Advanced Multicast Solution for MAN

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2008 D-Link Switch Training
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DHCP Relay Agent Information (Option 60/61)
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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

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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.

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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.

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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

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config dhcp_relay option_60 state

• config dhcp_relay option_60 state
  enabledisable
• 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.

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config dhcp_relay option_60 add

• configure dhcp_relay option_60 add string ltdesc
  64gt relay ltipaddrgt exact_matchpartial_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.

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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.

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config dhcp_relay option_60 default

• config dhcp_relay option_60 default relay
  ltipaddrgt mode droprelay
• 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.

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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.

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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
  configuredfor example, you might specify that
  all clients with non-matching strings be dropped.

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Network Diagram
D-Link Set-Top Box DHCP Server with VCI to
dlink 192.168.0.2/24
10.90.90.91/8
192.168.0.1/24
Internet DHCP Server (default Server) 192.168.0.3/
24
DGS-3612
DES-3526 (10.90.90.90)
Need assign IP by the Set-Top Box DHCP Server
Internet Clients
D-Link Set-Top Box Client With Option 60
specified string dlink
Need assign IP by the Internet DHCP Server
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Network Diagram
D-Link Set-Top Box DHCP Server with VCI to
dlink 192.168.0.3/24
10.90.90.91/8
192.168.0.1/24
Internet DHCP Server (default Server) 192.168.0.2/
24
DGS-3612
config dhcp_relay option_60 add string "dlink"
relay 192.168.0.3 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
192.168.0.2
DES-3526 (10.90.90.90)
Need assign IP by the Set-Top Box DHCP Server
Internet Clients
D-Link Set-Top Box Client With Option 60
specified string dlink
Need assign IP by the Internet DHCP Server
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Switches Configuration

• DGS-3612
• config ipif System ipaddress 10.90.90.91/8
• config vlan default delete 7-12
• create vlan v2 tag 2
• config vlan v2 add untagged 7-12
• create ipif ipif2 192.168.0.1/24 v2
• DES-3526
• config ipif System ipaddress 10.90.90.90/8
• create iproute default 10.90.90.91
• config dhcp_relay option_60 add string "dlink"
  relay 192.168.0.3 exact_match
• config dhcp_relay option_60 default mode relay
• config dhcp_relay option_60 default relay
  192.168.0.2
• config dhcp_relay option_60 state enable
• enable dhcp_relay

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DHCP server setting (haneWIN DHCP server)
1Server IP 192.168.0.3
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DHCP server setting (haneWIN DHCP server) 2
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Result
D-Link Set-Top Box DHCP Server with VCI to
dlink 192.168.0.2/24
10.90.90.91/8
192.168.0.1/24
Internet DHCP Server (default Server) 192.168.0.3/
24
DGS-3612
Switch will send the DHPC requests to Setup Box
DHCP Server (192.168.0.2). To those Clients who
have matched option 60 VIC to dlink
Other Clientss DHCP requests without option 60
or mismatch the option 61 VIC will be sent to the
defualt server (192.168.0.3)
DES-3526 (10.90.90.90)
Need assign IP by the Set-Top Box DHCP Server
Internet Clients
D-Link Set-Top Box Client With Option 60
specified string dlink
Need assign IP by the Internet DHCP Server
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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.

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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.

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config dhcp_relay option_61 state

• config dhcp_relay option_61 state
  enabledisable
• 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.

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config dhcp_relay option_61 add

• config dhcp_relay option_61 add mac_address
  ltmacaddrgt string ltdesc 64gt relay ltipaddrgt
  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.

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Parameters

• mac_address
• The clients client-ID which is the hardware
  address of client.
• string
• The clients client-ID,which is specified by
  administrator.
• relay
• Specify to relay the packet to a IP address.
• drop
• Specify to drop the packet.

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config dhcp_relay option_61 default

• config dhcp_relay option_61 default relay
  ltipaddrgtdrop
• 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.

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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 clients 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
  its address Binding table.

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Network Diagram
DHCP Server with address Binding 192.168.0.3/24
10.90.90.91/8
192.168.0.1/24
Default DHCP Server 192.168.0.2/24
DGS-3612
DES-3526 (10.90.90.90)
Other clients will assign IP by the default DHCP
Server
Need assign IP by the Specific DHCP Server
Other Clients
Specific Clients need assign with specific IP
address base on their MAC Address
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Network Diagram
DHCP Server with address Binding 192.168.0.3/24
10.90.90.91/8
192.168.0.1/24
Default DHCP Server 192.168.0.2/24
DGS-3612
config dhcp_relay option_61 add mac_address
ltmacaddrgt relay 192.168.0.3 config dhcp_relay
option_61 state enable enable dhcp_relay
config dhcp_relay option_61 default relay
192.168.0.2
DES-3526 (10.90.90.90)
Other clients will assign IP by the default DHCP
Server
Need assign IP by the Specific DHCP Server
Other Clients
Specific Clients need assign with specific IP
address base on their MAC Address
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Switches Configuration

• DGS-3612
• config ipif System ipaddress 10.90.90.91/8
• config vlan default delete 7-12
• create vlan v2 tag 2
• config vlan v2 add untagged 7-12
• create ipif ipif2 192.168.0.1/24 v2
• DES-3526
• config ipif System ipaddress 10.90.90.90/8
• create iproute default 10.90.90.91
• config dhcp_relay option_61 add mac_address
  ltmac_addressgt relay 192.168.0.3
• config dhcp_relay option_61 default relay
  192.168.0.2
• config dhcp_relay option_61 state enable
• enable dhcp_relay

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DHCP server setting (haneWIN DHCP server)
1Server IP 192.168.0.3
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DHCP server setting (haneWIN DHCP server) 2
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Result
DHCP Server with address Binding 192.168.0.3/24
10.90.90.91/8
192.168.0.1/24
Default DHCP Server 192.168.0.2/24
DGS-3612
Other clients DHCP requests will be sent to the
default DHCP Server
Switch will send the DHPC requests to DHCP Server
(192.168.0.3). To those Clients ID (MAC address)
have matched in the Switch option 61 rules.
DES-3526 (10.90.90.90)
Other clients will assign IP by the default DHCP
Server
Need assign IP by the Specific DHCP Server
Other Clients
Specific Clients need assign with specific IP
address base on their MAC Address
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End