From: Ram Shummoogum (rshummoo@ca.ibm.com)
Date: Wed Feb 19 2003 - 16:19:11 GMT-3
Your sh int lo 0 wil probably have a bandwith of 8000000 kbit and a delay
of 5000 microsec
The formula is (10000000/8000000)=1.25
Cisco routers do not do floating point, therefore you should round down to
1.
Divide the delay by 10. i.e (5000/10) = 500
The magic number is (500 +1) * 256 = 128256
The second number within the parenthesis is the advertised distance and the
first one(FD) is equal to the AD + the metric to reach that next hop.
HTH
RAM
matijevi@bellsouth.net@groupstudy.com on 02/19/2003 11:18:46 AM
Please respond to matijevi@bellsouth.net
Sent by: nobody@groupstudy.com
To: <ccielab@groupstudy.com>
cc:
Subject: FD with EIGRP
I have enabled EIGRP on 2 routers placing a loopback and ethernet interface
only into the process.
r3#sh ip eigrp topology
IP-EIGRP Topology Table for AS(35)/ID(172.16.103.1)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 172.16.32.0/22, 1 successors, FD is 281600
via Connected, Ethernet0/0
P 172.16.105.0/24, 1 successors, FD is 409600
via 172.16.35.5 (409600/128256), Ethernet0/0
P 172.16.103.0/24, 1 successors, FD is 128256
via Connected, Loopback0
r5#sh ip eigrp topology
IP-EIGRP Topology Table for AS(35)/ID(172.16.35.5)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 172.16.32.0/22, 1 successors, FD is 281600
via Connected, Ethernet0
P 172.16.105.0/24, 1 successors, FD is 128256
via Connected, Loopback105
P 172.16.103.0/24, 1 successors, FD is 409600
via 172.16.35.3 (409600/128256), Ethernet0
How is the FD derived from the loopback on a local router, when that
loopback
is placed in EIGRP? The table shows FD is 128256. How is this number
derived?
Also, how is the other numbers derived? Finally I remeber reading in
Doyle's
book that the first number in parenthesis is the metric calculated by the
local router to the destination, and the second number in the partenthesis
is
the metric advertised by the neighbor, why is it using the loopback metric,
as
the advertised metric, is it because thats the lowest metric calculated by
the
dual algorithm?, I just want to know exactly how these numbers are
calculated
if I have a 10mb connection between R3 and R5?
Sincerely,
John
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