Excluding Ip Addresses From Address Pools; Interfaces; Configuring Dhcp Local Server - Juniper JUNOSE SOFTWARE 11.2.X - BROADBAND ACCESS CONFIGURATION GUIDE 7-20-2010 Configuration Manual

Excluding IP Addresses from Address Pools

Configuring DHCP Local Server to Support Creation of Dynamic Subscriber Interfaces
Copyright © 2010, Juniper Networks, Inc.
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.
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
NOTE: Limits that you specify on dynamic interfaces are not restored after a switchover
or reboot.
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 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
You can use the ip dhcp-local auto-configure agent-circuit-identifier command to
configure the DHCP local server to support the creation of dynamic subscriber interfaces
built over dynamic VLANs that are based on the agent-circuit-id option (suboption 1) of
the option 82 field in DHCP messages.
Use this command within a specific virtual router context.
Chapter 19: Configuring DHCP Local Server
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