IP Configuration
IPv4 Management and Interfaces
Cisco 350, 350X and 550X Series Managed Switches, Firmware Release 2.4, ver 0.4
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The following describes how DHCP request packets are handled when both DHCP Snooping
and DHCP Relay are enabled:
The following describes how DHCP Reply packets are handled when DHCP Snooping is
disabled:
DHCP Relay
VLAN with IP Address
DHCP Relay
VLAN without IP Address
Packet arrives
without Option 82
Packet arrives
with Option 82
Packet arrives
without Option
82
Packet arrives
with Option 82
Option 82
Insertion
Disabled
Packet is sent
without Option 82
Packet is sent
with the
original Option
82
Relay – inserts
Option 82
Bridge – no
Option 82 is
inserted
Relay – discards
the packet
Bridge – Packet
is sent with the
original Option
82
Option 82
Insertion
Enabled
Relay – is sent
with Option 82
Bridge – Option
82 is added
(if port is trusted,
behaves as if
DHCP Snooping is
not enabled)
Packet is sent
with the
original Option
82
Relay – is sent
with Option 82
Bridge – Option
82 is inserted
(if port is
trusted, behaves
as if DHCP
Snooping is not
enabled)
Relay –discards
the packet
Bridge – Packet
is sent with the
original Option
82
DHCP Relay
VLAN with IP Address
DHCP Relay
VLAN without IP Address
Packet arrives
without Option
82
Packet arrives
with Option 82
Packet arrives
without Option
82
Packet arrives
with Option 82