CE6870 port usage get high randomly when receives TC BPDU

Issue Description

Customer feedabck that the usage of CE6870 get 100% randomly and there are packets dropped.

Apr 1 2018 07:43:17+05:30 SYSCON_NETMAGIC_CORE_SWITCH %DEVM/4/hwIfMonitorOutputRateRising_active(l):CID=0x80fc0101-alarmID=0x081300af;Interface output flow bandwidth usage exceeded the trap threshold. (Interface=19, BandWidthUsage=100, TrapThreshold=90, InterfaceName=10GE1/0/15)

Apr 1 2018 07:43:19+05:30 SYSCON_NETMAGIC_CORE_SWITCH %DEVM/4/hwIfMonitorOutputRateRising_active(l):CID=0x80fc0101-alarmID=0x081300af;Interface output flow bandwidth usage exceeded the trap threshold. (Interface=17, BandWidthUsage=91, TrapThreshold=90, InterfaceName=10GE1/0/13)

Alarm Information

Apr 1 2018 07:43:17+05:30 SYSCON_NETMAGIC_CORE_SWITCH %DEVM/4/hwIfMonitorOutputRateRising_active(l):CID=0x80fc0101-alarmID=0x081300af;Interface output flow bandwidth usage exceeded the trap threshold. (Interface=19, BandWidthUsage=100, TrapThreshold=90, InterfaceName=10GE1/0/15)

Apr 1 2018 07:43:19+05:30 SYSCON_NETMAGIC_CORE_SWITCH %DEVM/4/hwIfMonitorOutputRateRising_active(l):CID=0x80fc0101-alarmID=0x081300af;Interface output flow bandwidth usage exceeded the trap threshold. (Interface=17, BandWidthUsage=91, TrapThreshold=90, InterfaceName=10GE1/0/13)

Handling Process

1. Checking the log information of the switch, there are many TC protection enable record, it means that there are many TC BPDU receives by the CE6870. After receive TC BPDU, the mac address table and arp table will be refreshed. After refresh the mac address table and arp table, there will be broadcast to learn mac and arp again, that cause the traffic increase on the ports.

Apr 1 2018 06:59:45+05:30 SYSCON_NETMAGIC_CORE_SWITCH %MSTP/4/MSTPLOG_PROTC_GUARDED(l):CID=0x80542724;With the TC protection enabled, if TC BPDUs were received after the number of TC BPDUs received by an instance exceeded the threshold, these TC BPDUs were processed after the TC protection time expires. (ProcessID=0, InstanceID=1)

2. Checking the log record, there are many bandwidth usage exceeded record and the timing match the TC BPDU receives.

Apr 1 2018 07:43:17+05:30 SYSCON_NETMAGIC_CORE_SWITCH %DEVM/4/hwIfMonitorOutputRateRising_active(l):CID=0x80fc0101-alarmID=0x081300af;Interface output flow bandwidth usage exceeded the trap threshold. (Interface=19, BandWidthUsage=100, TrapThreshold=90, InterfaceName=10GE1/0/15)

Apr 1 2018 07:43:19+05:30 SYSCON_NETMAGIC_CORE_SWITCH %DEVM/4/hwIfMonitorOutputRateRising_active(l):CID=0x80fc0101-alarmID=0x081300af;Interface output flow bandwidth usage exceeded the trap threshold. (Interface=17, BandWidthUsage=91, TrapThreshold=90, InterfaceName=10GE1/0/13)

3. After confgire stp flush disable, the port usage become stable. After add this configuration, when the switch receives TC BPDU, it will not refresh the mac address table and arp table, so there will be no broadcast.

<HUAWEI> system-view

[~HUAWEI] stp flush disable

Root Cause

After receive TC BPDU, the mac address table and arp table will be refreshed. After refresh the mac address table and arp table, there will be broadcast to learn mac and arp again, that cause the traffic increase on the ports. Root cause is that find out the TC resource and fix it.

Solution

1. After confgire stp flush disable, the port usage become stable. After add this configuration, when the switch receives TC BPDU, it will not refresh the mac address table and arp table, so there will be no broadcast.

<HUAWEI> system-view

[~HUAWEI] stp flush disable

2. Use command display stp global to find out the TC resource and fix it.

<HUAWEI> display stp global

Protocol Status :Enabled

Bpdu-filter default :Disabled

Tc-protection :Enabled

Tc-protection threshold :1

Tc-protection interval :2s

Edged port default :Disabled

Pathcost-standard :Dot1T

Timer-factor :3

Transmit-limit :6

Bridge-diameter :7

CIST Global Information:

Mode :MSTP

CIST Bridge :32768.0019-7459-3301

Config Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

Active Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

CIST Root/ERPC :32768.0019-7459-3301 / 0 (This bridge is the root)

CIST RegRoot/IRPC :32768.0019-7459-3301 / 0 (This bridge is the root)

CIST RootPortId :0.0

BPDU-Protection :Disabled

TC or TCN received :9

TC count per hello :0

STP Converge Mode :Normal

Share region-configuration :Enabled

Time since last TC :0 days 1h:37m:17s

Number of TC :10

Last TC occurred :10GE4/0/12

Topo Change Flag :0

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CE6870 port usage get high randomly when receives TC BPDU

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