Download Microsoft Windows 2000 Network Infrastructure

Microsoft Windows 2000 Network
Infrastructure Administration
• Chapter 10
• Implementing Dynamic Host Configuration Protocol
(DHCP)
1
Introducing and
Installing DHCP
• Lesson 1 Topics
• TCP/IP configuration issues
• Functionality of DHCP
2
Introducing and
Installing DHCP
• Lesson Objectives
• To describe the differences between manual and
automatic configuration of TCP/IP
• To identify TCP/IP configuration parameters that can
be assigned by a DHCP server
• To describe IP lease requests and offers
• To install DHCP in Windows 2000
3
DHCP and BOOTP
• DHCP is an extension of Boot Protocol (BOOTP).
• BOOTP enables diskless clients to start up and
automatically configure TCP/IP
• Allows diskless clients to configure TCP/IP automatically.
• Centralizes and manages the allocation of TCP/IP.
• Automatically assigns addresses.
4
How a DHCP Client
Interacts with a DHCP Server
Client
5
Configuring TCP/IP
Manually
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Administrative overhead
Bad or duplicate IP addresses
Moving between subnets
Difficult to trace to the cource
Typing the IP address, subnet mask, or default gateway
can lead to problems.
6
Configuring TCP/IP
Using DHCP
• Centralized management
• Automatic supply of address information to clients
• Supplies all of the necessary configuration information to
all of the DHCP clients.
• Easier to troubleshoot
7
TCP/IP Configuration
Parameters Assigned by DHCP
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IP address for network adapter
Subnet masks
Default gateways
Additional parameters such as IP address for DNS or
WINS servers a client may use
8
Phases Process of DHCP
• Most DHCP messages are sent by broadcast
• Routers must support forwarding DHCP broadcasts
• DHCP Phases
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IP
IP
IP
IP
lease discover
lease offer
lease request
lease acknowledgment
9
Four Phases of DHCP
Client Configuration
10
IP Lease Discover and Offer
11
IP lease Discover
The client initializes a limited version of TCP/IP and
broadcasts a request for the location of a DHCP sever and
IP addressing
12
IP lease offer
• All DHCP severs that have valid IP addressing information
available send and offer to the client.
13
IP lease request
• The client selects the IP addressing information from the
first offer it receives and broadcasts a message requesting
to lease the IP addressing information in the offer.
14
IP lease acknowledgment
• The DHCP sever that made the offer responds to the
message, and all other DHCP servers withdraw their
offers. The addressing information is assigned to the
client and an acknowledgment is sent. The client finishes
initializing and binding the TCP/IP protocol.
15
IP Lease Offer
• All DHCP severs that receive the request and have a valid
configuration for client broadcast an offer with the
following information:
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The client’s hardware address (MAC)
An offered IP address
Subnet mask
Length of the lease
A server identifier ( DHCP server IP address)
16
Sending a DHCPOFFER
Message
17
When No DHCP
Servers Online
• Client waits 1 second.
• Client rebroadcasts at 9, 13, 16 seconds and then at
random intervals.
• Client retries every 5 minutes.
18
Automatic Private IP
Addressing (APIPA)
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Client attempts request.
Autoconfiguration of a Class B address.
Clients tests for conflicts for 10 addresses.
Client rechecks for a DHCP server every 5 minutes.
19
IP Lease Request
• Client broadcasts DHCPREQUEST message and includes
the server identifier (IP Address) of the server whose
offer was accepted.
• Other DHCP servers retract offers so their IP addresses
are available for the next lease request.
20
DHCPACK
• DHCP server sends DHCPACK that contains a valid lease
for and IP address and possibly other configuration
information.
• Client is bound DHCP client.
21
DHCPNACK
An unsuccessful acknowledgment DHCPNACK is broadcast if
the client is trying to lease its previous IP address and IP
address is no longer available.
• The IP address is no longer available.
• The client has been moved to a different subnet.
• The client returns to the process of requesting an IP
lease.
22
Before Installing DHCP
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Hardware and storage requirements
Which computers to configure immediately
Which computers to configure manually
DHCP options and values to be predefined
23
Options that Determine
Configuration
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Default gateway
Domain Name System (DNS) server
NetBIOS over TCP/IP name resolution
Windows Internet Name Service (WINS) server
NetBIOS scope ID
24
Report Displayed for
Ipconfig /all
25
Ipconfig Command-Line
Switches
26
DHCP Relay Agent
• Relays messages between clients and servers on subnets
• One DHCP server per subnet when routed
• Relay agent to support clients on multiple subnets
27
Configuring DHCP
• Lesson 2 Topic
• Configuring DHCP on Windows 2000–based server
28
Configuring DHCP
• Lesson Objectives
• To identify the benefits of using DHCP on a network
• To configure a DHCP server and clients
29
Setting a Client to Obtain an IP
Address from a DHCP Server
30
How DHCP Servers
Provide Optional Data
• Default gateways that connect network segments
• IP addresses for DNS servers
• IP addresses for WINS servers
31
Installing DHCP
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Install Microsoft DHCP Server service.
Authorize the DHCP server.
Configure a scope or pool of addresses.
Configure global and client scope.
The DHCP server can be configured to always assign the
same IP address to the same DHCP client
32
Authorizing a DHCP Server
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Windows 2000 servers are verified.
DHCP servers are authorized.
• First server in Active Directory
• Installed as domain controller or member server—not standalone
Authorization process depends on server role.
• Domain controller
• Member server
• If you deploy Active Directory, all computers operating as
DHCP servers must be either domain controller or domain
member server before they can authorized in the directory
service and provide DHCP service to clients.
33
DHCP Scope
Scope is a pool of valid IP addresses available for lease to
DHCP lients.
• At least one scope for every DHCP server.
• Exclude static IP addresses from scope.
• Multiple scopes will centralize administration and to assign
IP addresses specific to a subnet.
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One scope to a subnet.
DHCP servers do not share scope information.
IP addresses must be unique to scope.
Determine starting and ending addresses.
34
DHCP Scope
Configuration Options
35
Scope and IP Address Ranges
for Server A and Server B
36
Integrating DHCP with
Naming Services
• Lesson 3 Topics
• Dynamic updates in DNS
• Integrating DHCP with DNS
37
Integrating DHCP with
Naming Services
• Lesson Objectives
• To integrate DNS and DHCP
• To describe how Dynamic DNS updates work
• To identify how DHCP client updates are typically
handled
38
Registering for DNS
Updates
• Windows 2000 can register with a DNS server.
• Supports DNS Dynamic update protocol for automatic
record updating.
• DHCP acts as registration proxy.
• An additional DHCP Option Code 81 enables return of fully
qualified domain name (FQDN).
• DHCP and static DNS are not compatible.
39
DHCP Clients and DNS
• DHCP servers provide default support for legacy DHCP
clients in DNS zones.
• DHCP/DNS update interaction for Windows 2000.
• DHCP/DNS update interaction for pre-Windows 2000.
40
A DHCP Client Interacting with the
DNS Dynamic Update Protocol
41
DHCP/DNS Interaction with
Older Windows Clients
42
Using DHCP with
Active Directory
• Lesson 4 Topics
• Integration with Active Directory and DNS service
• Monitoring as statistical reporting for DHCP servers
43
Using DHCP with
Active Directory
• Lesson Objectives
• To describe how IP address and naming management
is managed through DHCP and Active Directory
integration
• To describe how DHCP servers are authorized
44
Integrated IP Management
• Windows 2000 Sever naming and address services offer
flexibility and interoperability with other address and
naming systems
• Address assignment and naming services
• Support for legacy servers
• New with Windows 2000 Server is support for Dynamic
DNS, Active Directory integration of DHCP and DNS, and
DHCP rely agent
45
Rogue Server
Detection Feature
• Windows 2000 detects unauthorized DHCP servers.
• DHCP servers not authorized are not able to run the DHCP
service.
46
Troubleshooting DHCP
• Lesson 5 Topics
• Troubleshooting DHCP clients
• Troubleshooting DHCP servers
47
Troubleshooting DHCP
• Lesson Objectives
• To identify and solve DHCP client problems
• To identify and solve DHCP server problems
48
Preventing DHCP Problems
• Use 75/25 design rule.
• Use superscopes for multiple DHCP servers on each
subnet. A superscope allows a DHCP server to provide
leases from more than one scope to clients on a single
physical network.
• Deactivate scopes only when removing a scope
permanently.
• Use server-side conflict detection.
49
Preventing DHCP Problems
(con’t)
• Create reservations on all potential DHCP servers.
• DHCP is disk intensive; use optimal hardware. Consider
RAID 0 or RAID 5 solutions when purchasing hardware for
your server computer.
• Use audit log.
• Integrate DHCP with other services, such as DNS and
WINS
• Use appropriate number of DHCP servers.
50
Number of DHCP Servers
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Size of network
Number of DHCP-enabled clients
Transmission speed between network segments
Speed of network links
IP address class of the network
Isolated or multiple DHCP servers
51
Troubleshooting
DHCP Clients
• Failed IP configuration
• Invalid IP address configuration
• Autoconfiguration problems (Microsoft has reserved IP
addresses from 169.254.0.1 through 169.255.254 and
uses this range to support APIPA
• Missing configuration details
• DHCP not providing IP addresses
52
Failed IP Configuration
• Check for client problem.
• Check system event log and DHCP audit logs for clues.
• Use Ipconfig TCP/IP utility.
53
Invalid IP Address
• Client does not have IP address, or client has IP address
of 169.254.x.x.
• Client cannot contact DHCP server.
• Determine whether network hardware failure or DHCP
server is unavailable.
• Verify that client has valid functioning network
connection.
• Check hardware.
54
Autoconfiguration Problems
• Windows could not find a DHCP server and provided
APIPA IP address.
• In larger networks, consider disabling APIPA.
55
Missing Configuration
Details
• Client is missing DHCP options.
• Verify that options distribution is configured at server,
scope, client, or class level.
• Check DHCP option settings.
• DHCP is configured with incorrect DHCP router option
(Option Code 3).
56
DHCP Servers Do Not
Provide IP Addresses
• IP address of the DHCP server was changed.
• DHCP clients are located across router from subnet where
DHCP server resides.
• Multiple DHCP servers exist on same local area network
(LAN).
57
Three Ways to
Discover Problem
• Client configured to use an address not provided by the
server.
• Server sends error message back to client.
• Server leases IP address, but client has network
configuration-based problems.
58
Relay Agent Not Working
• DHCP Relay Agent and DHCP server are on the same
computer.
• Install DHCP server and DHCP Relay Agent on
different computers.
59
Console Reports Incorrect
Lease Expirations
• Scope time and lease time should be identical.
• Reassign lease times or add reservations to the scope.
60
No Address Leases
for New Scope
• Configure DHCP server to use superscope with old and
new scopes.
• Change primary IP address to that in new scope.
• Windows NT Server 3.51, change first IP address to
address in new scope range.
61
System Monitor
• All types of DHCP messages sent and received
• Average amount of processing time per message packet
sent and received
• Number of message packets dropped from internal delays
62
Moving DHCP
Server Database
• May need to move DHCP database to another computer
• May need to reconcile database
• Can force lease updates by typing Ipconfig /renew
63