HPE7-A01 Exam - Topic 5 Question 1 Discussion

Actual exam question for HP's HPE7-A01 exam

Question #: 1
Topic #: 5

A customer just upgraded aggregation layer switches and noticed traffic dropping for 120 seconds after the aggregation layer came online again. What is the best way to avoid having this traffic dropped given the topology below?

AConfigure the linkup delay timer to 240 seconds to double the amount of lime for the initial phase to sync

BConfigure the linkup delay timer to exclude LAGS 101 and 102, which will allow time for routing adjacencies to form and to learn upstream routes

CConfigure the linkup delay timer to include LAGs 101 and 102, which will allow time for routing adjacencies lo form and to learn upstream routes

DConfigure the linkup delay timer to 120 seconds, which will allow the right amount of time for the initial phase to sync

Show Suggested Answer

Suggested Answer: C

The reason is that the linkup delay timer is a feature that delays bringing downstream VSX links up, following a VSX device reboot or an ISL flap. The linkup delay timer has two phases: initial synchronization phase and link-up delay phase.

The initial synchronization phase is the download phase where the rebooted node learns all the LACP+MAC+ARP+STP database entries from its VSX peer through ISLP. The initial synchronization timer, which is not configurable, is the required time to download the database information from the peer.

The link-up delay phase is the duration for installing the downloaded entries to the ASIC, establishing router adjacencies with core nodes and learning upstream routes. The link-up delay timer default value is 180 seconds. Depending on the network size, ARP/routing tables size, you might be required to set the timer to a higher value (maximum 600 seconds).

When both VSX devices reboot, the link-up delay timer is not used.

Therefore, by configuring the linkup delay timer to include LAGs 101 and 102, which are part of the same VSX device as LAG 201, you can ensure that both devices have enough time to synchronize their databases and form routing adjacencies before bringing down their downstream links.

by Catarina at Oct 21, 2023, 02:20 PM

Limited Time Offer

25%

Off

Get Premium HPE7-A01 Questions as Interactive Web-Based Practice Test or PDF

Contribute your Thoughts:

Submit Cancel

Aliza

3 months ago

Definitely not option D, that won't solve the issue.

upvoted 0 times

...

Christiane

3 months ago

I’m surprised this is still a problem in modern setups!

upvoted 0 times

...

Anglea

3 months ago

Wait, why would you double the timer? That seems excessive.

upvoted 0 times

...

Jean

4 months ago

I think option B makes the most sense here.

upvoted 0 times

...

Amber

4 months ago

Sounds like a classic linkup delay issue.

upvoted 0 times

...

Alisha

4 months ago

I feel like including LAGs in the delay timer could be beneficial, but I’m not entirely confident about the specifics.

upvoted 0 times

...

Deja

4 months ago

I thought the linkup delay should be set to match the sync time, but I can't recall if 120 seconds is enough or if it should be longer.

upvoted 0 times

...

Jesus

4 months ago

This question feels similar to one we practiced where we had to manage LAGs. I think excluding them might help with routing adjacencies.

upvoted 0 times

...

Desmond

5 months ago

I remember something about linkup delay timers, but I'm not sure if increasing it is the right approach here.

upvoted 0 times

...

Leonora

5 months ago

I'm pretty confident that the right answer here is to configure the linkup delay timer to 120 seconds, which will allow the right amount of time for the initial phase to sync. This seems like the most straightforward and effective solution.

upvoted 0 times

...

Heidy

5 months ago

Based on the information provided, I think the best approach is to configure the linkup delay timer to include LAGs 101 and 102. This will allow time for routing adjacencies to form and to learn upstream routes, which should help prevent the traffic drop.

upvoted 0 times

...

Leonor

5 months ago

I'm a bit confused by this question. The topology seems complex, and I'm not sure I fully understand the implications of the different options. I might need to re-read the question and think it through more carefully.

upvoted 0 times

...

Venita

5 months ago

This question seems pretty straightforward. I think the best approach is to configure the linkup delay timer to exclude LAGs 101 and 102, which will allow time for routing adjacencies to form and to learn upstream routes.

upvoted 0 times

...

Raymon

5 months ago

Hmm, this is a tricky one. I'm leaning towards configuring the linkup delay timer to 240 seconds to double the amount of time for the initial phase to sync. That seems like it would give the system more time to stabilize and avoid the traffic drop.

upvoted 0 times

...

Azzie

5 months ago

Hmm, I'm a bit confused by all the different BGP attributes. I'll need to review my notes on the BGP decision process.

upvoted 0 times

...

Abraham

5 months ago

The MTU mismatch seems like the most obvious answer here. I'll double-check that first before considering the other options.

upvoted 0 times

...

Stefania

5 months ago

I thought SQL Server was part of it too, but now I'm not so confident.

upvoted 0 times

...

Rhea

5 months ago

This looks like a classic interview technique question. The key is making the suspect feel comfortable and not threatened, so the open door makes the most sense.

upvoted 0 times

...