
Configuring DHCP Relay Agent
617
However, if two equal-cost uplinks to the DHCP server exist, the packets from a
client may have different source IP addresses. As a result, some packets may fail to
pass the validity check.
Switch 7750 Ethernet switches supports specifying the source IP address of uplink
packets. With this feature enabled on the relay agent, the source IP address of a
client’s packet to be forwarded to the DHCP server is the IP address of the
receiving interface.
Configuring DHCP Relay
Agent Security
Functions
Configuring address checking
When a DHCP client obtains an IP address from a DHCP server through the DHCP
relay agent, the DHCP relay agent automatically generates the binding between
the client’s IP address, MAC address, VLAN ID, and port number. You can also
manually configure such bindings for clients on the DHCP relay agent.
The purpose of the address checking function on DHCP relay agent is to prevent
unauthorized users from statically configuring IP addresses to access external
networks. With this function enabled, a DHCP relay agent inhibits a user from
accessing external networks if the binding of the IP address, MAC address, VLAN
ID, and port number do not match any entries (including the entries dynamically
tracked by the DHCP relay agent and the manually configured static entries) in the
user address table on the DHCP relay agent.
Table 488
Specify the source IP address of uplink packets
Operation Command Description
Enter system view
system-view
-
Specify the source IP address of
packets on the DHCP relay
agent
dhcp relay source-ip
source-interface
Required
This feature is disabled
by default. That is, the
source IP address of the
packets sent to the
DHCP server is the IP
address of the relay
agent’s interface that
connects to the DHCP
server.
Table 489
Configure address checking
Operation Command Description
Enter system view
system-view
-
Configure a static user
address entry on the DHCP
relay agent
dhcp-security static
ip-address
mac
mac
-
address
[
vlan
vlan-id
|
port
interface-type
interface-number
]*
Optional
By default, no DHCP user
address entry is configured
Enter interface view
interface
interface-type
interface-number
-
Enable the address checking
function
address-check enable
Required
By default, the address
checking function is disabled
Summary of Contents for Switch 7754
Page 32: ...32 CHAPTER 1 CLI OVERVIEW ...
Page 70: ...70 CHAPTER 5 LOGGING IN USING MODEM ...
Page 76: ...76 CHAPTER 7 LOGGING IN THROUGH NMS ...
Page 86: ...86 CHAPTER 9 CONFIGURATION FILE MANAGEMENT ...
Page 120: ...120 CHAPTER 13 ISOLATE USER VLAN CONFIGURATION ...
Page 126: ...126 CHAPTER 14 SUPER VLAN ...
Page 136: ...136 CHAPTER 16 IP PERFORMANCE CONFIGURATION ...
Page 152: ...152 CHAPTER 17 IPX CONFIGURATION ...
Page 164: ...164 CHAPTER 19 QINQ CONFIGURATION ...
Page 172: ...172 CHAPTER 21 SHARED VLAN CONFIGURATION ...
Page 182: ...182 CHAPTER 22 PORT BASIC CONFIGURATION ...
Page 198: ...198 CHAPTER 24 PORT ISOLATION CONFIGURATION ...
Page 208: ...208 CHAPTER 25 PORT SECURITY CONFIGURATION ...
Page 224: ...224 CHAPTER 27 DLDP CONFIGURATION ...
Page 232: ...232 CHAPTER 28 MAC ADDRESS TABLE MANAGEMENT ...
Page 240: ...240 CHAPTER 29 CENTRALIZED MAC ADDRESS AUTHENTICATION CONFIGURATION ...
Page 280: ...280 CHAPTER 30 MSTP CONFIGURATION ...
Page 348: ...348 CHAPTER 35 IS IS CONFIGURATION ...
Page 408: ...408 CHAPTER 39 802 1X CONFIGURATION ...
Page 412: ...412 CHAPTER 40 HABP CONFIGURATION ...
Page 422: ...422 CHAPTER 41 MULTICAST OVERVIEW ...
Page 426: ...426 CHAPTER 42 GMRP CONFIGURATION ...
Page 480: ...480 CHAPTER 47 PIM CONFIGURATION ...
Page 506: ...506 CHAPTER 48 MSDP CONFIGURATION ...
Page 552: ...552 CHAPTER 51 TRAFFIC ACCOUNTING CONFIGURATION ...
Page 570: ...570 CHAPTER 53 HA CONFIGURATION ...
Page 582: ...582 CHAPTER 54 ARP CONFIGURATION SwitchA arp protective down recover interval 200 ...
Page 622: ...622 CHAPTER 58 DHCP RELAY AGENT CONFIGURATION ...
Page 684: ...684 CHAPTER 61 QOS CONFIGURATION ...
Page 718: ...718 CHAPTER 63 CLUSTER ...
Page 738: ...738 CHAPTER 67 UDP HELPER CONFIGURATION ...
Page 752: ...752 CHAPTER 69 RMON CONFIGURATION ...
Page 772: ...772 CHAPTER 70 NTP CONFIGURATION ...
Page 796: ...796 CHAPTER 72 FILE SYSTEM MANAGEMENT ...
Page 802: ...802 CHAPTER 73 BIMS CONFIGURATION ...
Page 814: ...814 CHAPTER 74 FTP AND TFTP CONFIGURATION ...
Page 830: ...830 CHAPTER 75 INFORMATION CENTER ...
Page 836: ...836 CHAPTER 76 DNS CONFIGURATION ...
Page 852: ...852 CHAPTER 77 BOOTROM AND HOST SOFTWARE LOADING ...
Page 858: ...858 CHAPTER 78 BASIC SYSTEM CONFIGURATION DEBUGGING ...