Hi!!
I Got Learn something new today in EIGRP troubleshooting it's BFD-Bidirectional Forward Detection. it is protocol that design by cisco based of IETF.

This detection accomplish via Hardware detection mechanism, signal from mechanism are not always conveyed direct upper layer protocols.

Protocol detection failure is slower, Usually timer more than one minute. but BFD detect failure rapidly and of course maintain low overhead on link.

BFD- (transmit Interval) * ( detect multiplier) = Detect Timer

Where,
Interval:- Determine how frequency (milliseconds) BFD packet sent.

Min_RX:- Determine how frequency (milliseconds)BFD packet received from neighbors.

Multiplier :- The number of consecutive BFD packet which are missed from BFD peers before declaring dead or informing higher level protocol for failure.

********Configuration********
!
[no] bfd interval <50-999> min_rx <1-999> multiplier <3-50>
!
router eigrp 123
bfd all-interface

or
!
router eigrp 123
bfd interface serial 1/0
!
show bfd neighbor [details]
!

Thank you,
Regards,
Jignesh