RE: EIGRP metric calculation demystified

From: Bit Gossip (bit.gossip@chello.nl)
Date: Sun Aug 12 2007 - 10:57:18 ART


On my opinion there is a mistake in the metric explanation from this link:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cr/hirp_r/
rte_eih.htm#wp1000111

Where it says: "Delay is in units of 10 microseconds"
should be something like that: Delay Eigrp = "Sum of all delay accross the
path SCALED BY 256"

Forgetting to multiply it by 256 leads to a wrong calculation. I have verified
instead that if I scale the delay I get exactly the same number shown in 'show
ip eigrp topology'

Thanks,
Bit.

-----Original Message-----
From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx] On Behalf Of
Gregory Gombas
Sent: Monday, August 06, 2007 7:10 PM
To: Group study
Subject: EIGRP metric calculation demystified

Cisco documentation shows the EIGRP metric calculation as this:
metric = [K1*bandwidth + (K2*bandwidth)/(256 - load) + K3*delay] *
[K5/(reliability + K4)]

Popular literature says it breaks down to this:
256(BW + Delay)

In reality the calculation is this:
256((10,000,000/BW)) + (Delay/10))

Does anyone know if this final formula can be found on the DOC cd?

The closes match I could find was on WARP:
http://www.cisco.com/warp/public/103/3.html

But can this handy formula be accessed from the lab? Its kind of a
pain to memorize.

Regards,
Greg



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