-- Exhibit --
user@R2> show
protocols {
isis {
export leak;
interface ge-1/1/0.0;
interface ge-1/1/1.0 {
level 1 disable;
}
interface lo0.0;
}
}
policy-options {
policy-statement leak {
term 1 {
from level 1;
to level 2;
then accept;
}
}
}
-- Exhibit --
Click the Exhibit button.
R1 and R2 have a Level 1 IS-IS adjacency. R2 participates in both Level 1 and Level 2, and is receiving routes from a Level 2 neighbor. A policy on R2 has been created to leak routes to Level 1, but R1 is not receiving the routes.
Referring to the exhibit, what is the solution on R2?
Click on the arrows to vote for the correct answer
A. B. C. D.C
The exhibit shows a portion of the configuration for two routers, R1 and R2, that are using the IS-IS routing protocol. R2 is participating in both Level 1 and Level 2 of the IS-IS hierarchy, and has a policy configured to leak Level 2 routes to Level 1. However, R1 is not receiving these routes, indicating that there is an issue with the policy configuration on R2.
To solve this issue, we need to examine the policy configuration in more detail. The policy statement "leak" is defined in the "policy-options" section of the configuration. It has a single term that matches routes from Level 1 and to Level 2, and then accepts those routes. This is the correct policy configuration to leak Level 2 routes into Level 1.
However, the problem may be that the policy is not being applied correctly. There are two options for applying a policy in IS-IS: as an export policy or as an import policy. Export policies are applied to routes leaving a router, while import policies are applied to routes entering a router.
Option A suggests that the policy should be applied as an export policy at the interface level. This means that the policy would be applied to routes leaving the interface specified in the IS-IS configuration. In this case, the policy is named "leak" and is configured to match Level 1 routes and accept them if they are going to Level 2. If this option is correct, we would need to apply the policy as an export policy on the interface ge-1/1/0.0, since this is the interface that is participating in Level 1 IS-IS.
Option B suggests that the policy should be changed to include "from protocol isis". This option is not correct, as the "from protocol isis" statement is not necessary in this case. The policy is already correctly matching routes from IS-IS, as indicated by the "from level 1" statement.
Option C suggests that the policy should be changed to specify "from level 2 and to level 1". This option is not correct, as the policy is already correctly configured to match Level 1 routes and accept them if they are going to Level 2.
Option D suggests that the policy should be applied as an import policy. This option is not correct, as the policy is designed to leak routes from Level 2 to Level 1. Import policies are used to filter incoming routes, and would not be appropriate for this scenario.
Therefore, the correct solution to the problem is option A: the policy must be applied as an export policy at the interface level. This will ensure that Level 2 routes are correctly leaked into Level 1, and that R1 will be able to receive those routes.