M-LAG Consistency Check
The M-LAG is a dual-active system composed of two devices. It is a horizontal virtualization technology that virtualizes two devices into one device (a Layer 2 logical node). The logical topology is clear, and some configurations of two devices in the M-LAG must be consistent. If some configurations of two devices in the M-LAG are inconsistent, the M-LAG may fail to work or a loop may occur.
When the M-LAG is applied to an enterprise data center network, if the configuration of two devices in the M-LAG is manually performed or compared, the efficiency is low and there are many potential risks of incorrect configurations.
To address the preceding issues, Huawei proposes M-LAG consistency check. The M-LAG mechanism provides the configuration consistency check to request the configuration of each module. Based on the comparison result after M-LAG consistency check is enabled, you can adjust the configurations of devices in the M-LAG to prevent problems such as network loops or data loss.
- Key configuration (Type 1): If the configurations of two devices in the M-LAG are inconsistent, problems may occur, for example, loops may occur or packets are discarded for a long period of time though the M-LAG status is normal.
In strict mode, if the key configuration of two devices in the M-LAG is inconsistent, member interfaces on the M-LAG backup device enter the Error-Down state and the alarm about key configuration inconsistency is generated.
In loose mode, if the key configuration of two devices in the M-LAG is inconsistent, the alarm about key and common configuration inconsistency is generated.
- Common configuration (Type 2): If the configurations of two devices in the M-LAG are inconsistent, the M-LAG status may be abnormal. Compared with the key configuration, the common configuration problem can be easily detected and has less impact on the live network.
Regardless of the mode, if the following common configuration of two devices in the M-LAG is inconsistent, the alarm about key and common configuration inconsistency is generated.
View |
Configuration |
Type |
|---|---|---|
System view |
Whether STP is enabled |
Type 1 |
STP working mode |
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Whether BPDU protection is enabled |
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Mapping between VLANs and MSTIs NOTE:
The device checks the mapping between VLANs and MSTIs in STP process 0. |
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M-LAG member interface view |
Whether STP is enabled |
|
Whether root protection is enabled |
||
LACP mode |
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System view |
VLAN configuration |
Type 2 |
Static MAC address entries
|
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Aging time of dynamic MAC address entries |
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Static ARP entries
NOTE:
The switch cannot check short static ARP entries of a specified VPN instance. If the outbound interface of a long static ARP entry is an M-LAG member interface and is bound to a VPN instance or the VLANIF interface corresponding to the VLAN to which the outbound interface belongs is bound to a VPN instance, the switch cannot check the static ARP entry. |
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Aging time of dynamic ARP entries |
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Bridge Domain (BD) configuration
|
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VBDIF interface configuration
NOTE:
The device only checks the virtual MAC address by default. For the IPv6 address and VRRP4 configuration, the consistency check only take effect when the VBDIF interface is up. If the VBDIF interface is down, the preceding configurations do not take effect on the interface. |
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VLANIF interface configuration
NOTE:
The device only checks the virtual MAC address by default. For the IPv6 address and VRRP4 configuration, the consistency check only take effect when the VLANIF interface is up. If the VLANIF interface is down, the preceding configurations do not take effect on the interface. |
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M-LAG member interface view |
STP priority |
|
VLAN ID |
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Parameters |
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Number of member interfaces of the Eth-Trunk to which an M-LAG member interface belongs
NOTE:
Only the numbers of member interfaces of Eth-Trunks are compared. The physical Up/Down status or bandwidth of member interfaces is not checked. |