0 - OSPF QCM - Noah Van Horenbeke - TFE

This QCM will help you understand the next exercises by ensuring you understand the specific characteristics of OSPFv3.

Documentation:

FRRouting OSPFv3: https://docs.frrouting.org/en/latest/ospf6d.html
RFC 5340 (OSPF for IPv6): https://datatracker.ietf.org/doc/rfc5340/
Cisco : OSPF MTU mismatch behaviour: https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/119384-technote-ospf-00.html

Paste this command into your terminal:

The password to connect is

Please answer to all the questions. Interner Fehler {} has not a valid extension. {} is too heavy.

Question 1: Passive interface

In FRRouting, what is the effect of marking an OSPFv3 interface as passive?

Drops all OSPFv3 packets received

Disables OSPFv3 on the interface entirely

The router stops sending Hellos on that interface

Question 2: Cost and path selection

R1 has two possible paths to reach the prefix announced by R5:

via R2, with a total cost of 20
via R3, with a total cost of 30

Which next-hop(s) will R1 install in its routing table for that prefix?

R1 only

Neither

Both R2 and R3, with ECMP load balancing

R2 only

Question 3: What is the MTU?

What does the MTU represent?

The Hello interval used to maintain adjacencies

The metric used by SPF to compute the shortest path

The maximum number of OSPF neighbors allowed on each node's interface within a single area

The maximum size (in bytes) of an IP packet the interface can transmit without fragmentation

Question 4: Stuck in ExStart

Two OSPFv3 neighbors remain stuck in ExStart/Exchange and never reach Full. What is the most likely cause?

MTU mismatch on the link

Different OSPF areas

One side is passive

Duplicate router-id

Question 5: MTU mismatch symptom

Two OSPFv3 routers on the same link have different interface MTUs.

What do you observe?

(See the Cisco note linked above for details on this behaviour.)

Hellos are never exchanged

Neighbor stuck in ExStart/Exchange

Adjacency reaches Full but routes are missing

Adjacency flaps every dead interval

Author(s)	Noah Van Horenbeke
Deadline	Keine Frist
Abgabenlimit	No limitation

Information

Einloggen

0 - OSPF QCM

Question 1: Passive interface

Question 2: Cost and path selection

Question 3: What is the MTU?

Question 4: Stuck in ExStart

Question 5: MTU mismatch symptom

Information

Einloggen

0 - OSPF QCM Collapse context

Question 1: Passive interface

Question 2: Cost and path selection

Question 3: What is the MTU?

Question 4: Stuck in ExStart

Question 5: MTU mismatch symptom

0 - OSPF QCM