DHCP server

1. Function Overview

The DHCP server function assigns (leases) IPv4 addresses to DHCP clients.
Depending on the options, information such as the default gateway and DNS server can also be provided.

2. Definition of Terms Used

None

3. Function Details

The operating specifications for the DHCP server function are outlined below:

  1. The DHCP server function of this product allows you to enable or disable the entire system, as well as for each interface.
    To enable the DHCP server function on an interface, the system-wide settings must be enabled.

    • To configure system-wide settings, use the dhcp-server command in global configuration mode.

    • To configure settings for each interface, use the dhcp-server command in the corresponding interface mode.

  2. The default settings for the DHCP server function are as follows: (In the initial state, this function is not operating.)

    • System-wide settings: Disabled

    • Interface settings: Disabled

  3. When configuring the DHCP server function settings for an interface, do so for the VLAN interface.

    • Configure the settings using the dhcp-server command.

    • The VLAN interface must have an IPv4 address configured.

    • This is disabled by default.

    • To assign IP addresses using the DHCP server function, the DHCP pool described below must be configured properly.

    • Up to 32 VLAN interfaces can be configured.

  4. The DHCP pool determines the information distributed to DHCP clients.

    • Use the dhcp pool command to switch to DHCP mode and create a DHCP pool.

    • You can create up to 64 DHCP pools.

  5. The following settings can be configured for the DHCP pool:

    • Specifying the network portion

    • IP address range to be assigned to clients

    • IP address assigned to a specific client

    • Lease time

    • Duplicate check for leased IP addresses

    • Default gateway address

    • DNS server

    • Domain name

    • Boot file name

    • Server containing boot files

    • User-defined DHCP options

      When dynamically assigning addresses as a DHCP server, it is necessary to set the network portion and the IP address to be assigned.
      You cannot configure multiple pools with the same network portion.

  6. The IP address to be assigned must be within the network specified as the DHCP pool.
    Specify the network portion of the DHCP pool as follows:

    • If the DHCP client is on the same network as the VLAN interface with the DHCP server function to be enabled, specify the network of the IP address set on the VLAN interface.

    • When accepting requests from DHCP clients via a DHCP relay agent, specify the network to which the client belongs.

  7. The IP address assigned to a specific client can be set using the bind host command.

    • The maximum number of bind host commands is 4096 across all pools.

  8. When the DHCP server startup completes, the following log is output at the debug level.

    • "DHCPv4 server started up using the new configuration."

  9. When the DHCP server receives a packet with Option 82 enabled, it can set the IP address to be distributed based on the remote-id, circuit-id, and subscriber-id.

    • You can use the dhcp class command to enter class mode and set each of the above ids.

      • You can create up to 16 DHCP classes.

    • You can use the dhcp pool class command to apply the class set by the above command to the pool.

      • You can create up to 16 DHCP classes.

      • If the contents of Option 82 match the id of the applied class, the settings within the DHCP pool class are used by the DHCP server.

    • The following settings can be made for the DHCP pool class:

      • IP address range to be assigned to clients

      • Lease time

      • Default gateway address

      • DNS server

      • Domain name

    • When passing through a device with DHCP snooping enabled, packets with Option 82 enabled are generated. For more information about DHCP snooping, refer to the link below.

  10. The following can be used for user-defined DHCP options.

    • You can define options with the option command.

      Option No. Option Name Mnemonics Available for Commands Option Type

      1

      Subnet Mask

      subnet_mask

      IP address

      2

      Time Offset

      time_offset

      4-octet integer

      3

      Router

      router

      Array of IP addresses

      4

      Time Server

      time_server

      Array of IP addresses

      5

      Name Server

      name_server

      Array of IP addresses

      6

      Domain Name Server

      dns

      Array of IP addresses

      7

      Log Server

      log_server

      Array of IP addresses

      8

      Cookie Server

      cookie_server

      Array of IP addresses

      9

      LPR Server

      lpr_server

      Array of IP addresses

      10

      Impress Server

      impress_server

      Array of IP addresses

      11

      Resource Location Server

      resource_location_server

      Array of IP addresses

      12

      Host Name

      hostname

      String

      13

      Boot File Size

      boot_file_size

      2-octet integer

      14

      Merit Dump File

      merit_dump_file

      String

      15

      Domain Name

      domain

      String

      16

      Swap Server

      swap_server

      IP address

      17

      Root Path

      root_path

      String

      18

      Extensions Pathname

      extensions_pathname

      String

      19

      IP Forwarding

      ip_forwarding

      Switch

      20

      Non-Local Source Routing

      non_local_source_routing

      Switch

      21

      Policy Filter

      policy_filter

      IP address array *An even number of IP addresses must be set, each consisting of an IP address and a mask.

      22

      Maximum Datagram Reassembly

      maximum_datagram_reassembly

      2-octet integer

      23

      Default IP TTL

      default_ip_ttl

      1-octet integer

      24

      Path MTU Aging Timeout

      path_mtu_aging_timeout

      4-octet integer

      25

      Path MTU Plateau Table

      path_mtu_plateau_table

      Array of 2-octet integers

      26

      Interface MTU

      interface_mtu

      2-octet integer

      27

      All Subnets are Local

      all_subnets_are_local

      Switch

      28

      Broadcast Address

      broadcast_address

      IP address

      29

      Perform Mask Discovery

      perform_mask_discovery

      Switch

      30

      Mask Supplier

      mask_supplier

      Switch

      31

      Perform Router Discovery

      perform_router_discovery

      Switch

      32

      Router Solicitation Address

      router_solicitation_address

      IP address

      33

      Static Route

      static_route

      IP address array *An even number of IP addresses must be set, each consisting of a pair of destination address and router address.

      34

      Trailer Encapsulation

      trailer_encapsulation

      Switch

      35

      Arp Cache Timeout

      arp_cache_timeout

      4-octet integer

      36

      Ethernet Encapsulation

      ethernet_encapsulation

      Switch

      37

      TCP Default TTL

      tcp_default_ttl

      1-octet integer

      38

      TCP Keepalive Interval

      tcp_keepalive_interval

      4-octet integer

      39

      TCP Keepalive Garabage

      tcp_keepalive_garbage

      Switch

      40

      NIS Domain

      nis_domain

      String

      41

      NIS Server

      nis_server

      Array of IP addresses

      42

      NTP Server

      ntp_server

      Array of IP addresses

      44

      WINS Server

      wins_server

      Array of IP addresses

      45

      NBT-DD Server

      nbt_dd_server

      Array of IP addresses

      46

      NBT Node Type

      nbt_node_type

      1-octet integer

      47

      NBT Scope

      nbt_scope

      String

      48

      X Font Server

      x_font_server

      Array of IP addresses

      49

      X Display Manager

      x_display_manager

      Array of IP addresses

      62

      Netware/IP Domain Name

      netware_domain_name

      String

      64

      NIS+ Domain

      nis+_domain

      String

      65

      NIS+ Server

      nis+_server

      Array of IP addresses

      66

      TFTP Server Name

      tftp_server_name

      String

      67

      Boot File Name

      boot_file_name

      String

      68

      Mobile IP Home Agent

      mobile_ip_home_agent

      Array of IP addresses

      69

      SMTP Server

      smtp_server

      Array of IP addresses

      70

      POP3 Server

      pop3_server

      Array of IP addresses

      71

      NNTP Server

      nntp_server

      Array of IP addresses

      72

      Default WWW Server

      default_www_server

      Array of IP addresses

      73

      Default Finger Server

      default_finger_server

      Array of IP addresses

      74

      Default IRC Server

      default_irc_server

      Array of IP addresses

      75

      StreetTalk Server

      streettalk_server

      Array of IP addresses

      76

      StreetTalk Directory Assistance Server

      streettalk_directory_assistance_server

      Array of IP addresses

      85

      NDS Server

      nds_server

      Array of IP addresses

      86

      NDS Tree Name

      nds_tree_name

      String

      87

      NDS Context

      nds_context

      String

4. Related Commands

Related commands are indicated below.
For details on the commands, refer to the Command Reference.

Operations Operating commands

DHCP server function settings (system)

dhcp-server

DHCP server function settings (interface)

dhcp-server

DHCP server operation type settings

server-type

DHCP pool settings

dhcp pool

Network portion settings

network

Setting the range of IP addresses to be assigned (DHCP)

range

Setting IP addresses to be assigned to specific clients

bind host

Lease time settings (DHCP)

lease

Duplicate check settings for leased IP addresses

probe

Timeout settings for duplicate checks on leased IP addresses

probe timeout

Setting the default gateway address to notify (DHCP)

default-router

Setting the DNS server to notify (DHCP)

dns-server

Setting the Domain Name to Notify (DHCP)

domain-name

Boot file name settings

bootfile

Setting the server containing boot files

next-server

User-defined DHCP option settings

option

DHCP class settings

dhcp class

remote-id settings

remote-id

circuit-id settings

circuit-id

subscriber-id settings

subscriber-id

DHCP pool class settings

dhcp pool class

Setting the range of IP addresses to be assigned (DHCP pool class)

range

Lease time settings (DHCP pool class)

lease

Setting the default gateway address to notify (DHCP pool class)

default-router

Setting the DNS server to notify (DHCP pool class)

dns-server

Setting the domain name to notify (DHCP pool class)

domain-name

Show DHCP pool information

show dhcp pool

Show IP address allocation information for DHCP clients

show dhcp binding

Displaying the DHCP server status

show dhcp server

Deleting DHCP server lease information

clear dhcp-server lease

5. Examples of Command Execution

5.1. DHCP Server Settings

Enable the DHCP server to run on vlan1.
The DHCP client is assumed to be on the same network as the VLAN interface.
The IP address of vlan1 is "192.168.100.240/24", and the range of addresses to be distributed is "192.168.100.2-192.168.100.191/24".

■ Setting Procedure

  1. Set the IP address of vlan1 to "192.168.100.240/24".

    Yamaha(config)# interface vlan1
Yamaha(config-if)# ip address 192.168.100.240/24

  2. Create the DHCP pool "pool_vlan1".

    Yamaha(config)# dhcp pool pool_vlan1
Yamaha(config-dhcp)#  (1)
    1 Switch to the DHCP mode

  3. Specify the vlan1 network portion 192.168.100.0/24 as the DHCP pool.

    Yamaha(config-dhcp)# network 192.168.100.0/24

  4. Set the address range to distribute, “192.168.100.2-192.168.100.191” as the DHCP pool.

    Yamaha(config-dhcp)# range 192.168.100.2 192.168.100.191

  5. Specify the default gateway to be notified in DHCP option settings and specify the DNS server in the DHCP pool.

    Yamaha(config-dhcp)# default-router 192.168.100.240 (1)
Yamaha(config-dhcp)# dns-server 192.168.100.1 (2)
    1 The default gateway address is 192.168.100.240 (its own address)
    2 The DNS server address is 192.168.100.1

  6. Activate the DHCP server functions on vlan1.

    Yamaha(config-dhcp)# exit (1)
Yamaha(config)# interface vlan1 (2)
Yamaha(config-if)# dhcp-server enable (3)
    1 Exit the DHCP mode
    2 Switch to interface mode vlan1
    3 Enable the DHCP server functions for the interface

  7. Activate the DHCP server functions for the entire system.

    Yamaha(config-dhcp)# exit (1)
Yamaha(config)# dhcp-server enable (2)
    1 Exit the interface mode
    2 Enable the DHCP server functions for the entire system

5.2. DHCP Server Option 82 Settings

The DHCP client is assumed to be on the same network as the VLAN interface.
The IP address of vlan1 is "192.168.100.240/24", and the range of addresses to be distributed is "192.168.100.2-192.168.100.191/24".
If the remote-id of Option 82 of the received packet matches the setting for "Customer_A", distribute from "192.168.100.200-192.168.100.210/24".

■ Setting Procedure

  1. Set the IP address of vlan1 to "192.168.100.240/24".

    Yamaha(config)# interface vlan1
Yamaha(config-if)# ip address 192.168.100.240/24

  2. Create a DHCP class "Customer_A".

    Yamaha(config)# dhcp class Customer_A
Yamaha(config-dhcp-class)#  (1)
    1 Switch to DHCP class mode

  3. Set the remote-id for the target DHCP class.

    Yamaha(config-dhcp-class)#remote-id 00:06:ac:44:f2:00:00:01

  4. Create a DHCP pool "pool1".

    Yamaha(config)# dhcp pool pool1
Yamaha(config-dhcp)#  (1)
    1 Switch to the DHCP mode

  5. Specify the vlan1 network portion 192.168.100.0/24 as the DHCP pool.

    Yamaha(config-dhcp)# network 192.168.100.0/24

  6. Set the address range to distribute, “192.168.100.2-192.168.100.191” as the DHCP pool.

    Yamaha(config-dhcp)# range 192.168.100.2 192.168.100.191

  7. Apply the class “Customer_A” set with the dhcp class command to the DHCP pool “pool1”.

    Yamaha(config-dhcp)#dhcp pool class Customer_A
Yamaha(config-dhcp-pool-class)#  (1)
    1 Switch to DHCP pool class mode

  8. Set the IP address range to be assigned to “Customer_A”.

    Yamaha(config-dhcp-pool-class)#range 192.168.100.200 192.168.100.210

  9. For “Customer_A”, set the default gateway and DNS server to be notified in the DHCP options in the DHCP pool class.

    Yamaha(config-dhcp-pool-class)#default-router 192.168.100.220 (1)
Yamaha(config-dhcp-pool-class)#dns-server 192.168.100.230 (2)
    1 The default gateway address is 192.168.100.220
    2 The DNS server address is 192.168.100.230

  10. Activate the DHCP server functions on vlan1.

    Yamaha(config-dhcp-pool-class)# exit (1)
Yamaha(config-dhcp)# exit (2)
Yamaha(config)# interface vlan1 (3)
Yamaha(config-if)# dhcp-server enable (4)
    1 Exit the DHCP pool class mode
    2 Exit the DHCP mode
    3 Switch to interface mode vlan1
    4 Enable the DHCP server functions for the interface

  11. Activate the DHCP server functions for the entire system.

    Yamaha(config-dhcp)# exit (1)
Yamaha(config)# dhcp-server enable (2)
    1 Exit the interface mode
    2 Enable the DHCP server functions for the entire system

6. Points of Caution

  • When using the AliasIP address function, addresses in the secondary IP address segment cannot be distributed via DHCP.

7. Related Documentation