Most Efficient Load Balancing Routing protocol

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Sep 23rd, 2009
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Hi,


I want to know what is the most efficient way to achieve load balancing and load sharing? What routing protocol to be use, if I have 3 routers (Router A, Router B and Router C) all of them were interconnected via Fast Ethernet Interface. And Router C has the only route to the internet. I'm thinking of using EIGRP, but is this enough ? I've been studying BGP and I am not yet familiar with it. Hope you can help me on this.

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Joseph W. Doherty Wed, 09/23/2009 - 03:48
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Many routing protocol support equal cost routing across multiple paths, EIGRP also supports unequal cost (routing is directed to paths in proportion to cost). However, all the foregoing balancing, just using routing is "static". Flows are directed and actual path utilization, especially as the measured time is reduced, can be uneven.


Cisco routing also often supports packet-by-packet forwarding, which provides very good balancing but can resequence packets which often can be (very) bad.


A more recent option with some Cisco platforms is the OER/PfR technology which dynamically directs traffic across multiple paths; link load being one of the criteria it can use. (The original versions were limited to static routes and/or BGP, the the latest PIRO variant supports usage of other routing protocols.) Since this technology does dynamic analysis, it might be considered the most "efficient", if your concern is best utilization without impacting packet sequencing.

kaushikvadali Wed, 09/23/2009 - 05:26
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1. LAN Load sharing and balancing

EIGRP is recommended if you have all Cisco L3 devices.

OSPF is the choice if you are having multi vendor network devices.


2. WAN Load sharing and balancing


If you have your own Public IP pool

BGP is required to advertise your networks to internet

If you add another internet connection in future

BGP is required to advertise your networks to both ISPs

Load sharing and Load Balancing is achieved by maximum-paths command to install multiple paths in the routing table for multipath load sharing


Load balancing over the multipaths is performed by CEF. For more info on CEF follow link below:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/swit_vcg.htm


Few Queries

Do Router A & B serve different campus.

On Router C any priority/SLA for Router A & B traffic

Do you use default route or run BGP with your ISP


john.dejesus Thu, 09/24/2009 - 01:35
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There has been a change of topology.


router A will share the bandwidth from router B and router c. Router b and router c each has a default route to two different ISP. router b and router c has 10mbps link to the internet. So router a will share the internet from either router a or router b.

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