08-11-2009 08:23 AM - edited 03-06-2019 07:12 AM
Hi every body.
According to my book, eigrp uses following formula for metric calculation by default( only bandwidth and delay).
m= { (10 exp 7/bandwidth) *delay}*256
Let say router receives two updates about a network 10.0.0.0.
First update list delay 200 micro seconds
minimum bandwidth along the path 10G
Second update
delay 200 u sec
miminmum bandwidth 1G
router takes first updates then calculates the delay 10 micro seconds unit 1.e 200/10= 20
router then find the reported bandwidth is less than the one configured on the int, the update was received.
Router use theabove fomula plugging the values as:
M ={(10exp 7/10 exp 9)*20}*256
According to my book, the ( 10exp 7/10 exp 9) will be rounded down to closer interger. With this mind , would the router calculate and find the same metric value for two updates ?
Thanks a lot.
Solved! Go to Solution.
08-11-2009 09:10 AM
The router also rounds to the closer integer, it should be the same value.
08-11-2009 09:23 AM
Hi Sarah,
The formula is:
metric = (10exp7/Bandwidth + SumofDelays/10)*256
Where Bandwidth is in kbps, SumofDelays is in microseconds and is the total delay along the path.
According to your data:
1st update:
(10exp7/10000000 (kbps) + 200/10)*256 = 5376
2nd update:
(10exp7/1000000 (kbps) + 200/10)*256 = 7680
The integer is calculated when the 10exp7/bandwidth calculation is done.
For example:
bandwidth=512 kbps
delay 200 microseconds
(10exp7/512(kbps) + 200/10) = (19531 + 20)*256 = 5005056.
Cheers:
Istvan
08-11-2009 09:10 AM
The router also rounds to the closer integer, it should be the same value.
08-11-2009 09:23 AM
Hi Sarah,
The formula is:
metric = (10exp7/Bandwidth + SumofDelays/10)*256
Where Bandwidth is in kbps, SumofDelays is in microseconds and is the total delay along the path.
According to your data:
1st update:
(10exp7/10000000 (kbps) + 200/10)*256 = 5376
2nd update:
(10exp7/1000000 (kbps) + 200/10)*256 = 7680
The integer is calculated when the 10exp7/bandwidth calculation is done.
For example:
bandwidth=512 kbps
delay 200 microseconds
(10exp7/512(kbps) + 200/10) = (19531 + 20)*256 = 5005056.
Cheers:
Istvan
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