H3C Technologies H3C S5560 Series Switches - Manual (Page 255)

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Step Command Remarks
4. Assign the port to the
translated VLANs.
• port trunk permit vlan vlan-id-list
• port hybrid vlan vlan-id-list tagged
N/A
5. Configure the port as a DHCP
snooping trusted port.
dhcp snooping trust
By default, all ports that support
DHCP snooping are untrusted
ports when DHCP snooping is
enabled.
6. Configure the port as an ARP
trusted port.
arp detection trust
By default, all ports are ARP
untrusted ports.
7. 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.
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 mappings, 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.
Configuration task list
Tasks at a glance
(Required.) Enabling ARP snooping
(Required.) Configuring the customer-side port