Cisco IE-3000-8TC User Manual

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Cisco IE 3000 Switch Software Configuration Guide
OL-13018-03
Chapter 23 Configuring DHCP Features and IP Source Guard
Configuring DHCP Server Port-Based Address Allocation
When configured, the DHCP server port-based address allocation feature ensures that the same IP
address is always offered to the same connected port even as the client identifier or client hardware
address changes in the DHCP messages received on that port. The DHCP protocol recognizes DHCP
clients by the client identifier option in the DHCP packet. Clients that do not include the client identifier
option are identified by the client hardware address. When you configure this feature, the port name of
the interface overrides the client identifier or hardware address and the actual point of connection, the
switch port, becomes the client identifier.
In all cases, by connecting the Ethernet cable to the same port, the same IP address is allocated through
DHCP to the attached device.
The DHCP server port-based address allocation feature is only supported on a Cisco IOS DHCP server
and not a third-party server.
Configuring DHCP Server Port-Based Address Allocation
This section contains this configuration information:
• Default Port-Based Address Allocation Configuration, page 23-16
• Port-Based Address Allocation Configuration Guidelines, page 23-16
• Enabling DHCP Server Port-Based Address Allocation, page 23-17
Default Port-Based Address Allocation Configuration
By default, DHCP server port-based address allocation is disabled.
Port-Based Address Allocation Configuration Guidelines
These are the configuration guidelines for DHCP port-based address allocation:
• Only one IP address can be assigned per port.
• Reserved addresses (preassigned) cannot be cleared by using the clear ip dhcp binding global
configuration command.
• Preassigned addresses are automatically excluded from normal dynamic IP address assignment.
Preassigned addresses cannot be used in host pools, but there can be multiple preassigned addresses
per DHCP address pool.

Cisco IE-3000-8TC Specifications

General

Switching Capacity	16 Gbps
MAC Address Table Size	8000
Uplink Ports	2 x 10/100/1000Base-T or SFP (Small Form-Factor Pluggable)
Operating Temperature	-40°C to 70°C
Mounting	DIN rail
Ports	8 x Ethernet 10/100Base-TX ports
Jumbo Frame Support	Yes