Configuring DHCP Relay Agent
615
n
■
You can configure up to eight external DHCP IP addresses in a DHCP server
group.
■
You can map multiple VLAN interfaces to one DHCP server group. But one
VLAN interface can be mapped to only one DHCP server group. If you execute
the
dhcp-server
groupNo command repeatedly, the new configuration
overwrites the previous one.
■
You need to configure the group number specified in the
dhcp-server
groupNo command in VLAN interface view by using the command
dhcp-server
groupNo
ip
ipaddress-address&<1-8> in advance.
Configuring a DHCP
Relay Agent to
Broadcast Responses to
Clients
Generally, the DHCP relay agent determines to broadcast or unicast responses
(including DHCP-OFFER, DHCP-ACK, or DHCP-NAK) from the DHCP server to the
clients according to the flag field in the DHCP-DISCOVER packet.
■
When the first bit of the flag field is set to 1, the DHCP relay agent broadcasts
the response packets to the clients.
■
When the flag field is set to 0, the DHCP relay agent unicasts the response
packets to the clients.
In actual networking, if clients have special requirements, Switch 7750 Ethernet
switches support the following commands so as to force the DHCP relay agent to
broadcast the responses to the clients. After this function is enabled, even if the
flag field in the DHCP-DISCOVER packet is set to 0, the DHCP relay agent still
broadcasts responses to the clients.
Specifying Gateways for
DHCP Clients
To implement this feature on the DHCP relay agent, you need to bind ports in a
VLAN to either the VLAN interface’s primary IP address or one of its secondary IP
addresses (a gateway address). The binding entries will be stored in a binding
table.
Upon receiving a DHCP request message with the giaddr field being 0 from a port
in this VLAN, the DHCP relay agent will search the binding table and then insert
the bound gateway IP address into the giaddr field of the message. If the DHCP
relay agent cannot find a match in the binding table, it inserts the primary IP
Map an interface to a DHCP
server group
interface
interface-type
interface-number
Required
By default, a VLAN interface is
not mapped to any DHCP
server group
dhcp-server
groupNo
Table 483
Configure an interface to operate in DHCP relay agent mode
Operation Command Description
Table 484
Configure the DHCP relay agent to broadcast responses to clients
Operation Command Description
Enter system view
system-view
-
Configure the DHCP
relay agent to
broadcast responses
to clients
dhcp relay reply
broadcast
Required
Generally, the DHCP relay agent determines
to broadcast or unicast responses to the
clients according to the flag field in the
DHCP-DISCOVER packet.
Содержание Switch 7754
Страница 32: ...32 CHAPTER 1 CLI OVERVIEW ...
Страница 70: ...70 CHAPTER 5 LOGGING IN USING MODEM ...
Страница 76: ...76 CHAPTER 7 LOGGING IN THROUGH NMS ...
Страница 86: ...86 CHAPTER 9 CONFIGURATION FILE MANAGEMENT ...
Страница 120: ...120 CHAPTER 13 ISOLATE USER VLAN CONFIGURATION ...
Страница 126: ...126 CHAPTER 14 SUPER VLAN ...
Страница 136: ...136 CHAPTER 16 IP PERFORMANCE CONFIGURATION ...
Страница 152: ...152 CHAPTER 17 IPX CONFIGURATION ...
Страница 164: ...164 CHAPTER 19 QINQ CONFIGURATION ...
Страница 172: ...172 CHAPTER 21 SHARED VLAN CONFIGURATION ...
Страница 182: ...182 CHAPTER 22 PORT BASIC CONFIGURATION ...
Страница 198: ...198 CHAPTER 24 PORT ISOLATION CONFIGURATION ...
Страница 208: ...208 CHAPTER 25 PORT SECURITY CONFIGURATION ...
Страница 224: ...224 CHAPTER 27 DLDP CONFIGURATION ...
Страница 232: ...232 CHAPTER 28 MAC ADDRESS TABLE MANAGEMENT ...
Страница 240: ...240 CHAPTER 29 CENTRALIZED MAC ADDRESS AUTHENTICATION CONFIGURATION ...
Страница 280: ...280 CHAPTER 30 MSTP CONFIGURATION ...
Страница 348: ...348 CHAPTER 35 IS IS CONFIGURATION ...
Страница 408: ...408 CHAPTER 39 802 1X CONFIGURATION ...
Страница 412: ...412 CHAPTER 40 HABP CONFIGURATION ...
Страница 422: ...422 CHAPTER 41 MULTICAST OVERVIEW ...
Страница 426: ...426 CHAPTER 42 GMRP CONFIGURATION ...
Страница 480: ...480 CHAPTER 47 PIM CONFIGURATION ...
Страница 506: ...506 CHAPTER 48 MSDP CONFIGURATION ...
Страница 552: ...552 CHAPTER 51 TRAFFIC ACCOUNTING CONFIGURATION ...
Страница 570: ...570 CHAPTER 53 HA CONFIGURATION ...
Страница 582: ...582 CHAPTER 54 ARP CONFIGURATION SwitchA arp protective down recover interval 200 ...
Страница 622: ...622 CHAPTER 58 DHCP RELAY AGENT CONFIGURATION ...
Страница 684: ...684 CHAPTER 61 QOS CONFIGURATION ...
Страница 718: ...718 CHAPTER 63 CLUSTER ...
Страница 738: ...738 CHAPTER 67 UDP HELPER CONFIGURATION ...
Страница 752: ...752 CHAPTER 69 RMON CONFIGURATION ...
Страница 772: ...772 CHAPTER 70 NTP CONFIGURATION ...
Страница 796: ...796 CHAPTER 72 FILE SYSTEM MANAGEMENT ...
Страница 802: ...802 CHAPTER 73 BIMS CONFIGURATION ...
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Страница 830: ...830 CHAPTER 75 INFORMATION CENTER ...
Страница 836: ...836 CHAPTER 76 DNS CONFIGURATION ...
Страница 852: ...852 CHAPTER 77 BOOTROM AND HOST SOFTWARE LOADING ...
Страница 858: ...858 CHAPTER 78 BASIC SYSTEM CONFIGURATION DEBUGGING ...