| Lesson 5 | Designing functional DHCP solution for LAN |
| Objective | Describe how to design a DHCP service in a non-routed LAN environment. |
Designing functional DHCP solution for LAN
When putting together your design document for a functional DHCP solution in a LAN
environment, you should consider the types of hosts as well as the network configuration in which those hosts exist. For example, a DHCP Server
can support hosts that participate on the network via a single non-routed LAN, a complex routed LAN, or even via dial-up connections.
The network configuration and the hosts' locations in that configuration are important when allocating your DHCP Server's resources. A simple non-routed LAN will have a DHCP Server on the same segments as the hosts, a routed LAN may have DHCP Servers on each segment or perhaps take advantage of BOOTP Forwarding or DHCP Relay Agents.
Dial-up hosts may use the RAS Server configurations or take advantage of the DHCP Relay Agent to obtain DHCP option information.
The network configuration and the hosts' locations in that configuration are important when allocating your DHCP Server's resources. A simple non-routed LAN will have a DHCP Server on the same segments as the hosts, a routed LAN may have DHCP Servers on each segment or perhaps take advantage of BOOTP Forwarding or DHCP Relay Agents.
Dial-up hosts may use the RAS Server configurations or take advantage of the DHCP Relay Agent to obtain DHCP option information.
Designing for a LAN environment
A single DHCP Server can support the DHCP service for several thousand DHCP Clients in a non-routed LAN. Many small to medium-sized LANs are built by using ISO layer 2 switches,
thereby allowing large client counts on a single logical subnet.
Thus, if you are in a large corporation, you may have a Class B network ID of 131.107.0.0. By implementing switching technology in your LAN environment, you can limit MAC broadcast traffic and create what are essentially two-computer collision domains. In this case, you can have a single DHCP Server service the thousands of computers that may exist on a single logical IP subnet.
A DHCP service for switched environments with multiple broadcast domains may require DHCP Relay Agents even though the network is not routed.
Thus, if you are in a large corporation, you may have a Class B network ID of 131.107.0.0. By implementing switching technology in your LAN environment, you can limit MAC broadcast traffic and create what are essentially two-computer collision domains. In this case, you can have a single DHCP Server service the thousands of computers that may exist on a single logical IP subnet.
A DHCP service for switched environments with multiple broadcast domains may require DHCP Relay Agents even though the network is not routed.
Designing for a LAN environment, you will encounter many different design decisions.
The following Slide Show shows you
- where to place DHCP Servers and
- how to select TCP/IP options,
1) Answer File 1
2) Answer File 2
3) Answer File 3
4) Answer File 4
5) Answer File 5
6) Answer File 6
7) Answer File 7
8) Answer File 8
9) Answer File 9
10) Answer File 10
11) Answer File 11
12) Answer File 12
13) Answer File 13
- Where to place a DHCP Server. With a single DHCP server, DHCP Client requests are allocated from a single Scope. This single Scope defines all addresses and TCP/IP options offered for the LAN.
- With many DHCP Servers, it is unknown which server will answer a DHCP client broadcast first. In this case, share the IP address range equally between the DHCP scopes.
- For example, on one DHCP Server you can define a scope for 192.168.1.0 and another DHCP Server a scope for 192.168.2.0. Each of these Scopes are created on each DHCP server, and then a Superscope is created on each Server.
- You then disable one of the Scopes on each DHCP Server. Remember, each Scope can only contain a single subnet, and you do not know what DHCP Server will answer the DHCP broadcast message.
In the next lesson, you will design a DHCP service for a routed network.
MAC: Message Authentication Code, or Media Access Control. A Message Authentication Code is the result of hashing, and often referred to as a Hash Message Authentication Code or HMAC. This is the digital signature applied to signed packets. A Media Access Control address is a hardware addressed applied to a network interface.
