ATM High-Speed Signaling Link Testing Capability

Local Loopback Support

There are five link testing capabilities for an ATM high-speed signaling link. All five of these tests can be used for an ANSI ATM high-speed signaling link; three of these tests can be used for an E1 ATM high-speed signaling link. Table C-2 gives a description of each test and shows which the type of ATM high-speed signaling link each test can be used. Figure C-9 and Figure C-10 show diagrams of each test.

Table C-2 ATM High-Speed Signaling Link Loopback Support

Loopback Type	ANSI ATM High-Speed Signaling Link	E1 High-Speed High-Speed Signaling Link	When can the Loopback Test be Performed	How does the Loopback test Work	What is Tested (Assume Near End Unless Specified)
SLTC	Yes	Yes	When the link is in service and activated	MTP-3 exchanges SLTM/SLTA messages with remote MTP-3. Appears as normal MSU traffic to SSCF and SSCOP.	MTP-3 layer, ATM protocol stack (near end and far end), and wire
OAM	Yes	Yes	When the link is connected to a remote STP. The state of the link is either activated or deactivated.	ATM driver exchanges OAM F5 Loopback cells with remote ATM driver. One OAM cell per request with a maximum of three attempts made.	ATM driver (near end and far end) and wire
LXVR	Yes	Yes	When the link is deactivated.	MTP-3 attempts to align link. If alignment fails, test fails. Appears as normal alignment request to SSCF and SSCOP.	SSCF, SSCOP, ATM driver and T1 hardware (for an ANSI ATM high-speed link) or E1 hardware (for an E1 ATM high-speed signaling link) on near end
Payload	Yes	No	When the link is deactivated, connected to remote STP and no Yellow Alarm BOC is being transmitted.	MTP-3 attempts to align link. If alignment fails, test fails. Appears as normal alignment request to SSCF and SSCOP.	SSCF, SSCOP, ATM driver (near end only) and T1 hardware (near end and far end) and wire
Line	Yes	No	When the link is deactivated and connected to remote STP and no Yellow Alarm BOC is being transmitted.	MTP-3 attempts to align link. If alignment fails, test fails. Appears as normal alignment request to SSCF and SSCOP.	SSCF, SSCOP, ATM driver (near end only) and T1 hardware (near end and far end) and wire

Figure C-9 ANSI ATM High-Speed Signaling Link Loopback Support

Figure C-10 E1 ATM High-Speed Signaling Link Loopback Support

Remote Loopback Support

The LIM containing the ATM high-speed signaling link must provide remote loopback support so that the EAGLE 5 ISS can act as the far end STP as shown in Figure C-9 or Figure C-10. The support provided for ATM high-speed signaling link cards is identical to low-speed signaling link cards by providing the same initialization and detection capabilities.

initialization - The MTP-3 layer, independent of hardware interface, allows remote loopbacks when the link is deactivated. Upon receiving a bit-oriented code for a line or payload loopback, the ATM high-speed signaling link reprograms the AATM hardware if MTP-3 has determined a remote loopback is allowed.
detection - Every 500 ms, the hardware is read to determine if remote loopback is in progress and the maintenance block is updated. This generates a UAM to the local node. For DS1 links, an AATM hardware register is read to determine if the T1 layer is currently configured for remote loopback.

Link Status Logging Capability

The Enhanced Link Diagnostics capability stores link status information. The link status information is divided into 2 categories: service data and alignment data. Currently, each logging routine can store up to 69 events, all of which can be displayed using the rept-stat-slk command. The service data and alignment data categories are described in the following sections.

Service Data Category

Service events and their timestamps are buffered during transitions between the In-Service/Data Transfer Ready states and all other states. This buffer contains a history of the link failure reasons (as seen from Level 2’s point of view) and the subsequent realignments. Each entry in the buffer is either the link failure reason and time, or the time the link came back in service. Table C-3 provides a list of all high-speed signaling link failure reasons, however, not all of these failures will show up in the service data. Several types of failure that are recognized by Level 3 (like Changeover Order Received or Failed SLT) are mapped to a Stop Commanded event at Level 2. If the history indicates the link did not realign after the failure, the alignment data buffer shows the reason the link was unable to be realigned.

The service data history contains only the high-speed signaling link failure reason as seen by Level 2. As highlighted above, there actual failure reason can be hidden from the Level 2 Service Data if it is an event that is detected by level 3. For example, there are many reasons why Level 3 sends a Stop command to Level 2, such as link deactivated by user, changeover order received, false link congestion, etc. Therefore, the service data should only be used as a guide in determining a link failure.

Table C-3 High-Speed Signaling Link vs. Low-Speed Signaling Link Unavailability Reasons by Priority

High-Speed Signaling Link Unavailability Reason	Low-Speed Signaling Link Unavailability Reason
Remote Loopback	Remote Loopback
LOS
LOF
LCD
Too Many Interrupts	Too Many Interrupts
	Stopped Receiving Data
ISERM threshold exceeded
	SUERM
Remote Out of Service
Remote Protocol Error
Remote Management Initiated
Remote Processor Outage
Local Processor Outage
Timer_No_Credit expired
Timer_No_Response expired
	T1 expired(ready, not ready)
	T3 expired
	T2 expired
	Exceeded Proving Period Count
	SIO received
	SIN received
	SIE received
	SIOS received
	SIPO received
	RC/BSNR link failure
	RC/FIBR link failure
	T6 expired
	T7 expired
COO Received	COO Received
False SLK Congestion	False SLK Congestion
SLK Restart Delayed	SLK Restart Delayed
Far End Loopback	Far End Loopback
Link Not Aligned (default)	Link Not Aligned (default)
Remote Blocked	Remote Blocked
Local Blocked	Local Blocked
Remote Inhibited	Remote Inhibited
Local Inhibited	Local Inhibited

Alignment Data Category

Alignment events are buffered at all times when link is not in service. Only the first unique occurrence of an event and its timestamp is buffered. High-speed signaling link alignment events are divided into:

SSCOP, SSCF and MAAL state transitions
SSCOP and SSCF transmitted PDUs
SSCOP and SSCF received PDUs
Special level 1 events.

Table C-4, Table C-5, and Table C-6 list all the possible alignment events sorted by event type.

Table C-4 High-Speed Signaling Link State Transition Alignment Events

SSCOP	SSCF	MAAL
Idle	OOS Idle	OOS
Outgoing Conn. Pending	OOS ODP	Alignment
Incoming Conn. Pending	Alignment Idle	Proving
Outgoing Disc. Pending	Alignment OCP	Aligned/Ready
Outgoing Resync Pending	Alignment ODP	In Service
Incoming Resync Pending	Proving Data Transfer Ready
Outgoing Recovery Pending	Aligned/Ready Data Transfer Ready
Recovery Response Pending	In Service/Data Transfer Ready
Incoming Recovery Pending
Data Transfer Ready

Table C-5 High-Speed Signaling Link Transmitted/Received Alignment PDUs

SSCOP	SSCF
BGN	Out of Service
BGAK	Processor Outage
END	In Service
ENDAK	Normal
RS	Emergency
RSAK	Alignment Not Successful
BGREJ	Mgmt Initiated
SD	Protocol Error
ER	Proving Not Successful
POLL
STAT
USTAT
UD
MD
ERAK

Table C-6 High-Speed Signaling Link Special Level 1 Alignment Events

Special Events
LCD
LCD Cleared
LOF
LOF Cleared
LOS
LOS Cleared
Too Many Interrupts
Stop Commanded

Display of Buffered Data

The buffered data are displayed using the rept-stat-slk command. All events are buffered with the day and time of the event. The buffered timestamp is displayed in a day of year and time of day format (YY-MM-DD HH:MM:SS.sss). The time of day and day of year are passed to the LIM card when polling for the maintenance block. A timer on the LIM card, with a 5 millisecond granularity, provides the millisecond portion of the time displayed. The user has the ability to request either alignment data, service data or both be displayed. A maximum of 69 service and/or alignment events are displayed. However, the user has the ability to display only the last 10 alignment events. See the Commands Manual for a description of the rept-stat-slk command.