Routes Advertised by OSPF Demo Policy
Question
-- Exhibit --
user@router> show route
inet.0: 9 destinations, 9 routes (9 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
10.10.10.91/32 *[Direct/0] 00:09:40
>via lo0.0
10.10.10.92/32 *[OSPF/10] 00:01:50, metric 1
>to 172.16.1.2 via ge-0/0/2.0
100.100.1.0/24 *[Static/5] 00:01:50
Reject -
172.16.1.0/24 *[Direct/0] 00:06:09
>via ge-0/0/2.0
172.16.1.1/32 *[Local/0] 00:06:09
Local via ge-0/0/2.0 -
192.168.0.0/16 *[Aggregate/130] 00:00:06
Reject -
192.168.0.0/17 *[Aggregate/130] 00:00:06
>to 172.16.1.2 via ge-0/0/2.0
192.168.50.0/24 *[Static/5] 00:00:06
>to 172.16.1.2 via ge-0/0/2.0
192.168.51.0/24 *[Static/5] 00:00:06
>to 172.16.1.2 via ge-0/0/2.0
user@router> show configuration policy-options
policy-statement demo {
term 1 {
from {
protocol aggregate;
route-filter 192.168.0.0/16 longer;
}
then accept;
}
}
user@router> show configuration protocols ospf
export demo;
area 0.0.0.0 {
interface ge-0/0/2.0;
}
-- Exhibit --
Given the configuration and routing table shown in the exhibit, which routes will be advertised to OSPF neighbors because of the demo policy?
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D.B
Based on the configuration and routing table provided in the exhibit, the demo policy is applied to the OSPF protocol and will determine which routes are advertised to OSPF neighbors.
The demo policy is defined with a single term 1, which includes a from statement specifying the protocol to match (aggregate) and a route-filter matching the 192.168.0.0/16 network with a longer prefix (which includes all subnets of the 192.168.0.0/16 network).
The then statement of the term is set to accept, which means that any route matching the criteria in the from statement will be accepted and advertised to OSPF neighbors.
Looking at the routing table, we see several routes that could potentially match the demo policy:
- 192.168.0.0/16 - This route matches the policy's route-filter criteria and will be accepted and advertised to OSPF neighbors.
- 192.168.0.0/17 - This route also matches the policy's route-filter criteria and will be accepted and advertised to OSPF neighbors.
- 192.168.50.0/24 - This route does not match the policy's route-filter criteria and will not be advertised to OSPF neighbors.
- 192.168.51.0/24 - This route does not match the policy's route-filter criteria and will not be advertised to OSPF neighbors.
Therefore, the correct answer is option C: 192.168.0.0/16 and 192.168.0.0/17 will be advertised to OSPF neighbors because they match the policy's criteria.
