15 flexible configurations automatic host gets

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Unformatted text preview: gurations Automatic: Host gets permanent address Dynamic: Address has expiration date/time (leasing) ! Manual: Fixed mapping MAC IP (C) Herbert Haas 2005/03/11 16 In the slide above you see the three different kind of configuration methods. BOOTP uses a manual configuration, a fixed mapping (MAC -> IP). DHCP has a dynamic configuration. The offered IP address from the server will be expire after a special time (leasing idea). 16 Parameters IP address Subnet mask DNS Server NetBIOS Name Server List of default gateways Ethernet Encapsulation Router Discovery (RFC 1256) Path MTU Discovery (RFC 1191) etc... (C) Herbert Haas 2005/03/11 17 In this slide you see some configuration parameters which can send with DCHP. It is also possible to transfer info about the maximal fragment size, ARP cache timeout, TCP keepalive, default TTL, source routing options and MTU. 17 How Does It Work - 1 1. IP LEASE REQUEST [DHCPDISCOVER] Here is MAC A. I need an IP Address ! DHCP Server 1 IP LEASE OFFER [DHCPOFFER] DHCP Client (C) Herbert Haas 2005/03/11 2. DHCP Server 2 18 In the slide above you see the basic principle of DHCP. It is possible in a bigger network that there are not only one DHCP server. The DHCP client connect to the network at starts sending out a IP LEASE REQUEST [DHCPDISCOVER] (via broadcast, like BOOTP). Every DHCP server in the network receives this message. Every DHCP server has a own address pool. If one server has addresses left in this pool, he sends back an IP LEASE OFFER [DHCPOFFER] (in this offer there is the IP address for the client) to the client. 18 How Does It Work - 1 DETAILED DHCPDISCOVER 1. Source IP Address: 0.0.0.0 Dest. IP Address: 255.255.255.255 HW Address: MAC A 10.1.0.10 DHCPOFFER 2. Source IP Address: 10.1.0.20 Dest. IP Address: 255.255.255.255 Offered IP Address: 10.1.0.99 Client HW Address: MAC A Subnetmask: 255.255.255.0 Leaselength: 48h Server ID: 10.1.0.20 10.1.0.99 (C) Herbert Haas 2005/03/11 10.1.0.20 19 This picture shows the same as the last o...
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This document was uploaded on 02/12/2014.

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