Which two statements are true about route leaking in a Level 1-Level 2 network environment? (Choose two.)
A.
Level 1 internal routes can be leaked into Level 2, but require a policy.
B.
Level 1 external routes are leaked into Level 2 without a policy if the wide-metrics parameter is configured.
C.
Level 2 internal routes can be leaked into Level 1, but require a policy.
D.
Level 2 external routes are leaked into Level 1 without a policy if the wide-metrics parameter is configured.
Explanation:
B: Normally, IS-IS metrics can have values up to 63. The total cost to a destination is the sum of the metrics on
all outgoing interfaces along a particular path from the source to the destination. By default, the total path metric
is limited to 1023. This metric value is insufficient for large networks and provides too little granularity for traffic
engineering, especially with high-bandwidth links. A wider range of metrics is also required if route leaking is
used.
C: By default, IS-IS protocol leaks routing information from a Level 1 area to a Level 2 area. However, to leak
routing information from a Level 2 area to a Level 1 area, an export policy must be explicitly configured.
https://www.juniper.net/techpubs/en_US/junos16.1/topics/example/example-configuring-is-isroute-leaking-L2-to-L1.html
http://www.juniper.net/documentation/en_US/junos14.1/topics/topic-map/isis-wide-metrics.html