Which bit should be set in the link-state PDU of an IS-IS L1/L2 router to indicate that it is a potential
exit point of the area?
A.
the ABR bit
B.
the ATT bit
C.
the down bit
D.
the P bit
Which bit should be set in the link-state PDU of an IS-IS L1/L2 router to indicate that it is a potential exit point of the area?
Which bit should be set in the link-state PDU of an IS-IS L1/L2 router to indicate that it is a potential
exit point of the area?
Default routing is achieved in two distinct ways with Integrated IS-IS:
•
Attached bit—Set by a Level 1/Level 2 router in its own Level 1 LSP and used to indicate to all
Level 1 routers (within the area) that this router is a potential exit point of the area. Level 1-only
routers will default to the nearest attached Level 2 router.
•
Default information originate—Can be configured in Level 1 as well as Level 2. The default route
(0.0.0.0/0) is inserted in the router LSP (Level 1 or Level 2, according to the configuration
command) and the LSP is flooded according to the router type (Level 1 or Level 2). A Level 2
router doesn’t need to have a default route to originate a default route.
Reference.
http://www.cisco.com/en/US/products/ps6599/products_white_paper09186a00800a3e6f.shtml