Troubleshooting

This appendix explores the types of problems that might interrupt or prevent call transmission, and suggests some procedures for addressing those problems. This appendix covers these topics:

LEDs

ISDN cause codes

Common problems and their solutions

LEDs

MAX front panel

Figure A-1. MAX front panel LEDs

The front-panel LEDs report on the status of the system, the PRI interface, and the data transfer in active sessions.

Table A-1 lists and describes each LED.

Table A-1. MAX LEDs

LED	Description
Power	This LED is on when the MAX power is on.
Fault	This LED is on in one of two cases-either a hardware self-test is in progress or there is a hardware failure. When a hardware self-test is in progress, the LED is on. If any type of hardware failure occurs, the LED flashes. If the failure is isolated to a expansion card, the MAX may continue functioning without the expansion card.
Data	This LED is on when calls are active.
Alarm	This LED is on when there is a WAN alarm or a trunk is out of service, such as during line loopback diagnostics. WAN alarms include Loss of Sync, Red Alarm, Yellow Alarm, and All Ones (or AIS).

Figure A-2. Location of LEDs on the Redundant MAX

Table A-2. Redundant MAX LEDs

LED	Description
Power	This LED is on when the Redundant MAX power supply is on.
A Fail	This LED is on only when there is a failure on power supply A, (if one or more of the voltages on the A side has failed: +5, +3.3, +12, -12, -5.)
B Fail	This LED is on only when there is a failure on power supply B, (if one or more of the voltages on the B side has failed: +5, +3.3, +12, -12, -5.)
Fan	This LED is on when the fans are functioning properly (if +12 VDC from either A or B is good.) This LED is off when there is a fan failure.

Table A-2 lists and describes each LED.

MAX back panel

Figure A-3. Ethernet interface LEDs on MAX back panel

Table A-3. Ethernet interface LEDs on back panel

LED	Description
ACT (Activity)	This LED is on when the MAX is detecting activity (network traffic) on its Ethernet interface.
COL (Collisions)	This LED is on when the MAX detects packet collisions on the Ethernet.
FDX	When this LED is on it indicates full duplex on the Ethernet.
100ST	When this LED is on, it indicates 100BT; when it is off, it indicates 10BT.
LINK (Link integrity)	This LED is on when the Ethernet interface is functional.

The Ethernet interface LEDs are described in Table A-3.

ISDN cause codes

Table A-4 lists the numerical cause codes and provides a description of each.

Table A-4. ISDN cause codes

Code	Cause
0	Valid cause code not yet received
1	Unallocated (unassigned) number
2	No route to specified transit network (WAN)
3	No route to destination
4	Send special information tone
5	Misdialed trunk prefix
6	Channel unacceptable
7	Call awarded and being delivered in an established channel
8	Prefix 0 dialed but not allowed
9	Prefix 1 dialed but not allowed
10	Prefix 1 dialed but not required
11	More digits received than allowed, but the call is proceeding
16	Normal clearing
17	User busy
18	No user responding
19	No answer from user (user alerted)
21	Call rejected
22	Number changed
23	Reverse charging rejected
24	Call suspended
25	Call resumed
26	Non-selected user clearing
27	Destination out of order
28	Invalid number format (incomplete number)
29	Facility rejected
30	Response to STATUS ENQUIRY
31	Normal, unspecified
33	Circuit out of order
34	No circuit/channel available
35	Destination unattainable
37	Degraded service
38	Network (WAN) out of order
39	Transit delay range cannot be achieved
40	Throughput range cannot be achieved
41	Temporary failure
42	Switching equipment congestion
43	Access information discarded
44	Requested circuit channel not available
45	Pre-empted
46	Precedence call blocked
47	Resource unavailable, unspecified
49	Quality of service unavailable
50	Requested facility not subscribed
51	Reverse charging not allowed
52	Outgoing calls barred
53	Outgoing calls barred within CUG
54	Incoming calls barred
55	Incoming calls barred within CUG
56	Call waiting not subscribed
57	Bearer capability not authorized
58	Bearer capability not presently available
63	Service or option not available, unspecified
65	Bearer service not implemented
66	Channel type not implemented
67	Transit network selection not implemented
68	Message not implemented
69	Requested facility not implemented
70	Only restricted digital information bearer capability is available
79	Service or option not implemented, unspecified
81	Invalid call reference value
82	Identified channel does not exist
83	A suspended call exists, but this call identity does not
84	Call identity in use
85	No call suspended
86	Call having the requested call identity has been cleared
87	Called user not member of CUG
88	Incompatible destination
89	Nonexistent abbreviated address entry
90	Destination address missing, and direct call not subscribed
91	Invalid transit network selection (national use)
92	Invalid facility parameter
93	Mandatory information element is missing
95	Invalid message, unspecified
96	Mandatory information element is missing
97	Message type non-existent or not implemented
98	Message not compatible with call state or message type non-existent or not implemented
99	Information element nonexistent or not implemented
100	Invalid information element contents
101	Message not compatible with call state
102	Recovery on timer expiry
103	Parameter nonexistent or not implemented, passed on?
111	Protocol error, unspecified
127	Internetworking, unspecified

Table A-5. ISDN cause codes for 1TR6 switch type

1TR6 Code	Cause
1	Invalid call reference value
3	Bearer service not implemented. (Service not available in the A-exchange or at another position in the network, or no application has been made for the specified service.)
7	Call identity does not exist. (Unknown call identity)
8	Call identity in use. (Call identity has already been assigned to a suspended link.)
10	No channel available. (No useful channel available on the subscriber access line-only local significance.)
16	Requested facility not implemented. (The specified FAC code is unknown in the A-exchange or at another point in the network.)
17	Request facility no subscribed. (Request facility rejected because the initiating or remote user does not have appropriate authorization.)
32	Outgoing calls barred. (Outgoing call not possible due to access restriction which has been installed.)
33	User access busy . (If the total made up of the number of free B-channels and the number of calling procedures without any defined B-channel is equal to four, then any new incoming calls will be cleared down from within the network. The calling party receives a DISC with cause "user access busy" (= 1st busy instance) and engaged tone.)
34	Negative CUG comparison. (Link not possible due to negative CUG comparison.)
37	Communication as semi-permanent link not permitted
48 - 50	Not used. (Link not possible, e.g. because RFNR check is negative.)
53	Destination not obtainable. (Link cannot be established in the network due to incorrect destination address, services or facilities)
56	Number changed. (Number of B-subscriber has changed.)
57	Out of order. (Remote TE not ready)
58	No user responding. (No TE has responded to the incoming SETUP or call has been interrupted, absence assumed-expiry of call timeout T3AA.)
59	User busy. (B-subscriber busy)
61	Incoming calls barred. (B-subscriber has installed restricted access against incoming link or the service which has been requested is not supported by the B-subscriber)
62	Call rejected. (To A-subscriber: Link request actively rejected by B-subscriber -by sending a DISC in response to an incoming SETUP. To a TE during the phase in which an incoming call is being established: The call has already been accepted by another TE on the bus.)
89	Network congestion. (Bottleneck situation in the network; e.g. all-trunks-busy, no conference set free)
90	Remote user initiated. (Rejected or cleared down by remote user or exchange.)
112	Local procedure error. (In REL: Call cleared down due to local errors; e.g. invalid messages or parameters, expiry of timeout, etc. In SUS REJ: The link must not be suspended because another facility is already active. In RES REJ: No suspended call available. In FAC REJ: No further facility can be requested because one facility is already being processed, or the specified facility may not be requested in the present call status.)
113	Remote procedure error. (Call cleared down due to error at remote end.)
114	Remote user suspended. (The call has been placed on hold or suspended at the remote end.)
115	Remote user resumed. (Call at remote end is no longer on hold, suspended or in the conference status.)
127	User Info discarded locally. (The USER INFO message is rejected locally. This cause is specified in the CON message.)
35	Non existent CUG. (This CUG does not exist.)

Table A-5 lists the cause codes for the 1TR6 switch type.

Common problems and their solutions

General problems

• For a local loopback toward an application at its AIM port interface, use the Local LB command in the Port Diag menu.

• For a loopback toward an application at its remote-end AIM interface, use the DO Beg/End Rem LB command.

• For a channel-by-channel error measurement, use the DO Beg/End BERT command.

• To resynchronize a multichannel call, use the DO Resynchronize command.

DO menus do not allow most operations

Note that you cannot dial if Operations=No for the control port. If a call is already active, DO 2 (Hang Up) appears instead of DO 1 (Dial). If the T1 or E1 line is not available, Trunk Down appears in the message log and you cannot dial.

POST takes more than 30 seconds to complete

The 12MOD digital modem slot card boots every time the MAX power-cycles, and requires boot-up configuration data from the MAX. This means the MAX makes two further attempts to download the code for the MAX unit's MOD12 digital 12-modem slot card if the first boot-up fails.

Previously, the MAX downloaded the required code and immediately commenced with AT POST (which sends the string AT to each modem and waits for the modem to respond with "OK"). Now the MAX downloads the modem code, waits for the modems to checksum the downloaded code, and then verifies that the checksum matches before continuing. If the checksum does not match, the MAX will download the code again, up to 2 more times. If the checksum still doesn't match after three download attempts, the MAX will fail the entire slot card.

Configuration problems

The MAX cannot dial out on a T1 or E1 line

1. Make certain that you have entered the correct phone number to dial.

2. Check that the Data Svc parameter specifies a WAN service available on your line.

   If you request a WAN service that is not available on your line, the WAN rejects your request to place a call.

3. Check whether the channels using the requested WAN service are busy.

   If these channels are busy, an outgoing call might be routed to channels for which you did not request the specified WAN service. Check the Data Svc, Call-by-Call, and PRI # Type parameter values in the profile.

4. Determine whether you have correctly set the parameters controlling Dynamic Bandwidth Allocation.

   For detailed information, see Chapter 2, Configuring the MAX for WAN Access, and Chapter 3, Configuring WAN Links.

An international MAX placed the call or the call was from the U.S. to another country. In some countries, setting the Parallel Dial parameter in the System profile above 1 or 2 violates certain dialing rules, and only some of the channels can connect during call setup. Try reducing the Parallel Dial parameter to the value 2. If the problem persists, try reducing it to 1.

Data is corrupted on some international calls

Only the base channel connects

The most common error in defining Line profiles is specifying incorrect phone numbers. The MAX cannot successfully build inverse multiplexing or MP+ calls if the phone numbers in the Line profile of the called unit are incorrect. The phone numbers that you specify in the Line profile are the numbers local to your unit. Do not enter the phone numbers of the MAX you are calling in the Line profile. The numbers you are calling belong in the Call profile, Destination profile, or Connection profile.

In addition, when you are using E1 or T1 lines, any phone numbers you specify must correspond to those channels within the circuit that are available for data transmission. For example, if channels 13-21 are allocated to a particular slot, you must specify the phone numbers for channels 13-21 in the Line profile. Switched data channels do not have to be contiguous within the circuit.

No Channel Avail error message

Restored configuration has incorrect RADIUS parameters

Hardware configuration problems

Cannot access the vt100

1. Verify that the MAX and your terminal are set at the same speed.

2. Locate the LED labeled FAULT.

3. Switch on the MAX.

If the FAULT LED remains on longer than a minute, there is a MAX hardware failure. A blinking FAULT LED also indicates a hardware failure. Should these situations arise, contact Ascend Customer Support.

FAULT LED is off but no menus are displayed

1. Check the pin-out carefully on the 9-pin cable.

   The control terminal plugs into the HHT-vt100 cable or 9-pin connector labeled Control on the back of the MAX. If you are connecting to an IBM PC-like 9-pin serial connector, a straight-through cable is appropriate. Otherwise, you might need a 9-to-25 pin conversion cable.

2. Check the flow control settings on your vt100 terminal.

   If you are not communicating at all with the MAX, see whether you can establish communications after you have turned off all transmit and receive flow control at your terminal or terminal emulator.

3. Determine whether you need a null-modem cable converter.

   In general, these are not required for communications to the MAX. However, so many different cable and terminal configurations are available that occasionally a null-modem cable converter might be required.

• 9600 bits per second data rate

• 8 data bits

• 1 stop bit

• No flow control

• No parity

A power-on self test fails

AIM port interface problems

• A local loopback test

• Through true end-to-end communications

Local loopback testing is the best aid when troubleshooting the AIM port interface-the interface between the codec and the MAX. All of the symptoms and operations described in this section assume you are working from the local loopback diagnostics menu. Unless otherwise specified, the AIM port interfaces in this section can include the Ascend Remote Port Modules (RPMs).

The first and most critical aspect of the AIM port interface is the cable or cables connecting the codec to the MAX. If you are unsure about the cabling required, contact Ascend Customer Support.

The MAX reports data errors on all calls

Calls cannot be made, answered, or cleared using control leads

Frequently, a DB-25 breakout box is useful for monitoring control leads and for making quick changes to the cabling. However, because the host interface is running V.35 or RS-422 signal levels, you must verify that the breakout box is passive; that is, you must verify that the breakout box is not regenerating RS-232 level signals.

The codec indicates that there is no connection

The codec does not receive data

1. Verify that the codec is configured to accept a loopback at the communications device. Frequently, a codec requires certain control lines to be active during data transfer. Therefore, you might want to toggle the various host interface output lines, especially DSR and CD, to ensure that they are active.

2. If there is still no data transfer, your cable might not provide one or more control lines required by the host; refer to the documentation of your equipment for a description of what pins it requires to be active. These control lines are generally the most important ones:

   • Carrier Detect (CD)

   • Clear To Send (CTS)

   • Data Set Ready (DSR)

3. If you are convinced that the control lines are in their correct states, but there is still no data transfer, you might have a clocking problem. The MAX provides both the transmit data clocks and the receive data clocks to your equipment through the host interface.The codec must be configured to accept the clocks from the MAX.

4. Check your cable length.

   If the cable length exceeds the recommended distances, you should be using terminal timing. Alternately, you might need to install RPMs.

5. Check the data rate.

   You can adjust the data rate from the local loopback diagnostics menu by choosing the number of channels. Some applications cannot work above or below a certain data rate; for example, some high performance codecs cannot operate at data rates less than 384 kbps. In such cases, adjust the number of channels of data being looped back.

1. Disable each of the MAX output control lines except DSR.

   To disable an output control line, toggle it to be Inactive (-). At this time, the codec should indicate that there is no connection.

2. Request an outgoing call from your equipment and monitor the Port Leads status menu of the ports active in the call.

   One or more of the control line inputs should go active and remain active for some period of time. If the DTR input is not one of the leads that changes state, your cable is not properly configured. In this case, you must change the cable to route the appropriate host output signal to the DTR input of the MAX. The MAX must use the DTR lead to establish outgoing calls.

3. Once you have made any changes required to verify that the DTR lead becomes active when the MAX requests the call, configure the Port profile to expect the DTR input.

   In the Port profile, set the Dial Call = DTR Active.

1. Place an outgoing call from the codec while monitoring the Port Leads status menu of the AIM ports used in the call.

2. Watch the DTR input carefully while the MAX is establishing the call.

   If the DTR input indicates Active (+) and then shortly thereafter returns to Inactive (-), the MAX is using DTR as a pulse to place the call. Make sure that the Clear parameter in the Port profile does not have the value DTR Inactive. (DTR Inactive should be selected for Clear only when the application maintains DTR positive during the call.)

3. While your equipment is still dialing the call, toggle the value of the CD output to indicate to your equipment that the call completed. At this time, watch the control leads very carefully. Make certain that any control leads that toggle while the call is being established are not used in the Clear parameter to clear the call. This type of configuration error is the most likely cause of a call being cleared almost immediately.

1. Place an outgoing call from your equipment while monitoring the Port Leads status menu of the AIM ports used in the call.

2. Toggle the CD output to Active (+) once the host has requested the outgoing call. The codec should recognize that the call is online.

3. Make a request to clear the call from the codec.

4. Watch the control leads very carefully as one or more of the input control lines toggle. Generally, either DTR or RTS is the line that toggles. Record whether the control lead input goes to Active (+) or Inactive (-) when the call is cleared; then, check that the value of the Clear parameter in the Port profile matches the action that the codec takes when the call is cleared.

1. Check your cabling.

   The first and most critical aspect of the interface is the physical cable connecting the MAX to the line or terminating equipment. Typically, WAN interface cabling problems appear immediately after installation. If you are unsure about the cabling required, contact Ascend Customer Support. MAX Getting Started describes the general PRI and BRI interface requirements, and lists cabling pin-outs.

2. If the cabling is not the problem and the MAX is a T1 unit, check that the value of the Buildout parameter or the Length parameter in the Line profile matches the actual distance in your configuration.

   • The MAX displays the Buildout parameter if its interface to the T1 line is equipped with an internal CSU. Its enumerated values can be 0 db, 7.5 db, 15 db, and 22.5 db. Contact your carrier representative to determine which value to choose.

   • If the line interface is not equipped with an internal CSU, the Length parameter is displayed. Its value can be 1-133, 134-266, 267-399, 400-533, or 534-655 feet, which should correspond to the distance between the MAX and the WAN interface equipment, typically a CSU or multiplexer.

The Net/BRI lines do not dial or answer calls

No Logical Link status

In some countries outside the U.S., it is common for no logical link to exist before the MAX places a call. In the U.S., when you first plug a line into the MAX or switch power on, the central office switch can take as long as 15 minutes to recognize that the line is now available. You might have to wait that long for the line state to change to Active (A). The physical link can exist without a logical link up on the line.

If you wait longer than 15 minutes and the line is still not available:

1. Check whether all the ISDN telephone cables are wired straight through.

   If you are running multipoint (passive bus) on your switch, all of the ISDN telephone cables must be wired straight through. If any of the cables are wired to cross over, you will not be able to place calls.

2. Check that 100% termination is provided on each ISDN line.

3. Check whether you have correctly specified the SPIDs (Service profile Identifiers) in the Line profile for each line. If the SPIDs are not correctly specified, the line status might indicate No Logical Link. Check with your system manager or carrier representative to obtain the SPID or SPIDs for your line. You specify your SPIDs using the Pri SPID and Sec SPID parameters in the Line profile.

1. Check the value of the Data Svc parameter in the Call or Connection profile.

   Try both the 64K and 56K options for Data Svc to see whether using a different value solves the problem.

2. Check whether you are using the correct dialing plan.

   Depending on how the BRI lines are configured, you might need to type four, seven, or ten digits to communicate with the remote end.

   Four-digit dialing involves the last four digits of your phone number. For example, if your phone number is (415) 555-9015, four-digit dialing requires that you type only the last four digits-9015. Seven-digit dialing specifies that you dial the digits 5559015, and ten-digit dialing requires 4155559015.

   If you are sending the incorrect number of digits, the MAX cannot route the call. Ask your carrier representative for the correct dialing plan, or simply try all of the possibilities.

3. Verify explicitly with your carrier representative that the line is capable of supporting the call types you are requesting.

If you have verified that the MAX is correctly installed and configured, and you have previously placed calls without excessive errors, run the BERT using the command DO Beg/End BERT. Do not clear the call before running the BERT. You can run a BERT only under these conditions:

• A call is active.

• The Call Type parameter is set to AIM, FT1-B&O, or FT1-AIM.

• The Call Mgm parameter is set to Manual, Dynamic, or Delta.

Excessive handshaking on calls to AIM ports

Inbound data is scrambled during an AIM Static call

Problems indicated in LEDs

The E1 or T1 line is in a Red Alarm state

If the Red Alarm condition persists for longer than 30 seconds:

1. Check the value of the Framing Mode parameter in the Line profile.

   Change the value to the other available option and check to see whether the Red Alarm condition goes away within 30 seconds.

2. If the Red Alarm state still persists, check the cabling.

   You might have a crossover cable installed when a straight-through cable is required, or vice versa. If the MAX is connected through bantam plugs, reverse the transmit and receive plugs. Then, allow the MAX to attempt to establish synchronization for an additional 30 seconds.

3. You can eliminate the cabling as a possible cause by replacing the connection with a loopback plug. The LS LED should go off immediately, followed by the RA LED in about 30 seconds.

1. Verify with your carrier representative that the D channel is channel 16 (E1) or 24 (T1).

2. If the D channel number is correct, check the value of the Line Encoding parameter in the Line profile. When B8ZS encoding is in use, a non-inverted D channel is established. If AMI encoding is selected, an inverted D channel is established. Check the line translations provided by your carrier representative and set the line encoding to match the inversion requirements.

3. Determine whether your WAN interface or the MAX T1 unit is equipped with a CSU.

   If the WAN interface or the MAX is not equipped with a CSU, the ALARM LED blinks. Check whether you have specified the proper Length or Buildout value in the Line profile.

4. Check whether the D channel is in service.

   If no equipment has been plugged into the line for a short period of time (five to ten minutes), the D channel is taken out of service. You might need to contact your carrier to put the D channel back into service.

1. Verify that there are enough channels enabled for switched services in the Line profile to meet the requirements of the Parallel Dial parameter in the System profile.

   Most WAN providers can place a limited number of calls simultaneously from a single E1 or T1 line. If more concurrent attempts are made than the WAN can support, the WAN applies a congestion tone-a fast busy signal.

2. Try adding bandwidth once the call is up.

   If you can add bandwidth, the solution is to adjust the Parallel Dial parameter in the System profile. A value of 5 works for almost all WAN providers, while some support substantially more. If adding bandwidth does not work, the problem is most likely within the individual channel translations. In this case, call your carrier representative.

1. If you are making AIM or BONDING calls, verify that the affected channels are enabled for switched services in the Line profile.

2. If you have an E1 unit, check whether it has been connected recently to a device that does not support the full 31 channels. If so, the switch might take the unused channels out of service. This situation can arise on either the local or the remote end.

3. If you have a T1 unit, check whether it has been connected recently to a device that does not support the full 23 channels. If so, the switch might take the unused channels out of service. This situation can arise on either the local or the remote end.

4. Check whether the channels enabled in your Line profile correspond to the channels enabled in the circuit. If only some of the channels in the circuit are available for data calls, you must specifically enable those channels in your Line profile.

5. If you place a call and some channels are always skipped, call your carrier representative.

1. Make sure that your Line profile is properly configured for wink-start or idle-start.

   The Rob Ctl parameter in the Line profile determines which of these call-control mechanisms the MAX uses. Check with your carrier representative to find out which inband signaling your line supports.

2. If the Line profile is configured correctly and you still cannot place an outgoing call, check the service state of the line.

   Frequently, if a T1 or E1 line has been unplugged for an extended duration, the switched services available on the line are taken out of service. Once you install the MAX, you might need to call your carrier representative to have the line reactivated. If this is the case, leave the MAX on all the time, even when you are not using it; otherwise, you will have to call your carrier to reactivate the line each time the unit is switched off and on.

3. Ask your carrier representative whether the line is configured for DTMF dialing; the line must support this type of dialing in order to recognize digits being dialed.

Call status drops back to IDLE

Dual-port call status drops back to IDLE

AIM or BONDING call status drops back to IDLE

Bridge/router problems

You can check link quality in the WAN Stat status window, or by running a ping between the same endpoints. Dropped packets hurt the link's efficiency, as does round-trip delay. Random round-trip delay indicates heavy traffic, a condition that also drops the efficiency of the link.

The MAX hangs up after answering an IP call

1. If you are running PPP, check that you have entered the proper passwords.

2. Check that Auth is set to PAP or CHAP.

3. If you are routing IP over PPP, check that the calling device gives its IP address

   Some calling devices supply their names, but not their IP addresses. However, you can derive an IP address if the calling device is listed in a local Connection profile or on a RADIUS authentication server. Try enabling PAP or CHAP for the Recv Auth parameter so that the MAX matches the caller's name to the Station parameter in a Connection profile and gets the corresponding LAN Adrs.

Copyright © 1998, Ascend Communications, Inc. All rights reserved.