SNMP probelms on Auba 2920 (J9727A)

[RocketRon]

I must prefice my post by that I am fairly new to networking but a keen learner. I'm having SNMP problems with two identical switches - Aruba 2920-24G (J9726A) - and only with switches of this exact specification. They are both running WB.16.10.0009 .

To give context, I am currently testing librenms for viability and left default configurations in place since this is only temporary. Once we have a clear picture whether librenms serves our monitoring needs I plan to configure snmpv3.

We have just shy of a dozen switches at one of our facilities, a couple of 2530s and fourl 2920s, of which two are J9729A in a stack and the other two are J9727A. The latter two are the problematic devices. All switches are on the same LAN segment as the librenms server, and all of them were added into librenms by a few clicks (specifying IP addresses and the default 'public' snmp community - done), except these two.

- They have never been part of any snmp setup so there are no conflicting pre-existing configurations that I'm aware of.
- Both switches can ping the librenms server and viceversa
- There is no firewall between librenms server and these switches. Only a 2530 8-port and the stacked 2920 (J9729A), both of which have been successfully enrolled in librenms
- Both switches have the same configuration as shown in the original post except the exluded MIBs.

So far i have tried: (not sure if all of these even apply to the matter)

* defining the librenms ip as an snmp trap receiver
* specifying the librenms ip as authorized manager IP
* even tried skipping snmp v2c  and setting up v3 instead
* checked the names of the switches (whether they are identical to other switch names)
* tried snmpwalk from librenms but it times out

Nothing makes these switches talk to librenms. The message i get on the librenms WebUI is:

    Could not connect to 10.10.10.239, please check the snmp details and snmp reachability"

    SNMP v2c: No reply with community public

Librenms runs on a virtual machine (their official virtualbox image) with a bridged adapter.

Here is the snmp configuration on the switches:

hl-villa# sh snmp-server

 SNMP Communities

  Community Name       MIB View Write Access
  -------------------- -------- ------------
  public               Manager  Unrestricted

 Trap Receivers

  Link-Change Traps Enabled on Ports [All] : All

  Traps Category                          Current Status
  _____________________________________   __________________
  SNMP Authentication                   : Extended
  Password change                       : Enabled
  Login failures                        : Enabled
  Port-Security                         : Enabled
  Authorization Server Contact          : Enabled
  DHCP-Snooping                         : Enabled
  DHCPv6-Snooping Out of Resource       : Enabled
  DHCPv6-Snooping Errant Replies        : Enabled
  Dynamic ARP Protection                : Enabled
  Dynamic IP Lockdown                   : Enabled
  Dynamic IPv6 Lockdown Out of Resource : Enabled
  Dynamic IPv6 Lockdown Violations      : Enabled
  Startup Config change                 : Disabled
  Running Config Change                 : Disabled
  MAC address table changes             : Disabled

  DHCP-Server                           : Enabled
  NTP-Client                            : Disabled

  ND Snooping Out of Resources Traps    : Enabled

  Address                Community              Events   Type   Retry   Timeout
  ---------------------- ---------------------- -------- ------ ------- -------


 Excluded MIBs


 Snmp Response Pdu Source-IP Information

Any help or pointers would be greatly appreciated!

[parnassus · Accepted solution]

Hi! So you're dealing with two standalone Aruba 2920 (J9727A) (where "standalone" means "not stacked by means of Hardware Stacking Modules and Stacking Cables").

I will suggest you this approach (I'm using LibreNMS too with a bunch of Aruba switches), it worked for me:

1. Start with default SNMP values (if possible)
2. Enable SNMPv3 Only
3. Register (Add) Aruba 2920 into LibreNMS specifying SNMPv3 with all required passwords

CREDENTIAL SNMPv3 Credentials

SNMPv3 User "initial" Authentication Password: <init-auth-psw>
SNMPv3 User "initial" Privacy Password: <init-priv-psw>
SNMPv3 new User (SHA->AES-128): <snmp-user>
SNMPv3 User "<snmp-user>" Authentication Password: <snmp-user-auth-psw>
SNMPv3 User "<snmp-user>" Privacy Password: <snmp-user-priv-psw>

Follow this steps:

snmpv3 enable
snmpv3 only
no snmp-server community public
snmpv3 user <snmp-user> auth sha <snmp-user-auth-psw> priv aes <snmp-user-priv-psw>
snmpv3 group managerpriv user <snmp-user> sec-model ver3
no snmpv3 user initial
snmpv3 restricted-access
snmp-server response-source dst-ip-of-request
snmp-server location <switch-location>
snmp-server contact <switch-contact>

[RocketRon]

Thank you very much! I will try this over the weekend

[RocketRon]

It worked, thank you very much!