02-26-2004 12:42 PM - edited 03-02-2019 01:53 PM
hi
What will my variance be in this case. I set it to 2 but don't eigrp load balancing across unequal paths
here is the scenario. I have two routers at the lab. Each has two 64K serial links. One serial link is directly connected to the second router. The second serial link is connected via a satellite provider.
Routing Descriptor Blocks:
xx.xx.xx.xx (Serial0/0.1), from x.x.x.x, Send flag is 0x0
Composite metric is (40515072/28672), Route is Internal
Vector metric:
Minimum bandwidth is 64 Kbit
Total delay is 20120 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 3
x.x.x.x (Serial0/1.1), from x.x.x.x, Send flag is 0x0
Composite metric is (41027072/40515072), Route is Internal
Vector metric:
Minimum bandwidth is 64 Kbit
Total delay is 40120 microseconds
Reliability is 255/255
Load is 15/255
Minimum MTU is 1500
Hop Count 4
02-26-2004 12:42 PM
conf t
int se 0/0.x
delay 2000
(please add 'delay 2000' two sides)
now the metric 40515072 should change to 41027072
that is it, if it doesn't work, give me the new metric value after you add 'delay 2000'.
03-04-2004 03:27 PM
thank u
for my benefit could u please post the equation with the variables. This delay must be added at both the end. thanks
03-04-2004 06:52 PM
http://www.cisco.com/warp/customer/103/eigrp-toc.html#eigrpmetrics
Is what you're after... The delay isn't added on both ends, but the total metric does have to be less than the feasible distance for the route to be considered loop free, and thus to be used as an unequal cost load share in the routing table. You also have to be careful of the math, do it in the right order, and round in the right places.
:-)
Russ.W
03-04-2004 07:26 PM
hi
I used the formula
metric - [(10^7/64)*256]= total delay *256
Thus using this formula i get 40512000 slight shy of my delay of 40515072
thanks
however i get Total delay of 4012 when i use
metric= bandwidth + delay and solve for the delay
41027072 = (1000000/64)*256 + 256*total delay
total delay is 4012
Please verify
Thus my show ip eigrp top should read the following. Since i have not tested this in a lab i assume that my reported distance is less than my feasible distance
Thus a
int s0/0.1
delay 4012
Should work and eigrp should load balance across the links
xx.xx.xx.xx (Serial0/0.1), from x.x.x.x, Send flag is 0x0
Composite metric is (41027072/28672), Route is Internal
Vector metric:
Minimum bandwidth is 64 Kbit
Total delay is 20120 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 3
x.x.x.x (Serial0/1.1), from x.x.x.x, Send flag is 0x0
Composite metric is (41027072/40515072), Route is Internal
Vector metric:
Minimum bandwidth is 64 Kbit
Total delay is 40120 microseconds
Reliability is 255/255
Load is 15/255
Minimum MTU is 1500
Hop Count 4
03-05-2004 02:54 PM
It's actually:
10000000/64 = 156250
156250 + 4012 (total delay) = 160262
(if you stopped here, this would be the IGRP metric--the EIGRP metric is the IGRP metric pushed left by 8 bits, so multiply by 256)
160262 * 256 = 41027072
This should be right. Based on what you are showing in the output above, though, the two routes are equal cost, not unequal cost (?). Do you have actual output from the router? The left number is the distance through this path, the right is the reported distance, which is our neighbor's cost to reach the destination. The right number of the alternate paths has to be less than the left number of the best path.
Anyway, I'd verify the metrics on a router. If this output is right, you shouldn't need variance here, I don't think.
:-)
Russ.W
03-05-2004 05:46 PM
i think variance doesn't work on ethernet or fastethernet, so i only use delay
and (metric1-metric2)/256 is the delay value.
99% it will be right, if not, i can get the right value at the second time.
03-06-2004 04:28 AM
Variance shouldn't have anything to do with the media type (?).... If there are two routes, both provable loop free (both feasible successors, or rather the successor and a feasible successor), and the total cost through one is less than the best path times the variance, both routes are installed in the routing table. There isn't a check for the media type.
:-)
Russ.W
03-06-2004 07:36 AM
hi,
you got me wrong.
the range of variance is from 1 to 128, just see the topology.
R1----64k-----R2
R1---1544k----R2
R1----10M-----R2
run eigrp
the variance doesn't work for the topology.
only delay works
I add the below delays, and 3 metircs are equal(=40537600)
add delay of 149774 for 1544 link
add delay of 157250 for 10M link
tell me why the variance range is 1-128
Thanks
03-07-2004 07:52 AM
Could you post the actual metrics of a route learned through these three links in this case?
:-)
Russ.W
03-07-2004 11:10 AM
R1 ----64K-----R3
R1 e0----10M-----e0 R3
R1---1544K----R2
R2---1544K----R3
now, from R1 to E1 of R3, there are 3 routes, the metrics are,
first,
(10000000/10000+(1000+1000)/10)*256=307200
second
(10000000/64+(20000+1000)/10)*256=40637600
third
(10000000/1544+(20000+20000+1000)/10)*256=2707456
right now, for the metric 307200 and 40637600, the variance doesn't work, because the range is from 1 to 128.
and I add delay 149774 on the link of 1544K,
now the metric is
(10000000/1544+(20000+20000+1000)/10+(149774-2000))*256=40537600
please note, 2000 of (149774-2000)
same as above
I add delay 157250 on the link of 10M
now the three metric are equal.
sometimes i can not explain it clearly because the language. just give me your email, ruwhite, i send the picture to you.
03-08-2004 10:56 AM
Just my 2 cents
For variance to work you must have a Feasible successor. Your backup routes may not be Feasible successors and hence variance will not work. To be a feasible successor reported distance of the backup should be less than Feasible distance of the primary route.
thanks
03-10-2004 08:14 AM
Yes, exactly.... Which is why I asked for the actual topo table entries, to see if they were feasible succesors.... :-)
Russ.W
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide