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# 1.2.1.5.2 DHCP Server V2 Configurations

DHCP Server V2 Specific User Configurations

- Maximum Number Leases per Interface:

  - Specifies the maximum number of leases that the DHCP server can support for an interface
  - The actual number of leases per interface could be smaller than this
  - Multiple of 32
  - Default value 32
  - Symbol TCPIP_DHCPS_MAX_LEASES

- Number of ICMP Echo Probes:

  - Number of ICMP echo probes to send when doing address conflict detection
  - Default value 1

- Number of Conflict Attempts for new IP Address:

  - Number of attempts to find a new IP address when ICMP detected an address conflict
  - Default value 1

- Number of Leases:

  - Maximum number of leases for this interface
  - Must be <= TCPIP_DHCPS_MAX_LEASES

- Default Lease Duration(in Sec):

  - Default lease duration to be granted to clients, seconds
  - Default value 28800 seconds (8 hours)

- DHCPS Server IP Address:

  - Server IP address on this interface

- Lease IP Address Starting from:

  - Start lease IP address
  - The pool of addresses will be
  - where endIPAddress is given by the prefixLen

- Prefix Length (CIDR notation):

  - The number of the leading 1 bits in the network mask
  - number <= 32
  - the address is specified in the CIDR format: add/prefix_len
  - the maximum size of the pool is dictated by the prefixLen
  - For example: 192.168.0.0/24 will have 254 leases available
  - (192.168.0.0 and 192.168.0.255 are excluded)
  - and endIPAddress == 192.168.0.254
  - Note: the number of possible leases == min(leaseEntries, endIPAddress - startIPAddress).
  - The number of leases derived from startIPAddress/prefixLen should be > leaseEntries.

- Client Options:

  - DHCP server configuration of provided client options

  - Lists the options to be presented to clients requiring an address lease

  - Router IP Address:

    - Provide router/gateway option

  - DNS IP Address:

    - Provide DNS option

  - Time Server IP Address:

    - Provide time server option

  - Name Server IP Address:

    - Provide name server option

  - NTP Server IP Address:

    - Provide NTP server option

- Configuration Flags:

  - Disabled at Start of Interface:

    - DHCP server should start disabled on this interface
    - Note: this setting is currently not used and overridden by the
    - TCPIP_NETWORK_CONFIG:: startFlags.TCPIP_NETWORK_CONFIG_DHCP_SERVER_ON

  - Delete Lease Info on Restart:

    - DHCP server should delete the existent info for leases
    - when the interface is restarted

  - Disable Conflict Detection:

    - Disable DHCP server conflict detection of newly allocated addresses
    - By default the server should send an ICMP echo request when using a new IP address

  - Disable Lease Extension Request:

    - Disable DHCP clients request for extending the lease
    - By default the server grants lease extension to the clients

  - Keep Info of Not Requested Offers:

    - Keep DB info for offers that have not been requested by the client
    - i.e. when client selected another server (multi-server environment)
    - By default the info for these clients is deleted to free some space in the DB

  - ICMP Probe Failure Abort:

    - When DHCP server conflict detection is enabled, if sending echo requests failed
    - (ICMP module rejected the calls, TCPIP_DHCPS_EVENT_ECHO_FAIL event)
    - abort offering the lease to the client.
    - By default the server will send the offer to the client

  - Keep Silent if No Record:

    - Keep silent when receiving a client request for which there is no previous record
    - (i.e. do not verify the requested IP address and send NAK, etc.)
    - By default the server will reply with NAK if the requested lease is invalid

- Minimum Lease Duration(in Sec):

  - Minimum lease duration that can be requested by a client, seconds
  - If 0, then a default of 60 seconds will be used
  - Should be <= leaseDuration

- Maximum Lease Duration(in Sec):

  - Maximum lease duration that can be requested by a client, seconds
  - If 0, then the leaseDuration will be used
  - Should be >= leaseDuration

- Unrequested Offer Timeout(in Sec):

  - Timeout for unrequested offer sent to the client, seconds
  - Note: used if TCPIP_DHCPS_CONFIG_FLAG_KEEP_UNREQ_OFFERS is not set
  - If 0, a default of 5 seconds will be used

- T1 Renewal Time Calculation:

  - Timeout used for TCPIP_DHCPS_CLIENT_OPTION_T1_RENEWAL

  - Multiplication/Division Factors:

    - The multiplication/division factors of T1
    - The T1 is obtained as percentages of lease time:
    - T1 = (leaseTime * mult) / div; default values are mult = 1, div = 2;
    - Default values are used for mult or div if any of them are 0
    - T2 needs to be greater than T1!

- T2 Rebind Time Calculation:

  - Timeout used for TCPIP_DHCPS_CLIENT_OPTION_T2_REBINDING

  - Multiplication/Division Factors:

    - The multiplication/division factors of T2
    - The T2 is obtained as percentages of lease time:
    - T2 = (leaseTime * mult) / div; default values are mult = 7, div = 8;
    - Default values are used for mult or div if any of them are 0
    - T2 needs to be greater than T1!

- DHCP Server Interface Count:

  - Maximum number of interfaces on which DHCPs could run
  - Note that this could be less than the maximum number of interfaces in the stack for this build (TCPIP_STACK_NETWORK_INTERAFCE_COUNT)!
  - Symbol: TCPIP_DHCPS_INTERFACE_COUNT

- DHCP Server Task Rate (in msec):

  - DHCPS task processing rate, in milliseconds.
  - The DHCPS module will process a timer event with this rate for maintaining its own queues, processing timeouts, etc.
  - Choose it so that the other TMO are multiple of this
  - The default value is 200 milliseconds.
  - The lower the rate (higher the frequency) the higher the module priority and higher module performance can be obtained
  - The value cannot be lower than the TCPIP_STACK_TICK_RATE.

- Client ID Maximum Size:

  - Maximum size of the client identifier field
  - Needs to be >= size of a MAC Address
  - Note: when a client is requesting a lease using a longer client ID the ID will be truncated!

- ICMP Echo Request Buffer Size:

  - Size of the buffer when sending a ICMP echo request for address conflict detection
  - Should be between 8 and 32 bytes
  - Default value is 16

- Number of ICMP Request Retries:

  - Number of retries if ICMP is not able to send a ping
  - This should only happen if there are too many ICMP echo requests ongoing
  - Default value is 2

- Maximum Number of Router Value Options:

  - Maximum number of values for the options to be sent to clients
  - A value defined as 0 excludes that option

- Maximum Number of DNS Value Options:

  - Maximum number of values for the options to be sent to clients
  - A value defined as 0 excludes that option

- Maximum Number of Time Server Value Options:

  - Maximum number of values for the options to be sent to clients
  - A value defined as 0 excludes that option

- Maximum Number of Name Server Value Options:

  - Maximum number of values for the options to be sent to clients
  - A value defined as 0 excludes that option

- Maximum Number of NTP Server Value Options:

  - Maximum number of values for the options to be sent to clients
  - A value defined as 0 excludes that option

- Suppress T1 Renewal and T2 Rebind:

  - Suppress the 'renewal T1' and 'rebinding T2' options when replying to a client request
  - By default these options are enabled

- Maximum Number of Event Registrations:

  - Maximum number of event registrations
  - If 0 or not defined, there is no event registration

- Enable Error Events Report:

  - Enable the report of error events using the event notification mechanism

- Enable Client Events Report:

  - Enable the report of client events using the event notification mechanism

- Enable Statistics:

  - Maintain DHCPs statistics counts
  - Symbol TCPIP_DHCPS_ENABLE_STATISTICS

- Enable Dynamic DB Manipulation:

  - Allow dynamic manipulation of the DHCPs DB
  - Symbol TCPIP_DHCPS_DYNAMIC_DB_ACCESS

- Enable Multi-Threaded Access:

  - Enable multi-threaded access
  - Symbol TCPIP_DHCPS_MULTI_THREADED_ACCESS

- DHCP Server Heap Size (bytes):

  - An estimation of the heap required by the DHCP server