System information

SIGNAMAX a.s.
Seat: Palackeho trida 38, 612 00 Brno, CZ l Office: Vlarska 22, P. O. Box 214, 658 14 Brno, CZ
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196
3-17-2. DHCP Snooping Entry
Function name:
DHCP Snooping Entry
Function description:
DHCP snooping Entry allows a switch to add the an trust DHCP server and 2 trust port
to build the DHCP snooping available entry. This information can be useful in tracking
an IP address back to a physical port and enable or disable the DHCP Option 82.
Fig. 3-17-1 DHCP Snooping State
Parameter description:
VID
：
When DHCP snooping is enabled, and enabled on the specified VLAN, DHCP
packet filtering will be performed on any un-trusted ports within the VLAN. It set
a available VLAN ID to enable the DHCP snooping on VLAN interface.
Trust Port 1
：
If DHCP snooping is enabled globally, and also enabled on the VLAN
where the DHCP packet is received, all DHCP packets are forwarded for a
trusted por. It set a trust port 1. available port from 0 to 24. 0 is disabled.
Trust port 2 : It set a trust port 2. available port from 0 to 24. 0 is disabled.
Trust VID： It set a trust VLAN ID. available VID from 1 to 4094.
Server IP： It set a trust DHCP Server IP address for DHCP Snooping.
Option 82：It set the DHCP Option 82 function on the switch, default is Disable.
Action：
It set the switch when received a client DHCP request packet then action for
filtering. available action : keep/ drop / replace.
Note
： Filtering rules are implemented as follows:
- If the DHCP snooping is disabled, all DHCP packets are forwarded.
- If DHCP snooping is enabled and also enabled on the VLAN where the DHCP
packet is received, all DHCP packets are forwarded for a trusted port.
- If DHCP snooping is enabled and also enabled on the VLAN where the DHCP
packet is received, but the port is not trusted, it is processed as follows:
* If the DHCP packet is a reply packet from a DHCP server, the packet is
dropped.
* If the DHCP packet is from a client, such as a DISCOVER, REQUEST INFORM,
DECLINE or RELEASE message, the packet is forwarded if MAC address
verification is disabled. However, if MAC address verification is enabled, then