D-Link DWS-4026 Product Manual - Page 184

D-Link Unified Access System Software User Manual 12/10/09 DHCP L2 Relay VLAN Configuration You can enable L2 DHCP relay on a particular VLAN. The VLAN is identified by a service VLAN ID (S-VID), which a service provider uses to identify a customer's traffic while traversing the provider network to multiple remote sites. The switch uses the VLAN membership of the switch port client (the customer VLAN ID, or C-VID) to perform a lookup a corresponding S-VID. If the S-VID is enabled for DHCP L2 Relay, then the packet can be forwarded. If the C-VID does not correspond to an S-VID that is enabled for DHCP L2 relay, then the switch will not relay the DHCP request packet. To access this page, click LAN > L2 Features > DHCP Snooping > DHCP L2 Relay > VLAN Configuration. Figure 109: DHCP L2 Relay VLAN Configuration Table 94: DHCP L2 Relay VLAN Configuration Field VLAN ID DHCP L2 Relay Mode DHCP L2 Relay Circuit-Id DHCP L2 Relay Remote-Id Description Select a VLAN ID from the list for configuration. This is an S-VID (as indicated by the service provider) that identifies a VLAN that is authorized to relay DHCP packets through the provider network. Enable or disable the selected VLAN for DHCP L2 relay services. When enabled, if a client sends a DHCP request to the switch and the client is in a VLAN that corresponds to the selected S-VID, the switch adds the client's interface number to the Circuit ID sub-option of Option 82 in the DHCP request packet. This enables the switch to reduce the broadcast domain to which the server replies are switched when the broadcast bit is set for DHCP packets. When this bit is set, the server is required to echo the Option82 in replies. Since the circuit-id field contains the client interface number, the L2 relay agent can forward the response to the requesting interface only, rather to all ports in the VLAN). When a string is entered here, if a client sends a DHCP request to the switch and the client is in a VLAN that corresponds to the selected SVID, then the switch adds the string to the Remote-ID sub-option of Option 82 in the DHCP request packet. This sub-option can be used by the server for parameter assignment. The content of this option is vendor-specific. If you change any settings on this page, click Submit to apply the changes to system. DHCP L2 Relay Interface Statistics Use this page to display statistics on L2 DHCP Relay requests received on a selected port. To access this page, click LAN > Monitoring > DHCP Snooping > DHCP L2 Relay > Interface Statistics. Page 184 Configuring DHCP Snooping Document 34CSFP6XXUWS-SWUM100-D7