EIGRP - cbtv3 VID 39 ​- basic concept

Question 1

EIGRP neighbour packets are ?

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Answer 1

hello : forms relationship
Updates : sends updates
Query : ask about routes
Reply : response to a query
Ack : acknowledged the above - update, query, and reply messages
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Question 2

During EIGRP neighbor relationship messages the routers first send message to ?

Answer 2

multicast address : 224.0.0.10
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The reply message will be via unicast : specific up add of the original sender of multicast message sender
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Question 3

Neighbor relationship forms by matching ?

Answer 3

-Autonomous system number
-k values (composite metric)
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Question 4

After routes are exchanged the routers both go back to taking in ?
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Answer 4

After routes are exchanged the routers both go back to talking to each other via multicast.
They will only switch back to unicast if the have a route update
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Question 5

what is a the EIGRP Metric
and how many in the list ?
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Answer 5

1-Bandwidth (k1)
2-Delays (k3) - how long it take to get across the link
3-reliability (k4 and k5) - if the links has been flapping a lot
4-Load how much actual traffic is being used across the link, if the load has now effected the speed. Different to bandwidth (k2)
5-MTU -maximum transmission unit: how large packet is sent across
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Question 6

In the Eigrp Metric list.
Which ones are set statically,
which ones are set dynamically

Answer 6

Bandwidth & delays ( static config )

Reliability, load, MTU ( dynamic )

Because the 3 are dynamic they don’t trigger EIGRP to re-calculate the routes. Example the load changes all the time on a links this would be to processor intensive if Eigrp always re-calculated routes based on this.
(they can be set but it isn’t recommended)
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Question 7

Hello timer on EIGRP is ?

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Answer 7

1 in every 5 sec (ppp, Ethernet, all)
1 in every 60 for NBMA (WAN)
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Question 8

Default dead timer on EiGRP is?

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Answer 8

3 x the hello timer

5x3 = 15 - All network types
60x3 = 180 - NBMA
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Question 9

if router B sets to :
hello - 1 sec
Dead - 3 sec
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Does router A timer change too ?

Answer 9

No Router A hello message dont change, the stay as they were.

But Router A will consider B dead if it does not hear from B in 3 secs.
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