Juniper JUNOSE 11.0.X MULTICAST ROUTING, Руководство по настройке

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Local Address Pool Aliases
An alias is an alternate name for an existing local address pool. It comprises an alias
name and a pool name.
When the AAA server requests an IP address from a specific local address pool, the
local address server first verifies whether an alias exists for the requested pool. If an
alias exists, the IP address is allocated from the pool specified by the alias. If no alias
exists, the IP address is allocated from the pool originally specified in the request.
The use of aliases simplifies management of subscribers. For example, you can use
an alias to migrate subscribers from one local address pool to another. Instead of
having to modify countless subscriber records on the AAA server, you create an alias
to make the configuration change.
Shared Local Address Pools
Typically, the local address server allocates IP addresses from a pool of addresses
that is stored locally on the router. However,
shared local address pools enable a local
address server to hand out addresses that are allocated from DHCP local server
address pools within the same virtual router. The addresses are configured and
managed within DHCP. Therefore, thresholds are not configured on the shared pool,
but are instead managed by the referenced DHCP local server pool.
A shared local address pool references one DHCP address pool. The shared local
address pool can then obtain addresses from the referenced DHCP address pool and
from any DHCP address pools that are linked to the referenced DHCP address pool.
Figure 2 on page 55 illustrates a shared local address pool environment that includes
four linked DHCP address pools. In the figure, both Shared_LAS_Pool_A and
Shared_LAS_Pool_B reference DHCP_Pool_1, and can therefore obtain addresses
from all four DHCP address pools. Shared_LAS_Pool_C references DHCP_Pool_3 and
can get addresses from DHCP_Pool_3 and DHCP_Pool_4.
Figure 2: Shared Local Address Pools
When the local address server requests an address from a shared address pool, the
address is returned from the referenced DHCP pool or a subsequent linked pool. If
no address is available, DHCP notifies the local address server and the search is
ended.
Keep the following guidelines in mind when using shared local address pools:
Configuring Local Address Servers
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Chapter 1: Configuring Remote Access