Load Balancing EIGRP 1

[encarter]

We have two sites. They both have 100 Meg links between them.
Each circuit connects to its own router.
So:
R1/1-------2/1
| |
R1/2-------2/2

The IGP is OSPF.
We are looking to load-balance these links better in the event that the bandwidth is pegged.

We are thinking about running EIGRP across the links, and redistrubting back into OSPF on each side which we are running else where in the company.

R1/1 and R1/2 are a stub, they need to exit across these links regardless for internet and WAN Connectivity.


Thoughts??

 

[unclerico]

...the bandwidth is pegged.

eigrp won't help with this. it will load share across multiple links, but it won't take circuit load into consideration. you need to look at OER (

http://www.cisco.com/en/US/docs/ios/oer/configuration/guide/oer-overview.html)

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[encarter]

can you explain what is the difference between load share and load balance.

I thought the bandwidth part of EIGRP will base its cost or metric on how much the circuit is being used.

So if Circuit A is being used to say 90% capacity it will give routes being advertised over that link a higher cost, no?

 

[unclerico]

Load balancing is an equitable distibution. Load sharing isn't necessarily equal distibution. As for eigrp using link saturation, yes load is one of the k values but technically it isn't used in calculating the metric, bandwidth and delay are.

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[encarter]

So is there any down side to turning on LOAD for Eigrp?

I did look at OeR but it looks like it wont work with OSPF, only BGP, or static routes

 

[unclerico]

it will work with any IGP or BGP

here's a good blurb about why you don't want to use load in the metric calculation:

http://blog.ioshints.info/2007/03/eigrp-load-balancing-based-on-interface.html

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[encarter]

This pretty much says it all....


"To make the whole idea even more impractical, EIGRP does not scan the interface load (and other parameters influencing the metric) on periodical basis, but only when triggered by a change in network topology (for example, interface or neighbor up/down even)."


OeR it is then, i just have to figure out how to get this working with OSPF yay!!!

Thanks for your help unclerico

 

[ISPKing]

star him

CCNP

 

[encarter]

Stared! Thanks again!

 

[encarter]

So even though OER is the way to go, ive been given direction to do EIGRP load share because we'd have to replace some devices to do OER.

Anyways, I've labbed this up in GNS3 and i cant get the load share working.

I was wondering if this would even work considering the two WAN links do no term into this same router.

In my lab i see both routes in the eigrp topology table.
I have configured my variance command, and bounced EIGRP. However the second route is not showing in the IP Route table.

What gives?


R1#sh ip eigrp topology 172.17.162.1/32
IP-EIGRP (AS 100): Topology entry for 172.17.162.1/32
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 25600512
Routing Descriptor Blocks:
172.17.50.2 (GigabitEthernet1/0), from 172.17.50.2, Send flag is 0x0
Composite metric is (25600512/25600256), Route is External
Vector metric:
Minimum bandwidth is 100 Kbit
Total delay is 20 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 1
External data:
Originating router is 192.168.2.1
AS number of route is 1
External protocol is OSPF, external metric is 3
Administrator tag is 0 (0x00000000)
192.168.1.2 (GigabitEthernet2/0), from 192.168.1.2, Send flag is 0x0
Composite metric is (25600768/25600512), Route is External
Vector metric:
Minimum bandwidth is 100 Kbit
Total delay is 30 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 2
External data:
Originating router is 192.168.2.2
AS number of route is 1
External protocol is OSPF, external metric is 2
Administrator tag is 0 (0x00000000)

R1#sh ip route 172.17.162.1
Routing entry for 172.17.162.1/32
Known via "eigrp 100", distance 170, metric 25600512, type external
Redistributing via eigrp 100
Last update from 172.17.50.2 on GigabitEthernet1/0, 00:14:58 ago
Routing Descriptor Blocks:
* 172.17.50.2, from 172.17.50.2, 00:14:58 ago, via GigabitEthernet1/0
Route metric is 25600512, traffic share count is 1
Total delay is 20 microseconds, minimum bandwidth is 100 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1


router eigrp 100
variance 80
network 172.16.0.0
network 172.17.50.0 0.0.0.255
network 192.168.1.0
no auto-summary