MGX Switch SNMP Walk Configuration Example

Introduction

This document describes how to perform the Simple Network Management Protocol (SNMP) walk on Cisco MGX switches with a user-configured SNMP group.

Prerequisites

Requirements

Cisco recommends that you meet this requirement before you attempt this configuration: the IP address configured on the lnPci interface on the MGX must be reachable from the system on which you intend to perform the SNMP walk.

Components Used

This document is based on an MGX 8850 with a PXM45C as the processor card. However, this document is not restricted to specific software and hardware versions.

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.

Background

When you poll an Object Identifier (OID) with a SNMP walk in a public/ private group on an MGX, it works well (see the output). But if you define a new SNMP group and perform a walk, you receive timeouts.

MGX.7.PXM.a > dspsnmpgroups
            GroupName               SecurityModel     SecurityLevel
 -------------------------------- ----------------- -----------------
 public                             SNMPV1              NoAuthNoPriv
 private                            SNMPV1              NoAuthNoPriv
 cisco_group                        SNMPV3              AuthPriv
 trapCommunity                      SNMPV1              NoAuthNoPriv

snmp_server% snmpwalk -Os -c public -v1 192.168.2.2 system
sysDescr.0 = STRING: Cisco MGX8880 Media Gateway
sysObjectID.0 = OID: enterprises.9.1.598
sysUpTimeInstance = Timeticks: (497996272) 57 days, 15:19:22.72
sysContact.0 = STRING:
sysName.0 = STRING: MGX
sysLocation.0 = STRING:
sysServices.0 = INTEGER: 72

snmp_server% snmpwalk -Os -c private -v1 192.168.2.2 system
sysDescr.0 = STRING: Cisco MGX8850 Wide Area Switch
sysObjectID.0 = OID: enterprises.9.1.228
sysUpTimeInstance = Timeticks: (10648330) 1 day, 5:34:43.30
sysContact.0 = STRING:
sysName.0 = STRING: MGX
sysLocation.0 = STRING:
sysServices.0 = INTEGER: 72

Restrictions

By default, an SNMP walk on an MGX is allowed only on public and private SNMP groups.

Configure

Complete these steps in order to configure.

1. Add a new SNMP group (such as test) with the addsnmpgroup command.
   
   

   MGX.7.PXM.a > addsnmpgroup
   
   Syntax:  addsnmpgroup <groupName> <securityModel> <securityLevel>
   
   groupName -- String with length less than 33 characters
           securityModel -- 1 - snmpv1, 3 -  usm (snmpv3)
           securityLevel -- 1 - noAuthNoPriv, 2 - authNoPriv, 3 - authPriv
           (for securityModel = snmpv1, securityLevel has to be 1)
           read -- String with length less than 33 characters
           write -- String with length less than 33 characters
           notify -- String with length less than 33 characters
           (for SII, use SII-RW-VIEW as Read & Write view and SII-TRAP-VIEW
           as Notify view)
   
   MGX.7.PXM.a > addsnmpgroup test 1 1 >>> Adding SNMP group named 'test' for
   SNMPv1 and noAuthNoPriv.
   
   MGX.7.PXM.a > dspsnmpgroups
               GroupName               SecurityModel     SecurityLevel 
    -------------------------------- ----------------- -----------------
    test                               SNMPV1              NoAuthNoPriv   
    public                             SNMPV1              NoAuthNoPriv    
    private                            SNMPV1              NoAuthNoPriv    
    cisco_group                        SNMPV3              AuthPriv        
    trapCommunity                      SNMPV1              NoAuthNoPriv 

   
   
   
2. Perform an SNMP Walk.
   
   

   snmp_server% snmpwalk -Os -c test -v1 192.168.2.2 system
   Timeout: No Response from 192.168.2.2 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
   >>>> does not work

   
   
   The reason behind this behavior is that the OID with a SNMP walk works ONLY for public and private groups (as described the Restriction section).
   
   
3. Configure the SNMP community.
   
   

   MGX.7.PXM.a > dspsnmp
   MGX                               System Rev: 05.05   May. 10, 2014 03:16:57 GMT
   MGX8850                                              Node Alarm: MAJOR
   
   Community (rw):          private
   Community (ro):          public
   System Location:
   System Contact:

   
   
   
4. Add test to the read/write privileges.
   
   

   MGX.7.PXM.a > cnfsnmp community
   ERR: Syntax: cnfsnmp community <string> [ro|rw]
           cnfsnmp contact   [string] -- a printable string of 0-255 characters
           cnfsnmp location  [string] -- a printable string of 0-255 characters
   
   MGX.7.PXM.a > cnfsnmp community  test rw
   
   M5.7.PXM.a > dspsnmp
   MGX                              System Rev: 05.05   May. 05, 2014 05:05:02 GMT
   MGX8850                                              Node Alarm: CRITICAL
   
   Community (rw):          test >>>>>>>>>>>>>>earlier it was private
   Community (ro):          public
   System Location:
   System Contact:

Verify

Use this section in order to verify that your configuration works properly.

1. Verify that the SNMP group test is added.
   
   

   MGX.7.PXM.a > dspsnmpgroups
               GroupName               SecurityModel     SecurityLevel 
    -------------------------------- ----------------- -----------------
    test                               SNMPV1              NoAuthNoPriv   
    public                             SNMPV1              NoAuthNoPriv    
    private                            SNMPV1              NoAuthNoPriv    
    cisco_group                        SNMPV3              AuthPriv        
    trapCommunity                      SNMPV1              NoAuthNoPriv  

   
   
   
2. Check the SNMP group community.
   
   

   M5.7.PXM.a > dspsnmp
   MGX                              System Rev: 05.05   May. 05, 2014 05:05:02 GMT
   MGX8850                                              Node Alarm: CRITICAL
   
   Community (rw):          test >>>>>>>>>>>>>>earlier it was private
   Community (ro):          public
   System Location:
   System Contact:

   
   
   
3. Perform an SNMP walk again with the test community.
   
   

   snmp_server@kyudo-1% snmpwalk -Os -c test -v1 192.168.2.2 system
   sysDescr.0 = STRING: Cisco MGX8850 Wide Area Switch
   sysObjectID.0 = OID: enterprises.9.1.228
   sysUpTimeInstance = Timeticks: (10699803) 1 day, 5:43:18.03
   sysContact.0 = STRING:   [string] -- a printable string of 0-255 characters
   sysName.0 = STRING: M5
   sysLocation.0 = STRING:  [string] -- a printable string of 0-255 characters
   sysServices.0 = INTEGER: 72

Troubleshoot

There is currently no specific troubleshooting information available for this configuration.

Related Information

• Cisco MGX 8800/8900 Series Software Configuration Guide Release 5.5.10
• Technical Support & Documentation - Cisco Systems