Configuring many-to-one VLAN mapping in a network with static IP address assignment

In a network that uses static IP addresses, configure many-to-one VLAN mapping with ARP snooping.

The switch replaces the SVLAN tag of the downlink traffic with the associated CVLAN tag based on the ARP snooping entry lookup.

Configuration restrictions and guidelines

When you configure many-to-one VLAN mapping in a network that uses static address assignment, follow these restrictions and guidelines:

Before you configure many-to-one VLAN mapping, create the original VLANs and the translated VLANs.
Make sure two hosts in different CVLANs do not use the same IP address.
When an IP address is no longer associated with the MAC address in a VLAN as in the ARP snooping table, perform one of the following operations:
- Use the reset arp snooping ip ip-address command to clear this ARP snooping entry.
- Wait for this ARP snooping entry to be aged out.
Customer-side many-to-one VLAN mapping is not supported on Layer 2 aggregate interfaces.
Before you modify many-to-one VLAN mapping, use the reset arp snooping vlan vlan-id command to clear the ARP snooping entries in each CVLAN.
To ensure correct traffic forwarding from the service provider network to the customer network, do not configure many-to-one VLAN mapping together with uRPF. For more information about uRPF, see Security Configuration Guide.

Tasks at a glance
(Required.) Enabling ARP snooping
(Required.) Configuring the customer-side port
(Required.) Configuring the network-side port

Enable ARP snooping for the original VLANs and the translated VLANs.

To enable ARP snooping:

Step

Command

Remarks

1. Enter system view.

system-view

N/A

2. Enter VLAN view.

vlan vlan-id

N/A

3. Enable ARP snooping.

arp snooping enable

By default, ARP snooping is disabled.

For more information about ARP snooping commands, see Layer 3—IP Services Command Reference.

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3. Set the link type of the port.	Set the port link type to trunk:port link-type trunk Set the port link type to hybrid:port link-type hybrid	By default, the link type of a port is access.
4. Assign the port to the original VLANs and the translated VLANs.	For the trunk port:port trunk permit vlan vlan-id-list For the hybrid port:port hybrid vlan vlan-id-list tagged	N/A
5. Configure a many-to-one VLAN mapping.	vlan mapping uni { range vlan-range-list \| single vlan-id-list } translated-vlan vlan-id	By default, no VLAN mapping is configured on an interface.

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Layer 2 Ethernet interface view or Layer 2 aggregate interface view.	Enter Layer 2 Ethernet interface view:interface interface-type interface-number Enter Layer 2 aggregate interface view:interface bridge-aggregation interface-number	N/A
3. Set the link type of the port.	Set the port link type to trunk:port link-type trunk Set the port link type to hybrid:port link-type hybrid	By default, the link type of a port is access.
4. Assign the port to the translated VLANs.	For the trunk port:port trunk permit vlan vlan-id-list For the hybrid port:port hybrid vlan vlan-id-list tagged	N/A
5. Configure the port to use the original VLAN tags of the many-to-one mapping to replace the VLAN tags of the packets destined for the user network.	vlan mapping nni	By default, the port does not replace the VLAN tags of the packets destined for the user network.

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