Limiting The Number Of Ip Addresses Supplied By Dhcp Local Server; Excluding Ip Addresses From Address Pools - Juniper JUNOSE SOFTWARE 11.0.X - BROADBAND ACCESS CONFIGURATION GUIDE 4-1-2010 Configuration Manual

Limiting the Number of IP Addresses Supplied by DHCP Local Server

You can specify the maximum number of IP addresses that the DHCP local server
can supply to each VPI/VCI, VLAN, Ethernet subnetwork, or POS access interface
type, or to a particular interface or subinterface.
You can set global limits for a given interface type all interfaces of that type that
are subsequently created, whether dynamically or statically, inherit that limit value.
You can also set an individual interface limit for a specific interface and override the
global limit configured for that interface type. For example, suppose the VLAN
interface type limit is five. You can specify a limit of 10 for the VLAN interface
FastEthernet 1/0.100. All other VLAN interfaces retain the global limit of five.
The global limits for interface types and the individual interface limits set on static
interfaces are kept in NVS. These values are restored during a switchover or a reload.
When you assign an individual limit to a dynamic interface, that limit is in force only
until either a switchover or reload takes place. After the switchover or reload, if the
action that caused the dynamic interface to be created occurs again, a new dynamic
interface is created. The new dynamic interface then inherits the limit set by the
global values based on the type of interface that is created.
NOTE: Limits that you specify on dynamic interfaces are not restored after a
switchover or reboot.

Excluding IP Addresses from Address Pools

You can use the ip dhcp-local excluded-address command to specify IP addresses
that you do not want the DHCP local server to supply from the default address pool.
You might exclude addresses if because those addresses are already used by devices
on the subnetwork.
You can exclude a single IP address or a range of addresses. To exclude a range, you
specify the start-of-range IP address and the end-of-range IP address.
To set a global limit for an interface type:
host1(config)#ip dhcp-local limit ethernet 6
To set a limit for a specific interface:
host1(config)#ip dhcp-local limit interface atm 3/1 15
To exclude a specific IP address:
host1(config)#ip dhcp-local excluded-address 10.10.3.4
To exclude a range of IP addresses:
host1(config)#ip dhcp-local excluded-address 10.10.3.4 10.10.3.100
Limiting the Number of IP Addresses Supplied by DHCP Local Server
Chapter 19: Configuring DHCP Local Server
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