SCOPES OF

DYNAMIC HOST CONFIGURATION PROTOCOL

A DHCP scope is a valid range of IP addresses which are available for assignments or lease to client computers on a particular subnet.

DHCP Scope

Scopes determine which IP addresses are provided to the clients.

Scopes should be defined and activated before DHCP clients use the DHCP server for its dynamic IP configuration.

You can configure as many scopes on a DHCP server as is required in your network environment.

Scopes…

DHCP Scope and Subnet

•One DHCP scope is required for each subnet.

A DHCP scope consists of a pool of IP addresses on a subnetwork, such as 10.223.223.1 to 10.223.223.200, that the DHCP server can lease to DHCP clients.

Each physical network can have only one DHCP scope or a superscope with one or more ranges of IP addresses.

DHCP Scope and Subnet…

TYPES OF SCOPE

•SUPER-SCOPE

•MULTI-SCOPE

Superscope

A range of IP addresses that span several Subnets.

The DHCP server can assign these addresses to clients that are on several subnets.

A superscope is an administrative feature of DHCP servers that you can create and manage through the DHCP console.

Using a superscope, you can group multiple scopes as a single administrative entity.

Using Superscopes

• Support DHCP clients on a single physical network segment having multiple logical IP subnets, often called multinets.

• Support remote DHCP clients located on the far side relay agents

Situations for which superscopes are useful

• More hosts must be added than originallyplanned.

• The network is renumbered.

• Two DHCP servers are used to manage separate logical subnets on the same physical subnet.

•A range of class D addresses from 224.0.0.0 to 239.255.255.255 that can be assigned to computers when they ask for them. •Multicasting can be used to send messages to a group of computers at the same time with only one copy of the message.

•The Multicast Address Dynamic Client Allocation Protocol (MADCAP) is used to request a multicast address from a DHCP server.

Multicast scope

DHCP Scope Properties

Network ID: The network ID for the range of IP addresses.

Subnet mask: The subnet mask for the network ID

Network IP address range: The range of IP addresses that are available.

Lease duration: The period of time that the DHCP server holds a leased IP address for a client before removing the lease.

Router A DHCP option that allows DHCP clients to access remote networks.

DHCP Scope Properties…..

DHCP Scope Properties…..

Scope name: An alphanumeric identifier for administrative purposes.

Exclusion range: The range of IP addresses in the scope that is excluded from being leased.

Reserving IP Addresses

• DHCP Manager allows the reservation of a specific IP address for a computer or other IP addressable device on the network.

• Reserving selected IP addresses for special-function devices on the network ensures that DHCP does not duplicate or reassign the address.

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Here the black computer wants to register itself on the network. So it sends a request packet to the dhcp server requesting an IP address

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It broadcasts DHCPDISCOVER msg over local network with dest address 255.255.255.255

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The packet contains MAC address, source port, dest ip address, port,and transaction id.

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Each network has a relay agent or dhcp server

The req recievd from the black system is processed by dhcp server or agent. Others ignore it.

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Relay agents r configured wit the ip address of dhcp server

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Agent will forward the msg from black computer to dhcp server

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Dhcp contains a pool of ip addresses that can be leased to hosts on demand

DHCP server

Ip address pool

Various scopes

DHCP server

Ip address pool

Various scopes

To subnet 1

To subnet x

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Server sends ip address, default gateway, subnet mask

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Dhcp ip address Client’s MAC, new ip addrss and information.

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Relay agent pass the msg from server to the black computer

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Now the client has a new ip adress. It has to renew it time to time.

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scope

Scope and Administrator

•A scope is an administrative grouping of computers for a subnetwork using DHCP service.

• Administrators create a scope for each physical subnetwork, which is then used as parameters by clients for this subnetwork.

Administrator plans the Scopes based on the needs of particular groups of users, with appropriate lease durations defined for the related scopes.

Scope and Administrator…

Characteristics of scopes

•A range of possible IP addresses from which to include or exclude addresses used in DHCP service lease offerings.

•A unique subnet mask to determine the subnet related to a given IP address.

Characteristics of scopes…

•A scope name assigned when the scope is created.

•Lease duration values to be assigned to DHCP clients that receive dynamically allocated IP addresses.

DHCP scopes makes all the clients happy .

THANK YOU