How do I configure an Ethernet sub-interface to implement inter-VLAN communication


Generally, only one primary IP address can be configured for a physical interface. When a Layer 3 device connects to a Layer 2 network device through a Layer 3 Ethernet interface and interfaces on the Layer 2 network device are assigned to different VLANs, one primary IP address of the Layer 3 physical interface cannot implement inter-VLAN communication.
You can configure secondary IP addresses or sub-interfaces for the Layer 3 Ethernet interface to solve this problem. The secondary IP addresses depend on the primary IP address. When the primary IP address becomes invalid, the secondary IP addresses also become invalid. The sub-interfaces and main interface are independent. Sub-interfaces share physical layer parameters of their main interface, and are configured with their respective link layer parameters and network layer parameters. The IP address of the main interface and IP addresses of sub-interfaces are independent. You can create sub-interfaces on the Ethernet interface connecting the Layer 3 device to the Layer 2 device so that users in different VLANs can communicate.

Other related questions:
How to configure inter-VLAN communication on an AR router
An AR router provides two technologies to implement inter-VLAN communication: 1. VLANIF interface Create VLANIF interfaces and configure their IP addresses for VLANs of different services, and configure route interconnection to achieve the access between VLANs. For details, see the URL: Example for Configuring a VLANIF Interface to Implement Inter-VLAN Communication . Create a sub-interface on the CE interface of the device, configure an IP address and a termination VLAN for the sub-interface, and configure the default gateways of user hosts as IP addresses of the sub-interface to implement user communication between VLANs. For details, see the URL: Example for Configuring VLANs to Communicate Through Sub-interfaces .

How to implement communication between some sub-VLANs in a super-VLAN
When VLAN aggregation is configured, hosts in a super-VLAN use IP addresses on the same network segment and share the same gateway address. Hosts in different sub-VLANs belong to the same subnet, so the switch forwards packets between the hosts by searching for ARP entries but not through the gateway. Proxy ARP allows the switch to establish ARP entries for all sub-VLANs for interworking. To implement interworking between some sub-VLANs, configure static ARP entries to bind destination MAC addresses to the gateway IP address on hosts in the sub-VLANs. For example, when host A with the gateway IP address of wants to access host B with the MAC address of 00-aa-00-62-c6-09, perform the following operations: Choose Start > Run, enter cmd, and press Enter. Enter arp -s 00-aa-00-62-c6-09. After the preceding configuration is complete, host A can access host B. If host B needs to access host A, configure a static ARP entry to bind host A's MAC address to the gateway IP address on host B.

IP address configuration on S series switch
An S series switch, except S1700, supports primary and sub IP addresses on interfaces. Each Layer 3 interface can have multiple IP addresses, including one primary IP addresses and multiple sub IP addresses. (Note: Sub IP addresses become invalid when the primary address is deleted.)Each interface on the modular switch supports 255 sub IP addresses, and each interface on the fixed switch supports 8 sub IP addresses. For example, configure a primary IP address and a sub IP address for VLANIF10, with subnet mask [HUAWEI] interface vlanif 10 [HUAWEI-Vlanif10] ip address [HUAWEI-Vlanif10] ip address sub (Note: After IP addresses are configured for a VLANIF interface, the clients connected to the switch use one of the IP addresses as gateway address. After sub IP addresses are configured, users can change them as required, but the new IP addresses must be on the same subnet as the primary or one sub IP address; otherwise, the subnets cannot communicate with each other.)For most models in V200R005C00 and later versions, run the undo portswitch command to switch a Layer 2 interface to a Layer 3 interface, and then configure an IP address for the interface. For example, configure a primary IP address and a sub IP address for GE1/0/1, with subnet mask [HUAWEI] interface gigabitethernet 1/0/1 [HUAWEI-GigabitEthernet1/0/1] undo portswitch [HUAWEI-GigabitEthernet1/0/1] ip address [HUAWEI-GigabitEthernet1/0/1] ip address sub

NMS monitoring for multiple OSN 1800 devices at the same site
All NEs at a site can be set to gateway NEs. Three inter-NE communication modes are supported: Manual extended ECC mode: In this mode, extended ECC can be performed between OSN 1800 devices or between an OSN 1800 device and another OTN or SDH device in the same equipment room. OSC mode for RM/TM port interconnection Master/Slave subrack mode

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