Reference Guide
command in ROUTER ISIS mode. To view the current IPv6 IS-IS configuration, use the show config command in
ROUTER ISIS-ADDRESS FAMILY IPV6 mode.
Configuring Authentication Passwords
You can assign an authentication password for routers in Level 1 and for routers in Level 2.
Because Level 1 and Level 2 routers do not communicate with each other, you can assign different passwords for Level
1 routers and for Level 2 routers. However, if you want the routers in the level to communicate with each other,
configure them with the same password.
To configure a simple text password, use the following commands.
• Configure authentication password for an area.
ROUTER ISIS mode
area-password [hmac-md5] password
FTOS supports HMAC-MD5 authentication.
This password is inserted in Level 1 LSPs, Complete SNPs, and Partial SNPs.
• Set the authentication password for a routing domain.
ROUTER ISIS mode
domain-password [encryption-type | hmac-md5] password
FTOS supports both DES and HMAC-MD5 authentication methods.
This password is inserted in Level 2 LSPs, Complete SNPs, and Partial SNPs.
To view the passwords, use the show config command in ROUTER ISIS mode or the show running-config
isis command in EXEC Privilege mode.
To remove a password, use either the no area-password or no domain-password commands in ROUTER ISIS
mode.
Setting the Overload Bit
Another use for the overload bit is to prevent other routers from using this router as an intermediate hop in their shortest
path first (SPF) calculations. For example, if the IS-IS routing database is out of memory and cannot accept new LSPs,
FTOS sets the overload bit and IS-IS traffic continues to transit the system.
To set or remove the overload bit manually, use the following commands.
• Set the overload bit in LSPs.
ROUTER ISIS mode
set-overload-bit
This setting prevents other routers from using it as an intermediate hop in their shortest path first (SPF) calculations.
• Remove the overload bit.
ROUTER ISIS mode
no set-overload-bit
When the bit is set, a 1 is placed in the
OL
column in the show isis database command output. The overload bit is
set in both the Level-1 and Level-2 database because the IS type for the router is Level-1-2.
Example of Viewing the Overload Bit Setting
FTOS#show isis database
IS-IS Level-1 Link State Database
LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/
OL
453