568
C
HAPTER
32: DHCP O
VERVIEW
■
flags: The leftmost bit is defined as the BROADCAST (B) flag. This flag indicates
whether the DHCP server sends a reply back by unicast or broadcast. If this flag
is set to 0, the DHCP server sent a reply back by unicast; if this flag is set to 1,
the DHCP server sent a reply back by broadcast. The remaining bits of the flags
field are reserved.
■
ciaddr: Client IP address.
■
yiaddr: ’your’ (client) IP address, assigned by the server.
■
siaddr: Server IP address, from which the clients obtained configuration
parameters.
■
giaddr: The first relay agent IP address a request message traveled.
■
chaddr: Client hardware address.
■
sname: The server host name, from which the client obtained configuration
parameters.
■
file: Bootfile name and routing information, defined by the server to the client.
■
options: Optional parameters field that is variable in length, which includes the
message type, lease, DNS IP address, WINS IP address and so forth.
DHCP Options
DHCP Options Overview
The DHCP message adopts the same format as the Bootstrap Protocol (BOOTP)
message for compatibility, but differs from it in the option field, which identifies
the new features of DHCP.
DHCP uses the option field in DHCP messages to carry control information and
network configuration parameters, implementing dynamic address allocation and
providing more network configuration information for clients.
Figure 164
shows the DHCP option format.
Figure 164
DHCP option format
Introduction to DHCP
Options
The common DHCP options are:
■
Option 6: DNS server option. It specifies the DNS server IP address to be
assigned to the client.
■
Option 51: IP address lease option.
■
Option 53: DHCP message type option. It identifies the type of the DHCP
message.
■
Option 55: Parameter request list option. It is used by a DHCP client to request
specified configuration parameters. The option contains values that correspond
to the parameters requested by the client.
Option type
Option length
0
7
15
Value (variable)
Содержание MSR 50 Series
Страница 152: ...152 CHAPTER 5 ATM CONFIGURATION...
Страница 209: ...Troubleshooting 209 Use the debugging dialer event and debugging dialer packet commands to locate the problem...
Страница 210: ...210 CHAPTER 6 DCC CONFIGURATION...
Страница 234: ...234 CHAPTER 7 DLSW CONFIGURATION...
Страница 344: ...344 CHAPTER 14 X 25 AND LAPB CONFIGURATION...
Страница 350: ...350 CHAPTER 15 LINK AGGREGATION OVERVIEW...
Страница 358: ...358 CHAPTER 17 MODEM CONFIGURATION...
Страница 486: ...486 CHAPTER 23 MSTP CONFIGURATION...
Страница 506: ...506 CHAPTER 25 VOICE VLAN CONFIGURATION...
Страница 510: ...510 CHAPTER 26 PORT ISOLATION CONFIGURATION...
Страница 524: ...524 CHAPTER 27 DYNAMIC ROUTE BACKUP CONFIGURATION...
Страница 538: ...538 CHAPTER 28 LOGICAL INTERFACE CONFIGURATION...
Страница 548: ...548 CHAPTER 29 CPOS INTERFACE CONFIGURATION...
Страница 572: ...572 CHAPTER 32 DHCP OVERVIEW...
Страница 604: ...604 CHAPTER 36 DHCP SNOOPING CONFIGURATION...
Страница 608: ...608 CHAPTER 37 BOOTP CLIENT CONFIGURATION...
Страница 646: ...646 CHAPTER 42 IP UNICAST POLICY ROUTING CONFIGURATION...
Страница 650: ...650 CHAPTER 43 UDP HELPER CONFIGURATION...
Страница 738: ...738 CHAPTER 50 IPV6 UNICAST POLICY ROUTING CONFIGURATION...
Страница 770: ...770 CHAPTER 51 TERMINAL ACCESS CONFIGURATION...
Страница 798: ...798 CHAPTER 52 FEP INSTALLATION AND CONFIGURATION...
Страница 808: ...808 CHAPTER 53 TERMINAL ACCESS TROUBLESHOOTING...
Страница 814: ...814 CHAPTER 54 TERMINAL ACCESS FAQ...
Страница 824: ...824 CHAPTER 55 IP ROUTING OVERVIEW...
Страница 876: ...876 CHAPTER 56 BGP CONFIGURATION...
Страница 916: ...916 CHAPTER 57 IS IS CONFIGURATION...
Страница 970: ...970 CHAPTER 58 OSPF CONFIGURATION...
Страница 1006: ...1006 CHAPTER 60 ROUTING POLICY CONFIGURATION...
Страница 1013: ...Configuration Example 1013 3 1 ms 1 ms 1 ms 1 1 2 2 Trace complete...
Страница 1014: ...1014 CHAPTER 61 STATIC ROUTING CONFIGURATION...
Страница 1048: ...1048 CHAPTER 63 IPV6 IS IS CONFIGURATION...
Страница 1068: ...1068 CHAPTER 64 IPV6 OSPFV3 CONFIGURATION...
Страница 1080: ...1080 CHAPTER 65 IPV6 RIPNG CONFIGURATION...
Страница 1114: ...1114 CHAPTER 68 MULTICAST ROUTING AND FORWARDING CONFIGURATION...
Страница 1160: ...1160 CHAPTER 70 MSDP CONFIGURATION...
Страница 1234: ...1234 CHAPTER 73 MLD CONFIGURATION...
Страница 1278: ...1278 CHAPTER 74 IPV6 PIM CONFIGURATION...
Страница 1310: ...1310 CHAPTER 75 MULTICAST VPN CONFIGURATION...
Страница 1344: ...1344 CHAPTER 76 MPLS BASICS CONFIGURATION...
Страница 1458: ...1458 CHAPTER 78 MPLS L2VPN CONFIGURATION...
Страница 1555: ...MPLS L3VPN Configuration Example 1555 5 packet s received 0 00 packet loss round trip min avg max 66 79 109 ms...
Страница 1556: ...1556 CHAPTER 79 MPLS L3VPN CONFIGURATION...
Страница 1588: ...1588 CHAPTER 80 DVPN CONFIGURATION...
Страница 1648: ...1648 CHAPTER 85 QOS POLICY CONFIGURATION...
Страница 1696: ...1696 CHAPTER 89 MPLS QOS CONFIGURATION...
Страница 1708: ...1708 CHAPTER 90 DAR CONFIGURATION...
Страница 1728: ...1728 CHAPTER 91 FRAME RELAY QOS CONFIGURATION...
Страница 1750: ...1750 CHAPTER 92 802 1X CONFIGURATION...
Страница 1788: ...1788 CHAPTER 93 AAA RADIUS HWTACACS CONFIGURATION...
Страница 1810: ...1810 CHAPTER 95 MAC AUTHENTICATION CONFIGURATION...
Страница 1850: ...1850 CHAPTER 97 PKI CONFIGURATION...
Страница 1872: ...1872 CHAPTER 98 PORTAL CONFIGURATION...
Страница 1970: ...1970 CHAPTER 106 BACKUP CENTER CONFIGURATION...
Страница 2048: ...2048 CHAPTER 110 NETSTREAM CONFIGURATION...
Страница 2084: ...2084 CHAPTER 112 RMON CONFIGURATION...
Страница 2094: ...2094 CHAPTER 113 SNMP CONFIGURATION...
Страница 2114: ...2114 CHAPTER 115 FTP CONFIGURATION...
Страница 2123: ...System Maintaining Example 2123 The above output shows that nine routers are involved from the source to the destination device...
Страница 2124: ...2124 CHAPTER 117 SYSTEM MAINTAINING AND DEBUGGING...
Страница 2154: ...2154 CHAPTER 119 INFORMATION CENTER CONFIGURATION...
Страница 2170: ...2170 CHAPTER 121 MAC ADDRESS TABLE MANAGEMENT CONFIGURATION...
Страница 2186: ...2186 CHAPTER 123 POE CONFIGURATION...
Страница 2198: ...2198 CHAPTER 125 ACFP CONFIGURATION...
Страница 2206: ...2206 CHAPTER 126 ACSEI CONFIGURATION...
Страница 2216: ...2216 CHAPTER 127 TRACK CONFIGURATION...
Страница 2232: ...2232 CHAPTER 128 IPX CONFIGURATION...
Страница 2242: ...2242 CHAPTER 129 VOICE OVERVIEW...
Страница 2244: ...2244 CHAPTER 130 VOIP OVERVIEW...
Страница 2288: ...2288 CHAPTER 132 VOICE ENTITY CONFIGURATION...
Страница 2342: ...2342 CHAPTER 134 E1 AND T1 CONFIGURATION...
Страница 2354: ...2354 CHAPTER 135 FAX OVER IP CONFIGURATION...
Страница 2366: ...2366 CHAPTER 136 H 323 CONFIGURATION...
Страница 2384: ...2384 CHAPTER 137 SIP OVERVIEW...