3com MSR 20-20 참조 매뉴얼

level-1: Specifies to set the password for Level-1.

level-2: Specifies to set the password for Level-2.

ip: Specifies the system to check IP related fields in a LSP.

osi: Specifies the system to check OSI related fields in a LSP.

Whether a password should use ip or osi is not affected by the actual network 
environment.

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Use the isis authentication-mode command to set the IS-IS authentication 
mode and password for an interface.

Use the undo isis authentication-mode command to disable the 
authentication and remove the password.

There is no password or authentication by default.

If you set a password without specifying any other parameter, the password 
applies to both Level-1 and Level-2, and the system checks the OSI related fields in 
a LSP.

area-authentication-mode, domain-authentication-mode.

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The level-1 and level-2 keywords are supported only on an Ethernet or 
GigabitEthernet interface of a router. Before using the command with the 
keywords, you need use the isis enable command to enable IS-IS on the 
interface.

# Set the plain text password easykey for the Serial2/0 interface.

<Sysname> system-view

[Sysname] interface serial 2/0

[Sysname-Serial2/0] isis authentication-mode simple easykey 

isis circuit-level [ level-1 | level-1-2 | level-2 ]

Interface view

level-1: Specifies to set up only level-1 adjacency on the interface.

level-1-2: Specifies to set up level-1-2 adjacency on the interface.

level-2: Specifies to set up only level-2 adjacency on the interface.