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Troubleshoot the PGW 2200 Softswitch with SNMP

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Document ID: 62683

Updated: Jul 23, 2008



This document provides troubleshooting information for the Simple Network Management Protocol (SNMP) on the Cisco PGW 2200 Public Switched Telephone Network (PSTN) Gateway (referred to as simply Cisco PGW 2200 in this document). The information in this document applies specifically to the Cisco PSTN Gateway Solution for both call control and call signaling modes. This document contains tips and warnings on the use of SNMP components with the solution, as well as troubleshooting steps for solving potential problems.

The SNMP agent provides a simple network management task. The SNMP exchanges information about the status of a device, in this case a device linked to the Cisco PGW 2200, within the management framework using Protocol Data Units (PDUs) coded in Abstract Syntax Notation (ASN) format.



There are no specific requirements for this document.

Components Used

The information in this document is based on these software and hardware versions:

Platform Platform Name Release
Cisco PGW 2200 Node Cisco Media Gateway Controller (MGC)
Cisco PGW 2200 Management Information Bases (MIB) Information   Cisco bug ID CSCeb37011 (registered customers only) —SNMP security enhancement

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.


For more information on document conventions, refer to the Cisco Technical Tips Conventions.

Troubleshoot SNMP Information on the Cisco PGW 2200

The default SNMP security (community) string is public for read and notification purposes. The write security (community) string is randomly generated for the process recovery function. SNMP configurations vary; for specific defects, check Cisco bug ID CSCeb73838 (registered customers only) which is linked to a Cisco PGW 2200 config-snmp command that needs to be used to configure the SNMP items on the Cisco PGW2200.

The config-snmp command, located in the /opt/CiscoMGC/local directory, is a menu-driven tool which can be executed from the UNIX superuser mode. Its migration feature can limit the set operation to only two MIB objects which either enable or disable the process recovery. The security string of set operation is randomly generated and limited to local host access. The config-snmp command also provides the user the capability to add and delete the security (community) string and trap destination. This is sample output of the config-snmp command:

mgcusr@mgc-bru-20% su - root
# config-snmp

Migrating snmpd.cnf into a more secure setting...

===================   SNMPD Configuration Main Menu  =================== 

1. View Configuration Entries
2. Add an SNMP Community
3. Delete an SNMP Community
4. Add a Trap Destination
5. Delete a Trap Destination
6. Activate the New Settings

Enter a selection (1 through 6) or 'q' to quit:   1

===================   Entries Menu  =================== 

1. sysDescr
2. sysObjectID
3. sysLocation
4. sysContact
5. sysName
6. snmpEnableAuthenTraps
11. subagent
12. snmpCommunityEntry
13. communityEntry
14. snmpEngineBoots
15. usmUserEntry
16. vacmAccessEntry
17. vacmSecurityToGroupEntry
18. vacmViewTreeFamilyEntry
19. snmpNotifyEntry
20. snmpTargetAddrEntry
21. snmpTargetParamsEntry
22. snmpNotifyFilterProfileEntry
23. snmpNotifyFilterEntry
24. httpUserNameEntry
Enter a selection (1 through 24) or 'q' to quit to Main Menu: 
===================   SNMPD Configuration Main Menu  =================== 

1. View Configuration Entries
2. Add an SNMP Community
3. Delete an SNMP Community
4. Add a Trap Destination
5. Delete a Trap Destination
6. Activate the New Settings

Enter a selection (1 through 6) or 'q' to quit: 2

===================   Add CommunityString Menu =================== 

SnmpCommunityName       CommunitySecurityName   

public                  ReadAndNotifyToAll      

-- Where:

CommunitySecurityName   SecurityModel  Read           Write            Notification            

ReadAndNotifyToAll      snmpv1         AllMibObjects   -               AllMibObjects           
ReadAndNotifyToAll      snmpv2c        AllMibObjects   -               AllMibObjects           
ReadWriteAll            snmpv1         AllMibObjects   AllMibObjects   -                       
ReadWriteAll            snmpv2c        AllMibObjects   AllMibObjects   -                       

 Would you like to proceed with the Add  [n]/[y]?

From this level you can change the SnmpCommunityName  on the Cisco PGW 2200.

Note: If the SNMP daemon is disabled on the Cisco PGW 2200, there is no recovery feature for Cisco PGW 2200 processes (see /opt/CiscoMGC/snmp/critagt.cnf). Processes monitored by the Critical Application Subagent (critagt) cannot be recovered if this agent is killed unintentionally. There is no recovery support.

Once you have set all information correctly, you may still encounter some issues. Here are some troubleshooting steps:

  1. Ensure the snmpdm process is running on the Cisco PGW 2200:

    mgcusr@PGW 2200a% ps -ef | grep snmp
    root   931     1  0   Mar 29 ?   3:20 /opt/CiscoMGC/snmp/snmpdm -tcplocal -d
    root   932     1  0   Mar 29 ?   0:31 /opt/CiscoMGC/snmp/mib2agt -d
    root 15519     1  0   Jun 29 ?   0:06 /opt/CiscoMGC/snmp/critagt -d
    root   933     1  0   Mar 29 ?   1:26 /opt/CiscoMGC/snmp/hostagt -d
    root   934     1  0   Mar 29 ?   0:25 /opt/CiscoMGC/snmp/fsagt -d
    root   935     1  0   Mar 29 ?   4:34 /opt/CiscoMGC/snmp/brassagt -d
  2. Criatgt is supervised from init. Verify that you have this entry in the /etc/inittab directory:

    ca:3:respawn:/opt/CiscoMGC/snmp/critagt -d
  3. Critagt supervises the snmpdm, mib2agt, hostagt, fsagt, brassagt, procM and LogServer agents. Verify that you see these SNMP processes running in /opt/CiscoMGC/snmp/criagt.cnf:

    mgcusr@PGW 2200a% ps -ef | grep snmp
        root   931  1  0   Mar 29 ?   3:20 /opt/CiscoMGC/snmp/snmpdm -tcplocal -d
        root   932  1  0   Mar 29 ?   0:31 /opt/CiscoMGC/snmp/mib2agt -d
        root 15519  1  0   Jun 29 ?   0:06 /opt/CiscoMGC/snmp/critagt -d
        root   933  1  0   Mar 29 ?   1:26 /opt/CiscoMGC/snmp/hostagt -d
        root   934  1  0   Mar 29 ?   0:25 /opt/CiscoMGC/snmp/fsagt -d
        root   935  1  0   Mar 29 ?   4:34 /opt/CiscoMGC/snmp/brassagt -d
  4. Issue the UNIX command netstat -a | grep 161 and check that the command returns an idle status for the User Datagram Protocol (UDP) SNMP ports.

    mgcusr@PGW 2200a% netstat -a | grep 161
          *.161                                 Idle
    localhost.7161             *.*                0      0 24576      0 LISTEN
    30006f41610 stream-ord 00000000 00000000 ../var/lsd_addr                
    mgcusr@PGW 2200a%netstat -a | grep 162
          *.162                                 Idle
    mgcusr@PGW 2200a%

    Note: Standard SNMP sends responses to management requests over UDP port 161 and trap information over UDP port 162.

    Note: You can issue the UNIX snoop command to find out what has been sent between the Cisco PGW 2200 and the network management system (NMS) station. On the NMS station, you can issue freeware command snmpwalk in combination with the UNIX snoop command.

  5. Issue the snoop -v <IP address NMS> command on the Cisco PGW 2200 to find out what messages have been sent from and to the NMS station. Also read the man snoop command details; you may want to store them in a file. You can also capture this information and check the content using the Ethereal network protocol analyzer.

  6. Issue the snmpwalk -c public <PGW 2200 IP address> command on your NMS system. This command queries for a tree of information.

    The version of the snmpwalk command used for the purposes of this document is:

    % snmpwalk
    No hostname specified.
    USAGE: snmpwalk [OPTIONS] AGENT [OID]
      Version:  5.0.9

    This is a sample output of the snmpwalk command:

    SNMPv2-MIB::sysDescr.0 = STRING: SNMPv3 agent from Cisco Systems, Inc.
    SNMPv2-MIB::sysObjectID.0 = OID: SNMPv2-SMI::enterprises.2496.1.1
    DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (1599337216) 
    185 days, 2:36:12.16
    SNMPv2-MIB::sysContact.0 = STRING: Cisco Systems, Inc.  +1 703 484 3000
    SNMPv2-MIB::sysName.0 = STRING: NSSU - MGC
    SNMPv2-MIB::sysLocation.0 = STRING: Herndon, Virginia
    SNMPv2-MIB::sysServices.0 = INTEGER: 72
    SNMPv2-MIB::sysORLastChange.0 = Timeticks: (0) 0:00:00.00
    IF-MIB::ifNumber.0 = INTEGER: 3
    IF-MIB::ifIndex.1 = INTEGER: 1
    IF-MIB::ifIndex.2 = INTEGER: 2
    IF-MIB::ifIndex.3 = INTEGER: 3
    IF-MIB::ifDescr.1 = STRING: lo0
    IF-MIB::ifDescr.2 = STRING: eri0
    IF-MIB::ifDescr.3 = STRING: eri1
    IF-MIB::ifType.1 = INTEGER: softwareLoopback(24)
    IF-MIB::ifType.2 = INTEGER: ethernetCsmacd(6)
    IF-MIB::ifType.3 = INTEGER: ethernetCsmacd(6)
    IF-MIB::ifMtu.1 = INTEGER: 8232
    IF-MIB::ifMtu.2 = INTEGER: 1500
    IF-MIB::ifMtu.3 = INTEGER: 1500
    RFC1213-MIB::atNetAddress. = Network Address: 32:00:00:01
    RFC1213-MIB::atNetAddress. = Network Address: E0:00:00:00
    RFC1213-MIB::atNetAddress. = Network Address: 0A:30:55:14
    RFC1213-MIB::atNetAddress. = Network Address: E0:00:00:00
    IP-MIB::ipForwarding.0 = INTEGER: notForwarding(2)
    IP-MIB::ipDefaultTTL.0 = INTEGER: 255
    IP-MIB::ipInReceives.0 = Counter32: 535077888
    IP-MIB::ipInHdrErrors.0 = Counter32: 0
    IP-MIB::ipInAddrErrors.0 = Counter32: 0
    IP-MIB::ipForwDatagrams.0 = Counter32: 0
    !--- Output suppressed due to the enormity of information, which 
    !--- would require several HTML pages to display.

You cannot start the snmpdm process in the /opt/CiscoMGC/snmp directory from the UNIX superuser mode, using the argument ''-apall'' as log all messages anymore. This is not possible because the software removes this argument and brings it back into the normal setup scenario as snmpdm -tcplocal -d, shown in this sample output: This results in this error message:

#/etc/init.d/snmpd stop
# /opt/CiscoMGC/snmp/snmpdm -tcplocal -d -apall &

!--- Start the snmpdm process with the command snmpd -tcplocal -d -apall &.

SNMP Research SNMP Agent Resident Module Version 
Copyright 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 
1999, 2000, 2001, 2002, 2003 SNMP Research, Inc.
Successfully opened log file /tmp/snmpd.log
                              at line 397 in file mastmain.c
Only APERROR and APWARN messages are being printed to the log file 
(override with -log_tracefile)
                              at line 421 in file mastmain.c
[1] 11204
# init_fnames: searching for configuration files in /opt/CiscoMGC/snmp 
from getenv("SR_AGT_CONF_DIR")
                              at line 90 in file ./../../snmpd/shared/fnames.c
AgentSocketCreate: bind failed: Address already in use
                              at line 262 in file tcp.c
InitMaster: IPCFP[0].AgentSocketCreate failed
                              at line 735 in file master.c
master agent initialization failed, exiting
                              at line 478 in file mastmain.c

# /opt/CiscoMGC/snmp/snmpdm -h

usage: ./snmpdm [options]

        -d                execute in the foreground window
        -trap_send_port PORT   send SNMP trap/inform messages from port PORT
        -tcpany           accept connections from any TCP subagent
        -tcplocal         accept connections from local TCP subagents 
        -tcpnone          disallow connections from TCP subagents (default)
        -apnone           no log messages
        -apwarn           log warning messages
        -aperror          log error messages
        -apconfig         log config file i/o messages
        -appacket         log SNMP packet build/parse messages
        -aptrap           log trap/inform messages
        -apaccess         log agent processing messages
        -apemanate        log master/subagent messages
        -aptimer          log timer debug messages
        -apthread         log thread debug messages
        -apverbose        log verbose debug messages
        -apuser           log user messages
        -hexdump          dump packets in hex
        -vbdump           dump packets as varbinds
        -aptrace          trace packet in application
        -apaudit          audit SET processing in application
        -apall            log all messages
        -log_mtos         allow sending log messages to Subagents
        -log_nomtos       disallow sending log messages to Subagents
        -log_stom         allow receiving log messages from Subagents
        -log_nostom       disallow receiving log messages from Subagents
        -log_format 0     use traditional log message format
        -log_format 1     use new log message format
        -log_stdout       allow log messages to go to standard output
        -log_nostdout     disallow log messages to go to standard output
        -log_stderr       allow log messages to go to standard error
        -log_nostderr     disallow log messages to go to standard error
        -log_file         allow log messages to go to snmpd.log
        -log_nofile       disallow log messages to go to snmpd.log
        -log_tracefile    allow APTRACE messages to go to snmpd.log
        -log_notracefile  disallow APTRACE messages to go to snmpd.log
        -log_append       append log messages to snmpd.log
        -log_noappend     discard previous contents of snmpd.log, if any
        -large_v1_pdus    lift 484 byte restriction for v1/v2c PDUs
        -help             print this usage line
        -pkt_size value   use supplied value as max packet size
mgcusr@PGW 2200a%

The critagt.cnf file in the /opt/CiscoMGC/snmp directory, shown here, is responsible for the above error message:

mgcusr@pw2200a% more critagt.cnf
# Entry type: critAppProcEntry 
# Entry format: integer
#               octetString
#               octetString
#               octetString
#               integer
#               integer
#               integer
#               integer
#               integer
#               integer
critAppProcEntry  1 snmpdm "/opt/CiscoMGC/snmp/snmpdm -tcplocal -d" 
- 1 true 0  true true true

Because critagt restarts the SNMP daemon and once it is started, the port becomes busy, you encounter the error message described.

Note: You cannot change any entry in the critagt.cnf file, because after you restart the Cisco PGW 2200 application, it automatically restores the default settings.

Note: For detailed information on the snmpd.log file, check under the /tmp directory.

For DDTS records linked to Cisco PGW 2200 snmpd details, refer to Cisco bug ID CSCef55514 (registered customers only) —Missing SNMP generic traps for link down and up.

Related Information

Updated: Jul 23, 2008
Document ID: 62683