Juniper JUNOSE 11.1.X - BROADBAND ACCESS CONFIGURATION GUIDE 6-4-2010, Руководство по настройке

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host1(config-dhcp-local)# snmpTrap
host1(config-dhcp-local)# warning 50 40
13.
(Optional) Configure a grace period for address leases allocated from the current
DHCP local address pool. Specify the number of days and, optionally, the number
of hours, minutes, and seconds in the grace period.
host1(config-dhcp-local)# grace-period 0 12
This command applies only to address leases that expire. Use the
use-release-grace-period command to also apply the configured grace period
to the local pool addresses that are explicitly released by clients. See “Setting
Grace Periods for Address Leases” on page 486 for more information about grace
periods.
14.
(Optional) Specify that the grace period is applied to addresses that have been
explicitly released by clients. By default, the grace period is applied only to
address leases that expire, not to addresses that have been released. See “Setting
Grace Periods for Address Leases” on page 486 for more information about grace
periods.
host1(config-dhcp-local)# use-release-grace-period
Linking Local Address Pools
In both equal-access mode and standalone mode, you can link a DHCP local pool to
another local pool. The linked pool serves as a backup pool. If no addresses are
available in a pool, the DHCP local server attempts to allocate an address from the
linked pool. The address pools that are linked are viewed as a group.
Setting Grace Periods for Address Leases
The JUNOSe software enables you to configure a grace period for a particular local
address pool—the grace period is applied to all address leases associated with the
address pool. The grace period is the amount of time that a client continues to retain
its address lease after the lease expires or is released. An address cannot be assigned
to any other client during the grace period. When the grace period expires, the
address is released back to the address pool.
Grace periods help to ensure that a DHCP client retains its previously assigned IP
address in situations that might normally cause a lease termination followed by a
new address assignment. For example, if a client loses its lease due to a network
disruption, the grace period enables the client to be reassigned the same address
when the client requests an address after the network stabilizes. Grace periods are
also useful during client reboots and in cases where a non-compliant or unreliable
DHCP implementation triggers a lease renewal.
You configure a grace period for a local address pool. The grace period is immediately
applied to all addresses that are allocated from the pool, including previously allocated
addresses that are currently active—the new grace period takes precedence over a
previously configured grace period for the address pool.
486 ■
Linking Local Address Pools
JUNOSe 11.1.x Broadband Access Configuration Guide