From: Brent D. Stewart (brent@stewart.hickory.nc.us)
Date: Wed May 28 2003 - 17:37:02 GMT-3
No. For an excellent discussion of this, refer to Alvaro Retana's book
"EIGRP for IP".
EIGRP builds a metric using the equation:
Metric= (k1*bw + k2*bw/(256-load) + k3*delay) (k5/(reliability+k4)
By default, k1=1, k2=0, k3=1, k4=0, k5=0 and k2, k4, and k5 really
shouldn't ever be changed. K1 and k3 are very seldom changed. If k5=0,
the last part is ignored, so this reduces to:
Metric= bw + delay
Each of these deserves a discussion.
"bw" is actually 10^7/min(bw). In other words, the bw part uses the
slowest link along the path and is inversely proportional to 1 million.
"delay" is an accumulation of all interface delays along the path.
Load and reliability should not be included in the calculation (by
changing k values) because EIGRP does not send out updates if they
change. MTU isn't even an option, but the idea was that it might be
used for minimum MTU discovery along a path. As far as I know, this was
never implemented.
EIGRP actually also tracks hops. The default max is 100. EIGRP doesn't
use this in the metric, it's there as a loop-detection mechanism.
Regards,
Brent D. Stewart
-----Original Message-----
From: Danny.Andaluz@triaton-na.com [mailto:Danny.Andaluz@triaton-na.com]
Sent: Wednesday, May 28, 2003 2:41 PM
To: ccielab@groupstudy.com
Subject: EIGRP metric (just to be sure)
Hello, Group. Is the below correct with regards to how eigrp picks a
best
route? Does it do it like the below or does each value get taken into
account for the composite metric?
BW
Delay (in case of tie with BW) ?
relia (in case of tie with delay) ?
load (in case of tie with relia) ?
MTU (in case of tie with load) ?
Thanks,
Danny
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