IPWorks DHCP Parameter Description

Contents

1Introduction
1.1Prerequisites
1.1.1Documents
1.2Related Information

2
Basic Concepts

3
Managed Object Format
3.1Data Types
3.2Enumerations

4
Managed Objects
4.1DHCP Policy Objects
4.1.1Subnet
4.1.2Pool
4.1.3Link
4.1.4Client
4.1.5ClientClass
4.1.6ClientSubclass
4.2Dhcpv4AuthKey
4.3Option
4.3.1ISC DHCPv4 Options
4.3.2IPWorks Specific DHCPv4 Options
4.3.3DhcpV4Option
4.4Option82
4.4.1Dhcpv4Option82Format
4.4.2Dhcpv4Option82IPRange
4.5Dhcpv4Server
4.6Lease

5
DHCP Expressions
5.1Boolean Expressions
5.2Data Expressions
5.3Numeric Expressions

Reference List

1   Introduction

This document describes the objects and fields for DHCP in IPWorks.

Scope

This document covers the following topics:

Target Groups

This document is intended for personnel configuring and fine tuning the IPWorks. All the objects in this document are configured by using IPWorks CLI. It is assumed that readers of this document are familiar with basic concepts and operations of IPWOrks CLI. For details, refer to Command Line Interface User Guide for IPWorks SS, Reference [1].

1.1   Prerequisites

Not applicable.

1.1.1   Documents

Not applicable.

1.2   Related Information

Trademark information, typographic conventions, definition, and explanation of acronyms and terminology can be found in the following documents:

2   Basic Concepts

This section describes the following:

The Managed Object Model (MOM) presents a view of manageable resources in the IPWorks, and attributes and actions associated with the resources.

A Managed Object (MO) is an entity presented to the user for the purpose of controlling the aspects of a function. The object carries attributes that reflect the behavior of the function.

The MOs are identified by means of a naming attribute, also called the Relative Distinguished Name (RDN). The ID part of this attribute is defined when the MO is created, and cannot be changed afterwards. A Local Distinguished Name (LDN) is a sequence of RDNs, which forms a unique name within the node.

All the objects in this document are configured by using IPWorks CLI. It is assumed that readers of this document are familiar with basic concepts and operations of IPWOrks CLI. For details, refer to Command Line Interface User Guide for IPWorks SS, Reference [1].

3   Managed Object Format

This section describes the format used to display information about objects.

Key The key is an identifier of an object. The combination of the key field values must be unique for an object.
Required The required field indicates that the field must be configured, otherwise the CLI generates an error.
Note:  
If the field Partition is required, unless the user wants to work within a different partition, the partition being worked on does not need to be specified. IPWorks assumes the active partition at all times. For more information, see the Partition section of IPWorks Configuration ManagementReference [5].

3.1   Data Types

Blob A large text string. The theoretic maximum size of this data type is 2GB.
BooleanTrueFalse A Boolean value that is either true or false. You can enter yes/no or 1/0 and they will be converted to true/false as appropriate.
DnsName A domain name with maximum length not exceeding 128 characters.
Dhcpv4Option A DHCPv4 configuration option, where each option setting is in the form "option value [, value...]". The option and subsequent value(s) are separated by a single space. The "option" is specified by the option tag. The format of the option value(s) are determined by the option definition.
Int32 A 32 bit signed integer value.
IPv4Address An IPv4 address in dotted decimal notation.
IPv4AddressRange An IPv4 address range, in dotted decimal notation using the hyphen as a separator between the start and end addresses.
Note:  
Note that you can omit the first three octets in the end address if they are the same as the first three octets in the first address, for example, 192.168.1.1-255.

IPv6Address An IPv6 address, which can be specified using the standard abbreviated forms, but stored in the fully expanded form.
MACAddress Short for Media Access Control address, a hardware address that uniquely identifies each node of a network.
Name The name of the configured object.
SortKey A signed 32 bit integer that is computed from an IPv4 address that can be used as an alternate sorting key that returns addresses in sorted order. For example, 0.0.0.0 is equivalent to the smallest 32 bit integer using this scheme, and 255.255.255.255 is the largest.
SubnetMask The subnet mask is the network address plus the bits reserved for identifying the subnet work. (By convention, the bits for the network address are all set to 1, though it would also work if the bits were set exactly as in the network address.) It is called a mask because it can be used to identify the subnet to which an IP address belongs by performing a bitwise AND operation on the mask and the IP address. The result is the subnet work address.
UInt8 An 8-bit unsigned integer value, between 0 and 255.
UInt16 A 16-bit unsigned integer value, between 0 and 65535.

3.2   Enumerations

DhcpV4Implementation DHCPv4
DhcpV4OptionDatatype Boolean, Custom, DnsName, Encapsulated, GmtDate, Hba, Int8, Int16, Int32, IPAddress, IPAddressMask, IPAddressMaskPair, IPAddressMaskIPAddressTriplet, IPAddressPair, LocalTimeDate, MTU, NameString, QuotedString, String, Text, Time, UInt8, UInt16, UInt32, UIntPer, IPv4Address
DhcpV4Scope Client, ClientClass, ClientSubclass, Link, Subnet, Pool, DhcpV4Server
PtrStrategy Manual, Auto, Prompt, Dynamic, Generated, Delegated

4   Managed Objects

This section describes some of the concepts that are required for managing DHCP for IPv4, the Managed Object Classes, and attributes.

The Dynamic Host Configuration Protocol (DHCP) is an extension of the Bootstrap Protocol (BOOTP) that handles dynamic IP address assignments for remote clients. It allows a remote client to plug into a network and broadcast a request, to one or more DHCP servers managing a particular subnet, for network configuration information. One or more DHCP servers reply to the remote client and one server ultimately negotiates a lease of terms including an IP address, a specified period of usage for the address, and other client configuration parameters.

If a client finds a favorable lease offer with the required configuration parameters, the client can accept the offer. After successful negotiation, the server instructs the client to set a lease-renewal timer and a lease-expiry timer, and directs the client where to find system resources (such as the system printer, mail server and terminal fonts).

When the DHCP server receives a client request packet, the process that determines which IP address to assign to the client and which options to send to the client is as follows:

Note:  
This may not be the exact algorithm used by the server, but it is accurate enough to understand how the configuration defined impacts the way the server responds to clients.

  1. When the packet is first received, the server checks the source subnet of the packet to determine if it came from a subnet for which the server is responsible. The source subnet is determined in the following ways:

    If the packet was received from a relay agent, the relay agent includes its IP address in the giaddr field and that is used to determine the source subnet.

    Otherwise, the IP address of the interface on which the packet was received is used to determine the source subnet.

  2. Based on the packet’s source hardware address and the DHCP client identifier (if present), the server finds any host declarations for this client. If there are any matching host declarations with a fixed address for the source subnet (or related shared network), that will be the address assigned to the client. If there are any host declarations that deny addresses to the client, the request is dropped and logged. The presence of host declarations also determines whether the client is considered a known client. If there are any global option settings that would deny an address to the client, the request is dropped.
  3. Next, the server determines which classes the client belongs to by evaluating the match expression of each class against the contents of the client packet. This also determines the subclasses for those classes that have them.
  4. Based on the class membership and whether the client is known, the server examines each of the lease pools for the source subnet (or related shared network) to see if the client is allowed to lease addresses in that pool. The first pool that allows the client to lease an address is used.
  5. If no address is available for the client the request is dropped.
  6. Once the address has been determined, the server determines which options will be sent to the client by merging the option settings from all the declarations that apply to the client. If there is a conflict between two declarations, the most specific declaration is used as follows (with highest precedence first):

    The relevant host client declaration

    Subclasses

    Classes

    The pool declaration (if it is not a fixed address)

    The subnet declaration

    The shared network link declaration (if there is one)

    The global default option settings

  7. Once all the option settings have been determined, the server sends a response back to the client.

4.1   DHCP Policy Objects

In IPWorks, DHCP is configured for both IPv4 and IPv6 by creating policy objects. Different types of policy objects define how a DHCP server behaves under different situations. The policies are specific to IPv4, IPv6, or both.

If a server is not specified for a policy, most policies will be associated with all servers for that area. There are a few exceptions to this, but they are noted in the descriptions of the specific types of policies.

Common Parameters

Some parameters are common to all policy objects. These parameters are used to associate the policy with the servers that implement the policy. The parameters are listed as follows:

4.1.1   Subnet

A subnet is a DHCP policy object that represents the configuration for a contiguous set of addresses within an IPv4 subnet. Subnet objects can be used to specify information about the address space, but most of the time, they are created to assist with the configuration of the DHCP protocol.

Key Partition, Area, Name
Required Partition, Area, Name, Address, Mask, MaskLength

4.1.2   Pool

A pool, also called a lease pool, is a DHCP policy object that represents a contiguous set of addresses that are available for dynamic address assignment. All the addresses in a pool must be contained within a declared subnet and the subnet must be defined prior to defining the pool.

Key Partition, Name
Required Partition, Name, Subnet, AddressRange, Server, Area

4.1.3   Link

A Link Policy stores information about how a DHCP server is configured for a shared network (a set of one or more logical subnets that all share the same physical wire). A link, also known as a shared network, is a DHCP policy object that represents a physical network segment that has subnets operating on it. If there are multiple subnets on the same network segment, the DHCP server must be declared to correctly process DHCP requests on those subnets. During the DHCP server request processing, the server tries to find an address in other subnets of the same link before dropping the request if no address is available in any subnets.

Note:  
A link must include at least one subnet. If a link includes no subnets, the DHCP server fails to start.

Key Partition, Area, Name
Required Partition, Area, Name

4.1.4   Client

A client, also known as a host policy, is a DHCP policy object that represents the configuration for a specific DHCP client (usually a specific computer system) on the network.

Key Partition, Area, Name
Required Partition, Area, Name

4.1.5   ClientClass

A ClientClass is a DHCP policy object that represents configuration for a group of clients. When the DHCP server receives a request from a client, the contents of the DHCP packet are examined to determine which client classes should be associated with that request. Each request can be associated with multiple classes.

Key Partition, Area, Name
Required Partition, Area, Name

4.1.6   ClientSubclass

A ClientSubclass is a DHCP policy object that represents the configuration for a subset of the members of a client class.

Key Partition, Area, ClientClass, Name
Required Partition, Area, ClientClass, Name

4.2   Dhcpv4AuthKey

An Authentication Key is used for DHCPv4 Server Authentication.

Key Partition, AuthKeyID
Required Partition, AuthKeyID, AuthKey, ClientID, Server

4.3   Option

All of the DHCP management concepts described thus far (DHCPV4 servers and all the policy objects) have the ability to be further customized by specifying configuration options. This is done by adding values on a special field on the objects.

Each of these objects have a field called V4Option. This field can have multiple values. Each value is used to specify a configuration option. The syntax of the value is as follows:

<option-name> <value 1> <value 2> ...

There are many configuration options that can be specified. Some options can only be applied to certain types of objects. Many of these options may have somewhat complicated values when they are specified, so it is important to understand the meanings of both the option and the syntax. IPWorks CLI provides a command to display information about a configuration option.

IPWorks> show dhcpv4 option routers -verbose on

		routers
  Tag:            3
  Alias(es):      router, gateway, gateways, default-gateway
  Multi-Valued:   yes
  Description:    This specifies a list of router IP addresses on the client`s
                  subnet. List routers in order of preference. This may also
                  serve as default gateway to the client.
  Datatype:       IPAddress
    Description:  A valid IPv4 address. The server also allows you to specify
                  a valid dns name and it will be translated (via DNS) to
                  obtain an IPv4 address.
  Example(s):     routers rtr1.domain.com, rtr2.domain.com
                  router 10.1.0.1
  Server Config:  option routers <values>;

IPWorks>

If unsure how to define a configuration option for an object, use this command to review the option before setting it. IPWorks checks the syntax of any values set for configuration options.

In the following example, the options for both a pool and subnet that were previously created are set and the new configuration with these options are examined.

IPWorks> modify pool pool1 -add option="default-lease-time 86400"
Working on 1 object(s).
1 object(s) created.
IPWorks> select subnet 10.1.1.0/24
Selected 1 Object(s)
IPWorks> modify -add option="routers rtr.example.com" -add
option="dns-server 10.1.0.1"
Working on 1 object(s).
1 object(s) created.
IPWorks> list -format=conf

# Subnet 10.1.1.0/24
subnet 10.1.1.0 netmask 255.255.255.0 {
	option routers rtr.example.com;
	option domain-name-servers 10.1.0.1;

	# Pool pool1
	pool {
	   pool-index 739763669;
     range 10.1.1.1 10.1.1.100;
     allow known clients;
     default-lease-time 86400;
	}
}

Note:  
An IPWorks component must be created before using the select command. If the selected object does not exist, the following message will be displayed:

IPWorks> No matching object(s) found


4.3.1   ISC DHCPv4 Options

The following table shows the Internet Systems Consortium, Inc. (ISC) standard DHCPv4 options supported by the IPWorks DHCP server:

Table 1    Standard DHCPv4 Options

Option

Description

all-subnets-local

This specifies whether the client assumes that all subnets of the IP network, which the client is connected, use the same Maximum Transmission Unit (MTU) as the subnet of that network, to which the client is directly connected. A value of true means that all subnets share the same MTU.

arp-cache-timeout

This specifies the timeout, in seconds, for Address Resolution Protocol (ARP) cache entries.

boot-size

This specifies the length, in 512-octet blocks, of the default boot image for the client.

bootfile-name

This identifies a bootfile when the file field or the DHCP header has been used for DHCP options.

broadcast-address

This specifies the broadcast address in use on the client‘s subnet.

cookie-servers

This specifies a list of cookie servers available to the client. See RFC 865 for the list of cookie servers. List servers in order of preference.

classless-static-routes

The classless-static-routes option (121) supported by the DHCPv4 server used to specify the subnet mask with the subnet number and gateway IP address. This subnet mask is implicit incase of the static-route option (33).

default-ip-ttl

This specifies the default TTL the client uses on outgoing datagrams.

default-tcp-ttl

This specifies the default TTL the client uses when sending TCP segments. The value is represented as an 8-bit unsigned integer, with the minimum value of 1.

domain-name

This specifies the domain name the client uses when resolving host names through the DNS.

domain-name-servers

This specifies a list of DNS name servers available to the client. See STD 13, RFC 1035 for the list of name servers. List servers in order of preference.

extensions-path

This specifies a file, retrievable using TFTP, which contains information that can be interpreted the same way as the 64-octet vendor-extension field within the BOOTP response. There are exceptions: the length of the file is unconstrained and all references to Tag 18 (instances of the BOOTP Extensions Path field) within the file are ignored.

finger-server

This specifies a list of Finger servers available to the client. List servers in order of preference.

font-servers

This specifies a list of Window System font servers available to the client. List servers in order of preference.

host-name

This specifies the name of the client, which may be qualified with the local domain name. See RFC 2132, Section 3.17 for the preferred way to retrieve the domain name and RFC 1035 for character set restrictions.

ieee802-3-encapsulation

This specifies whether the client uses Ethernet Version 2 (see RFC 894) or IEEE 802.3 (see RFC 1042) encapsulation, if the interface is ethernet. A value of false indicates the client needs to use RFC encapsulation; a value of true means the client needs to use RFC 1042 encapsulation. If the option is not specified, the client uses its default.

ien116-name-servers

This specifies a list of IEN 116 name servers available to the client. List servers in order of preference.

impress-servers

This specifies a list of Imagen Impress servers available to the client. List servers in order of preference.

interface-mtu

This specifies the Maximum Transmission Unit (MTU) to use on the network interface.

ip-forwarding

This specifies whether the client configures its IP layer for packet forwarding. A value of false means to disable IP forwarding; a value of true means to enable IP forwarding. If the option is not specified, the client uses its default.

irc-server

This specifies a list of Internet Relay Chat (IRC) servers available to the client. List servers in order of preference.

log-servers

This specifies a list of MIT-LCS UDP log servers available to the client. List servers in order of preference.

lpr-servers

This specifies a list of line printer servers available to the client. See RFC 1179 for the list of line printer servers. List servers in order of preference.

mask-supplier

This specifies whether the client responds to subnet mask requests using ICMP. A value of false indicates the client should not respond; a value of true means the client should respond. If the option is not specified, the client uses its default.

max-dgram-reassembly

This specifies the maximum size datagram that the client should be prepared to reassemble.

merit-dump

This specifies the pathname of a file where the client‘s core image is to be dumped, if the client crashes.

mobile-ip-home-agent

This specifies a list of IP addresses indicating mobile IP home agents available to the client. List agents in order of preference.

nds-context

This specifies the initial Netware Directory Service (NDS) context for the client.

nds-servers

This specifies a list of NDS servers available to the client. List servers in order of preference.

nds-tree-name

This specifies the NDS tree name for the client to use.

netbios-dd-server

This specifies a list of RFC 1001/1002 NBDD servers. List the servers in order of preference.

netbios-name-servers

This specifies a list of RFC 1001/1002 NBNS name servers. List the servers in order of preference.

netbios-node-type

This allows NetBIOS over TCP/IP clients to be configured as described in RFC 1001/1002. The value is specified as a single octet, which identifies the client type.

netbios-scope

This specifies the NetBIOS over TCP/IP scope parameter for the client as specified in RFC 1001/1002.

nis-domain

This specifies the name of the client‘s Network Information Service (NIS) domain. The domain is formatted as a string of characters from the NVT ASCII character set.

nis-servers

This specifies a list of IP addresses indicating NIS servers available to the client. List servers in order of preference.

nisplus-domain

This specifies the name of the client‘s NIS+ domain. The domain is formatted as a string of characters from the NVT ASCII character set.

nisplus-servers

This specifies a list of IP addresses indicating NIS+ servers available to the client. List servers in order of preference.

nntp-server

This specifies a list of Network News Transport Protocol (NNTP) servers available to the client. List servers in order of preference.

non-local-source-routing

This specifies whether the client configures its IP layer to allow forwarding of datagrams with non-local source routes. A value of false prevents forwarding of such datagrams; a value of true allows forwarding. If the option is not specified, the client uses the default value.

ntp-servers

This specifies a list of IP addresses indicating NTP (Network Time Protocol) servers available to the client. List servers in order of preference.

path-mtu-aging-timeout

This specifies the timeout period, in seconds, for Path MTU values discovered by the mechanism defined in RFC 1191.

path-mtu-plateau-table

This specifies a table of MTU sizes to use when performing Path MTU Discovery as defined in RFC 1191. The table is formatted as a list of 16-bit, unsigned integers in ascending numerical order. The minimum MTU value is 68.

perform-mask-discovery

This specifies whether the client performs subnet mask discovery using ICMP. A value of false indicates the client should not perform mask discovery; a value of true means the client should perform subnet mask discovery. If the option is not specified, the client uses the default value.

policy-filter

This specifies policy filters for non-local source routing. The filters are a list of IP addresses and masks that specify destination or mask pairs to filter incoming source routes. Any source routed datagram whose next hop address does not match one of the filters should be discarded by the client.

pop-server

This specifies a list of Post Office Protocol (POP3) servers available to the client. List servers in order of preference.

resource-location-servers

This specifies a list of Resource Location servers available to the client. See RFC 887 for the list of Resource Location servers. List servers in order of preference.

root-path

This specifies the pathname that contains the client‘s root disk. The path is formatted as a string of characters from the NVT ASCII character set.

router-discovery

This specifies whether the client solicits routers using the Router Discovery mechanism, as defined in RFC1256. A value of false indicates the client should not perform router discovery; a value of true means the client should perform router discovery. If the option is not specified, the client uses its default.

router-solicitation-address

This specifies the address to which the client transmits router solicitation requests.

routers or default-gateway

This specifies a list of router IP addresses on the client‘s subnet. List routers in order of preference.

sip-servers

This specifies a list of Session Initiation Protocol (SIP) servers to be used by the SIP client for all outbound SIP requests, also known as outbound proxy servers. The list can be IP addresses or domain names, but it should not contain both. The order of the addresses or domain names dictates which SIP server the client tries first.

smtp-server

This specifies a list of SMTP servers available to the client. List servers in order of preference.

static-routes

This specifies a list of static routes the client installs in its routing cache.


If multiple routes to the same destination are specified, the routes are listed in descending order of priority. The routes are a list of IP address pairs: the first address is the destination and the second address is the router for the destination.

streettalk-directory-assistance-server

This specifies a list of STDA (StreetTalk Directory Assistance) servers available to the client. List servers in order of preference.

streettalk-server

This specifies a list of StreetTalk servers available to the client. List servers in order of preference.

subnet-mask

This specifies the client‘s subnet mask. By default, the server will provide this option to the client using the subnet mask for the leasepool. See RFC 950 for further information.

swap-server

This specifies the IP address of the client‘s swap server.

tcp-keepalive-garbage

This specifies whether the client sends TCP keep-alive messages with an octet of garbage for compatibility with older implementations. A value of false indicates a garbage octet should not be sent; a value of true indicates a garbage octet should be sent. If the option is not specified, the client uses its default.

tcp-keepalive-interval

This specifies the interval, in seconds, the client TCP waits before sending a keep alive message on a TCP connection. The time is specified as a 32-bit unsigned integer. A value of 0 indicates the client should not generate keep-alive messages on connections, unless specifically requested by an application.

tftp-server-name

This identifies a TFTP server when the sname field in the DHCP header has been used for DHCP options.

time-offset

This specifies the time offset of the client‘s subnet, in seconds, from Coordinated Universal Time (UTC). The offset is expressed as a complement 32-bit integer for 2 and is positive (east) or negative (west).

time-servers

This specifies a list of time servers available to the client. See RFC 868 for the time servers list. List servers in order of preference.

trailer-encapsulation

This specifies whether the client negotiates the use of trailers (see RFC 893) when using the ARP protocol. A value of false indicates the client should not attempt to use trailers; a value of true means the client should attempt to use trailers. If the option is not specified, the client uses the default value.

vendor-encapsulated-options

This is used by clients and servers to exchange vendor-specific information. The information is an object of n octets and the definition of the information is vendor-specific.

www-server

This specifies a list of World Wide Web (WWW) servers available to the client. List servers in order of preference.

x-display-managers

This specifies a list of X Window System display managers available to the client. List managers in order of preference.

4.3.2   IPWorks Specific DHCPv4 Options

The following table shows the IPWorks-specific DHCPv4 options that are available.

Table 2    IPWorks Specific DHCPv4 Options

Option

Description

allow-all-clients

This indicates whether a pool is available (or unavailable) for all clients. It is either true (any client can use addresses in the pool) or false (no clients can use addresses in the pool) Setting the value tofalse is useful when the user is staging a pool that is not ready to be activated. If no value is specified, then access to the pool is determined by the other allow options.

allow-bootp

This indicates whether the server responds to BOOTP queries. It is either true (queries are processed) or false (queries are ignored). The default value is false if no value is specified.

allow-dhcp-inform

This option is used to enable or disable DHCPINFORM command processing. By default, the DHCP server will process DHCPINFORM commands.

allow-known-clients

This indicates whether addresses need to be leased to known clients. Known clients are those which have an explicit client policy (aka Host) defined. It is either true (known clients are allowed) or false (known clients are denied). The default value is true.

allow-ras-servers

This option is used to allow or deny RAS Servers from obtaining addresses. By default, RAS Servers are allowed to obtain addresses.

allow-unknown-clients

This indicates whether addresses should be leased to unknown clients. Unknown clients are those which do not have an explicit Client (aka Host) policy defined. It is either true (unknown clients are allowed) or false (unknown clients are denied). The default value is true.

always-reply-rfc1048

Some BOOTP clients expect RFC 1048-style responses, if the user wants to send RFC1048 options to BOOTP clients set this option to true. The default value is false.

authoritative

The DHCP server normally assumes it does not have the complete configuration information for all networks. Thus, if a client requests an invalid IP address for a network segment, the server ignores the client and does not send it a DHCPNAK message to force the client to obtain a new (and valid) address. If the DHCP server has complete configuration information, add this option to allow the server to send DHCPNAK messages. The default value is false.

clf-address

Specifies the IPv4 address of the CLF node which the Network Access Configuration Function (NACF) or IPWorks DHCPv4 Server interacts with.


It is required to ensure that the NACF interacts with the CLF.

clf-address-zone

Specifies the collective address space (Topology Zone) that one pool is designated to.
It is a pool level option, and can contain either a string or DNS name.
It is used when the NACF interacts with the CLF, and the NACF will only send message to CLF if the IP address belongs to a pool having this option.

custom

This allows the user to specify custom options that are not supported by the server.

ddns-ttl

This specifies the time (in seconds) to be used as the TTL value in the A and PTR resource records when the DHCP server performs a DDNS update. The default value is 600 seconds.

default-lease-time

This specifies the time (in seconds) to be used as the length of the lease if the client does not ask for a specific expiration time. The servers default lease time is 12 hours (43200 seconds). The maximum- lease-time must also be specified if the user wants leases longer than its default of 1 day.

deny-booting

This indicates whether the server is to respond to queries. Define this option only for specific clients. It is true (ignore queries from this client) or false (respond to queries). The default value is false.

dynamic-bootp-lease-cutoff

This specifies a fixed date when leases assigned dynamically to BOOTP clients will end. BOOTP clients do not have a way of renewing leases and do not know leases can expire, therefore, the server normally assigns unlimited leases to all BOOTP clients. It is recommended in certain situations to set a cutoff date for all BOOTP leases — for example, the end of a school term, or the time at night when a facility is closed and all machines are required to be powered off.

dynamic-bootp-lease-length

This specifies the length (in seconds) of leases assigned to BOOTP clients. At some sites, it may be possible to assume that a lease is no longer in use if the holder has not used BOOTP or DHCP to get its address within a certain time period. If a client restarts using BOOTP during the time-out period, the lease duration is reset, so a BOOTP client that boots frequently enough never loses its lease.

dynamic-update

This specifies whether Dynamic DNS needs to be be enabled. It is either true (Dynamic DNS updates will be performed) or false (Dynamic DDNS updates are not performed). The default value is false.

filename

This specifies the name of the initial bootfile to be loaded by a client. It should be the name of a file that is recognizable to whatever file transfer protocol the client is expected to use to load the file. Some clients may prefer to receive this information in the DHCP bootfile-name option.

get-lease-hostnames

This indicates whether the DHCP server should look up the host name for a client in DNS (based on the address being assigned). It is either true (get the name from DNS) or false (do not get the name). The default value is false.

hba

This specifies the load balancing hash bucket entries the server will respond to. When a client request is received the server hashes the client’s unique identifier using an algorithm that hashes to a value between 0 and 255. If the hba is set, then the server will only respond to clients when the hash value corresponds to a bit that is set to 1 in the hba. This allows the user to divide the clients between any number of servers and to divide the load between the servers any way.

lease-limit

Limits the number of members of a class that can be assigned a lease at any given time.

leasethreshold

This specifies the threshold for active lease on server or pool level. Once the percentage of the active-state occupied leases in configured leases is crossing the value, the corresponding level alarm will be generated and sent to agent. Its range is [10,100] with integer and the fraction is forbidden.

max-delayed-acks

To improve performance under heavy loads, the DHCP server delays sending DHCPACK messages by up to 2 seconds. All DHCPACKs accumulated in that time are batched. This parameter specifies the maximum number of DHCPACKs in a batch. The default value is 8. To disable the delaying of DHCPACKs, specify a value of 1.

max-lease-time

This specifies the maximum length of a lease, in seconds. If not specified, the default value is 1 day (86400 seconds).

min-lease-time

This specifies the minimum length of a lease, in seconds. If not specified, the default value is 300 seconds.

name-by-client

This specifies whether clients are allowed to specify their own DNS names. It is either true (clients can specify their own names) or false (clients cannot specify their own names). The default value is false.

network-type

This indicates the type of access aggregation network where the messages are coming from. It can be set as ATM Aggregation network or Gigabit Ethernet Aggregation network. If the network-type is set, the clf-address must be set as well.

next-server

This specifies the address of the server where the boot file for the client is located.

one-lease-per-client

If true, it allows only one lease per client. The default value is false.

ping

This specifies whether the server needs to ping an address before offering it to a client. This is done to make sure that the address is not already in use by another network host. Set the option to either true (ping) or false (do not ping). The default value is false.

ping-retries

If the ping option is enabled, this specifies the number of times an address will be pinged unsuccessfully before it is considered to be unused (and therefore available to be leased).

ping-timeout

If the ping option is enabled, this specifies the maximum number of seconds to wait for a response from the address.

pool-index

It is a unique number generated automatically when a pool is created. It is used to differentiate the pools. This option cannot be either modified or deleted.

requested-options-only

Some DHCP clients cannot handle receiving any options other than the ones they request or a specific list of options. In order to send the options requested by the client, set this option to true. The default value is false.

secure-ddns

If true, the DHCP server will sign all DNS transactions relating to DDNS with a TSIGKey. The default value is false.

server-identifier

Specifies the IP Address sent to clients for the DHCP server. Normally, it is not specified as the server determines it. However, either the server has multiple interfaces or an interface has multiple addresses or the user wants to use an IP alias address for the server, it needs to be specified using this option.

server-name

This specifies the server name sent to the client when it is booting.

stash-agent-options

This specifies whether the DHCP server is to keep a copy of the relay agent information option it receives when a DHCP client acquires its lease, for use when the lease is renewed. If the flag is true, the relay agent information options are saved.

update-a-record

This is only used if the dynamic-update option is true. This specifies whether the DHCP server should make Dynamic DNS updates to ARecords. It is either true (update ARecords) or false (do not update ARecords). The default value is false.

use-host-decl-names

This indicates that the DHCP server needs to use the name of the host declaration as the client‘s host name if no other name is specified. If the option is not specified, the host declaration name is not used as the client‘s host name.

use-lease-addr-for-default-route

If true, the IP address of the lease being assigned is used as the router address and is sent to the client instead of the value specified in the router option. The default value is false.

option-100

A POSIX TZ string. Use of such a string can provide accuracy
for at least one transition into and out of daylight saving
time (DST), and possibly for more transitions if the
transitions are regular enough. Forms(spaces inserted for
clarity): std offset dst offset, rule

Table 3    Configure Failover Options

Option

Description

failover-load-balance-max-seconds

This specifies the maximum number of seconds, based on the secs field of DHCP requests, before the peer will respond to a client‘s request regardless of the load balancing hash bucket assignment for the server.

failover-split

This specifies the percentage of the address space in dynamic pools that will be allocated to the primary server for failover purposes. The remainder of the address space will be assigned to the secondary server. This option is limited by the hba option. If there are n ”1” bits in hba, the option should have values between 0 and n. If no value is specified, this defaults to n/2.

failover-max-response-delay

If a message is not received from the failover peer within this time (in seconds), the peer is assumed to be down.

failover-max-unacked-updates

This specifies the maximum number of outstanding binding updates allowed at any time.

failover-mclt

This is the length (in seconds) of a first-time lease given to a client by the server for the failover protocol. The lead time is used by the server to communicate the lease activity to the secondary server and should be less than the normal lease time for the client.

max-lease-misbalance

It specifies the DHCP server what percentage of total free leases (as defined as the total number of leases in either the free or backup states) a peer is allowed to own before a rebalance check is made. Configuring higher values causes the server to rebalance less frequently, but permits a larger imbalance between the free and backup lease pools. Configuring a lower value causes the server to rebalance more frequently, but keeps the pools more balanced. ISC DHCP servers no longer send POOLREQ messages unless the imbalance is at least twice this percentage in favor of the peer . Valid values are between 0 and 100. The default value is 15.

max-lease-ownership

It specifies the DHCP server what percentage of total free leases either it or its peer are normally allowed to own in excess of balance for the purpose of MAC address affinity. When a server undergoes a lease rebalancing operation, it first tries to move as many leases as it can to the peer whose previous client was load-balanced to that peer (as governed by the Load Balance Algorithm, see the split configuration value). The max-lease-ownership value determines the maximum percentage of leases either server holds before giving its peer the oldest leases (regardless of the previous client’s place in the Load Balance Algorithm). Valid values are between 0 and 100, and should be less than the max-lease-misbalance value. Larger values will allow servers to retain leases to reallocate to returning clients, smaller values promote pool balance. The default value is 10.

max-balance

It specifies the maximum length of time that the DHCP server schedules pool rebalance events. The default value is 3600 (seconds).

min-balance

It specifies the minimum length of time that the DHCP server schedules pool rebalance events. The default value is 60 (seconds).

4.3.3   DhcpV4Option

A DHCP Option defines information about both configurable parameters in the DHCP Server and DHCP options that are exchanged between the client and server in the DHCP protocol. The server determines how to respond to a client by examining the values for these options in the policies within the server's configuration. The collection of all the DHCP Option objects serves as a dictionary of the all the configurable parameters for the server.

Key Name
Required Name, Datatype

4.4   Option82

NACF offers a flexible mechanism to extract the input data stream from Option82 based on the predefined input formats of virtual circuits or physical links, and convert the CLID or RemoteId to the new one based on the predefined output formats. Then the reformatted CLID or RemoteId are sent to CLF. To make the mechanism operational, dhcpv4option82format and dhcpv4option82iprange are introduced.

4.4.1   Dhcpv4Option82Format

This Dhcpv4Option82Format is used to store input format parsing rule of Option82 and format of the output message which will be sent to CLF

Key Partition, Name
Required Partition, Name, Category, Suboptionid, Informat, Outformat

4.4.2   Dhcpv4Option82IPRange

The Dhcpv4Option82IPRange will be used to specify the rules used for each Relay Agent IP range.

Sometimes, two or more format rules can be used to parse the specific input data. However, only one of those format rules is the correct match for the specific input data. Therefore, the object dhcpv4option82iprange is introduced to determine which format rule applies to the input data from a certain IP range.

Key Partition, Name
Required Partition, Name, Address, Mask, MaskLength, Option82Format

4.5   Dhcpv4Server

A Dhcpv4Server object represents an IPv4 DHCP server running on the network.

Key Partition, Name
Required Partition, Name

4.6   Lease

A lease object represents an actively leased address in the DHCP server. Lease objects are read-only objects: they cannot be created or modified. They are not used for configuration and are only created by the normal processing of the DHCP server. In other words, they are managed by and stored in the DHCP server, not the central IPWorks database.

Key Partition, Server, Address
Required Partition, Server, Address

5   DHCP Expressions

Three types of DHCP expressions are shown as follows:

5.1   Boolean Expressions

The following is the current supported list of boolean expressions. All boolean expressions depend on the results of evaluating data expressions.

5.2   Data Expressions

A list of data expressions is provided below. The boolean expressions listed above depend on the results of evaluating data expressions.

5.3   Numeric Expressions

Numeric expressions are expressions that evaluate to an integer. In general, the maximum size of such an integer should not be assumed to be represented in less than 32 bits, but the precision of such integers may be more than 32 bits. This can be elaborated as in the following:


Reference List

IPWorks Library Documents
[1] Command Line Interface User Guide for IPWorks SS.
[2] Trademark Information.
[3] Glossary of Terms and Acronyms.
[4] Typographic Conventions.
[5] IPWorks Configuration Management.
[6] IPWorks DNS, ASDNS, ENUM Parameter Description.


Copyright

© Ericsson AB 2018. All rights reserved. No part of this document may be reproduced in any form without the written permission of the copyright owner.

Disclaimer

The contents of this document are subject to revision without notice due to continued progress in methodology, design and manufacturing. Ericsson shall have no liability for any error or damage of any kind resulting from the use of this document.

Trademark List
All trademarks mentioned herein are the property of their respective owners. These are shown in IPWorks Trademark Information.

    IPWorks DHCP Parameter Description