213Configuring many-to-one VLAN mappingConfigure many-to-one VLAN mapping on campus switches (see Figure 55) to transmit the same type oftraffic from different users in one VLAN.Configuring many-to-one VLAN mapping in a network withdynamic IP address assignmentIn a network where IP addresses are dynamically assigned, configure many-to-one VLAN mapping withDHCP snooping.The switch replaces the SVLAN tag of the downlink traffic with the associated CVLAN tag based on theDHCP snooping entry lookup.Configuration restrictions and guidelinesWhen you use this method to configure many-to-one VLAN mapping, follow these restrictions andguidelines:• Before configuring many-to-one VLAN mapping, create the original VLANs and the translatedVLAN.• To ensure correct traffic forwarding from the service provider network to the customer network, donot configure many-to-one VLAN mapping together with uRPF. For more information about uRPF,see Security Configuration Guide.• Customer-side many-to-one VLAN mapping is not supported on Layer 2 aggregate interfaces.• To modify many-to-one VLAN mappings, first use the reset dhcp snooping binding command toclear the DHCP snooping entries.Configuration task listTasks at a glance• (Required.) Enabling DHCP snooping• (Required.) Enabling ARP detection• (Required.) Configuring the customer-side port• (Required.) Configuring the network-side portEnabling DHCP snoopingStep Command Remarks1. Enter system view. system-view N/A2. Enable DHCPsnooping. dhcp snooping enableBy default, DHCP snooping is disabled.For more information about DHCP snoopingconfiguration commands, see Layer 3—IPServices Command Reference.Enabling ARP detectionEnable ARP detection for all involved VLANs, including the original VLANs and the translated VLANs.
