ignore-attached-bit
Syntax
ignore-attached-bit;
Hierarchy Level
[edit logical-systems logical-system-name protocols isis], [edit logical-systems logical-system-name routing-instances routing-instance-name protocols isis], [edit protocols isis], [edit routing-instances routing-instance-name protocols isis]
Description
Ignore the attached bit on IS-IS Level 1 routers. Configuring this statement enables the routing device to ignore the attached bit on incoming Level 1 link-state PDUs. If the attached bit is ignored, no default route, which points to the routing device which has set the attached bit, is installed.
There might be times, such as during a denial-of-service (DoS) attack, that you do not want a Level 1 router to be able to forward traffic based on a default route.
To prevent a routing device from being able to reach interarea
destinations, you can prevent the routing device from installing the
default route without affecting the status of its IS-IS adjacencies.
The ignore-attached-bit statement is used to tell the routing
device to ignore the presence of the attached bit in Level 1 link-state
PDUs, which blocks the installation of the IS-IS default route.
Default
The ignore-attached-bit statement is disabled
by default.
Required Privilege Level
routing—To view this statement in the configuration.
routing-control—To add this statement to the configuration.
Release Information
Statement introduced before Junos OS Release 7.4.