Exam JN0-663 topic 1 question 13 discussion

Remember metric is only "counted" on outbound interface. So when the path is R1 to R3, its 10+63(as 63 is max when 300 is set on the outbound interface towards R3 when wide metrics is not enabled). If the traffic came the other way from R3 to R1, it would actually be 10+10 = 20

A is correct: 10 + 63 -> 73

A is the correct 3.3.3.3/32 *[IS-IS/18] 00:00:20, metric 73 > to 10.1.0.2 via ge-0/0/0.0 Config R1 : root@vMX-1> show configuration protocols isis level 1 disable; interface ge-0/0/0.0; interface lo0.0 { level 1 passive; } Config R2 : root@vMX-2> show configuration protocols isis level 1 disable; interface ge-0/0/0.0; interface ge-0/0/1.0 { level 2 metric 300; } interface lo0.0 { passive; } config R3 : root@vMX-3> show configuration protocols isis level 1 disable; interface ge-0/0/1.0; interface lo0.0 { passive; }

"By default, Junos OS supports the sending and receiving of wide metrics. Junos OS allows a maximum metric value of 63 and generates both pairs of TLVs. To configure IS-IS to generate only the new pair of TLVs and thus to allow the wider range of metric values, you must include the wide-metrics-only statement in the IS-IS configuration." https://www.juniper.net/documentation/us/en/software/junos/is-is/topics/concept/isis-wide-metrics.html

I labbed it up and answer is 73, 63 (which is max port cost under narrow metrics) plus 10

Cost for R1 to reach R3, so the cost of the path will be the cost of ge-0/0/1.0 of R3 which is 10 and the cost of ge-0/0/0.0 of R2 which is also 10. So it must be 20.

Test it in lab environment and the answer is A. below R1> show isis route 172.16.56.0/24 2 44 73 int ge-0/0/1.0 IPV4 P3

10+63 - A

A 63 plus 10 as narrow is still active

I think answer should be 73 (10+63). Without wide metric enabled, TLV from R2 will advertise metric of 63 to R1.

Answer is 73 as both wide and narrow metrics enabled; router will only use narrow metric; 300 will become 63 when advertised in narrow.

Agree. A is correct

A is correct. Wide metric is not enabled, thus, the max cost of for metric 300 will be 63.

D is correct: Default IS-IS metric is 10, so 300 + 10 = 310 https://www.juniper.net/documentation/us/en/software/junos/is-is/topics/concept/isis-wide-metrics.html