4A0-112: Nokia IS-IS Routing ProtocolDemo

By Nokia · Question Mode

QuestionQ4

SR OS Control Plane Security

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In the diagram, all routers use IS-IS as the routing protocol. The number beside each link represents its metric value.

What path will traffic take from router R6 to router R3, and from router R3 to router R6?

  • A Router R6 to router R3 will follow (R6-R5-R2-R3). Router R3 to router R6 will follow (R3-R2-R5-R6).
  • B Router R6 to router R3 will follow (R6-R5-R2-R3). Router R3 to router R6 will follow (R3-R4-R2-R5-R6).
  • C Router R6 to router R3 will follow (R6-R5-R2-R3). Router R3 to router R6 will follow (R3-R4-R7-R5-R6).
  • D Router R6 to router R3 will follow (R6-R5-R7-R4-R3). Router R3 to router R6 will follow (R3-R4-R7-R5-R6).
Explanation

A Level 1 router forwards traffic destined outside its area to the nearest attached L1/L2 router. R6 therefore sends traffic through R5; R5 reaches R3 most efficiently through R2, for R6-R5-R2-R3. R3 selects R4 as its nearest L1/L2 router, and R4’s lowest-metric Level 2 path toward R5 is through R7, producing R3-R4-R7-R5-R6. Juniper IS-IS Overview

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