXM-622-2 or BXM-622-1 of revision E or higher.
RDNT-BP daughter backplane - special APS redundancy backplane
BXM OC-3 or OC-12 APS backcards (they have two connectors on the back instead of one and require the daughter backplane in order to fit into the BPX backframe.
Card redundancy (addcdred or addyred) must be set up on the card pair prior to addapsln, see section on Y-cable issues. APS does not use the special Y-cable, it uses straight cables on both ports to the remote port. The redundant card must be in adjacent slots.
Using a backcard frame containing internal card cage stiffeners requires that only slots 2-5 and 10-13 be used for APS 1+1 configurations. This is due to the stiffeners preventing the daughter backplane from fitting into the backcard frame.
A newer backcard frame removes the slot restriction of having to put daughter backplane and APS backcards in slots 2-5 and 10-13.

Workaround

None.

Unable to set up APS 1:1 line redundancy configuration

Description

The addapsln user interface command fails to execute correctly for APS 1:1 line addition.

Initial Investigation

For APS 1:1 configuration, two adjacent lines on the same card are used. No special hardware is required however the maximum connections supported must be reduced by half using the cnfcdaps command. FW and SW support of APS is required.

Workaround

APS 1:1 can be run on non APS enhanced BXM card by halving the number of channels the card can support (cnfcdaps). No special backcards are needed for APS 1:1.

Detailed Debugging

For APS 1:1 configuration the APS line must be configured (addapsln) before a line (upln) or trunk (uptrk) can be upped. Conversely, the line or trunk must be downed before the APS line can be deleted (delapsln). Use dspapsln to verify that the APS line has been added.

Operator information about APS architectures

Description

The cnfapsln user interface command fails to allow the user to configure any combination of APS architectures.

Initial Investigation

The APS configuration can be changed using the cnfapsln command, however not all combinations are allowed. Here is a table of combinations allowed and disallowed.

Table 9-8: Possible APS System Architectures

Mode

APS 1:1

APS 1+1, 1+1 ignore K1

APS 1+1 Annex B

Revertive

Non-revertive

Revertive

Non-revertive

Revertive

Non-revertive

Bi-

directional

Default

Not Valid

Valid option

Not Valid

Default

Uni-

directional

Not Valid

Valid option

Default

Not Valid

Once the APS configuration 1+1, 1:1, 1+1 Annex B, or 1+1 ignore K1 is chosen by the addapsln, it cannot be changed except by deleting the APS line (delapsln) and re-adding the APS line with the new configuration (addapsln).

Work Arounds

None.

Operational Problems

The following sections describe possible APS operational problems.

What the various APS switches mean

Description

There are ten reasons an APS switch may occur. These reasons can be seen logged using the dsplog command. When the BXM switches an APS line it returns an event message to the SWSW with the reason why it switched and which line is active.

Initial Investigation

The following list shows the possible conditions which may cause/prevent a switch. The list is arranged starting from highest precedence and ending with lowest precedence.

1. Lock out of Protection - An external user requested switch which prevents switching from working line to protection line from taking place.

2. Forced Switch - An external user requested switch which forces a switch from working line to protection line or vice-versa even if there is an alarm on the destination line.

3. Signal Fail - An automatically initiated switch due to a signal failure condition on the incoming OC-N line including loss of signal, loss of frame, AIS-L defects, and a line BER exceeding 10-3.

4. Signal Degrade - An automatically initiated switch due to a "soft failure" condition resulting from the line BER exceeding a pre-selected threshold (cnfapsln).

5. Manual Switch - An external user requested switch which requests a switch from working line to protection line or vice-versa but only if there is no alarm on the destination line.

6. Wait To Restore - A state request switch due to the a revertive switch back to the working line because the wait-to-restore timer has expired.

7. Exercise - Not supported

8. Reverse Request - A state request switch due to the other end of an APS bi-directional line performing an APS switch.

9. Do not Revert - A state request due to the external user request being cleared (such as a forced switch) while using non-revertive switching.

10. No Request - A state request due to the external user request being cleared (such as a forced switch) while using revertive switching.

Unable to perform APS external switch after forced or manual APS switch.

Description

The user performs a forced switch from the working line to the protection line (switchapsln Ln1 Ln2 3) and then another forced switch back to working line (switchapsln Ln1 Ln2 4). After this the user again tries to perform a forced switch to the protection line but sees nothing happen.

Investigation

Once a forced switch is made from the working line to the protection line and back again, a clear switch (switchapsln Ln1 Ln2 1) must be issued in order to perform another forced switch. This applies to APS manual and lockout switching also.

"Cannot request manual W->P when manual P->W switch in progress"

If users desire to perform repetitive switchapls commands, they need to issue a clear switch between each W-P, P-W pair of commands, for example:

switchapsln 2.1  1

APS manual switch to a line does not occur right away.

Description

The user has issued a manual switch either to working or protection line. The switch did not occur because the destination line was in alarm. When the alarm is cleared on that line the switch does occur.

Explanation

The BXM firmware remembers the "last user switch request" (also called external request) and tries to switch to that line when it becomes available.

Switch occurs after lockout issued.

Description

With protection line active, the user issues an APS switch lockout and a switch occurs back to the working line.

Investigation

This is normal operation. When the protection line is active and an APS switch lockout is issued, a switch to the working line will happen. The lockout function locks the working line as active. Only an external (user request) APS clear switch (switchapsln Ln1 Ln2 1) will disable the lockout.

APS switch made to a line in alarm.

Description

The user performs a forced switch to a line with a line alarm. The switch is successful making an alarmed line active with possible loss of traffic.

Investigation

It is normal operation for a forced switch to cause a switch to a line even though it may be faulty. This allows the user to "force" a switch to standby line even if it is in alarm. A traffic outage may occur. During a manual switch request, the BXM firmware decides whether the switch should occur and the switch may not occur if there is an alarm on the standby line. An APS clear switch will allow automatic switching to resume following a forced switch.

Reverse switch

Description

User performs a forced or manual switch on local end of APS line in bidirectional mode but other end indicates a reverse switch was performed.

Investigation

This is normal operation. A reverse switch in bidirectional mode occurs on the far end of the APS line when the local end of the APS line performs a switch for any reason.

APS switch occurs at the same time as a yred switch.

Description

Two related scenarios could cause this to occur.

1. A forced or manual switch is in effect. In dspapsln, the Last User Switch Request is forced or manual w->p or p->w. If a switchcdred/switchyred is performed (could be caused by card failure or physically removing card also) the front card switches and an APS switch occurs.

2. A clear switch is in effect. In dspapsln, the Last User Switch Request is clear. If a switchyred is performed (could be caused by card failure or physically removing card also) the front card switches and an APS switch occurs.

Explanation

Following a switchcdred/switchyred, or active card reset the BXM card will be instructed to perform an APS switch to align itself with the Last User Switch Request (switchapsln).When a yred (switchcdred) switch takes place on a BXM card pair being used for APS 1+1, the card being switched is sent configuration messages including the last user switch request. The BXM card will initially become active in an APS "clear" switch mode following a switchcdred or reset. This means that the APS switching is on automatic. However if the Last User Switch Request is a manual or forced switch, the software sends this request to the BXM, and the BXM will switch to this line if it is not already active. This switch is done to comply with the users last APS switch request.

In the second case, if the last user request is "clear", full automatic APS switching is in effect with the working line being active by default. When there is no last user switch request (switchapsln to protection, for example) to switch to any particular line, the working line will become active.

APS switch occurs after issuing an APS clear switch.

Description

User issues an APS clear switch (switchapsln Ln1 Ln2 1) command while protection line is active and a switch occurs to the working line.

Explanation

This is normal operation. An APS clear switch request causes the APS switching mechanism in the BXM to initialize. This will cause a switch back to the working line if the working line is in better shape than the protection line. If the protection line is not faulty, no switch will occur.

APS Switch Occurs even though APS Forced switch in effect.

Description

A forced switch to protection line is performed. LOS on protection line causes a switch back to working line even though a forced switch is in progress

Explanation

Signal Fail on Protection line has higher priority than Forced switch. Whenever the protection line is in failure, there will be a switch to working line, even if the working line is failed or there is a forced W->P in effect.

APS line is failing to switch

Description

The user issues an APS forced or manual switch request but no switch occurs

Investigation

This could be due to a forced, manual, or lockout switch being in progress and a clear switch is required (switchapsln Ln1 Ln2 1). Need to issue an APS clear switch (switchapsln) to exit forced, manual, or lockout switch state.

If running the ITUT APS standard protocol which does not report an Architecture Mismatch APS alarm the problem could be that one end of the line is bi-directional and the other is uni-directional.

Check that configuration is the same on both ends, specifically uni/bidirectional mode, 1:1/1+1 configuration.

A manual switch will not occur if the standby line is in alarm.

Large cell loss when performing a front card switchover

Description

A line which is configured for APS 1+1 line redundancy has its active front card switched either due to card failure, switchyred (switchcdred), or resetting the card. A loss of cells is observed.

Investigation

Cell loss at card switchover is not due to faulty APS. It is a a result of the card redundant switch (YRED switch) and there will be up to 250ms worth of traffic disruption during BXM front card switchovers.

APS service switch description

Description

What is an APS service switch? Does it work on APS 1:1 configurations?

Investigation

An APS service switch is only applicable to APS 1+1 configuration. It allows the user to switch all the APS lines on a card with a single switchapsln command with an "s" option at the end of the command. All APS lines on this card pair will be switched and made active on a single backcard allowing the other backcard to be removed for service. IMPORTANT: Be sure that the associated front card is active for the backcard which is to remain in the rack. You may have to perform a switchcdred so that the backcard that the service switch switches to has its associated front card active. A service switch is not required in order to remove a BXM front card with APS 1+1 lines on it. The card redundancy will handle the switch to the other card without affecting the lines.

APS line does not seem to switch and active line is in alarm

Description of problem

A major line alarm is indicated on the active line yet it remains active due to no APS switch to the redundant line.

Initial Investigation

1. Verify that the configuration is correct (dspapsln, cnfapsln). See above configuration problems.

2. Use dspapsln to check the APS line's status. The dspapsln display shows the active and standby line's alarm status. It also shows if there are any APS alarms. If the active line alarm status shows OK but the standby line alarm status shows an alarm then a switch will not occur due to the standby line alarm. Troubleshoot the standby line problem. If the standby line alarm status shows OK but the active line alarm status shows an alarm then a switch should have occurred and there is a more obscure problem. If there is an APS alarm shown under Current APS alarms then this could be the problem, see above section on APS Alarms. If APS 1+1 is configured, use dspcds to check the status of the protection line's card. If there is a problem with this card a switch may not occur.

3. Verify the sequence of events by using dsplog and tracing the entries which contain information about this line or APS on this line. If a switch was attempted and succeeded due to a Loss of Signal, the message "APS SignalFail switch from LN 1 to LN 2" should be logged. If the switch failed there will be a message such as "Cannot do APS SigFail switch from LN 1 to LN 2".

Work Around

Perform a clear switch on each end of the APS line (switchapsln 2.1 1). This may get both ends in sync and clear up the problem.

A forced switch from working to protection may be performed (example: switchapsln 2.1 3). WARNING: If the protection line is in LOS and we force a switch to it, traffic will be lost.

If the line is an APS 1+1 line, then the front cards are redundant and the user may try a switchcdred (switchyred) to induce APS switching. This should normally have no affect on APS switching. APS switching and card redundancy switching are independent.

The BXM card may be reset in combination with an APS clear switch either before of after the reset at both ends of the APS line. Perform an APS clear switch on both on both ends of the line. Reset the BXM cards (resetcd h).

BXM backcard LED green and yellow indications

Description

Prior to an APS switch the active card LED is green and the standby card LED is yellow. After the APS switch, both LEDs are green

Explanation

The BXM backcard LED is meant to show whether the card is currently being used by at this time. Green means that this card is in use. Yellow means that the card is not in use and could be removed for service. If the standby line's card's LED is green it means that part of this card is being used at this time. This could happen due to the APS 1+1 cross over circuit where the working line's front card is active but the protection line itself is active. The working line's backcard is being used to shunt traffic to the protection line's backcard.

BXM Port LED states

Scenario

For an APS 1+1 or APS 1:1 line pair, the port LEDS are the same color on working and protection line.

Explanation

To switch software, the APS line pair is a single logical line. Although required to send BXM messages to both lines, these messages will be the same message. Thus switch software cannot send different LED states to the BXM for the same APS line. The BXM firmware makes the protection line LED state the same as the working line LED state.

Alarms

What do APS Alarms Represent.

The following sections describe APS alarm types

Description

An APS alarm occurs in dspalms and dspapsln.

Initial Investigation

APS alarms can be of two types. There are APS specific alarms and there are line alarms reported by the standby line. The standby line alarm will be displayed in the dspapsln screen under "Standby Line Alarm Status". If there are no other APS specific alarms, the standby line alarms will also show under "Current APS Alarm Status". The meaning of the standby line alarms are the same as the meaning of the active line alarms which are reported in the 0x55 Line Alarms command and are discussed in other documentation. The APS specific alarms consist of seven alarms in addition to APS OK, and APS Deactivated, and Line Looped.

Some of the APS alarms reflect problems with the underlying APS channel protocol, the K1/K2 bytes. The K1 byte carries the request for a switch action on a specific channel to the remote end of the line. The K2 byte indicates the status of the bridge in the APS switch and also carries mode information.

Remote Signl FAIL - A remote signal failure indicates that there is a problem with the far end signalling information in the K1K2 bytes. There is a problem with the protection line's physical layer. So, one has to disable APS and try to bring up the protection line as a normal line and diagnose the physical layer (by putting loopback etc.).
Channel Mismatch - Can only happen in bidirectional mode and indicates that there is a problem with the underlying APS channel protocol. The receive K2 channel number does not equal the transmit K1 channel number. There is a problem with the protection line's physical layer. So, one has to disable APS and try to bring up the protection line as a normal line and diagnose the physical layer (by putting loopback etc.).
Prot Sw Byt FAIL - Protection Switch Byte failure or PSB. In bidirectional mode indicates that there is an invalid K1 byte. The receive K1 request does not match the reverse request and is less than the transmit K1 request. In all modes a PSB alarm indicates that K1/K2 protocol is not stable. There is a problem with the protection line's physical layer. So, one has to disable APS and try to bring up the protection line as a normal line and diagnose the physical layer (by putting loopback etc.). This alarm will be seen if the local end of an APS working line or trunk is connected directly to the remote end's protection line or trunk.
APS Card Missing - This alarm is seen in APS 1+1 configurations when BXM firmware determines that any BXM front or back card is missing. Check dspcds or look in the dsplog to see which card associated with the APS line is missing.
FarEnd Prot FAIL - Far end protection failure indicates that the far end's protection line is failing. When there is Signal Failure on the protection channel, the remote end sees Far End Protection Fail. There is a problem with the protection line's physical layer. So, one has to disable APS and try to bring up the protection line as a normal line and diagnose the physical layer (by putting loopback, etc).If the other end shows the "Architect Mismtch" APS alarm then the APS standards could be different at each end. Use cnfcdaps or cnfapsln to check for this.
Architect Mismtch -Architecture mismatch indicates that one end of the APS line is configured for APS 1+1 and the other end is configured for APS 1:1 which will not work. If the line is configured for GR-253 standard operation an architecture mismatch can also mean that one end is bi-directional and the other end is uni-directional (ITUT will not report this). Verify that the APS architecture is configured the same on either end of the APS lines using the cnfapsln command. This alarm will also be seen if the local end of an APS working line or trunk is connected directly to the remote end's protection line or trunk. In this case one end of the line usually will have a "Prot Sw Byt FAIL" alarm present. If the other end shows the "FarEnd Prot FAIL" APS alarm then the APS standards could be different at each end. Use cnfcdaps or cnfapsln to check for this.
Standard Mismatch - indicates that on the local end of an APS 1+1 configuration that one card is running the ITUT standard and the redundant card is running the GR-253 standard. Use the cnfcdaps command to check and change the standard.
Usr Line Loop - The line is looped. Use the dellnlp command to clear the loop. Both working and protection lines are looped when an APS line is looped.
APS Standby Line Alarms are also shown as APS alarms unless there is a higher priority APS alarm (those above) masking the standby line alarm. The APS standby alarms are the integrated line alarms reported by the standby line in the BXM Line Alarms message (0x55 ). If one of these alarms is shown, there is a problem with the standby line. Trouble shoot the line using standard line fault isolation procedures.
- Rmt Sec Trc Fail
- Rmt Path Trc Fai
- Path Yellow
- Path AIS
- Loss of Pointer
- Loss of Cell
- Remote Framing
- Frame Sync Alarm
- Remote (YEL)
- AIS (BLU)
- Loss of Frm(RED)
- Loss of Sig(RED)

Table of Contents

SONET APS

Syntax

Syntax

Example 1

Related Commands

Attributes

Description

Syntax

Syntax

Syntax

Syntax

Syntax

Syntax

Example 1