Dhcp Snooping Binding Database - Cisco 300 Series Administration Manual

Managed switch

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IP Configuration

IPv4 Management and Interfaces

Cisco Small Business 200, 300 and 500 Series Managed Switch Administration Guide (Internal Version)

The following describes how DHCP reply packets are handled when both DHCP

Snooping and DHCP Relay are enabled

VLAN with IP Address

sent without

sent without

DHCP Snooping Binding Database

DHCP Snooping builds a database (known as the DHCP Snooping Binding

database) derived from information taken from DHCP packets entering the device

through trusted ports.

The DHCP Snooping Binding database contains the following data: input port,

input VLAN, MAC address of the client and IP address of the client if it exists.

VLAN without IP Address

arrives with

sent with the

sent without

sent without

sent without

Packet arrives with

1. If reply originates

on the device,

packet is sent

without Option 82

2. If reply does not

originate on the

device, discards the

Bridge – Packet is

sent with the

original Option 82

Packet is sent

without Option 82