Module 01: Dynamic Host Configuration Protocol (DHCP)

Network Service -2 Why Use DHCP? DHCP 는 TCP/IP 를 자동 구성을 사용함으로써 구성상의 불편함과 복잡함을 해소 하였다. Manual TCP/IP Configuration IP addresses 를 User 가 직접 지정 잘못된 IP address 로 구성할 수 있는 가능성이 있다. 잘못된 network 구성은 Network issues 를 초래한다 Computer 의 Network 정보의 빈번한 변경은 관리 작업의 부하를 초래 IP addresses 를 User 가 직접 지정 잘못된 IP address 로 구성할 수 있는 가능성이 있다. 잘못된 network 구성은 Network issues 를 초래한다 Computer 의 Network 정보의 빈번한 변경은 관리 작업의 부하를 초래 Automatic TCP/IP Configuration IP addresses 를 자동으로 client computers 에 부여 Clients 에게 정확한 network 구성 정보를 제공한다 Client 의 Network 구성 정보를 자동으로 Update 를 제공한다. Network 상에 발생 할 수 있는 문제점을 제거 IP addresses 를 자동으로 client computers 에 부여 Clients 에게 정확한 network 구성 정보를 제공한다 Client 의 Network 구성 정보를 자동으로 Update 를 제공한다. Network 상에 발생 할 수 있는 문제점을 제거

Network Service -3 How DHCP Allocates IP Addresses DHCP Server DHCP Database IP Address1: Leased to DHCP Client1 IP Address2: Leased to DHCP Client2 IP Address3: Available to be leased IP Address1: Leased to DHCP Client1 IP Address2: Leased to DHCP Client2 IP Address3: Available to be leased DHCP Client2: IP configuration from DHCP server Non-DHCP Client: Static IP configuration DHCP Client1: IP configuration from DHCP server Lease Renewal Lease Generation

Network Service -4 How the DHCP Lease Generation Process Works DHCP client 가 broadcasts 로 DHCPDISCOVER packet 요청 1 1 DHCP servers 는 broadcast 로 DHCPOFFER packet 응답 2 2 DHCP client 가 broadcasts 로 DHCPREQUEST packet 요청 3 3 DHCP Server1 broadcasts 로 DHCPACK packet 을 응답 4 4 DHCP Client DHCP Server1 DHCP Server2

Network Service -5 How the DHCP Lease Renewal Process Works DHCP Client DHCP Server1 DHCP Server2 DHCP Client sends a DHCPREQUEST packet 1 1 DHCP Server1 sends a DHCPACK packet % of lease duration has expired 87.5% of lease duration has expired 100% of lease duration has expired If the client fails to renew its lease, after 50% of the lease duration has expired, then the DHCP lease renewal process will begin again after 87.5% of the lease duration has expired client 가 lease time 50% 가 지나면 갱신 요청을 한다, 만약 87.5% 의 lease time 지나도록 갱신되지 않은 경우 lease time 이 만료 된 후, DHCP client 는 다시 IP 정보를 받기 위해 broadcasting 으로 DHCPDISCOVER 메시지를 보낸다. DHCP Client DHCP Server1 DHCP Server2 DHCP client sends a DHCPREQUEST packet 1 1 DHCP Server1 sends a DHCPACK packet % of lease duration has expired

Network Service -6 How a DHCP Server Service Is Authorized Domain Controller Domain Controller Active Directory Active Directory DHCP Client DHCP Server1 는 domain controller 에게 DHCP servers 인증 요청을 한다. Unauthorized Does not service DHCP requests Authorized Services DHCP requests DHCP Server1 DHCP Server2 DHCP Server1 에 IP address 가 존재한다면, DHCP Client 에게 IP address 를 제공할 수 있다. 인증된 DHCP Server1 로 부터 DHCP client 는 IP address 제공 받는다. DHCP Server2 에 IP address 를 가지고 있지 않다면, DHCP clients 는 IP address 를 Service 를 받지 못한다 Active Directory domain 로부터 DHCP Server 인증을 받아야 DHCP client 들에게 DHCP Server service 를 할 수 있다 DHCP Server2 는 domain controller 에게 DHCP Server 인증 요청을 한다.

Network Service -7 Lesson: Configuring a DHCP Scope What Are DHCP Scopes? How to Configure a DHCP Scope

Network Service -8 What Are DHCP Scopes? Scope( 범위 ) 란 DHCP 서비스를 사용하는 Subnet 에서 관리 목적을 위해 컴퓨터의 IP addresses 그룹으로 묶은 것입니다 Scope Properties Network ID Lease duration Scope name Subnet mask Router Exclusion range Network IP address range LAN ALAN B DHCP Server Scope B Scope A

Network Service -9 Lesson: Configuring a DHCP Reservation What Is a DHCP Reservation? How to Configure a DHCP Reservation

Network Service -10 What Is a DHCP Reservation? Reservation 란 특정 DHCP Client 가 IP address 의 영구적인 사용에 대비하여 특정한 IP address 를 예약한 것을 말한다 Subnet A Subnet B Workstation 1 DHCP Server Workstation 2 File and Print Server IP Address1: Leased to Workstation 1 IP Address2: Leased to Workstation 2 IP Address3: Reserved for File and Print Server IP Address1: Leased to Workstation 1 IP Address2: Leased to Workstation 2 IP Address3: Reserved for File and Print Server

Network Service -11 Lesson: Configuring DHCP Options What Are DHCP Options? How DHCP Server, Scope, and Reserved Client Options Are Applied How DHCP Class-level Options Are Applied How to Configure DHCP Options

Network Service -12 What Are DHCP Options? DHCP options 에서 configuration parameters 들은 DHCP service 가 clients 에게 IP address 와 default gateway 를 제공한다. DHCP Client DHCP Server DHCP Client IP Configuration Data Client’s IP address Client’s subnet mask DHCP options such as:  Router’s IP address  DNS server’s IP address  WINS server’s IP address  DNS domain name Client’s IP address Client’s subnet mask DHCP options such as:  Router’s IP address  DNS server’s IP address  WINS server’s IP address  DNS domain name

Network Service -13 How DHCP Server, Scope, and Reserved Client Options Are Applied DHCP option applied at the server level DHCP option applied at the server level DHCP option applied at the scope level DHCP option applied at the scope level DHCP option applied at the reserved-client level DHCP option applied at the reserved-client level Scope A Scope B Windows XP DHCP Server Windows 98 Windows XP Router File and Print Server Scope A Scope B Windows XP DHCP Server Windows 98 Windows XP Router File and Print Server

Network Service -14 How DHCP Class-level Options Are Applied DHCP option applied at the class level DHCP option applied at the class level Scope A Scope B DHCP Server Windows 98 Windows XP Router File and Print Server

Network Service -15 Lesson: Configuring a DHCP Relay Agent What Is a DHCP Relay Agent? How a DHCP Relay Agent Works How a DHCP Relay Agent Uses Hop Count How a DHCP Relay Agent Uses Boot Threshold How to Configure a DHCP Relay Agent

Network Service -16 What Is a DHCP Relay Agent? DHCP relay agent 는 서로 다른 Subnet 에 있는 Server 와 Clinet 간에게 DHCP/BOOTP broadcasts 메시지를 relay 를 하는 작은 프로그램이다. DHCP Server Client DHCP Relay Agent Client Routers Non-RFC 1542 Compliant Routers Non-RFC 1542 Compliant Unicast Broadcast Subnet ASubnet B Broadcast

Network Service -17 How a DHCP Relay Agent Works Router Non-RFC 1542 Compliant Router Non-RFC 1542 Compliant Client1 DHCP Relay Agent Client2 DHCP Server Client3 Router Non-RFC 1542 Compliant Router Non-RFC 1542 Compliant Client1 DHCP Relay Agent Client2 DHCP Server Client3 Client1 broadcasts a DHCPDISCOVER packet 1 1 Relay agent forwards the DHCPDISCOVER message to the DHCP server 2 2 Server sends a DHCPOFFER message to the DHCP relay agent 3 3 Relay agent broadcasts the DHCPOFFER packet 4 4 Client1 broadcasts a DHCPREQUEST packet 5 5 Relay agent forwards the DHCPREQUEST message to the DHCP server 6 6 Server sends a DHCPACK message to the DHCP relay agent 7 7 Relay agent broadcasts the DHCPACK packet 8 8

Network Service -18 How a DHCP Relay Agent Uses Hop Count The hop count threshold 는 DHCP Relay Agent Packet 이 훼손 되지 않고 전달할 수 있는 routers 의 개수를 말한다. DHCP Relay Agent 2 DHCP Server Hop Count = 2 DHCP Relay Agent 1

Network Service -19 How a DHCP Relay Agent Uses Boot Threshold DHCP Server 2 DHCP Server 3 DHCP Relay Agent Boot Threshold = 10 seconds Local DHCP Server DHCP Server 2 DHCP Server 3 DHCP Relay Agent Boot Threshold = 10 seconds Local DHCP Server boot threshold 란 ? DHCP Client 가 Address 요청 시 얼마 후에 응답 할 것인지를 지정하는 값이다.

Network Service -20 Lab : IP Addressing by Using DHCP 1.Windows 2003 Server 를 이용하여 DHCP Server 를 구성한 후 XP Client 에 Address 할 당 내역을 확인한다. 2.Cisco Router 를 이용하여 DHCP 서버를 구성 하고 XP Client 에서 확인한다. 3. 서버구성 내용 1.IP Address 2.Subnet Mask 3.Default-Gateway 4.DNS Server Address 5.Domain Name 6.Option 150

LAB Network Service -21