2008 D-Link Switch Training

2 2 DHCP Relay Agent Information (Option 60/61)

3 3 Description Briefly speaking, this feature allow switch to watch option 60 and 61 content of DHCP client packet to decide to relay the packet to which DHCP server or simply drop it

4 4 Relationship about option 60,option 61,option 82 The relay will process option 82 first. About option 60 and option 61,the relay will process the option 60 first, then option 61.But if option 60 or option 61 need to drop the packet. The relay will perform drop regardless any other rule. If the option 60 and option 61 all are enable, but the packet do not contain them. The relay will process the DHCP packet as normal flow just like option 60 and option 61 are disable.

5 5 Option 60 Vendor Class Identifier (Option 60) can be used by DHCP clients to identify the vendor and functionality of a DHCP client. The information is a variable length string of characters or octets which has a meaning specified by the vendor of the DHCP client.

6 6 Option 60 configuration A string map to a DHCP server has two models. One is exact-match, the other is partial-match. exact-match is that the DHCP client string is an exact match of the specified string, and partial-match is that the DHCP client string is a partial match of the specified string. A string can map to multiple DHCP servers, but not over 4, also a DHCP server can map to multiple strings, but not over 50. The number of DHCP server must not be more than 4. The default state of DHCP option60 is disabled, and the default rule is “drop”

7 7 config dhcp_relay option_60 state config dhcp_relay option_60 state [enable|disable] –Used to configure dhcp_relay opton_60 state. This decides whether dhcp_relay will process the DHCP option 60 or not. When option_60 is enabled, if the packet does not have option 60, then the relay servers cannot be determined based on option 60. The relay servers will be determined based on either option 61 or per IPIF configured servers. If the relay servers are determined based on option 60 or option 61, then per IPIF configured servers will be ignored. If the relay servers are not determined either by option 60 or option 61, then per IPIF configured servers will be used to determine the relay servers.

8 8 config dhcp_relay option_60 add configure dhcp_relay option_60 add string relay [exact_match|partial_match] –Used to add a entry for dhcp_relay option_60 This command configures the option 60 relay rules. Note that different string can be specified with the same relay server, and the same string can be specified with multiple relay servers. The system will relay the packet to all the matching servers.

9 9 Parameters exact_match –The option 60 string in the packet must full match with the specified string. partial_match –The option 60 string in the packet only need partial match with the specified string. string –The specified string. ipaddress –Specify a relay server IP address.

10 config dhcp_relay option_60 default config dhcp_relay option_60 default [relay | mode [drop|relay] ] –Configure dhcp_relay option_60 default relay servers When there are no match servers found for the packet based on option 60, the relay servers will be determined by the default relay server setting. When drop is specified, the packet with no matching rules found will be dropped without further process. If the setting is no- drop, then the packet will be processed further based on option 61. The final relay servers will be the union of option 60 default relay servers and the relay servers determined by option 61.

11 Parameters ipaddress –The specified ipaadress for dhcp_relay forward. –Specify a relay server IP for the packet that has no matching option 60 rules. drop –Specify to drop the packet that has no matching option 60 rules. relay –The packet will be relayed based on the relay rules.

12 Opotion 60 in Real Network Example For example, you might have an environment in which some DHCP clients require only Internet access, while other clients require IPTV service. The clients that need Internet access get their addresses assigned by the DHCP local server on the router. Clients requiring IPTV must be relayed to a specific DHCP server that provides the service. To support both types of clients, you configure two option 60 strings on the DHCP relay. Now, when any DHCP client packets are received with option 60 strings configured, the strings are matched against all strings configured on the DHCP relay. If the client string matches the first string you configured, that client is directed to the DHCP local server and gains Internet access. Client traffic with an option 60 string that matches your second string is relayed to the DHCP server that provides the IPTV service. In addition, you can configure a default action, which DHCP relay performs when a client option 60 string does not match any strings you have configured—for example, you might specify that all clients with non- matching strings be dropped.

13 DES-3526 ( ) DGS-3612 Network Diagram D-Link Set-Top Box DHCP Server with VCI to “dlink” /24 D-Link Set-Top Box DHCP Server with VCI to “dlink” /24 Internet DHCP Server (default Server) /24 Internet DHCP Server (default Server) /24 Internet ClientsD-Link Set-Top Box Client With Option 60 specified string “dlink” Need assign IP by the Internet DHCP Server /8 Need assign IP by the Set-Top Box DHCP Server /24

14 DES-3526 ( ) DGS-3612 Network Diagram D-Link Set-Top Box DHCP Server with VCI to “dlink” /24 D-Link Set-Top Box DHCP Server with VCI to “dlink” /24 Internet DHCP Server (default Server) /24 Internet DHCP Server (default Server) /24 Internet ClientsD-Link Set-Top Box Client With Option 60 specified string “dlink” Need assign IP by the Internet DHCP Server /8 Need assign IP by the Set-Top Box DHCP Server /24 config dhcp_relay option_60 add string "dlink" relay exact_match config dhcp_relay option_60 state enable enable dhcp_relay config dhcp_relay option_60 default mode relay config dhcp_relay option_60 default relay

15 Switches Configuration DGS-3612 config ipif System ipaddress /8 config vlan default delete 7-12 create vlan v2 tag 2 config vlan v2 add untagged 7-12 create ipif ipif /24 v2 DES-3526 config ipif System ipaddress /8 create iproute default config dhcp_relay option_60 add string "dlink" relay exact_match config dhcp_relay option_60 default mode relay config dhcp_relay option_60 default relay config dhcp_relay option_60 state enable enable dhcp_relay

16 DHCP server setting (haneWIN DHCP server) 1 Server IP:

17 DHCP server setting (haneWIN DHCP server) 2

18 DES-3526 ( ) DGS-3612 Result D-Link Set-Top Box DHCP Server with VCI to “dlink” /24 D-Link Set-Top Box DHCP Server with VCI to “dlink” /24 Internet DHCP Server (default Server) /24 Internet DHCP Server (default Server) /24 Internet ClientsD-Link Set-Top Box Client With Option 60 specified string “dlink” Need assign IP by the Internet DHCP Server /8 Need assign IP by the Set-Top Box DHCP Server /24 Switch will send the DHPC requests to Setup Box DHCP Server ( ). To those Clients who have matched option 60 VIC to “dlink” Other Clients’s DHCP requests without option 60 or mismatch the option 61 VIC will be sent to the defualt server ( )

19 Option 61 This option is used by DHCP clients to specify their unique identifier. DHCP servers use this value to index their database of address bindings.

20 Option 61 configuration : The number of option61 rule can not over 500. The default state of DHCP option61 is disabled, and the default ruler is “drop”. A option61 can configure to forward a specific DHCP server or drop, multiple option61 can map to a specific DHCP server, but a option61 only can specified a specific DHCP server.

21 config dhcp_relay option_61 state config dhcp_relay option_61 state [enable|disable] –Used to configure dhcp_relay opton_61 state. This decides whether dhcp_relay will process the DHCP option 61 or not. When option_61 is enabled, if the packet does not have option 61, then the relay servers cannot be determined based on option 61. If the relay servers are determined based on option 60 or option 61, then per IPIF configured servers will be ignored. If the relay servers are not determined either by option 60 or option 61, then per IPIF configured servers will be used to determine the relay servers.

22 config dhcp_relay option_61 add config dhcp_relay option_61 add [mac_address |string ] [relay | drop] –Used to add a rule for dhcp_relay option_61 This command adds a rule to determine the relay server based on option 61. The match rule can base on either MAC address or a user-specified string. Only one relay server can be specified for a MAC-address or a string, If relay servers are determined based on option 60, and one relay server is determined based on option 61, the final relay servers will be the union of these two sets of the servers.

23 Parameters mac_address –The client’s client-ID which is the hardware address of client. string –The client’s client-ID,which is specified by administrator. relay –Specify to relay the packet to a IP address. drop –Specify to drop the packet.

24 config dhcp_relay option_61 default config dhcp_relay option_61 default [relay |drop] – Used to configure the default ruler for option 61. Up to default server IP address can be specified.This setting will be used to determine the rule to process those packets that have no option 61 matching rules. The default default-rule is drop.

25 Opotion 60 in Real Network Example An address binding is a mapping between the IP address and MAC address of a client. The IP address of a client can be assigned manually by an administrator or assigned automatically from a pool by a DHCP server. Manual bindings are IP addresses that have been manually mapped to the MAC addresses of hosts that are found in the DHCP database. Automatic bindings are IP addresses that have been automatically mapped to the MAC addresses of hosts that are found in the DHCP database. With option 61 all DHCP clients send a client identifier (DHCP option 61) in the DHCP packet. (In our case the Switch will add the client’s MAC address to option 61 field in the DHCP request packet) The DHCP Sever will check the client identifier information (for example MAC address) to assign a corresponded IP address to the Client base on it’s address Binding table.

26 DES-3526 ( ) DGS-3612 Network Diagram DHCP Server with address Binding /24 DHCP Server with address Binding /24 Default DHCP Server /24 Default DHCP Server /24 Other ClientsSpecific Clients need assign with specific IP address base on their MAC Address Other clients will assign IP by the default DHCP Server /8 Need assign IP by the Specific DHCP Server /24

27 DES-3526 ( ) DGS-3612 Network Diagram DHCP Server with address Binding /24 DHCP Server with address Binding /24 Default DHCP Server /24 Default DHCP Server /24 Other ClientsSpecific Clients need assign with specific IP address base on their MAC Address Other clients will assign IP by the default DHCP Server /8 Need assign IP by the Specific DHCP Server /24 config dhcp_relay option_61 add mac_address relay config dhcp_relay option_61 state enable enable dhcp_relay config dhcp_relay option_61 default relay

28 Switches Configuration DGS-3612 config ipif System ipaddress /8 config vlan default delete 7-12 create vlan v2 tag 2 config vlan v2 add untagged 7-12 create ipif ipif /24 v2 DES-3526 config ipif System ipaddress /8 create iproute default config dhcp_relay option_61 add mac_address relay config dhcp_relay option_61 default relay config dhcp_relay option_61 state enable enable dhcp_relay

29 DHCP server setting (haneWIN DHCP server) 1 Server IP:

30 DHCP server setting (haneWIN DHCP server) 2

31 DES-3526 ( ) DGS-3612 Result DHCP Server with address Binding /24 DHCP Server with address Binding /24 Default DHCP Server /24 Default DHCP Server /24 Other ClientsSpecific Clients need assign with specific IP address base on their MAC Address Other clients will assign IP by the default DHCP Server /8 Need assign IP by the Specific DHCP Server /24 Switch will send the DHPC requests to DHCP Server ( ). To those Clients’ ID (MAC address) have matched in the Switch option 61 rules. Other clients’ DHCP requests will be sent to the default DHCP Server

32 End