# FD Calculation

#### Have a question or want to start a discussion? Post it! No Registration Necessary.  Now with pictures!

•  Subject
• Author
• Posted on
Many thanks to all those who respond.

OK here is the scenario; focus on network 222.222.222.0

router#sh ip eigrp top
IP-EIGRP Topology Table for AS(1)/ID(192.168.100.2)

Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status

P 192.168.100.0/24, 1 successors, FD is 1761792
via Connected, Serial0/1
P 172.16.31.0/24, 1 successors, FD is 2169856
via Connected, Serial0/0
P 172.16.0.0/16, 1 successors, FD is 2169856
via Summary (2169856/0), Null0
P 222.222.222.0/24, 1 successors, FD is 1761792
via 192.168.100.2 (1761792/28160), Serial0/1

-------------------------------

Router#sh ip eigrp top 222.222.222.0 255.255.255.0
IP-EIGRP topology entry for 222.222.222.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is
1761792
Routing Descriptor Blocks:
192.168.100.2 (Serial0/1), from 192.168.100.2, Send flag is 0x0
Composite metric is (1761792/28160), Route is Internal
Vector metric:
Minimum bandwidth is 2048 Kbit
Total delay is 20000 microseconds
Reliability is 255/255
Minimum MTU is 1

The FD is 1761792 the AD is a direct link into that network so this is

BW + Delay does NOT = the FD

10,000,000 / 2048 *256 = BW part of the metric

20000 * 256 = delay part of metric

well?
I've tried a few combinations but no luck reaching that figure.

Thanks

Re: FD Calculation
stropiter wrote:

Almost. remember where the metrics come from. They are eigrp metrics, scaled by
256. I am not 100% certain if the individual parts of the metric are scaled, or
if the final is scaled.

try again, using:

INT(10,000,000 / 2048) *256 = BW part of the metric

Item    Value    igrp    eigrp
Band    2048    4882    1249792
Delay    20000    2000    512000
Total        6882    1761792
--
Paul Matthews
paul@cattytown.me.uk
http://www.hepcats.co.uk