Equalcost means that multiple routes must have the same metric to reach the destination, so that router can choose to load balance across equal cost links. You can play with the delay interface command to adjust this. In this tutorial, you will learn about different types of eigrp load balancing. Since both eigrp routes are placed in routing table with different cost traffic should be load balanced unequally. To better understand the equalcost load balancing concept, consider the following example. Eigrp enhanced interior gateway routing protocol eigrp is a ciscoproprietary hybrid routing protocol, incorporating features of both distancevector and linkstate routing protocols. Cisco ios software supports equal cost load sharing for a default of up to four paths for all routing protocols. In this lesson, well take a look at eigrp enhanced interior gateway routing protocol which is ciscos routing protocol. Cef on r3 overrides the perpacket balancing behavior of process switching with perdestination load balancing. Many of you have problems finding a comprehensive guide to load balancing for eigrp. How to test eigrp loadbalancing solutions experts exchange. If the feasible condition is not satisfied, the variance command is not considering the route for load balancing. How does unequal cost path load balancing variance work.
In this way, eigrp provides both unequal cost path load balancing and intelligent load balancing. They will choose which of those routers has the best metric. Does this mean that for eigrp, equal cost load balancing doesnt increase your bandwidth, it just divides the speed of one link. By default, eigrp has the auto summary feature enabled. This means that, even if variance is set to 3, the eda path is not selected for load balancing because router d is not a feasible successor. On r1, view the routing table and verify that r1 is loadbalancing to 10. Abstract we propose a routing and loadbalancing approach with the primary goal of.
Hi there, i have a question on how to check on how to load balancing works on eigrp. The configuration supports equalcost load balancing. This router connects to two wan links which has the same bandwidth. There are two things you must be aware of when using eigrp unequalcost load balancing, and well cover those and a whole lot more in this lab in the previous lab, we saw equalcost load balancing in action. Eigrp load balancing configuration example certiology. Bgp in large networks scaling bgp across multiple locations download ebook. We must use the variance command to tell eigrp to loadbalance across unequalmetric links. We often come across the requirement where we have to perform the load sharing in dualhomed network scenario.
Configure load balancing on cisco eigrp using unequal routes. How to configure eigrp variance to load balance traffic across unequal cost links. Even better it will share traffic in a proportional way, if you have a feasible successor that has a feasible distance which is 5 times worse than the. The configuration supports unequalcost load balancing. The enhanced interior gateway routing protocol eigrp is an enhanced version of the interior gateway routing protocol igrp developed by.
Topology r1 is the router we will be doing our tests from. Rip routing information protocol automatically performs equal cost load balancing. How to configure and verify eigrp stubs, eigrp load balancing and eigrp. The eigrp is commonly the routing protocol of choice when using the network with no. Before jumping in the ins and out lets run through a few things first when it comes to eigrp load sharing, also refereed to as load balancing sometimes. Your traffic share count is correct and the recommended setting is to leave the default per flow load balancing which will be ok for you. For more information on variance, refer to troubleshooting. A path has to be a feasible successor route to be used in unequal load balancing.
R1 has an fd of 5 0 via r12 the fd via r11 is lower than the fd via r12. Explore equal and unequal load balancing and how to adjust the metric values for routes with the enhanced. Because of this, routes are summarized to classful address at network boundaries in the routing updates. Cisco ios, by default, allows eigrp load balancing for four equalcost paths routes. Basic cisco router eigrp configuration pluralsight.
In this scenario, the topology and ip addressing is as shown in figure below and the routing protocol has been configured using eigrp with as number 99. By default, eigrp will automatically loadbalance across equalmetric routes four by default, six maximum. Have you ever wondered why among all igps only eigrp supports unequalcost load balancing uclb. I tried shutting down 3 of my 4 links and retesting and it gave me the same result. A significant advantage of eigrp and igrp over other routing protocols is the support for unequalcost load balancing. Eigrp load balancing and metrics overviewdescription expected duration lesson objectives course number expertise level overviewdescription. The degree to which eigrp performs load balancing is controlled. In this post i would like to explore unequal cost load balancing with eigrp and particularly how we configure eigrp in order to achieve load balancing. In this situation, eigrp sends two packets to eca and one packet to eba. Eigrp also supports loadbalancing across routes with an unequal metric. In this video we discuss load balancing with eigrp. Eigrp is a ciscoproprietary routing protocol that is based on igrp. Before jumping in the ins and out lets run through a few things first when it comes to eigrp load sharing, also refereed. Is there any special reason why only eigrp supports.
This document describes how to troubleshoot the most common enhanced interior gateway routing. Eigrp is an exceptional option as it mixes a number of the major advantages of other routing protocols including fast convergence, support for very large networks, efficient, support for load balancing and. Recently, i was asked a question regarding traffic load balancing across several links and i was able to provide two options that i thought would work. The output in figure 1 illustrates the topology for that we will use in this lesson and figure 2 illustrate that r1 is using the default equal. Implementing the variance command on the router that is connected to the 4 routers will allow that router to see the best metric then multiply it by. Hi all, i am trying to configure equal cost load balancing on a remote site that connects to the head office using a cisco 2901 router. Eigrp balancing load fingerinthenet for english guy. In this lab i will explore equal and unequalcost loadbalancing for eigrp and will explain how eigrp calculates its metric values.
Configure and verify equalcost load balancing with eigrp. The add path support in eigrp feature enables hubs in a single dynamic multipoint vpn dmvpn domain to advertise multiple best paths to connected spokes when the enhanced. Eigrp adheres to the following hybrid characteristics. Eigrp is a ciscoproprietary hybrid routing protocol, incorporating features of. For equal cost load balancing allboth routes have a. By default, eigrp supports equalcost load balancing over four links. Download cisco ccnp routing pdf study guide snabay. Eigrp variance command example this tutorial will demonstrate how you can use the eigrp variance command to make eigrp load balance over feasible successors. Eigrp makes it easy for us the network engineers to make this happen. Configure and verify unequalcost load balancing with eigrp. Providing load balancing and introduction the concept of. Any eigrplearned route with a metric less than 3 times the successor.
But generally, something is wrong with your output, path via 192. The command displays the number of equalcost paths currently configured on the router. Eigrp equal and unequal cost load sharing eric leahy. This unique feature on eigrp is called unequal cost load balancing and its very easy to be implemented. Equal cost load balancing with rip on packet tracer. Now its time to do a little unequalcost balancing, using this network. Ccnp route chapter 2 lab 21, eigrp load balancing version 7. Pdf improvement of performance of eigrp network by using a. Eigrp unequal cost load balancing trafficengineering. Configure load balancing on cisco eigrp mustbegeek. How does unequal cost path load balancing variance.
Eigrp equalcost load balancing equalcost load balancing is a routers capability to distribute traffic over all the routers that have the same metric for the destination address. Eigrp can exchange routes for ipv4, ipv6, appletalk and ipxspx. The manual summarization is needed on a hub to advertise the default route to a spoke. This paper presents a framework for global server load balancing of the web sites in a. Eigrp can also balance traffic across multiple routes that have different metrics, which is called unequalcost load balancing. Which two statements about eigrp load balancing are true. If you are unfamiliar with distance vector and rip i highly recommend to read my introduction to rip first before continuing eigrp stands for enhanced. As with autosummarization, the router performing manual summarization will add the. To see the full effect of eigrp equalcost load balancing, temporarily disable cef and route caching so that all ip packets are processed individually and not fastswitched by cef. I have three router going to same site, eigrp running. We can verify the eigrp load balancing using the show ip protocols command.
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