Alcatel Carrier Internetworking Solutions Switch/Router 사용자 설명서

Page 12-39

It is possible to place restriction flags on specific 

NTP

 entities in relation to the switch. Restric-

tion flags prevent messages or information coming from the 

NTP

 entity from affecting the 

switch.

To create a restriction flag, enter the 

 command as shown:

where 

 is the 

IP

 address of the 

NTP

 entity, 

 is the entity’s subnet mask, and 

 is the specific flag you want to place on the entity. For example to put an 

 

restriction on an entity with address 1.1.1.1 and a subnet mask of 255.255.0.0, enter the 
following:

The following is a list of possible restriction flags that can be used:

Ignore all packets from hosts which match this entry. If this flag 
is specified neither queries nor time server polls will be 
responded to

.

Ignore all 

NTP

 information queries and configuration requests 

from the source. Time service is not affected. 

Ignore all 

NTP

 information queries and configuration requests 

that attempt to modify the state of the server (i.e., run time 
reconfiguration). Queries which return information are permit-
ted. 

Decline to provide control message trap service to matching 
hosts. The trap service is a subsystem of the control message 
protocol which is intended for use by remote event logging 
programs. 

Declare traps set by matching hosts to be low priority. The 
number of traps a server can maintain is limited (the current 
limit is 3). Traps are usually assigned on a first come, first serve 
basis, with later trap requestors being denied service. This flag 
modifies the assignment algorithm by allowing low priority 
traps to be overridden by later requests for normal priority 
traps. For more information on setting traps see Configure a 
Trap in the Server on page 12-41

Ignore 

NTP

 packets other than information queries and configu-

ration requests. In effect, time service is denied, though queries 
may still be permitted. 

Provide stateless time service to polling hosts, but do not allo-
cate peer memory resources to these hosts even if they other-
wise might be considered useful as future synchronization 
partners. 

Treat these hosts normally in other respects, but never use 
them as synchronization sources.