4-byte vlan tag

Provides a mechanism for network resource control through VLAN.

MUX VLAN is divided into primary VLAN and secondary VLAN, and secondary VLAN is divided into isolated secondary VLAN and interoperable secondary VLAN.

4.1.3.1 Main vlan

4.1.3.1 From vlan

VLAN aggregation refers to using multiple VLANs to isolate broadcast domains within a physical network. And aggregate these Sub-VLANs into a logical VLAN. These Sub-VLANs Use the same IP subnet and default gateway to save IP address resources.

VLAN Mapping implements mutual mapping of different VLANs by modifying the VLAN Tag carried in packets.

After the Layer 2 packets with VLAN tags from the user network on one side enter the backbone network, the backbone network edge device VLAN (C-VLAN) is modified to a VLAN (S-VLAN) that can be identified and carried in the backbone network, and is transmitted to the other side. Then, the edge device changes the S-VLAN to C-VLAN. In this way, seamless layer 2 connection between two user networks can be achieved.

The device supports VLAN Mapping based on VLAN ID and 802.1p priority. Only basic QinQ, flexible QinQ or VLAN Mapping can be configured on a sub-interface. One type and cannot be configured at the same time.

This technology is a technology that expands the VLAN space. By adding an additional layer of 802.1Q Tags to the 802.1Q tagged messages, the function of expanding the VLAN space is achieved, and the private network VLAN can be transparently transmitted to the public network.

Basic QinQ

Flexible QinQ

Scenes Multiple hosts connected to different interfaces of the same device. If a host has security risks, it will send a large number of messages to other hosts. Broadcast packets can be isolated by other hosts by configuring one-way isolation between interfaces. Interfaces in the same port isolation group are isolated from each other, but interfaces in different port isolation groups are not isolated from each other. Isolation between interfaces in different port isolation groups can be achieved by configuring unidirectional isolation between interfaces.

Scenes In order to achieve Layer 2 isolation between interfaces, you can add different interfaces to different VLANs, but this will waste limited VLAN resources. The port isolation feature can be used to isolate interfaces within the same VLAN. Users only need to add the interface to the isolation group to realize the isolation of Layer 2 data between interfaces in the isolation group. The port isolation function is It provides users with a safer and more flexible networking solution.

In order to perform link backup and improve network reliability, redundant links are usually used in Ethernet switching networks. However, using redundant links will create loops on the switched network, causing broadcast storms and instability of the MAC address table. Wait for the malfunction to occur,

Eliminate loops: Eliminate possible network communication loops in the network by blocking redundant links. Link backup: When the currently active path fails, redundant backup links are activated to restore network connectivity.

1. Root bridge election

2. Root (RP) port (Choose one on each non-root bridge)

3. Specify (DP) port (Choose one for each link between switches)

4. BP port

RP, DP, BP

Learning goal: To know the status and function of ports

Note: In Huawei's STP mode, there is no BP port. The blocked ports are the backup port AP and the backup port BP, which are the results of optimization. The standard STP blocked port is Block Port.

①Disabled, does not process BPDU, does not forward user traffic, and the port is down ②Blocking, processes BPDU, does not forward user traffic, and the port is blocked ③Litening, select root bridge, RP, DP, transition state ④Learning, builds a MAC table and does not forward user traffic. This state is to prevent temporary loops. ⑤Forwarding, forwarding user traffic and processing BPDU, only RP and DP do this.

Configure BPDU

TCNBPDU

Root bridge failure

Direct link failure

Indirect link failure

When the network topology changes, the downstream device continues to send TCN BPDUs. After the upstream device receives it, it tells the downstream device to stop sending TCN BPDU by configuring the TCA position of Flags in the BPDU to 1, and then copies a copy of the TCN BPDU and sends it to the root bridge. After receiving the TCN BPDU, the root bridge sends a TC BPDU, in which Flags TC is set to 1 in the configuration BPDU message. After receiving the TC BPDU, the switch changes the aging time of the MAC table to 15 seconds to achieve rapid refresh of the MAC table.

In terms of port status and port role

Let’s talk about STP algorithm

In terms of configuration BPDU

Purpose: Improve network stability and rapid convergence

1. Optimization of port roles

2. Optimization of port status

3. Message

4. Processing of BPDU

5. Rapid convergence mechanism

6. Topology change mechanism

Enhanced features

7.Protective characteristics

PA mechanism