Which two elements comprise the backbone area while designing a new network utilizing IS-IS as the interior gateway protocol (choose two)

The correct answer is A. contiguous chain of Level 2 capable routers B. contiguous chain of Level1/Level 2 capable routers. "Backbone IS-IS does not have a backbone area like the OSPF area 0. The IS-IS backbone is a contiguous collection of Level 2-capable routers, each of which can be in a different area" "In most designs with routing hierarchy, the Level 2 routers are also Level 1 routers by…

Advanced Addressing and Routing Solutions

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Options

Acontiguous chain of Level 2 capable routers
Bcontiguous chain of Level1/Level 2 capable routers
Cset of Level 2 configured interfaces
Dcontiguous Level 1 capable routers
Eset of Level 1 configured interfaces

How the community answered

(17 responses)

A
76% (13)
C
6% (1)
D
6% (1)
E
12% (2)

Explanation

"Backbone IS-IS does not have a backbone area like the OSPF area 0. The IS-IS backbone is a contiguous collection of Level 2-capable routers, each of which can be in a different area" "In most designs with routing hierarchy, the Level 2 routers are also Level 1 routers by virtue of identification with a certain area. Therefore, in IS-IS, a router can function as Level 1-only or Level 2-only and possibly as both Level 1 and Level 2 (Level 1-2). Level 1-2 routers act as border routers to their respective areas, providing connectivity to other areas. The Level 2 backbone is essentially a virtual IS-IS area consisting of routers engaged in Level 2 routing"

Topics

#IS-IS#Level 2 routers#backbone area#IGP design

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