UTStarcom UOA5280 Manual Do Utilizador

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36                                                                                                                      JadeOS User Manual   
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Security Check 
Through binding table, DHCP snooping module determine whether the DHCP mes-
sage sent by user is legal or not, and then reject illegal DHCP request if illegal. 
Enabling MAC address detection, DHCP snooping can avoid attack by checking 
whether the MAC address of DHCP protocol match with the source MAC address of 
Ethernet. 
To enable MAC address detection of DHCP snooping, use the following command in 
config mode:   
ip dhcp snooping verify mac-address enable 
Broadcast Suppression 
JadeOS can automatically record DHCP request information into DHCP snooping 
session table by enabling DHCP snooping. When received broadcast message from 
DHCP server, JadeOS can look up the corresponding host and exit port in the DHCP 
snooping table, then change the broadcast into unicast. Therefore, JadeOS achieves 
broadcast suppression. 
To configure the broadcast suppression in QinQ interface, use the following com-
mand: 
ip dhcp snooping enable 
 
To display the DHCP snooping session table, use the following command: 
show ip dhcp snooping session 
6.6.5 ARP With DHCP 
Enabling ARP with DHCP, DHCP will issue ARP table that combined distributed IP 
address and MAC address in client to the system, at the same time, disable the func-
tion of ARP learning in the specified interface. Therefore, ARP table is strictly 
checked by DHCP snooping, which ensures the legality and avoid the ARP cheat and 
interfere to the user online and communication. 
 
For example: 
¾  Enable ARP with DHCP function: 
Step 1    Configure update arp in address pool 
(JadeOS) (config)#ip dhcp pool ABC     
(JadeOS) (config-dhcp)#update arp   
Step 2  Configure ARP authorized in the interface of distributed IP, disable ARP 
learning function: 
  (JadeOS) (config)#interface vlan 6