The link down alarm of switch can’t generate on U2000

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      Issue Description

7aca16338bea44988d5e4cc40953bc96

Networking topology: the switch in a loop network, and running mstp protocol for break the loop. And the port g0/0/1 is connected to core device and the g0/0/2 is connected to other access switch that on the loop. Both port are forwarding state, but g0/0/1 is on the upstream.<?xml:namespace prefix = "o" />


transparent.gif Handling Process

<!--[if !supportLists]-->1.       <!--[endif]-->We check the snmp configuration of switch1, it is correct. And when the port g0/0/2 is down, the U2000 can generate alarm immediately. So we excluded the snmp configuration reason.

<!--[if !supportLists]-->2.       <!--[endif]-->We debugging snmp trap information on switch, check whether send trap alarm information to U2000.

From the debugging snmp information, we found that: when the port g0/0/1 turn into down, the alarm trap information will be sent out at the same time.

After one second, we can see the port g0/0/1 has been set to discarding state.


<switch1>debugging snmp-agent trap

<switch1>debugging snmp-agent packet

<switch1>terminal debugging

<switch1>terminal monitor

<switch1>

Jun 28 2018 15:53:06+08:00 switch1%IFPDT/4/IF_STATE(l)[0]:Interface GigabitEthernet0/0/1 has turned into DOWN state.

<switch1>

Jun 28 2018 15:53:06+08:00 switch1 IFNET/1/IF_LINKDOWN:OID 1.3.6.1.6.3.1.1.5.3 Interface 7 turned into DOWN state.(AdminStatus=0,OperStatus=0,InterfaceName=GigabitEthernet0/0/1)

<switch1>

<switch1>

Jun 28 2018 15:53:07+08:00 switch1 MSTP/1/TOPOC:OID 1.3.6.1.2.1.17.0.2 Bridge topology change.

<switch1>

Jun 28 2018 15:53:07+08:00 switch1 MSTP/4/PDISC:OID 1.3.6.1.4.1.2011.5.25.42.4.2.2 The port has been set to discarding state. (InstanceID=0, PortInstanceID=0, PortID=1, IfIndex=7, PortName=GigabitEthernet0/0/1)

<switch1>

46a776d83e334612b3d685e1cf1ec524

<?xml:namespace prefix = "v" />

When the port g0/0/1 turn into up, we see the alarm resume OID send out at the same time too, after one second, we can see the port g0/0/1 has been set to forwarding state.

<switch1>

Jun 28 2018 16:01:10+08:00 switch1 %IFPDT/4/IF_STATE(l)[0]:Interface GigabitEthernet0/0/1 has turned into UP state.

<switch1>

Jun 28 2018 16:01:10+08:00 switch1 IFNET/1/IF_LINKUP:OID 1.3.6.1.6.3.1.1.5.4 Interface 6 turned into UP state.(AdminStatus=1,OperStatus=1,InterfaceName=GigabitEthernet0/0/1)

<switch1>

<switch1>

Jun 28 2018 16:01:11+08:00 switch1 MSTP/1/TOPOC:OID 1.3.6.1.2.1.17.0.2 Bridge topology change.

<switch1>

Jun 28 2018 16:01:11+08:00 switch1 MSTP/4/PDISC:OID 1.3.6.1.4.1.2011.5.25.42.4.2.2 The port has been set to discarding state. (InstanceID=0, PortInstanceID=0, PortID=2, IfIndex=7, PortName=GigabitEthernet0/0/2)

<switch1>

Jun 28 2018 16:01:11+08:00 switch1 MSTP/4/PFWD:OID 1.3.6.1.4.1.2011.5.25.42.4.2.1 The port has been set to forwarding state. (InstanceID=0, PortInstanceID=0, PortID=1, IfIndex=6, PortName=GigabitEthernet0/0/1)

<switch1>

Jun 28 2018 16:01:11+08:00 switch1 MSTP/1/TOPOC:OID 1.3.6.1.2.1.17.0.2 Bridge topology change.

<switch1>

Jun 28 2018 16:01:11+08:00 switch1 MSTP/4/PFWD:OID 1.3.6.1.4.1.2011.5.25.42.4.2.1 The port has been set to forwarding state. (InstanceID=0, PortInstanceID=0, PortID=2, IfIndex=7, PortName=GigabitEthernet0/0/2)

<switch1>

 

Form those logs, we know that the alarm OID information has been sent out, but U2000 didn’t receive.

Analyze the networking topology and the STP convergence information, we know that when the port turn into down, the alarm OID will be sent only once, but at this time the stp convergence still did not complete, because the port g0/0/1 is the upstream port, so the alarm OID information can’t be sent to U2000. It lead to U2000 did not generate the alarm.


transparent.gif Root Cause

when the port turn into down, the alarm OID will be sent only once, but at this time the stp convergence still did not complete, because the port g0/0/1 is the upstream port, so the alarm OID information can’t be sent to U2000. It lead to U2000 did not generate the alarm.

transparent.gif Solution

NA

transparent.gif Suggestions

When we see the NMS can't generate alarm, we can follow those steps check the issue:

1. check the snmp configurations, and test snmp connection on NMS;

2. debugging or capture packets on device and NMS, check whether the alarm trap information has been sent out from device, and whether the alarm trap information has been received by NMS.

3. after located the alarm has been sent out from device but can't receive by NMS, check where drop the alarm trap message.

  • x
  • convention:

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