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[EX2300/EX3400] Recommended setting for successfully sending SNMP coldstart traps

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Article ID: KB35452 KB Last Updated: 06 Mar 2020Version: 1.0
Summary:

Users may find that Simple Network Management Protocol (SNMP) coldstart traps are sometimes not sent to the SNMP server in EX2300 and EX3400 Series switches.

This article explains the reason these traps are not sent and provides the recommended settings to have the traps sent.

 

Symptoms:

In general, when devices with SNMP configuration are rebooted or powered off, SNMP traps for coldstart are sent to the SNMP server.

However, sometimes these coldstart traps may not be sent in EX2300 or EX3400 devices.

Note: Other SNMP traps will work as expected.

Non-Working Scenario

This issue could be seen when the SNMP server is connected to a network port.

EX2300(ge-0/0/0)--------SNMP server

 

Cause:

From the SNMP trace, SNMPD generates coldstart trap properly. However, EX2300 or EX3400 cannot send it out to the SNMP server. This is because there is a time delay in bringing up the network interfaces. The issue, however, is not seen on the management port since it comes up first.

A sample log when EX2300 is coming up from rebooting is as follows. For example, management port me0 came up at Jan 27 16:07:19.0 but ge-0/0/0 came up about 40 seconds later.

--------------------
Jan 27 16:07:19.033 2020  EX2300 mib2d[4341]: %DAEMON-6-SNMP_TRAP_LINK_UP: ifIndex 34, ifAdminStatus up(1), ifOperStatus up(1), ifName me0.0
Jan 27 16:07:58.363 2020  EX2300 mib2d[4341]: %DAEMON-6-SNMP_TRAP_LINK_UP: ifIndex 537, ifAdminStatus up(1), ifOperStatus up(1), ifName ge-0/0/0.0
--------------------

On the other hand, the SNMP coldstart trap was generated internally at 16:07:05.

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Jan 27 16:07:05.704721 SNMPD_TRAP_COLD_START: trap_generate_cold: SNMP trap: cold start
--------------------

This delay would cause a coldstart packet loss between the kernel and the Packet Forwarding Engine (PFE), resulting in the coldstart trap not being sent.

 

Solution:

For ARM-based EX platforms (EX2300 and EX3400), it takes considerably more time for network ports to come up.

In this case, it is recommended to use the management port instead of a network port for SNMP coldstart trap purposes.

Working Scenario

The coldstart trap will be sent properly when the SNMP server is connected to the management port.

EX2300(me0)-------------SNMP server

 

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