Cisco Catalyst 4500 Series Software Configuration Guide

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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 59 Configuring the Cisco IOS DHCP Server
Configuration Examples for the Cisco IOS DHCP Server
!
Switch(config)# ip dhcp pool 2
Switch(dhcp-config)# network 172.16.2.0 /24
Switch(dhcp-config)# default-router 172.16.2.100 172.16.2.101
Switch(dhcp-config)# lease 30
Example: Configuring a DHCP Address Pool with Multiple Disjoint Subnets
Multiple disjoint subnets in a DHCP pool can be used in any of the following network topologies:
• IP address pooling—The DHCP client and server reside on the same subnet.
• DHCP relay—The DHCP client and DHCP server communicate through a DHCP relay agent where
the relay interface is configured with secondary IP addresses.
• Hierarchical DHCP—The DHCP server is configured as the DHCP subnet allocation server. The
DHCP client and DHCP subnet allocation server communicate through an on-demand address pool
(ODAP) router.
In the following example, one DHCP address pool named pool3 is created; the primary subnet is
172.16.0.0/16, one secondary subnet is 172.16.1.0/24, and the other secondary subnet is 172.16.2.0/24.
• When IP addresses in the primary subnet are exhausted, the DHCP server inspects the secondary
subnets in the order in which the subnets were added to the pool.
• When the DHCP server allocates an IP address from the secondary subnet 172.16.1.0/24, the server
uses the subnet-specific default device list that consists of IP addresses 172.16.1.100 and
172.16.1.101. However, when the DHCP server allocates an IP address from the subnet
172.16.2.0/24, the server uses the pool-wide list that consists of the four IP addresses from
172.16.0.100 to 172.16.0.103.
• Other attributes from the primary subnet 172.16.0.0/16—such as the domain name, DNS server,
NetBIOS name server, and NetBIOS node type—are inherited in both the secondary subnets.
• DHCP clients are granted 30-day leases on IP addresses in the pool. All addresses in each subnet,
except the excluded addresses, are available to the DHCP server for assigning to clients.
The table below lists the IP addresses for the devices in the DHCP address pool that consists of three
disjoint subnets.
Table 59-3 DHCP Address Pool Configuration
Primary Subnet
(172.16.0.0/16)
First Secondary
Subnet
(172.16.1.0/24)
Second Secondary
Subnet (172.16.2.0/24)
Device Type IP Address IP Address IP Address
Default Devices 172.16.0.100
172.16.0.101
172.16.0.102
172.16.0.103
172.16.1.100
172.16.1.101
172.16.0.100
172.16.0.101
172.16.0.102
172.16.0.103
DNS Server 172.16.1.102
172.16.2.102

Cisco Catalyst 4500 Series Specifications

General

Series	Catalyst 4500 Series
Category	Switch
Layer Support	Layer 2, Layer 3
Form Factor	Modular chassis
Stackable	No
Chassis Slots	3, 6, 7, 10
Power Supply Options	AC, DC
Redundancy	Power supply, Supervisor engine
Network Management	Cisco IOS Software CLI, SNMP, Cisco Prime Infrastructure
Features	Security, QoS
Port Density	Up to 384 ports per chassis
Security Features	802.1X, ACLs, DHCP Snooping, Dynamic ARP Inspection, IP Source Guard
Supervisor Engine	8-E