EIGRP SRTT How is the value derived?

[deparkr1]

How is the value of SRTT derived for the "sh ip eigrp nei" command?

[Jon Marshall]

The SRTT is the time in milliseconds for a packet to be sent to a neigboring router and for the acknowledgement of that packet to come back to the local router.

Jon

[ruwhite]

It's computed using the round trip time (RTT) of the last acknowledge packet and the previous "smoothed round trip time).

srtt = (srtt * .8) + (rtt * .2)

So a single "out of whack" RTT doesn't really mess up the other timers reliant on it, which are the round trip timeout (RTO) and the multicast flow timer.

:-)

Russ