From: Victor Cappuccio (victor@ccbootcamp.com)
Date: Thu Apr 19 2007 - 18:56:43 ART
Hi Dennis,
Eigrp load balance with a variance = 1, meaning that Equal Cost FD is needed
in order to accomplish load balancing. The unequal-cost load-balancing with
EIGRP is subject to one aditional restriction, the best metric is selected
(FD) and multiplied by the variance, so anything in that range will be used to
load balance over unequal cost path
Sw1#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static
route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
1.0.0.0/24 is subnetted, 2 subnets
C 1.1.17.0 is directly connected, FastEthernet0/1
C 1.1.27.0 is directly connected, FastEthernet0/2
12.0.0.0/32 is subnetted, 1 subnets
D 12.12.12.12 [90/156160] via 1.1.17.1, 00:01:34, FastEthernet0/1
Sw1#
Sw1#
Sw1#
Sw1#
Sw1#
rack10>2
[Resuming connection 2 to R2 ... ]
R2#
R2#show ip eigrp inter
IP-EIGRP interfaces for process 1
Xmit Queue Mean Pacing Time Multicast
Pending
Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes
Lo0 0 0/0 0 0/1 0 0
R2#conf te
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)#do show run int f0/0
Building configuration...
Current configuration : 93 bytes
!
interface FastEthernet0/0
ip address 1.1.27.2 255.255.255.0
duplex auto
speed auto
end
R2(config)#router eigrp 1
R2(config-router)#net 1.1.27.2 0.0.0.0
R2(config-router)#do show ip eigrp inter
IP-EIGRP interfaces for process 1
Xmit Queue Mean Pacing Time Multicast
Pending
Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes
Lo0 0 0/0 0 0/1 0 0
Fa0/0 0 0/0 0 0/1 0 0
R2#
rack10>3
[Resuming connection 3 to cat1 ... ]
00:05:48: %DUAL-5
Sw1#
Sw1#show ip route eigrp
12.0.0.0/32 is subnetted, 1 subnets
D 12.12.12.12 [90/156160] via 1.1.27.2, 00:00:04, FastEthernet0/2
[90/156160] via 1.1.17.1, 00:00:04, FastEthernet0/1
Sw1#
Sw1#
Sw1#
Sw1#
Sw1#show ip eigrp topology
IP-EIGRP Topology Table for AS(1)/ID(1.1.27.7)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 12.12.12.12/32, 2 successors, FD is 156160
via 1.1.27.2 (156160/128256), FastEthernet0/2
via 1.1.17.1 (156160/128256), FastEthernet0/1
P 1.1.17.0/24, 1 successors, FD is 28160
via Connected, FastEthernet0/1
P 1.1.27.0/24, 1 successors, FD is 28160
via Connected, FastEthernet0/2
Sw1#! So for example we can modify the default calculation of EIGRP
Sw1#show ip proto | in K
EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
To configure this in the routers you can use the:
Router(config-router)# metric weights tos k1 k2 k3 k4 k5
using the EIGRP well know formula if K5 is different than 0
metric = [K1*bandwidth + (K2*bandwidth)/(256 - load) + K3*delay] *
[K5/(reliability + K4)]
Sw1#conf te
Enter configuration commands, one per line. End with CNTL/Z.
Sw1(config)#int f0/2
Sw1(config-if)#band 4
Sw1(config-if)#do show ip route eigrp
12.0.0.0/32 is subnetted, 1 subnets
D 12.12.12.12 [90/156160] via 1.1.17.1, 00:00:01, FastEthernet0/1
Sw1(config-if)#
rack10>1
[Resuming connection 1 to R1 ... ]
*Apr 19 21:46:07.92
R1#
R1#show ip eigrp top
IP-EIGRP Topology Table for AS(1)/ID(12.12.12.12)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 12.12.12.12/32, 1 successors, FD is 128256
via Connected, Loopback0
P 1.1.17.0/24, 1 successors, FD is 28160
via Connected, FastEthernet0/0
P 1.1.27.0/24, 1 successors, FD is 640005120
via 1.1.17.7 (640005120/640002560), FastEthernet0/0
R1#
You can also load share over unequal cost paths. To do this we use the
variance feature in the EIGRP routing process. The variance is defined with a
multiplier that represents the difference between the metrics of the paths.
The default variance is '1' which means that the multiple paths must have the
same metrics.
thanks,
Victor Cappuccio.-
Network Learning Inc - A Cisco Sponsored Organization (SO) YES! We take
Cisco Learning credits!
victor@ccbootcamp.com
http://www.ccbootcamp.com (Cisco Training and Rental Racks)
http://www.ccbootcamp.com/groupstudy.html (groupstudy member discounts!)
Voice: 702-968-5100
FAX: 702-446-8012
-----Original Message-----
From: nobody@groupstudy.com on behalf of Dennis Worth
Sent: Thu 4/19/2007 14:15
To: ccielab@groupstudy.com
Subject: EIGRP Variance help?
All,
I am trying to understand the variance command from a real world
problem.
R1 R2
\ \ / /
\ \/ /
\ /\ /
CAT1----CAT2
6Mb outbound on Wan R1
6Mb outbound on Wan R2
I need to take one Wan router and remove a 2Mb circuit leaving me 4Mb
Looking from the Cats, currently gives me a metric of:
TEST-R1#sh ip ro 10.0.0.0
Routing entry for 10.20.0.0/16
Known via "eigrp 1", distance 90, metric 13242368, type internal
Redistributing via eigrp 1
Last update from 10.16.4.230 on GigabitEthernet2/3, 3d09h ago
Routing Descriptor Blocks:
* 10.16.4.226, from 10.16.4.226, 3d09h ago, via GigabitEthernet2/2
Route metric is 13242368, traffic share count is 1
Total delay is 501010 microseconds, minimum bandwidth is 6146 Kbit
Reliability 255/255, minimum MTU 1427 bytes
Loading 30/255, Hops 2
10.16.4.230, from 10.16.4.230, 3d09h ago, via GigabitEthernet2/3
Route metric is 13242368, traffic share count is 1
Total delay is 501010 microseconds, minimum bandwidth is 6146 Kbit
Reliability 255/255, minimum MTU 1427 bytes
Loading 30/255, Hops 2
http://www.cisco.com/warp/public/103/19.pdf
Dennis Worth
Network Engineer
Option One Mortgage
Phone 949-790-3687
dennis.worth@oomc.com
This archive was generated by hypermail 2.1.4 : Tue May 01 2007 - 08:28:36 ART