H3C Technologies H3C S5560 Series Switches - Manual (Page 253)

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Configuring many-to-one VLAN mapping
Configure many-to-one VLAN mapping on campus switches (see Figure 62 ) to transmit the same type of
traffic from different users in one VLAN.
Configuring many-to-one VLAN mapping in a network with
dynamic IP address assignment
In a network that uses dynamic address assignment, configure many-to-one VLAN mapping with DHCP
snooping.
The switch replaces the SVLAN tag of the downlink traffic with the associated CVLAN tag based on the
DHCP snooping entry lookup.
Configuration restrictions and guidelines
When you configure many-to-one VLAN mapping in a network that uses dynamic address assignment,
follow these restrictions and guidelines:
• Before you configure many-to-one VLAN mapping, create the original VLANs and the translated
VLANs.
• Customer-side many-to-one VLAN mapping is not supported on Layer 2 aggregate interfaces.
• 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.
• To modify many-to-one VLAN mappings, first use the reset dhcp snooping binding command to
clear the DHCP snooping entries.
Configuration task list
Tasks at a glance
(Required.) Enabling DHCP snooping
(Required.) Enabling ARP detection
(Required.) Configuring the customer-side port
(Required.) Configuring the network-side port
Enabling DHCP snooping
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable DHCP snooping. dhcp snooping enable
By default, DHCP snooping is disabled.
For more information about DHCP
snooping configuration commands, see
Layer 3—IP Services Command
Reference.
Enabling ARP detection
Enable ARP detection for the original VLANs and the translated VLANs.