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Cisco WAN Switching Modules

Field Notice: UVM With Firmware Model E Version B Drops Signalling


October 13, 1999


Products Affected

Product

Description

IGX-UVM

UVI-J1 back card operating with Firmware D.E.B and configured for CAS.

Problem Description

UVM with firmware D.E.B will drop signalling in Channel Associated Signalling (CAS) mode. This affects both J1 circuits. The customer impact is that random channels on the J1 interface will not function.

Background

The IGX-UVM and IGX-CVM remove the signalling bits from the J1 CAS bit stream and send them in separate FastPackets? via the network. When loaded with firmware D.E.B, the UVM fails to pass the signalling FastPackets to the remote end of the connection.

Problem Symptoms

The UVM set for CAS signalling fails to transmit signalling to the remote end. Additionally, the dspdpsig slot.port.chan display shows incrementing signalling drops, the dspsig slot.port.chan does not show signalling transitions in the signalling bits. Either end or both ends of the connection may be dropping signalling packets.

The output of the dspdpsig slot.port.chan command is shown below. Observe the incrementing value of the Receive drop signal counts. One or all channel counts may be incrementing depending on the attached PBX activity and the channels added. Note that this screen does not dynamically refresh; the user must issue the dspdpsig command several times to observe incrementing values.

igxnode        VT    StrataCom       IGX 8420  9.1.09    Aug. 14 1999 09:14  G+09
                        Line 6.2
                               TRANSMIT                                 RECEIVE
                        Ch          Ch          Ch             Ch            Ch          Ch
                        1    0      12   0      23   0         1   11      12   6      23   3
                        2    0      13   0      24   0         2    1      13   3      24   7
                        3    0      14   0      25   0         3    5      14   0      25   4
                        4    0      15   0      26   0         4    2      15   8      26   3
                        5    0      16 ---      27   0         5   12      16 ---      27   5
                        6    0      17   0      28   0         6   10      17   1      28   2
                        7    0      18   0      29   0         7    6      18   5      29  10
                        8    0      19   0      30   0         8    2      19   0      30   4
                        9    0      20   0      31   0         9    6      20  14      31   3
                        10   0      21   0                     10   6      21   5
                        11   0      22   0                     11   3      22   9

Last Command: dspdpsig 6.2

Another useful tool for verifying this problem is the dspsig slot.port command. The attached PBX will send signalling bits when establishing a call to a remote PBX. These signalling bits may be displayed on the IGX console by issuing the dspsig command several times. The user must be certain that the PBX is attempting to set up a remote call and that the trunks attached to the UVM are not busied out or in a "conditioned" state. Below is the output of the dspsig command:

igxnode        TN    StrataCom       IGX 8420  9.1.09    Aug. 13 1999 01:21 GMT
                         
                                                        Signalling Information
                        From 12.1.1 TXAbit  TXBbit  TXCbit  TXDbit  RXAbit RXBbit RXCbit RXDbit no_serv
                        12.1.1-24   1       1       1       1       0      0      0      0
                        12.2.1-24   1       1       1       1       0      0      0      0

The RX_bit values will all ways appear stuck at "0" and never change. The user should remember that some PBX interface cards stop passing signalling and shut down if too many call attempts across the interface fail. Check the PBX to verify that the interface to be used is not out of service.

Workaround/Solution

Workaround:

  1. For networks with 9.1.xx, 8.5.xx, 8.2.5x or 8.2.6x, use firmware D.D.F

  2. Replace with IGX-CVM if G.728 (LD-CELP), G.729 (CS-CELP) or G.729a is not required.

Solution:

Download UVM firmware D.E.C and burn this into the affected UVMs. This firmware is posted to CCO in the "Software Center" under "WAN Switching Software" section. Look for the pulldown titled "Download Cisco WAN Card Firmware" for IPX-IGX. Any registered CCO user may download this firmware. The firmware order number is: IGX-UVM-FW-DEC or subsequent version.

DDTS

To follow the bug ID link below and see detailed bug information, you must be a registered user and you must be logged in.

DDTS

Description

CSCdm77018 (registered customers only)

UVM/J1 not receiving signalling info after fw upgrade D.D.F -> D.E.B

CSCdm78562 (registered customers only)

Signalling states & transitions not recognized by UVI-J1

CSCdm04354 (registered customers only)

UVM cd keeps resetting when signalling bits toggling fast

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

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