DHCP: Forskelle mellem versioner
Content deleted Content added
Glenn (diskussion | bidrag) præciséring |
Glenn (diskussion | bidrag) +==Lag placering i ISOs OSI-model==-afsnit |
||
Linje 14:
# Netkortet spørger DHCP server: kan jeg få tildelt en IP adresse
# DHCP server svarer og sender en IP adresse
==Lag placering i ISOs OSI-model==
På ISO lag 7 (applikationslaget) serviceres DHCP-pakker af f.eks. [[:en:Dhcpd|dhcpd]]-server-dæmonen, derfor er DHCP en lag 7-protokol.<ref>[http://www.dreamincode.net/forums/topic/233114-which-osi-layer-dhcp-belongs-to/ dreamincode.net: Which OSI Layer DHCP belongs to?]</ref>
Protokollen kan under en DHCP-forhandling starte med ikke-routebare source ([[0.0.0.0]]) og destinations ([[255.255.255.255]]) ip-adresser i lag 3-headeren, men kan senere benytte routebare ip-adresser. Herudover indeholder DHCP-pakker også valide [[UDP]]-porte. DHCP-protokollen kan starte med at respektere lag 2-protokollen og kan ende med at bootstrappe sig til at respektere lag 3 (IPv4) og lag 4 UDP-protokollen.<ref>[http://tools.ietf.org/html/rfc2131 RFC 2131] Citat: "...The server MUST broadcast the DHCPNAK message to the 0xffffffff broadcast address because the client may not have a correct network address or subnet mask, and the client may not be answering ARP requests...Normally, DHCP servers and BOOTP relay agents attempt to deliver DHCPOFFER, DHCPACK and DHCPNAK messages directly to the client using u[n]icast delivery...If the BROADCAST bit is cleared to 0, the message SHOULD be sent as an IP unicast to the IP address specified in the 'yiaddr' field..."</ref><ref>[http://www.eventhelix.com/RealtimeMantra/Networking/DHCP.pdf DHCP Sequence Diagram] - This sequence diagram covers several scenarios of DHCP operation.</ref>
==Kilder/referencer==
{{reflist}}
== Eksterne henvisninger ==
| |||