What are precautions for configuring the formats of sent and received BPDUs on an STP interface

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There are two STP BPDU formats: standard IEEE 802.1s format and proprietary format. The switch supports both formats and works in auto mode by default. You can run the stp compliance command on an STP interface to change the packet format. In auto mode, an STP interface can parse BPDUs in any format received from the peer interface.

When a Huawei switch is connected to another vendor's device, the two devices may fail to communicate because of different keys in BPDUs even though they have the same domain name, revision level, and VLAN mapping table. To solve this problem, run the stp config-digest-snoop command to enable digest snooping. This function enables the Huawei switch to keep its BPDU key consistent with that used on the peer device.

Other related questions:
Can interfaces on S series switches where the BPDU function is not enabled send BPDUs
To configure S series (except the S1700) and E series switches to transparently transmit BPDUs, perform the following operations: 1. Configure interface-based Layer 2 protocol transparent transmission. (1) Run the l2protocol-tunnel group-mac command in the system view to replace the multicast destination MAC address of Layer 2 protocol packets with a specified multicast MAC address. (2) Run the port default vlan command on the inbound and outbound interfaces to transparently transmit untagged BPDUs. (3) Run the l2protocol-tunnel { all | protocol-type } enable command on the inbound and outbound interfaces to enable interface-based Layer 2 protocol transparent transmission. 2. Configure VLAN-based Layer 2 protocol transparent transmission. (1) Run the l2protocol-tunnel group-mac command in the system view to replace the multicast destination MAC address of Layer 2 protocol packets with a specified multicast MAC address. (2) Run the port link-type hybrid and port hybrid tagged vlan commands on the inbound and outbound interfaces to transparently transmit tagged BPDUs. (3) Run the l2protocol-tunnel { all | protocol-type } vlan command on the inbound and outbound interfaces to enable VLAN-based Layer 2 protocol transparent transmission.

Can packets exchanged between external networks and intranet servers through two outbound interfaces of an AR be transmitted over different paths
Packets exchanged between external networks and intranet servers through two outbound interfaces of an AR may be transmitted over different paths. To avoid this problem, configurations need to be added. For example, configure redirection to ensure that packets are sent and received through the same interface. That is, response packets received from an internal server are transmitted along the same path as the request packets sent from the public network. For detailed configurations, see "Internet Access > NAT > Example for Configuring NAT and Redirection to Implement Two Egresses and Provide the Web Service" in the Typical Configuration Examples.

Precautions for STP interworking on an S series switch
S (except the S1700) series switches adopt the standard STP/RSTP/MSTP algorithm. When a Huawei switch that runs STP interworks with a non-Huawei device, pay attention to the following: 1. If the non-Huawei device runs the standard STP algorithm, the Huawei switch can interwork properly with the device. 2. If the non-Huawei device runs a non-standard STP protocol except the Cisco Per VLAN Spanning Tree (PVST) protocol, the Huawei switch can transparently transmit STP packets from the device after the stp disable and bpdu enable commands are executed on the interface of the Huawei device connected to the non-Huawei device. 3. If the non-Huawei device is a Cisco device that runs PVST, the Huawei switch cannot negotiate with the device, but can transparently transmit packets from the device. 4. Check whether the configurations (such as the mode, root priority, and path cost) between the non-Huawei device and Huawei switch are consistent with each other. 5. Check the Proposal/Agreement mechanism. In enhanced mode, the current interface calculates the root interface when calculating the synchronization flag bit. In common mode, the interface ignores the root interface when calculating the synchronization flag bit. You can run the stp no-agreement-check command to configure the common fast transition mechanism on an interface. By default, the enhanced fast transition mechanism is configured on an interface. 6. There are two formats of MSTP BPDUs. One is dot1s, the format regulated in IEEE802.1s; the other is legacy, a private BPDU format. If the format of MSTP BDPUs is set to dotls on one interface and legacy on the peer interface, the negotiation fails. You can run the stp compliance { auto | dot1s | legacy } command to configure the specified STP BDPU format. The auto mode is set to allow an interface to automatically use the format of MSTP BDPUs sent from the remote interface. In this manner, the two interfaces use the same MSTP BDPU format. By default, MSTP BDPUs use the auto mode. 7. When a Huawei device is connected to a non-Huawei device, if the region name, revision level, and VLAN-to-instance mapping configured on the two devices are the same but the BPDU keys are different, the two devices cannot communicate with each other. To address this problem, run the stp config-digest-snoop command to enable the digest snooping function so that the BPDU keys on Huawei and non-Huawei devices are consistent.

How to check the statistics on received and sent Hello messages
Run the display mpls ldp interface command to check the statistics on received and sent Hello messages on an interface. The command output is displayed as follows: display mpls ldp interface LDP Interface Information in Public Network Codes:LAM(Label Advertisement Mode), IFName(Interface name) A '*' before an interface means the entity is being deleted. ------------------------------------------------------------------------------ IFName Status LAM TransportAddress HelloSent/Rcv ------------------------------------------------------------------------------ Vlanif10 Active DU 1.1.1.1 29574/29539 ------------------------------------------------------------------------------ The value of the field HelloSent/Rcv indicates the statistics on received and sent Hello messages

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