Q8Network Design
Company XYZ’s network requires OSPF dead-neighbor detection in a subsecond timeframe. However, the company network does not support BFD. Which alternative feature can fulfill this design requirement?
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Discussion · 10
A 3
Selected Answer: A
Loop Free Alternates (LFA) is a mechanism by which a neighbor can be used as a backup next hop to provide a local repair path for the traffic to flow temporarily in case of failures in the primary next hop (node or link).
DPD is a method used by devices to verify the current existence and availability of IPsec peers.
The OSPF Support for Fast Hello Packets feature provides a way to configure the sending of hello packets in intervals less than 1 second (sub second). Such a configuration results in faster convergence in an Open Shortest Path First (OSPF) network.
A 2
Selected Answer: A
fast hello
D 2
Selected Answer: D
Answer is D, guys focus on in a subsecond matter which is not supported by fast hello as the dead interval can't be changed to less than 1 sec, while LFA can switch to an alternative path within 50ms.
A 1
Selected Answer: A
A is correct
1
A is the correct answer - LFA more on the backup route
D 1
Selected Answer: D
Hello interval can be set to subsecond, but dead interval is one second minimum.
https://fredrikjj.wordpress.com/2014/05/17/ospf-timers-part-5/
A 1
Selected Answer: A
A - Without BFD, you would choose fast hellos, simple. The sub second dead timer requirement can't be met with the options available, and only A is valid. LFA is for re-convergence after a route loss, not to use instead of BFD or fast hellos.
A 1
Selected Answer: A
I think the answer is A.
OSPF's Fast Hello feature lets you quickly discover adjacent router status by shortening the interval between Hello packet transmissions. This cuts dead-neighbor detection time to the sub-second level and improves network convergence speed; it is a good solution for rapid detection without using BFD.
A 1
Selected Answer: A
LFA is not correct because it depends on something like BFD or fast hello to detect a dead neighbor. The question is a bit misleading, but still fast hello will detect a dead neighbor in under a second in most cases.
D 1
Selected Answer: D
question is asking for a subsecond event, fast hellos minimum second can't work within subsecond, LFA is the right answer.