Precedence Rules - Cisco ASR 900 Series Configuration Manual

Precedence Rules

• Dialer map lookup—This method is used only if the peer requests an IP address, no other peer IP address
• PPP EXEC command—An asynchronous dialup user can enter a peer IP address or hostname when PPP
• IPCP negotiation—If the peer presents a peer IP address during IPCP address negotiation and no other
• Default IP address.
• TACACS+ assigned IP address—During the authorization phase of IPCP address negotiation, TACACS+
• DHCP retrieved IP address—If configured, the routers acts as a proxy client for the dialup user and
• Local address pool—The local address pool contains a set of contiguous IP addresses (a maximum of
• Chat script (asynchronous serial interfaces only)—The IP address in the dialer map command entry
• Virtual terminal/protocol translation—The translate command can define the peer IP address for a virtual
• The pool configured for the interface is used, unless TACACS+ returns a pool name as part of
Precedence Rules
The following precedence rules of peer IP address support determine which address is used. Precedence is
listed from most likely to least likely:
1 AAA/TACACS+ provided address or addresses from the pool named by AAA/TACACS+
2 An address from a local IP address pool or DHCP (typically not allocated unless no other address exists)
3 Dialer map lookup address (not done unless no other address exists)
4 Address from an EXEC-level PPP command, or from a chat script
5 Configured address from the peer default ip address command or address from the protocol translate
command
6 Peer-provided address from IPCP negotiation (not accepted unless no other address exists)
Time Division Multiplexing Configuration Guide, Cisco IOS XE Fuji 16.7.x (Cisco ASR 900 Series)
110
has been assigned, and the interface is a member of a dialer group.
is invoked from the command line. The address is used for the current session and then discarded.
peer address is assigned, the presented address is acknowledged and used in the current session.
can return an IP address that the user being authenticated on a dialup interface can use. This address
overrides any default IP address and prevents pooling from taking place.
retrieves an IP address from a DHCP server. That address is returned to the DHCP server when the timer
expires or when the interface goes down.
1024 addresses) stored in two queues. The free queue contains addresses available to be assigned and
the used queue contains addresses that are in use. Addresses are stored to the free queue in first-in,
first-out (FIFO) order to minimize the chance the address will be reused, and to allow a peer to reconnect
using the same address that it used in the last connection. If the address is available, it is assigned; if
not, another address from the free queue is assigned.
that started the script is assigned to the interface and overrides any previously assigned peer IP address.
terminal (pseudo asynchronous interface).
authentication, authorization, and accounting (AAA). If no pool is associated with a given interface, the
global pool named default is used.
PPP and Multilink PPP Configuration