PGW 2200 Nailed Solution for CGB and CGU [Telephony Signaling]

Document ID: 46487

Introduction
Prerequisites
      Requirements
      Components Used
      Conventions
CGB/CGU Messages in a Nailed Solution
      CGBA2 Property Information
      CDR Information
Troubleshoot CCB and CGBA Information
      Troubleshoot CGU and CGUA SS7 Messages
      Manually Bring One or More B-Channels Out of Service with IOS Commands
      CGB/CGU Processed Conclusion
NetPro Discussion Forums - Featured Conversations
Related Information

Introduction

This document provides a summary on how to work with the SS7 circuit supervision messages for Circuit Group Block (CGB) (message) and Circuit Group Unblock (CGU) (message) on the Cisco PGW 2200 Softswitch in Nailed solution.

Prerequisites

Requirements

Cisco recommends that you have knowledge of these topics:

Cisco Media Gateway Controller Release 7 Documentation
Cisco Media Gateway Controller Software Release 9 Documentation
ITU Q.764 through Q.767

Components Used

The information in this document is based on the Cisco PGW 2200.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

Conventions

Refer to Cisco Technical Tips Conventions for more information on document conventions.

CGB/CGU Messages in a Nailed Solution

This document explains how CGB and CGU messages work in a Nailed solution. The PGW 2200 [Nailed] and network access server (NAS) communicate via a signaling protocol based on National ISDN-2 (NI2), with custom enhancements.

Before you start, the main difference between a Switched and Nailed PGW solution are:

PGW 2200 Nailed solution—Between the PGW and NAS, an NI2+ protocol runs with Group Service Message handling
PGW 2200 Switched solution—Between the PGW and the gateway, the Media Gateway Control Protocol (MGCP) runs with RSIP message handling.

CGBA2 Property Information

The Circuit Group Block Acknowledge 2 (CGBA2) property is only applicable to ISUP SigPath. Since there is no validation of property, it is possible to assign it on all other types of SigPath. However, it has no impact on them. The property can only contain values 0 or 1 (the default is 0).

If the property is set to 1 on the ISUP SigPath, the PGW 2200 sends individual circuit supervision messages instead of group circuit supervision messages to indicate the range of circuits affected by the action in the message.

If the property was set to 0 on the ISUP SigPath, the PGW 2200 sends group circuit supervision messages instead of individual circuit supervision messages to indicate the range of circuits affected by the action in the message.

If a user assigns any other value to the property, it assumes a value of 1. A detailed description can be found in the Cisco MGC Software Release 9.3(2) Featurettes and Enhancements, MML Command Reference Guide.

Use the MML command PROV-ADD:sigsvcprop:name= "SS7path name",CGBA2= "0|1" to change the value.

CDR Information

MAINT Type TAG 4032 has values 1, 2, and 3 for Block, Unblock, and Reset respectively. For further information, refer to the Billing Interfaces documentation.

Whenever a CGB, CGU, or Circuit Group Reset (GRS) has to be written, it is done in TAG 4032 with 1 for CGB, 2 for CGU and 3 for GRS. It also writes the Circuit Identification Code (CIC) (TAG 4018) on which the message was sent.

Troubleshoot CCB and CGBA Information

These are the configuration settings from the gateway configuration:

!
controller E1 1/1/0 
framing NO-CRC4 
pri-group timeslots 1-31 nfas_d primary nfas_int 0 nfas_group 1 
!

The performance of a shutdown of this information results in this output:

v5800-2-sc(config)#controller E1 1/0/0 
v5800-2-sc(config-controller)#shutdown 
v5800-2-sc(config-controller)#

This information displays when you view the debug output on the gateway and run the debug isdn standard command.

Oct 17 11:01:44.795: ISDN Se1/0/0:15 SC EVENT: 
isdn_pri_t1_state_change: setting State to 0 
Oct 17 11:01:44: %CONTROLLER-5-UPDOWN: Controller E1 1/0/0, 
changed state to administratively down 
Oct 17 11:01:44.795: ISDN Se1/0/0:15 SC BACKHAUL: srl_send_l3_pak: 
        source_id = Q.931, dest_id = Q.921, prim = DL_DATA_REQ 
        priv_len = 4 int_id = 0x65B73580 datasize = 28 
Oct 17 11:01:44.795: ISDN Se1/0/0:15 SC BACKHAUL: 
data = 0x65B7358000000300024004AC00010005 
Oct 17 11:01:44.795:    430200000666050000000000 
Oct 17 11:01:44.799: ISDN Se1/0/0:15 SC Q931: TX -> GROUP SERVICE pd = 67 
                                    callref = 0x0000 
                                    Interface Service i = 0x0000000000 
Oct 17 11:01:44.799: ISDN Se1/0/0:15 SC RLM: process_tdial_message: 
Received Msg from SC 4 bytes :  0x0001014A 
Oct 17 11:01:44.819: ISDN Se1/0/0:15 SC RLM: process_tdial_message: 
Received Msg from SC 16 bytes :  0x0201464A430280000B66050000000000 
Oct 17 11:01:44.819: ISDN Se1/0/0:15 SC Q931: RX <- GROUP SERVICE ACK pd = 67 
                                   callref = 0x8000 
                                   Interface Service i = 0x0000000000 
Oct 17 11:01:44.819: ISDN Se1/0/0:15 SC BACKHAUL: srl_send_l2_pak: 
source_id = Q.921, dest_id = Q.931, prim = DL_DATA_IND 
        priv_len = 4 int_id = 0x65B73580 datasize = 28 
Oct 17 11:01:44.819: ISDN Se1/0/0:15 SC BACKHAUL: 
data = 0x65B73580000000000241049000016200 
Oct 17 11:01:44.819:    430280000B66050000000000 
Oct 17 11:01:44.819: ISDN Se1/0/0:15 SC BACKHAUL: L3IF_rx_L2_pak: 
received data 0x430280000B66050000000000 
Oct 17 11:01:44.819: ISDN Se1/0/0:15 SC RLM: process_sc_group_msg: 
Received msg 11 from SC 
Oct 17 11:01:49: %SYS-5-CONFIG_I: Configured from console by vty0 (144.254.9.64)

This graphic represents this call flow information:

Both the PGW and the gateway assume the initial service state of each bearer is In-Service.
On the gateway, the shutdown command is executed on the controller.
A Group Service message with Interface Service i information is sent to the PGW.
The PGW sends a CGB out to the PSTN.
The PSTN responds to each CGB message with a CGBA message.
The PGW responds with a Group Service Ack for each Group Service message received.

When you run the debug isdn q931 command, you can also capture the SS7 message that is sent out using the PTC-MC /snooper or SS7 analyzer.

Q.764 explains Section - 2.8.2.2 Circuit group blocking and unblocking messages. In ITU, in the CGB message (seen in this output) the hardware_failure_oriented block can only be cleared by hardware_failure_oriented unblock. In ANSI, hardware-block can be cleared by any type of CGU message (Linked to CIRCUIT GRP SUPERVISION of the CGB message). Refer to Cisco bug ID CSCuk45906 ( registered customers only) for additional information. This bug ID discusses when the PGW sends the wrong indication in CGB when GRS is enabled.

Note: For a Switched solution, always send maintenance block CGB/CGU. No hardware failure type is sent.

***************************************************************** 
* 03 SNOOPER INFO: Snooper is listening on interface "hme0".... * 
***************************************************************** 
11:38:40.792151  1-005-1[02089]   1-015-1[02169]  
ITU  ISUP. -> CGB (18) CIC=00001 
   SLS=01 Pr:0 Ni:NTL 
********************************** DETAIL ********************************** 
CIC                            1 
MESSAGE TYPE                   0x18 CGB - Circuit_Group_Blocking 
CIRCUIT GRP SUPERVISION MT IND 0x15 
   LENGTH:                        0x01 FIXED DATA 0x01 
   CIRCUIT GRP SUPERVISION MT IND 1 hardware_failure_oriented 
INDEX TO VARIABLE PART         0x01 
   RANGE                          30 
   LENGTH:                        0x04 STATUS 0xFF 0xFF 0xFF 0x7F 
   CIC     state                  255 
   1       1 blocking 
   2       1 blocking 
   3       1 blocking 
   4       1 blocking 
   5       1 blocking 
   6       1 blocking 
   7       1 blocking 
   8       1 blocking 
   CIC     state                  255 
   9       1 blocking 
   10       1 blocking 
   11       1 blocking 
   12       1 blocking 
   13       1 blocking 
   14       1 blocking 
   15       1 blocking 
   16       1 blocking 
   CIC     state                  255 
   17       1 blocking 
   18       1 blocking 
   19       1 blocking 
   20       1 blocking 
   21       1 blocking 
   22       1 blocking 
   23       1 blocking 
   24       1 blocking 
   CIC     state                  127 
   25       1 blocking 
   26       1 blocking 
   27       1 blocking 
   28       1 blocking 
   29       1 blocking 
   30       1 blocking 
   31       1 blocking 
   32       0 no blocking 
******************       END_OF_MSG   ****************** 
  

11:38:40.819013  1-015-1[02169]   1-005-1[02089]       
ITU  ISUP. -> CGBA(1a) CIC=00001 
  SLS=01 Pr:0 Ni:NTL 

********************************** DETAIL ********************************** 
CIC                            1 
MESSAGE TYPE                   0x1A CGBA - Circuit_Group_Blocking_Ack 
CIRCUIT GRP SUPERVISION MT IND 0x15 
   LENGTH:                        0x01 FIXED DATA 0x01 
   CIRCUIT GRP SUPERVISION MT IND 1 hardware_failure_oriented 
INDEX TO VARIABLE PART         0x01 
   RANGE                          30 
   LENGTH:                        0x04 STATUS 0xFF 0xFF 0xFF 0x7F 
   CIC     state                  255 
   1       1 blocking acknowledgment 
   2       1 blocking acknowledgment 
   3       1 blocking acknowledgment 
   4       1 blocking acknowledgment 
   5       1 blocking acknowledgment 
   6       1 blocking acknowledgment 
   7       1 blocking acknowledgment 
   8       1 blocking acknowledgment 
   CIC     state                  255 
   9       1 blocking acknowledgment 
   10       1 blocking acknowledgment 
   11       1 blocking acknowledgment 
   12       1 blocking acknowledgment 
   13       1 blocking acknowledgment 
   14       1 blocking acknowledgment 
   15       1 blocking acknowledgment 
   16       1 blocking acknowledgment 
   CIC     state                  255 
   17       1 blocking acknowledgment 
   18       1 blocking acknowledgment 
   19       1 blocking acknowledgment 
   20       1 blocking acknowledgment 
   21       1 blocking acknowledgment 
   22       1 blocking acknowledgment 
   23       1 blocking acknowledgment 
   24       1 blocking acknowledgment 
   CIC     state                  127 
   25       1 blocking acknowledgment 
   26       1 blocking acknowledgment 
   27       1 blocking acknowledgment 
   28       1 blocking acknowledgment 
   29       1 blocking acknowledgment 
   30       1 blocking acknowledgment 
   31       1 blocking acknowledgment 
   32       0 no blocking acknowledgment 
******************       END_OF_MSG                       ****************** 

******************       END_OF_MSG                       ****************** 
********************************** DETAIL **********************************

Note: In XECfgParm.dat under directory /opt/CiscoMGC/etc a new config parameter called engine is added. SendHardwareBlock equals false. If SendHardwareBlock is not true, always send a maintenance block.

Config parameter for in XECfgParm.dat

Description

engine.SendHardwareBlock

In order to enable the Cisco PGW 2200 to send hardware-oriented blocking messages for any blocks that originate from the media gateways:

true—Sends hardware-oriented blocking messages for any blocks that originate from the media gateways.
false—Sends only maintenance-oriented blocking messages for all blocking cases (default).

Note: The functionality for this parameter is added in a patch for Release 9.3(2) and later. If your system runs release 9.3(2) - Cisco bug ID CSCsb27752 ( registered customers only) [integrated in 9.3(2)P52] or release 9.4(1) - Cisco bug ID CSCsb27709 ( registered customers only) [integrated in 9.4(1)P48] you must enter this parameter in the XECfgParm.dat file manually after you install the patch. If your system runs release 9.5(2) - Cisco bug ID CSCsb27756 ( registered customers only) [integrated in 9.5(2)P29], the parameter is automatically added to the XECfgParm.dat file during the patch installation.

Troubleshoot CGU and CGUA SS7 Messages

This output displays when you issue the no shutdown command:

v5800-2-sc(config)#controller E1 1/0/0 
v5800-2-sc(config-controller)#no shutdown 
v5800-2-sc(config-controller)#

This information displays when you view the debug command output on the gateway and issue the debug isdn standard command:

! 
controller E1 1/0/0 
 pri-group timeslots 1-31 nfas_d primary nfas_int 0 nfas_group 0 
v5800-2-sc(config)#controller e1 1/0/0 
v5800-2-sc(config-controller)#no shutdown 
v5800-2-sc(config-controller)# 
v5800-2-sc(config-controller)# 
v5800-2-sc(config-controller)# 
Oct 17 11:02:18.762: ISDN Se1/0/0:15 SC RLM: process_tdial_message: 
Received Msg from SC 4 bytes :  0x0001014C 
Oct 17 11:02:23.614: ISDN Se1/1/0:15 SC RLM: process_tdial_message: 
Received Msg from SC 4 bytes :  0x00010129 
Oct 17 11:02:28: %CONTROLLER-5-UPDOWN: Controller E1 1/0/0, changed state to up 
Oct 17 11:02:28.154: ISDN Se1/0/0:15 SC EVENT: isdn_pri_t1_state_change: 
setting State to 4 
Oct 17 11:02:28.154: ISDN Se1/0/0:15 SC BACKHAUL: srl_send_l3_pak: 
                                   source_id = Q.931, dest_id = Q.921, 
                                   prim = DL_DATA_REQ 
                                   priv_len = 4 int_id = 0x65B73580 datasize = 28 
Oct 17 11:02:28.154: ISDN Se1/0/0:15 SC BACKHAUL: 
data = 0x65B73580000003000240043800010300 
Oct 17 11:02:28.154:    4302000006660500FFFFFFFE 
Oct 17 11:02:28.154: ISDN Se1/0/0:15 SC Q931: TX -> GROUP SERVICE 
pd = 67 callref = 0x0000 
                                    Interface Service i = 0x00FFFFFFFE 
Oct 17 11:02:28.158: ISDN Se1/0/0:15 SC RLM: process_tdial_message: 
Received Msg from SC 4 bytes :  0x0001014E 
Oct 17 11:02:28.170: ISDN Se1/0/0:15 SC RLM: process_tdial_message: 
Received Msg from SC 16 bytes :  0x02014A4E430280000B660500FFFFFFFE 
Oct 17 11:02:28.170: ISDN Se1/0/0:15 SC Q931: RX <- GROUP SERVICE ACK 
pd = 67  callref = 0x8000 Interface Service i = 0x00FFFFFFFE 
Oct 17 11:02:28.170: ISDN Se1/0/0:15 SC BACKHAUL: srl_send_l2_pak: 
                                   source_id = Q.921, dest_id = Q.931, 
prim = DL_DATA_IND 
                                   priv_len = 4 int_id = 0x65B73580 datasize = 28 
Oct 17 11:02:28.170: ISDN Se1/0/0:15 SC BACKHAUL: 
data = 0x65B7358000000000024104A800016258 
Oct 17 11:02:28.170:    430280000B660500FFFFFFFE 
Oct 17 11:02:28.170: ISDN Se1/0/0:15 SC BACKHAUL: L3IF_rx_L2_pak: 
received data 0x430280000B660500FFFFFFFE 
Oct 17 11:02:28.170: ISDN Se1/0/0:15 SC RLM: process_sc_group_msg: 
Received msg 11 from SC

Note: For the NI2+ Group Service Message = ''Interface Service i = 0x00FFFFFFFE'' 00 is linked to the ''Interface Number'' and FFFFFFFF is linked to Channel status. Operating state values are bitmaps, where the meaning of each bit is 0 = Channel is OUT OF SERVICE and 1 = Channel is IN SERVICE.

This procedure details the call flow information represented in the graphic:

Both the PGW and the gateway assume the initial service state of each bearer is Out of Service (OOS).
Execute the no shutdown command on the gateway.
A Group Service message with Interface Service i information is sent to the PGW 2200.
The PGW 2200 sends a CGU out to the PSTN.
The PSTN responds to each CGU message with a CGUA message.
The PGW 2200 responds with a Group Service Ack for each Group Service message received.

11:42:48.225329  1-005-1[02089]   1-015-1[02169] ITU  ISUP. -> CGU 
(19) CIC=00001 
                    SLS=01 
Pr:0 Ni:NTL 
********************************** DETAIL ********************************** 
CIC                            1 
MESSAGE TYPE                   0x19 CGU - Circuit_Group_Unblock 
CIRCUIT GRP SUPERVISION MT IND 0x15 
   LENGTH:                        0x01 FIXED DATA 0x01 
   CIRCUIT GRP SUPERVISION MT IND 1 hardware_failure_oriented 
INDEX TO VARIABLE PART         0x01 
   RANGE                          30 
   LENGTH:                        0x04 STATUS 0xFF 0xFF 0xFF 0x7F 
   CIC     state                  255 
   1       1 unblocking 
   2       1 unblocking 
   3       1 unblocking 
   4       1 unblocking 
   5       1 unblocking 
   6       1 unblocking 
   7       1 unblocking 
   8       1 unblocking 
   CIC     state                  255 
   9       1 unblocking 
   10       1 unblocking 
   11       1 unblocking 
   12       1 unblocking 
   13       1 unblocking 
   14       1 unblocking 
   15       1 unblocking 
   16       1 unblocking 
   CIC     state                  255 
   17       1 unblocking 
   18       1 unblocking 
   19       1 unblocking 
   20       1 unblocking 
   21       1 unblocking 
   22       1 unblocking 
   23       1 unblocking 
   24       1 unblocking 
   CIC     state                  127 
   25       1 unblocking 
   26       1 unblocking 
   27       1 unblocking 
   28       1 unblocking 
   29       1 unblocking 
   30       1 unblocking 
   31       1 unblocking 
   32       0 no unblocking 
******************       END_OF_MSG                       ****************** 
  

11:42:48.241989  1-015-1[02169]  1-005-1[02089]       
ITU  ISUP. ->CGUA(1b) CIC=00001 
                                    SLS=01 
Pr:0 Ni:NTL 

********************************** DETAIL ********************************** 
CIC                            1 
MESSAGE TYPE                   0x1B CGUA - Circuit_Group_Unblock_Ack 
CIRCUIT GRP SUPERVISION MT IND 0x15 
   LENGTH:                        0x01 FIXED DATA 0x01 
   CIRCUIT GRP SUPERVISION MT IND 1 hardware_failure_oriented 
INDEX TO VARIABLE PART         0x01 
   RANGE                          30 
   LENGTH:                        0x04 STATUS 0xFF 0xFF 0xFF 0x7F 
   CIC     state                  255 
   1       1 unblocking acknowledgment 
   2       1 unblocking acknowledgment 
   3       1 unblocking acknowledgment 
   4       1 unblocking acknowledgment 
   5       1 unblocking acknowledgment 
   6       1 unblocking acknowledgment 
   7       1 unblocking acknowledgment 
   8       1 unblocking acknowledgment 
   CIC     state                  255 
   9       1 unblocking acknowledgment 
   10       1 unblocking acknowledgment 
   11       1 unblocking acknowledgment 
   12       1 unblocking acknowledgment 
   13       1 unblocking acknowledgment 
   14       1 unblocking acknowledgment 
   15       1 unblocking acknowledgment 
   16       1 unblocking acknowledgment 
   CIC     state                  255 
   17       1 unblocking acknowledgment 
   18       1 unblocking acknowledgment 
   19       1 unblocking acknowledgment 
   20       1 unblocking acknowledgment 
   21       1 unblocking acknowledgment 
   22       1 unblocking acknowledgment 
   23       1 unblocking acknowledgment 
   24       1 unblocking acknowledgment 
   CIC     state                  127 
   25       1 unblocking acknowledgment 
   26       1 unblocking acknowledgment 
   27       1 unblocking acknowledgment 
   28       1 unblocking acknowledgment 
   29       1 unblocking acknowledgment 
   30       1 unblocking acknowledgment 
   31       1 unblocking acknowledgment 
   32       0 no unblocking acknowledgment 
******************       END_OF_MSG                       ****************** 
********************************** DETAIL **********************************

Manually Bring One or More B-Channels Out of Service with IOS Commands

v5800-2-sc(config-if)#isdn service b_channel 11 state ?  
<0-2>  Valid states are 0=Inservice 1=Maint 2=Outofservice
v5800-2-sc(config-if)#isdn service b_channel 11 state 2v5800-2-sc
(config-if)#

In this situation, a Group Service message is sent to the Cisco PGW 2200. A Group Service message sent from the Cisco NAS efficiently informs the Cisco PGW 2200 engine of the state of all bearer channels. The Cisco PGW 2200 engine decodes the message, changes the state of each NI-2 bearer channel, and propagates the changes to the SS7 side, from which corresponding block and unblock channel management messages must be sent. On the Cisco IOS NAS, check the status with the show isdn service command.

Jul 18 13:30:07.462: ISDN Se0:15 SC Q931: TX -> GROUP SERVICE
 pd = 67  callref = 0x0000 
        Interface Service i = 0x00FFDFFFFE
Jul 18 13:30:07.478: ISDN Se0:15 SC Q931: RX <- GROUP SERVICE ACK 
pd = 67  callref = 0x8000 
        Interface Service i = 0x00FFDFFFFE
Jul 18 13:30:07.478: ISDN Se0:15 SC Q931: do_statistics: 0x43 message 
0x0B not counted
Jul 18 13:30:37.489: ISDN Se0:15 SC Q931: RX <- GROUP SERVICE 
pd = 67  callref = 0x0000 
        Interface Service i = 0x0000000000
Jul 18 13:30:37.493: ISDN Se0:15 SC Q931: TX -> GROUP SERVICE ACK 
pd = 67  callref = 0x8000 
        Interface Service i = 0x00FFDFFFFE
Jul 18 13:30:37.493: ISDN Se0:15 SC Q931: do_statistics: 0x43 message 
0x0B not counted

Check the Cisco PGW 2200 error message in the platform.log file under the /opt/CiscoMGC/var/log directory. More information on the Cisco PGW 2200 error message can be found in the Log Messages documentation.

This is linked to this Cisco PGW 2200 error message in platform.log file.

Thu Jul 29 08:41:32:051 2004 GMT | engine (PID 16491) <Error>
CP_ERR_BC_INSV: cmgProtocolAdapter::setChanAsTermLeg:  UCID=00000007,
OSigPath=00150001, OTG=*NA*, OSPAN=*NA*, OTS/CIC=11,
TSigPath=00140001, TTG=*NA*, TSPAN=0, TTS/CIC=11,
 Bear channel is not inservice

Thu Jul 29 08:43:59:331 2004 GMT | engine (PID 16491) <Error>
CP_ERR_MAN_BC_BLK: cmgProtocolAdapter::setChanAsTermLeg:  UCID=00000008,
OSigPath=00150001, OTG=*NA*, OSPAN=*NA*, OTS/CIC=11,
TSigPath=00140001, TTG=*NA*, TSPAN=0, TTS/CIC=11,
 Bear channel is manual blocked

CGB/CGU Processed Conclusion

A CGB/CGU Processed Conclusion indicates that a problem has occurred but is used to inform the craftsperson that the far end switch has blocked a range of CICs.

The PGW 2200 does not send CGB/CGU during the start-up procedure. During start-up, the PGW 2200 sends GRS messages. The messages CGB/CGU are valid and are sent after the start-up procedure was finished. It depends on which SigPath recovered first after AS5xxx (NAS/gateway) reload (see scenario 1 below). For example, in scenario 1, the SS7 patch became IS after NAS, so there was no need to send CGB/CGU.

Scenario 1: No CGB/CGU to PSTN Side

Trigger	CIC state	SS7 SigPath State	NAS SigPath State
Initial Condition	IS	IS	IS
AS5xxx [Gateway - NAS ] Reload	OOS	OOS	OOS
NAS recovers	OOS	OOS	IS
SS7 recovers	IS	IS	IS

In scenario 2, once SS7 SigPath becomes IS, the far-end PSTN switch is able to send new calls (IAM message) towards PGW 2200. However, the calls fail because NAS did not become IS. Therefore, the PGW 2200 sends CGB to block (MATE_UNAVAILABLE) the CICs. Once NAS becomes IS, the PGW 2200 unblocks those CICs.

Scenario 2: CGB/CGU to the PSTN Side

Trigger	CIC State	SS7 SigPath State	NAS SigPath State
Initial Condition	IS	IS	IS
AS5xxx [Gateway - NAS] Reload	OOS	OOS	OOS
SS7 recovers	IS, (Mate_UN)	IS	OOS
NAS recovers	IS	IS	IS

Note: For more details about MATE_UNAVAIL, refer to Table 3-7: Circuit Block Types from the Cisco MGC Node Operations documentation.

Note: Other situations where you can run into this behavior are:

In the AS5xxx (NAS/gateway), the NI2+ Group Service Message indicates that SS7 CIC is not available which includes the SPAN being shutdown.
The connection between the Cisco PGW 2200 and AS5xxx (NAS/gateway) is down.
On the Cisco PGW 2200, when you manually set the admin state of NAS sigPath, SPAN, or PRI bearer channel to the lock state, all of them trigger CGB/BLO.

Since SS7 and PRI initialize independent to each other, once cannot guarantee who comes first.

There are more legitimate scenarios where CGB/CGU can be sent after SS7 SigPath becomes IS. For example:

Information	CIC State	SS7 SigPath State	NAS SigPath State
Initial Condition	IS	IS	IS
SS7 DPC was administratively taken down for maintenance	OOS	OOS	IS
NAS was administratively taken down for maintenance	OOS	OOS	OOS
SS7 DPC was brought up	IS,MATE_UN	IS	OOS

NetPro Discussion Forums - Featured Conversations

Networking Professionals Connection is a forum for networking professionals to share questions, suggestions, and information about networking solutions, products, and technologies. The featured links are some of the most recent conversations available in this technology.

NetPro Discussion Forums - Featured Conversations for Voice

Service Providers: Voice over IP

Voice & Video: Voice over IP

Voice & Video: IP Telephony

Voice & Video: IP Phone Services for End Users

Voice & Video: Unified Communications

Voice & Video: IP Phone Services for Developers

Voice & Video: General

Related Information

Tech Notes for the PGW 2200
Configuration Examples for the PGW 2200
Voice Technology Support
Voice and IP Communications Product Support
Recommended Reading: Troubleshooting Cisco IP Telephony
Technical Support & Documentation - Cisco Systems

Updated: Aug 10, 2006

Document ID: 46487

Hierarchical Navigation

Telephony Signaling