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VRRP Status Frequently Changes Because the S7700 Receives a Large Number of TC BPDUs

Publication Date:  2019-03-26 Views:  123 Downloads:  0

Issue Description

After the VRRP group of S7700 switches has run normally for half a year, the VRRP status is unstable and master/backup switchovers are performed repeatedly.

Alarm Information

Apr 30 2018 00:24:25 sw_core_1 %%01VRRP/4/STATEWARNINGEXTEND(l)[19]:Virtual Router state MASTER changed to INITIALIZE, because of interface down. (Interface=Vlanif130, VrId=130, InetType=IPv4)

Apr 30 2018 00:24:25 sw_core_1 %%01IFNET/4/LINK_STATE(l)[20]:The line protocol IP on the interface Vlanif130 has entered the DOWN state.

Apr 30 2018 00:24:25 sw_core_1 %%01IFNET/4/IF_STATE(l)[21]:Interface Vlanif130 has turned into DOWN state.

Apr 30 2018 00:24:25 sw_core_1 %%01VRRP/4/STATEWARNINGEXTEND(l)[22]:Virtual Router state MASTER changed to INITIALIZE, because of interface down. (Interface=Vlanif103, VrId=103, InetType=IPv4)

Apr 30 2018 00:24:25 sw_core_1 %%01IFNET/4/LINK_STATE(l)[23]:The line protocol IP on the interface Vlanif103 has entered the DOWN state.

Apr 30 2018 00:24:25 sw_core_1 %%01IFNET/4/IF_STATE(l)[24]:Interface Vlanif103 has turned into DOWN state.

Apr 30 2018 00:24:25 sw_core_1 %%01VRRP/4/STATEWARNINGEXTEND(l)[25]:Virtual Router state MASTER changed to INITIALIZE, because of interface down. (Interface=Vlanif102, VrId=102, InetType=IPv4)

Apr 30 2018 00:24:25 sw_core_1 %%01IFNET/4/LINK_STATE(l)[26]:The line protocol IP on the interface Vlanif102 has entered the DOWN state.

Apr 30 2018 00:24:25 sw_core_1 %%01IFNET/4/IF_STATE(l)[27]:Interface Vlanif102 has turned into DOWN state.

Apr 30 2018 00:24:25 sw_core_1 %%01VRRP/4/STATEWARNINGEXTEND(l)[28]:Virtual Router state MASTER changed to INITIALIZE, because of interface down. (Interface=Vlanif101, VrId=101, InetType=IPv4)

Apr 30 2018 00:24:25 sw_core_1 %%01IFNET/4/LINK_STATE(l)[29]:The line protocol IP on the interface Vlanif101 has entered the DOWN state.

Apr 30 2018 00:24:25 sw_core_1 %%01IFNET/4/IF_STATE(l)[30]:Interface Vlanif101 has turned into DOWN state.

Apr 30 2018 00:24:25 sw_core_1 %%01VRRP/4/STATEWARNINGEXTEND(l)[31]:Virtual Router state MASTER changed to INITIALIZE, because of interface down. (Interface=Vlanif100, VrId=100, InetType=IPv4)

Apr 30 2018 00:24:25 sw_core_1 %%01IFNET/4/LINK_STATE(l)[32]:The line protocol IP on the interface Vlanif100 has entered the DOWN state.

Apr 30 2018 00:24:25 sw_core_1 %%01IFNET/4/IF_STATE(l)[33]:Interface Vlanif100 has turned into DOWN state.

Apr 30 2018 00:24:25 sw_core_1 %%01VRRP/4/STATEWARNINGEXTEND(l)[34]:Virtual Router state MASTER changed to INITIALIZE, because of interface down. (Interface=Vlanif88, VrId=88, InetType=IPv4)

Apr 30 2018 00:24:25 sw_core_1 %%01IFNET/4/LINK_STATE(l)[35]:The line protocol IP on the interface Vlanif88 has entered the DOWN state.

Handling Process

1. VRRP flapping is caused by BFD flapping that occurs due to timeout.

https://support.huawei.com/enterprisecase/product/images/c97340607bb34432864dda55e8d19c8b

Line 43199: Apr 28 2018 14:46:23 sw_core_2 %%01BFD/4/STACHG_TODWN(l)[37734]:BFD session changed to Down. (SlotNumber=0, Discriminator=2, Diagnostic=DetectDown, Applications=VRRP, ProcessPST=False, BindInterfaceName=Vlanif150, InterfacePhysicalState=Up, InterfaceProtocolState=Up)

Line 43199: Apr 28 2018 14:46:23 sw_core_2 %%01BFD/4/STACHG_TODWN(l)[37734]:BFD session changed to Down. (SlotNumber=0, Discriminator=2, Diagnostic=DetectDown, Applications=VRRP, ProcessPST=False, BindInterfaceName=Vlanif150, InterfacePhysicalState=Up, InterfaceProtocolState=Up)

2. The log information shows that the device frequently receives TC BPDUs. After receiving the TC BPDUs, the device ages ARP entries, which may cause BFD flapping.

https://support.huawei.com/enterprisecase/product/images/56d284acbefa44858548bb4ab77acacb

 

 

3. Run the display stp tc-bpdu statistics command. The command output shows that an interface sends and receives a large number of TC BPDUs in a short period of time.

<HUAWEI> display stp tc-bpdu statistics 
 ------------------ STP TC/TCN information -------------------
 MSTID Port                  TC(Send/Receive) TCN(Send/Receive)
 0     GigabitEthernet0/0/6  5/60             0/0 

4. Run the display stp topology-change command. It is found that a large number of topology changes occur in a short period of time.

<HUAWEI> display stp topology-change

CIST Topology Change information

Number of Topology Changes             :60

Time since last Topology Change        :0 days 2h:38m:3s

Topology Change initiator(detected)    :GigabitEthernet0/0/6

Topology change last received from     :0000-1111-2222

Number of generated topologychange traps :   60

Number of suppressed topologychange traps:   3

 

5. If an interface continuously receives a large number of TC BPDUs, the topology changes frequently. This indicates that network flapping occurs.

Root Cause

The network topology changes because a non-edge port frequently alternates between Up and Down or the STP configuration is modified.

Solution

1. If an interface connected to terminals frequently alternates between Up and Down, you are advised to configure this interface as an edge port.

2. You are advised to configure the following commands:

arp topology-change disable

mac-address update arp

Suggestions

arp topology-change disable:

When STP detects network topology changes, the device sends TC BPDUs to instruct the ARP module to age or delete ARP entries. The device then needs to relearn ARP entries.

If the network topology changes frequently or there are many ARP entries on the network, ARP entry relearning will cause excess ARP packets to be generated. As a result, a large number of system resources are occupied and services are affected. To address this issue, run the arp topology-change disable command to disable the device from responding to TC BPDUs. The device does not age or delete ARP entries even if the network topology changes.

 

 

mac-address update arp:

On the Ethernet, MAC address entries are used to instruct Layer 2 data forwarding. The ARP entries that define the mapping between IP addresses and MAC addresses instruct communication between devices on different network segments.

The outbound interface in a MAC address entry is updated by packets, whereas the outbound interface in an ARP entry is updated after the aging time is reached. In this case, the outbound interfaces in the MAC address entry and ARP entry may be different.To address this issue, run the mac-address update arp command to enable the MAC address-triggered ARP entry update function.

END