Triple Play DHCP Command Reference

This command administratively disables an entity. When disabled, an entity does not change, reset, or remove any configuration settings or statistics.

The operational state of the entity is disabled as well as the operational state of any entities contained within. Many objects must be shut down before they may be deleted.

The no form of this command places the entity into an administratively enabled state.

This command creates a text description stored in the configuration file for a configuration context.

The description command associates a text string with a configuration context to help identify the content in the configuration file.

The no form of this command removes the string from the configuration.

This command configures the different DHCPv6 applications to send the NoAddrsAvail Status-Code in DHCPv6 Advertise messages at the global DHCP message level.

By default, all applications send the NoAddrsAvail Status-Code in DHCPv6 Advertise messages at the IA_NA Option level.

Different applications for which NoAddrsAvail Status-Code in DHCPv6 Advertise messages can be configured at the global DHCP message level.

The only valid combination in current SROS is “adv-noaddrs-global esm-relay server”.

This command configures the DHCP filter to bypass ESM host creation, drop DHCP messages, or perform no action.

This command instantiates a local DHCP server. A local DHCP server can serve multiple interfaces but is limited to the routing context it was which it was created.

This command configures the subscriber-interface level setting for delegated prefix length. The delegated prefix length for a subscriber- interface can be either set to a fixed value that is explicitly configured under the subscriber-interface CLI hierarchy or a variable value that can be obtained from various sources. This command can be changed only when no IPv6 prefixes are configured under the subscriber-interface.

This command enables the sending of sending forcerenew messages.

The no form of the command disables the sending of forcerenew messages.

This command enables the Rapid Commit Option.

The no form of the command disables the Rapid Commit Option.

If enabled, this command enables the behavior where unique /64 prefix is allocated per interface-id, and all clients having the same interface-id get an address allocated out of this /64 prefix. This is relevant for bridged clients behind the same local-loop (and same SAP), where sharing the same prefix allows communication between bridged clients behind the same local-loop to stay local. For SLAAC based assignment, downstream neighbor-discovery is automatically enabled to resolve the assigned address.

This command configures the time to remember this lease. This lease-hold-time is for unsolicited release conditions such as lease timeout and normal solicited release from DHCP client.

The no form of the command reverts to the default.

This command enables the context to configure lease-hold-time-for parameters which defines additional types of lease or triggers that cause system to hold up leases.

Use the lease-hold-time to enable or disable lease hold up on the server level.

This command enables the server to hold up the lease of local IPSec clients.

The no form of the command disables the server to hold up the lease of local IPSec clients.

This command enables server to hold up lease even in case of solicited release. For example, the server receives normal DHCP release message

This command configures a DHCP address pool on the router.

This command defines a prefix that to be excluded from available prefix in the pool. The typical use case is to exclude the interface address.

If enabled, the local DHCPv6 server will handle and reply to lease query messages.

The no form of the command disables lease query support.

This command enables the context to configure failover paramters.

With this flag enabled, the remote IP address/prefix can be taken over immediately upon entering the PARTNER-DOWN state of the intercommunication link, without having to wait for the MCLT to expire. By setting this flag, the lease times of the existing DHCP clients, while the intercommunication link is in the PARTNER-DOWN state, will still be reduced to the MCLT over time and all new lease times will be set to MCLT. This behavior remains the same as originally intended for MCLT.

Some deployments require that the remote IP address/prefix range starts delegating new IP addresses/prefixes upon the failure of the intercommunication link, without waiting for the intercommunication link to transition from the COMM-INT state into the PARTNER-DOWN state and the MCLT to expire while in PARTNER-DOWN state.

This can be achieved by enabling the ignore-mclt-on-takeover flag and by configuring the partner-down-delay to 0.

Enabling this functionality must be exercised with caution. One needs to keep in mind that the partner-down-delay and MCLT timers were originally introduced to prevent IP address duplication in cases where DHCP redundant nodes transition out-of-sync due to the failure of intercommunication link. These timers (partner-down-delay and MCLT) would ensure that during their duration, the new IP addresses/prefixes are delegated only from one node, the one with local IP address-range/prefix. The drawback is of course that the new IP address delegation is delayed and thus service is impacted.

But if one could ensure that the intercommunication link is always available, then the DHCP nodes would stay in sync and the two timers would not be needed. This is why it is of utmost importance that in this mode of operation, the intercommunication link is well protected by providing multiple paths between the two DHCP nodes. The only event that should cause intercommunication link to fail is the entire nodal failure. This failure is acceptable since in this case only one DHCP node is available to provide new IP addresses/prefixes.

The maximum-client-lead-time (MCLT) is the maximum time that a DHCP server can extend client’s lease time beyond the lease time currently known by the DHCP partner node. In dual-homed environment, the initial lease time for all DHCP clients is by default restricted to MCLT. Consecutive DHCP renews are allowed to extend the lease time beyond the MCLT.

The MCLT is a safeguard against IP address/prefix duplication in cases of a lease synchronization failure when local-remote failover model is deployed

Once the intercommunication link failure between the redundant DHCP servers is detected, the DHCP IP address range configured as remote will not be allowed to start delegating new leases until the MCLT + partner-down-delay intervals expire. This is to ensure that the new lease that was delegated from the ‘local’ IP address-range/prefix on one node, but was never synchronized due to the intercommunication link failure, will expire before the same IP address/prefix is allocated from the remote IP address-range/prefix on the other node.

However, the already existing (and synchronized) lease times can be renewed from the remote IP address range at any time, regardless of the state of the intercommunication link (operational or failed).

Lease synchronization failure can be caused either by a node failure, or a failure of the link over which the DHCP leases are synchronized (intercommunication link). Synchronization failure detection can take up to 3 seconds.

During the failure, the DHCP lease time for the new clients will be restricted to MCLT while for the existing clients the lease time will over time (by consecutive DHCP renews) be gradually reduced to the MCLT.

Since the DHCP lease synchronization failure can be caused by the failure of the intercommunication link (and not necessary the entire node), there is a possibility the redundant DHCP servers become isolated in the network. In other words, they can serve DHCP clients but they cannot synchronize the lease. This can lead to duplicate assignment of IP addresses, since the servers have configured overlapping IP address ranges but they are not aware of each other’s leases.

The purpose of the partner-down-delay is to prevent the IP lease duplication during the intercommunication link failure by not allowing new IP addresses to be assigned from the remote IP address range. This timer is intended to provide the operator with enough time to remedy the failed situation and to avoid duplication of IP addresses/prefixes during the failure.

During the partner-down-delay time, the prefix designated as remote will be eligible only for renewals of the existing DHCP leases that have been synchronized by the peering node. Only after the sum of the partner-down-delay and the maximum-client-lead-time will the prefix designated as remote be eligible for delegation of the new DHCP leases. When this occurs, we say that the remote IP address range has been taken over.

It is possible to expedite the takeover of a remote IP address range so that the new IP leases can start being delegated from that range shortly after the intercommunication failure is detected. This can be achieved by configuring the partner-down-delay timer to 0 seconds, along with enabling the ignore-mclt-on-takeover CLI flag. Caution must be taken before enabling this functionality. It is safe to bypass safety timers (partner-down-delay + MCLT) only in cases where the operator is certain that the intercommunication between the nodes has failed due to the entire node failure and not due to the intercommunication (MCS) link failure. Failed intercommunication due to the nodal failure would ensure that only one node is present in the network for IP address delegation (as opposed to two isolated nodes with overlapping IP address ranges where address duplication can occur). For this reason, the operator must ensure that there are redundant paths between the nodes to ensure uninterrupted synchronization of DHCP leases.

In access-driven mode of operation, partner-down-delay has no effect.

DHCP leases can be synchronized per DHCP server of DHCP pool. The pair of synchronizing servers or pools is identified by a tag. The synchronization information is carried over the Multi-Chassis Synchronization (MCS) link between the two peers. MCS link is a logical link (IP, or MPLS).

MCS runs over TCP, port 45067 and it is using either data traffic or keepalives to detect failure on the communication link between the two nodes. In the absence of any MCS data traffic for more than 0.5sec, MCS will send its own keepalive to the peer. If a reply is not received within three sec, MCS will declare its operation state as DOWN and the DB Sync state as out-of-sync. MCS will consequently notify its clients (DHCP Server being one of them) of this. It can take up to three seconds before the DHCP client realizes that the inter-chassis communication link has failed.

The inter-chassis communication link failure does not necessarily assume the same failed fate for the access links. In other words the two redundant nodes can become isolated from each other in the network. This would occur in cases where only the intercommunication (MCS) link fails. It is of utmost importance that this MCS link be highly redundant.

This command enables startup-wait-time during which each peer waits after the initialization process before assuming the active role for the prefix designated as local or access-driven. This is to avoid transient issues during the initialization process.

This command configures the maximum lease time.

The no form of the command returns the value to the default.

This command configures the minimum lease time.

The no form of the command returns the value to the default.

This command specifies the desired minimum number of free addresses in this pool.

The no form of the command reverts to the default.

With this command, if the local DHCPv4 server receives a DHCP request with option 50 (means client try to request a previous allocated message as described in section 3.2 of RFC 2131, Dynamic Host Configuration Protocol) and the address allocation algorithm ends up using a pool and the address in option50 is not in pool, then system will return a DHCP NAK, otherwise system just drop the DHCP packet.

This command configures the offer time.

The no form of the command returns the value to the default.

This command configures MSAP authentication defaults.

This command configures the group interface.

This command configures the MSAP policy.

This command sets default service for all subscribers created based on trigger packets received on the given capture SAP in case the corresponding VSA is not included in the RADIUS authentication response. This command is applicable to capture SAP only.

This command sets the retail-service ID for a given subscriber host.

This command enables the context to configure pool options. The options defined here can be overruled by defining the same option in the local user database.

This command configures specific DHCP options. The options defined here can overrule options in the local user database.

The no form of the removes the option from the configuration.

This command configures the IP address of the DNS server.

Configure IPv6 DNS server addresses that can be used for name resolution

This command configures the default domain for a DHCP client that the router uses to complete unqualified host names (without a dotted-decimal domain name).

The no form of the command removes the name from the configuration.

This command configures the time the client transitions to a rebinding state.

The no form of the command removes the time from the configuration.

This command configures the time the client transitions to a renew state.

The no form of the command removes the time from the configuration.

This command configures the amount of time that the DHCP server grants to the DHCP client permission to use a particular IP address.

The no form of the command removes the lease time parameters from the configuration.

This command configures up to four Network Basic Input/Output System (NetBIOS) name server IP addresses.

This command configures the Network Basic Input/Output System (NetBIOS) node type.

This command allocates a prefix to a pool from which Prefix Delegation prefixes and or wan addresses can be assigned.

This command enables the context to configure pool level thresholds.

This command enables the context to configure prefix level thresholds.

This command creates a threshold for a given prefix length on the pool level. Up to 128 thresholds could be created. For example, with minimum-free prefix-length 64, then the usage of /64 prefix in the pool is counted.

There are two types of thresholds that could be defined at the pool level:

Configuration of this command also enables the system stats collection for configure prefix length, which could be displayed via the show router <router-id>dhcp6 local-dhcp-server "d6" pool-threshold-stats command.

This command creates a threshold for a given prefix length on the prefix level. Up to 128 thresholds could be created. For example, with minimum-free prefix-length 64, then the usage of /64 prefix in the prefix is counted.

There are two types of thresholds that could be defined at the prefix level:

Configuration of this command also enables the system stats collection for configure prefix length, which can be displayed with the show router <router-id>dhcp6 local-dhcp-server "d6" prefix-threshold-stats command.

This command enables the system to send out warnings when the prefix with the configured length is no long available in the pool.

This command enables the system to send out a warning when the prefix with a configured length is no long available in the provisioned prefix.

For example:

With the above configuration, the system will send out a warning when there is no available /64 that can be allocated out of 2001:0:0:ffe0::/50.

This command specifies a percentage based threshold which represent the minimal available percentage of the prefix with configured length in the pool. The system will send out a warning if the actual percentage is lower than the configured percentage.

This command configures a percentage-based or number-based threshold which represents the minimal available percentage or number of the prefix with a configured length in the provisioned prefix. The system will send out a warning if the actual percentage or number is lower than the configured threshold.

For example:

With the above configuration, the system will send a warning when the number of available /64 in prefix 2001:0:0:ffe0::/50 is less than 3.

This command configures the DHCP options to send to the client.

This command specifies local user database for PPP PAP/CHAP access.

With this configuration, system will access the specified DB again during PPP PAP/CHAP phase.

This configuration only becomes effective when system is accessing parent DB during PPPoE discovery phase.

This command configures specific DHCP options. The options defined here can overrule options in the local user database.

The no form of the removes the option from the configuration.

This command configures DHCPv4 options via LUDB that will be passed in all DHCP messages to the client. The options will be blindly appended to any options already present in the DHCP message. In other words, there is no intelligent merging of the options where overlapping options from different sources are further evaluated to determine whether only one option or multiple options should be returned to the client.

Multiple DHCP options can be configured at the same time although each option requires its own option statement. Those options are equivalent to RADIUS VSAs Alc-ToCLient-Dhcp4-Options.

DHCPv4 options can be provided via DHCPv4 server in the relay case. In addition, DHCPv4 options provided via LUDB or RADIUS can be supplied and consequently appended to the already existing options. In case that DHCPv4 options are provided simultaneously via LUDB and RADIUS, the RADIUS as a source of DHCPv4 option will be blocked and the options supplied via LUDB will be passed to the client. This is valid for the relay and proxy case.

Any DHCP option may be encoded in the option statement. An example of the option statement for DHCPv4 default-gateway is given below:

option 3 192.168.1.254

DHCPv4 options may be fixed length or variable length. They are appended at the end of DHCPv4 messages. All options begin with a tag octet, which uniquely identifies the option. Fixed-length options without data consist of only a tag octet. Only options 0 and 255 are fixed length. All other options are variable-length.

This command creates a subnet of IP addresses to be served from the pool. The subnet cannot include any addresses that were assigned to subscribers without those addresses specifically excluded. When the subnet is created no IP addresses are made available until a range is defined.

This command configures a range of IP addresses to be served from the pool. All IP addresses between the start and end IP addresses will be included (other than specific excluded addresses).

This command subnet draining which means no new leases can be assigned from this subnet and existing leases are cleaned up upon renew/rebind.

The no form of the command means the subnet is active and new leases can be assigned from it.

This command specifies a range of IP addresses that excluded from the pool of IP addresses in this subnet.

This command configures the maximum number of declined addresses allowed.

This command configures the minimum number of free addresses in this subnet. If the actual number of free addresses in this subnet falls below this configured minimum, a notification is generated.

This command configures the IP address of the default router for a DHCP client. Up to four IP addresses can be specified.

The no form of the command removes the address(es) from the configuration.

This command specifies the subnet-mask option to the client. The mask can either be defined (for supernetting) or taken from the pool address.

The no form of the command removes the address from the configuration.

This command enables the use of gi-address matching. If the gi-address flag is enabled, a pool can be used even if a subnets is not found. If the local-user-db-name is not used, the gi-address flag is used and addresses are handed out by GI only. If a user must be blocked from getting an address the server maps to a local user database and configures the user with no address.

A pool can include multiple subnets. Since the GI is shared by multiple subnets in a subscriber interface the pool may provide IP addresses from any of the subnets included when the GI is matched to any of its subnets. This allows a pool to be created that represents a sub-int.

This command enables the use of the pool indicated by DHCP client. When enabled, the IP address pool to be used by this server is the pool is indicated by the vendor-specific sub-option 13 of the DHCP option 82. When disabled or if there is no sub-option 13 in the DHCP message, the pool selection falls back to the “use-gi-address” configuration.

This command configures the user identification method for the DHCPv4 server.

This command configures the keys for identification of the DHCPv6 lease being held in the lease-database (for configured period after lease timeout). Subscriber requesting a lease via DHCPv6 that matches an existing lease based on this configured key is handed the matched prefix or address. This allows address and prefix “stickiness” for DHCPv6 assigned prefixes (IA_NA or PD).

If configured, local pool selection for v6 address or prefix assignment will use the configured link-address under relay configuration. The selected pool will contain a prefix covering the link-address. The scope option defines the scope for the match. With scope subnet, the prefix or address selection is limited to the prefix in the pool that covers the link-address. With scope pool, all the prefixes in the selected pool are eligible for assignment.

This command configures a local user database for authentication.

This command enables the context to configure DHCP parameters.

This command enables the context to configure DHCP6 parameters.

This command enables the context to configure DHCPv6 relay parameters for this interface.

This command enables DHCP relay and proxy-server for the configured client types.

The no form of the command resets the default client application (dhcp).

This command enables matching Option 82 circuit ID on relayed DHCP packet matching.

For Routed CO, the group interface DHCP relay process is stateful. When packets are relayed to the server the virtual router ID, transaction ID, SAP ID, and client hardware MAC address of the relayed packet are tracked. When a response is received from the server the virtual router ID, transaction ID, and client HW MAC address must be matched to determine the SAP on which to send the packet out. In some cases, the virtual router ID, transaction ID, and client HW MAC address are not guaranteed to be unique.

When the match-circuit-id command is enabled this part of the key is used to guarantee correctness in the lookup. This is only needed when are dealing with an IP aware DSLAM that proxies the client HW mac address.

This command enables dynamic host lease state management for SAPs.

For VPLS, DHCP snooping must be explicitly enabled (using the snoop command) at all points where DHCP messages requiring snooping enter the VPLS instance (both from the DHCP server and from the subscribers). Lease state information is extracted from snooped DHCP ACK messages to populate lease state table entries for the MSAP.

The optional number-of-entries parameter is used to define the number lease state table entries allowed for an MSAP or IP interface. If number-of-entries is omitted, only a single entry is allowed. Once the maximum number of entries has been reached, subsequent lease state entries are not allowed and subsequent DHCP ACK messages are discarded.

The retained lease state information representing dynamic hosts may be used to:

The no form of the command disables dynamic host lease state management for the MSAP.

This command enables and disables dynamic host DHCPv4 lease state management for SAPs.

For VPLS, DHCP snooping must be explicitly enabled (using the snoop command) at all points where DHCP messages requiring snooping enter the VPLS instance (both from the DHCP server and from the subscribers). Lease state information is extracted from snooped DHCP ACK messages to populate lease state table entries for the SAP.

The optional number-of-entries parameter defines the number lease state table entries allowed.

If number-of-entries is omitted, only a single entry is allowed. Once the maximum number of entries has been reached, subsequent lease state entries are not allowed and subsequent DHCP ACK messages are discarded.

The retained lease state information representing dynamic hosts may be used to:

This command enables DHCP Option 82 (Relay Agent Information Option) parameters processing and enters the context for configuring Option 82 sub-options.

The no form of this command returns the system to the default.

This command configures the Relay Agent Information Option (Option 82) processing.

The no form of this command returns the system to the default value.

When enabled, the router sends an ASCII-encoded tuple in the circuit-id sub-option of the DHCP packet. This ASCII-tuple consists of the access-node-identifier, service-id, and SAP-ID, separated by “|”.

In order to send a tuple in the circuit ID, the action replace command must be configured in the same context.

If disabled, the circuit-id sub-option of the DHCP packet will be left empty.

The no form of this command returns the system to the default.

When enabled, the router sends an ASCII-encoded tuple in the circuit-id sub-option of the DHCP packet. This ASCII-tuple consists of the access-node-identifier, service-id, and SAP-ID, separated by “|”.

In order to send a tuple in the circuit ID, the action replace command must be configured in the same context.

If disabled, the circuit-id sub-option of the DHCP packet will be left empty.

The no form of this command returns the system to the default.

This command specifies what information goes into the remote-id sub-option in the DHCP relay packet.

If disabled, the remote-id sub-option of the DHCP packet will be left empty.

The no form of this command returns the system to the default.

This command configures the Alcatel-Lucent vendor specific sub-option of the DHCP relay packet.

This command enables the sending of the MAC address in the Alcatel-Lucent vendor specific sub-option of the DHCP relay packet.

The no form of the command disables the sending of the MAC address in the Alcatel-Lucent vendor specific sub-option of the DHCP relay packet.

This command sends the pool name in the Alcatel-Lucent vendor specific suboption of the DHCP relay packet.

The no form of the command disables the sending.

This command enables the sending of the SAP ID in the Alcatel-Lucent vendor specific sub-option of the DHCP relay packet.

The no form of the command disables the sending of the SAP ID in the Alcatel-Lucent vendor specific sub-option of the DHCP relay packet.

This command enables the sending of the service ID in the Alcatel-Lucent vendor specific sub-option of the DHCP relay packet.

The no form of the command disables the sending of the service ID in the Alcatel-Lucent vendor specific sub-option of the DHCP relay packet.

This command specifies the string in the Alcatel-Lucent vendor specific sub-option of the DHCP relay packet.

The no form of the command returns the default value.

This command specifies whether the system-id is encoded in the Alcatel-Lucent vendor specific sub-option of Option 82.

This command assigns a DHCP6 filter to the group-interface.

This command allows a DHCP IA_NA address to override and replace a host existing SLAAC address. When this feature is enabled, a subscriber SLAAC address is removed once the DHCP IA_NA address assignment is completed. If used with conjunction with the allow-multiple-wan-address command, the DHCP IA_NA address will also override the SLAAC address.

This command enables DHCP IA-PD (delegated prefix) to be modeled as managed (framed) route instead of as a subscriber-host. Antispoof filtering for the subscriber host associated with the IA-PD route must be set to nh-mac. The subscriber specific parameters (such as sla-profile or sub-profile) will be ignored during the authentication phase because IA-PD is not modeled as a subscriber host. Other subscriber host-specific functions (for example, host overrides via CoA or host accounting) are not possible with a PD as the managed route.

By default, or when configured with the next-hop ipv6 parameter, the next-hop for PD managed route is an IPv6 WAN sub-host (DHCP IA-NA or SLAAC) with the same mac address as the one in the DHCP lease state for the managed IA-PD. The DHCP IA-NA next-hop host will always override the SLAAC next-hop host if both are available. If the IPv6 next-hop is not present when the framed IA-PD is instantiated, the IA-PD will be set up but the PD managed route will not be installed in the IPv6 route table and the DHCPv6 lease state for the IA-PD will have the managed route status (DHCP6 MRt Status) set to “noNextHop”.

When configured with the next-hop ipv4 parameter the next-hop for PD managed route is a DHCPv4 sub-host that belongs to the same IPoE session or PPPoE session. For IPoE, ipoe-session must be enabled on the group-interface. If ipoe-session is disabled, an IPv4 next-hop will not be found. If the IPv4 next-hop is not found or not present at the time when the framed IA-PD is instantiated, the IA-PD will be set up but the PD managed route will not be installed in the IPv6 route table. In this case, the DHCPv6 lease state for the IA-PD will have the managed route status (DHCP6 MRt Status) set to “noNextHop”.

Note: IPv6 filters, QoS IPv6 criteria, and IPv6 multicast are not supported for DHCPv6 IA-PD as managed route pointing to an IPv4 subscriber host as next-hop.

The DHCP IA-PD modeled as a route is displayed differently than regular subscriber hosts in show commands related to subscriber host state. The PD managed route is always shown directly below the host it is using as the next hop. The forwarding status of the PD managed route is also shown, where (N) indicate that the PD managed route is not forwarding. In addition, DHCP IA-PD route is displayed as a managed route for the corresponding IPv6 subscriber host (DHCP IA-NA or SLAAC) or DHCPv4 subscriber host.

DHCP IA-PD information for managed IA-PD route is still maintained in the DHCPv6 lease state.

This command enables the collection of ingress interface IP stats. This command is only applicable to IP statistics, and not to uRPF statistics.

If enabled, then the following statistics are collected:

Octet statistics for IPv4 and IPv6 bytes at IP interfaces include the Layer 2 frame overhead.

This command configures the DHCP Unique Identifier (DUID) of the DHCP client.

This command configures the IPv6 prefix/mask preferred life time. The preferred-lifetime value cannot be bigger than the valid-lifetime value.

The no form of the command reverts to the default value.

This command specifies the remaining time for this prefix to be preferred, thus time until deprecation.

This command configures the time, in seconds, that the prefix is valid. The maximum value 4294967295 is considered equal to infinity.

The no form of the command reverts to the default value.

This command specifies the remaining time for this prefix to be valid for the purpose of on-link determination.

This command configures the valid lifetime for the IPv6 prefix or address in the option.

This command specifies the python-policy to be used for DHCPv4 relay.

This command specifies the python-policy to be used for DHCPv6 relay.