> DHCP Service Configuration Mode Commands
> The Dynamic Host Control Protocol (DHCP) Configuration Mode is used to create and manage DHCP service instances for the current context.
> allow
> This command allows the specified options on the DHCP service.
> Product
> P-GW
> Privilege
> Security Administrator, Administrator
> Syntax
> [ no ] allow { dhcp-inform | dhcp-relay-agent-auth-suboption | dhcp-relay-agent-option | dhcp-server rapid-commit }
> no
> Disables an option on the DHCP service.
> dhcp-inform
> Enables the sending of DHCP inform after configuration for address recovery.
> dhcp-relay-agent-auth-suboption
> Enables the sending of DHCP relay agent authentication suboption in all outgoing messages.
> dhcp-relay-agent-option
> Enables the sending of DHCP relay agent option in all outgoing messages.
> dhcp-server rapid-commit
> Enables support of the rapid commit feature for DHCP server functionality, as defined in RFC 4039.
> Usage
> Use this command to enable/disable options on the DHCP service.
> Example
> The following command enables support of the rapid commit feature for DHCP server functionality:
> allow dhcp-server rapid-commit
> bind
> This command binds the DHCP service to a logical IP interface facilitating the system’s connection to the DHCP server. This command also configures traffic from the specified DHCP service bind address to use the specified Multiple Protocol Label Switching (MPLS) labels.
> Product
> GGSN, ASN-GW
> Privilege
> Security Administrator, Administrator
> Syntax
> bind address ip_address [ nexthop-forwarding-address nexthop_ip_address [ mpls-label input in_mpls_label_value output out_mpls_label_value1 [ out_mpls_label_value2 ]]]
> no bind address ip_address
> no
> Removes a previously configured binding.
> ip_address
> Specifies the IP address of an interface in the current context through which the communication with the DHCP server occurs. ip_address must be expressed in dotted decimal notation.
> nexthop-forwarding-address nexthop_ip_address
> Specifies the next hop gateway address for in MPLS network to which the packets with MPLS labels will be forwarded.
> nexthop_ip_address must be expressed in IPv4/IPv6 notation.
> mpls-label input in_mpls_label_value
> This keywork specifies the MPLS label to identify inbound traffic destined for the configured DHCP service bind address ip_address.
> in_mpls_label_value is the MPLS label that will identify inbound traffic destined for the configured DHCP service and must be an integer from 16 through 1048575.
> Important: This keyword is license-enabled and available with valid MPLS feature license only.
> Caution: For DHCP over MPLS feature to work in StarOS 9.0 onward dhcp ip vrf command must be configured in DHCP service. Without dhcp ip vrf command the DHCP service using MPLS labels will not be started and as a part of DHCP over MPLS configuration in StarOS 9.0 onward this keyword is a critical parameter for the DHCP-Service. Any change in its value will result in DHCP-service restart and clearing of the existing calls.
> output out_mpls_label_value1 [ out_mpls_label_value2 ]
> This keyword adds the MPLS label to the outbound traffic sent from the configured DHCP service bind address ip_address. The labels out_mpls_label_value1 and out_mpls_label_value2 identify the MPLS labels to be added to packets sent from the specified dhcp service bind address.
> out_mpls_label_value1 is the inner output label and must be an integer from 16 through 1048575.
> out_mpls_label_value2 is the outer output label and must be an integer from 16 through 1048575.
> Important: This keyword is license-enabled and available with valid MPLS feature license only.
> Usage
> Use this command to associate or tie the DHCP service to a specific logical IP address previously configured in the current context and bound to a port. Once bound, the logical IP address or interface is used in the giaddr field of the DHCP packets.
> When this command is executed, the DHCP service is started and begins the process of requesting addresses from the DHCP server and storing them in cache memory for allocation to PDP contexts.
> This command can also be used to configure MPLS labels for inbound and outbound traffic through this DHCP address.
> Only one interface can be bound to a service.
> For DHCP over MPLS feature to work in StarOS 9.0 onward dhcp ip vrf command must be configured in DHCP service. Without dhcp ip vrf command the DHCP service using MPLS labels will not be started.
> Caution: As a part of DHCP over MPLS configuration mpls-label input keyword in bind address command is also a critical parameter for the DHCP-Service. Any change in its value will result in DHCP-service restart and clearing of the existing calls.
> Example
> The following command binds the DHCP service to the interface with an IP address of 192.168.1.210:
> bind address 192.168.1.210
> default
> Restores DHCP service parameters to their factory default settings.
> Product
> GGSN, ASN-GW
> Privilege
> Security Administrator, Administrator
> Syntax
> default { dhcp { deadtime | detect-dead-server { consecutive-failures } | server-selection-algorithm } | lease-duration | max-retransmissions | retransmission-timeout | T1-threshold | T2-threshold }
> dhcp { deadtime | detect-dead-server { consecutive-failures } | server-selection-algorithm }
> Restores the following DHCP parameters to their respective default settings:

> • | deadtime: Default 10 minutes

> • | detect-dead-server { consecutive-failures }: Default 5

> • | server-selection-algorithm: Default First-server

> lease-duration
> Restores the lease-duration parameter to its default setting of 86400 seconds.
> max-retransmissions
> Restores the max-retransmissions parameter to its default setting of 5.
> retransmission-timeout
> Restores the retransmission-timeout parameter to its default setting of 3000 milli-seconds.
> T1-threshold
> Restores the T1-threshold parameter to its default setting of 50%.
> T2-threshold
> Restores the T2-threshold parameter to its default setting of 88%.
> Usage
> After system parameters have been modified, this command is used to set/restore specific parameters to their default values.
> Example
> The following command restores the dhcp deadtime parameter to its default setting of 10 minutes:
> default dhcp deadtime
> dhcp client-identifier
> This command configures behavior relating to inclusion of client identifier DHCP option in DHCP messages.
> Product
> GGSN
> Privilege
> Security Administrator, Administrator
> Syntax
> dhcp client-identifier { msisdn | none }
> default dhcp client-identifier
> default
> Sets the behavior of DHCP client identifier to default; i.e. not to include client identifier option in any DHCP message.
> msisdn
> Default: disabled
> Specifies that subscriber’s MSISDN be included in client-identifier option of the relevant DHCP messages.
> Important: This keyword is GGSN license controlled.
> none
> Default: enabled
> Specifies that DHCP client-identifier option would not be included in any DHCP messages. This is the default behavior.
> Usage
> Use this command to configure behavior relating to inclusion or exclusion of DHCP client identifier option from DHCP messages.
> Example
> The following command specifies that DHCP client-identifier option be excluded from DHCP messages:
> dhcp client-identifier none
> dhcp deadtime
> Configures the amount of time that the system waits prior to re-communicating with a DHCP server that was previously marked as down.
> Product
> GGSN, ASN-GW
> Privilege
> Security Administrator, Administrator
> Syntax
> dhcp deadtime max_time
> max_time
> Default: 10 minutes
> Specifies the maximum amount of time to wait before communicating with DHCP server that were previously unreachable.
> max_time is measured in minutes and can be configured to any integer value from 1 to 65535.
> Usage
> If the system is unable to communicate with a configured DHCP server, after a pre-configured number of failures the system marks the server as being down.
> This command specifies the amount of time that the system waits prior to attempting to communicate with the downed server.
> Important: If all DHCP servers are down, the system will immediately treat all DHCP servers as active, regardless of the deadtime that is specified.
> Refer to the dhcp detect-dead-server and max-retransmissions commands for additional information on the process the system uses to mark a server as down.
> Example
> The following command configures the system to wait 20 minutes before attempting to re-communicate with a dhcp server that was marked as down:
> dhcp deadtime 20
> dhcp detect-dead-server
> Configures the number of consecutive communication failures that could occur before the system marks a DHCP server as down.
> Product
> GGSN, ASN-GW
> Privilege
> Security Administrator, Administrator
> Syntax
> dhcp detect-dead-server consecutive-failures max_number
> consecutive-failures max_number
> Default: 5
> Specifies the number of failures that could occur before marking a DHCP server as down.
> max_number could be configured to any integer value from 1 to 1000.
> Usage
> This command works in conjunction with the max-retransmissions parameter to set a limit to the number of communication failures that can occur with a configured DHCP server.
> The max-retransmissions parameter limits the number of attempts to communicate with a server. Once that limit is reached, the system treats it as a single failure. This parameter limits the number of consecutive failures that can occur before the system marks the server as down and communicate with the server of next highest priority.
> If all of the configured servers are down, the system ignores the detect-dead-server configuration and attempt to communicate with highest priority server again.
> If the system receives a message from a DHCP server that was previously marked as down, the system immediately treats it as being active.
> Example
> The following command configures the system to allow 8 consecutive communication failures with a DHCP server before it marks it as down:
> dhcp detect-dead-server consecutive-failures 8
> dhcp ip vrf
> This command provides the DHCP-over-MPLS support and associates the specific DHCP service with a pre-configured Virtual Routing and Forwarding (VRF) Context instance for virtual routing and forwarding.
> Product
> All
> Privilege
> Security Administrator, Administrator
> Syntax
> dhcp ip vrf vrf_name
> no dhc ip vrf
> no
> Removes/disassociates configured IP Virtual Routing and Forwarding (VRF) context instance.
> vrf_name
> Specifies the name of a pre-configured VRF context instance to be associated with a DHCP service.
> vrf_name is name of a pre-configured virtual routing and forwarding (VRF) context configured in context configuration mode and associated with the IP Pool used by the DHCP service.
> Usage
> Use this command to enable the DHCP-over-MPLS support and to associate/disassociate a pre-configured VRF context to a DHCP service for this feature.
> By default the VRF is NULL, which means that DHCP service is bound with binding address given by bind address command only.
> VRF is not a critical parameter for the DHCP Service but bind address is a critical parameter for DHCP Service, and while starting DHCP Service, if this command is configured, then the bind address should be present in that VRF, and If this command is not configured, bind address should be present in the context where DHCP Service is configured.
> For DHCP over MPLS feature to work in StarOS 9.0 onward this command must be configured in DHCP service. Without this command the DHCP service using MPLS labels will not be started.
> Caution: As a part of this configuration mpls-label input keyword in bind address command is also a critical parameter for the DHCP-Service. Any change in its value will result in DHCP-service restart and clearing of the existing calls.
> Example
> Following command associates VRF context instance dhcp_vrf1 with this DHCP service:
> dhcp ip vrf dhcp_vrf1
> dhcp server
> Configures DHCP servers with which the DHCP service is to communicate.
> Product
> GGSN, ASN-GW
> Privilege
> Security Administrator, Administrator
> Syntax
> dhcp server ip_address [ priority priority ]
> no dhcp server ip_address
> no
> Deletes a previously configured DHCP server.
> ip_address
> Specifies the IP address of the DHCP server expressed in dotted decimal notation.
> priority priority
> Specifies the priority of the server if multiple servers are configured.
> priority can be configured to any integer value from 1 to 1000. 1 is the highest priority.
> Usage
> Use this command to configure the DHCP server(s) that the system is to communicate with. Multiple servers can be configured each with their own priority. Up to 20 DHCP servers can be configured.
> All DHCP messages are sent/received on UDP port 67.
> Important: If a server is removed, all calls having an IP address allocated from the server will be released.
> Example
> The following command configures a DHCP server with an IP address of 192.168.1.200 and a priority of 1:
> dhcp server 192.168.1.200 priority 1
> dhcp server selection-algorithm
> Specifies the algorithm used to select DHCP servers with which to communicate when multiple servers are configured.
> Product
> GGSN, ASN-GW
> Privilege
> Security Administrator, Administrator
> Syntax
> dhcp server selection-algorithm { first-server | round-robin }
> first-server
> Default: Enabled
> Selects the first-server algorithm to be used. This algorithm dictates that the system select the DHCP servers according to their priority starting with the highest priority server. The system communicates with the server of the next highest priority only when the previous server is unreachable.
> round-robin
> Default: Disabled
> Selects the round-robin algorithm to be used. This algorithm dictates that the system communicates with the servers in a circular queue according to the server’s configured priority starting with the highest priority server. The next request is communicated with the next highest priority server, and so on until all of the servers have been used. At this point, the system starts from the highest priority server.
> Usage
> Use this command to determine how configured DHCP servers are utilized by the system.
> Example
> The following command configures the DHCP service to use the round-robin selection algorithm:
> dhcp server selection-algorithm round-robin
> end
> Exits the context configuration mode and returns to the Exec mode.
> Product
> All
> Privilege
> Security Administrator, Administrator
> Syntax
> end
> Usage
> Change the mode back to the Exec mode.
> exit
> Exits the context configuration mode and returns to the global configuration mode.
> Product
> All
> Privilege
> Security Administrator, Administrator
> Syntax
> exit
> Usage
> Return to the global configuration mode.
> lease-duration
> Configures the minimum and maximum allowable lease times that are accepted in responses from DHCP servers.
> Product
> GGSN, ASN-GW
> Privilege
> Security Administrator, Administrator
> Syntax
> lease-duration min min_time max max_time
> min min_time
> Default: 600
> Specifies the minimum acceptable lease time.
> min_time is measured in seconds and can be configured to any integer value from 600 to 3600.
> max max_time
> Default: 86400
> Specifies the maximum acceptable lease time.
> max_time is measured in seconds and can be configured to any integer value from 10800 to 4294967295.
> Usage
> To reduce the call setup time, the system requests IP addresses from the DHCP server in blocks rather than on a call-by-call basis. Each address received has a corresponding lease time, or time that it is valid. The values configured by command represent the minimum and maximum times that the system allows and negotiates for the lease(s).
> If the DHCP server responds with values that are out of the range specified by the min and max values, the system accumulates warning statistics. Responses that fall below the minimum value are rejected by the system and the system contacts the DHCP server with the next highest priority. Responses that are greater than the maximum value are accepted.
> When half of the lease time has expired, the system automatically requests a lease renewal from the DHCP server. This is configured using the T1-threshold command.
> Example
> The following command configures the minimum allowable lease time for the system to be 1000 and the maximum to be 36000:
> lease-duration min 1000 max 36000
> max-retransmissions
> Configures the maximum number of times that the system attempts to communicate with unresponsive DHCP server before it is considered a failure.
> Product
> GGSN, ASN-GW
> Privilege
> Security Administrator, Administrator
> Syntax
> max-retransmissions max_number
> max_number
> Default: 5
> Specifies the maximum number of re-attempts the system tries when no response is received from a DHCP server.
> max_number can be configured to any integer value from 1 to 20.
> Usage
> This command works in conjunction with the dhcp detect-dead-server parameter to set a limit to the number of communication failures that can occur with a configured DHCP server.
> When the value specified by this parameter is met, a failure is logged. The dhcp detect-dead-server parameter specifies the number of consecutive failures that could occur before the server is marked as down.
> In addition, the retransmission-timeout command controls the amount of time between re-tries.
> Example
> The following command configures the maximum number of times the system re-attempts communication with a DHCP server that is unresponsive to 5:
> max-retransmissions 5
> retransmission-timeout
> Configures the amount of time that must pass with no response before the system re-attempts to communicate with the DHCP server.
> Product
> GGSN, ASN-GW
> Privilege
> Security Administrator, Administrator
> Syntax
> retransmission-timeout time
> time
> Default: 10000
> Specifies the time that the system waits before retrying to communicate with the DHCP server.
> time is measured in milliseconds and can be configured to any integer value from 100 to 20000.
> Usage
> This command works in conjunction with the max-retransmissions command to establish a limit on the number of times that communication with a DHCP server is attempted before a failure is logged.
> This parameter specifies the time between retries.
> Example
> The following command configures a retry timeout of 1000 milliseconds:
> retransmission-timeout 1000
> T1-threshold
> Configures the DHCP T1 timer as a percentage of the allocated IP address lease.
> Product
> GGSN, ASN-GW
> Privilege
> Security Administrator, Administrator
> Syntax
> T1-threshold percentage
> percentage
> Default: 50%
> The percentage of the allocated IP address lease time at which the DHCP call-line state is changed to “RENEWING”. It can be configured to any integer value from 40 to 66%.
> Usage
> This command is used to identify the time at which a subscriber must renew their DHCP lease as a percentage of the overall lease time. (Refer to the lease-duration command in this chapter for information on configuring the IP address lease period.)
> For example, if the lease-duration was configured to have a maximum value of 12000 seconds, and this command is configured to 40%, then the subscriber would enter the RENEWING state after 4800 seconds.
> Example
> The following command configures the T1 threshold to 40%:
> T1-threshold 40
> T2-threshold
> Configures the DHCP T2 timer as a percentage of the allocated IP address lease.
> Product
> GGSN, ASN-GW
> Privilege
> Security Administrator, Administrator
> Syntax
> T2-threshold percentage
> percentage
> Default: 88%
> The percentage of the allocated IP address lease time at which the DHCP call-line state is changed to “REBINDING”. It can be configured to any integer value from 67 to 99%.
> Usage
> This command is used to identify the time at which a subscriber re-binds their DHCP leased IP address as a percentage of the overall lease time. (Refer to the lease-duration command in this chapter for information on configuring the IP address lease period.)
> For example, if the lease-duration was configured to have a maximum value of 12000 seconds, and this command is configured to 70%, then the subscriber would enter the REBINDING state after 8400 seconds.
> Example
> The following command configures the T1 threshold to 70%:
> T2-threshold 70

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