It also supports unequal cost load balancing between routers. In addition, interior gateway routing protocol igrp and eigrp also support. It is a ciscoproprietary routing protocol for tcpip. We can verify this by looking at the output of show ip. Eigrp allows load distribution among unequal paths which is controlled by the variance command. The multiplier parameter for the variance command is a value from 1 to 128, used for load balancing. Then the degree to that eigrp performs the load balancing is controlled by a variance multiplier router configuration command. If feasible distance end to end metric for active route variance metric of feasible successor then load balancing occurs for unequal cost paths. Load balancing with eigrp all of our interior gateway protocols can perform equalpath load balancing on up to 4 routes by default. Upon completion of this course, you will be prepared for the cisco certified network professional ccnp routing and switching certification exams 300101 route, 300115 switch, and 300.
Eigrp loopfree alternate lfa fast reroute frr is a feature that allows eigrp to switch to a backup path in less than 50 ms. To better understand the equalcost load balancing concept, consider the following example. Eigrp load balance with a variance 1, meaning that equal cost fd is needed in order to accomplish load balancing. It is also important to note that cisco ios release. Each router has a directly connected subnet that needs to be advertised through eigrp. Using routing capabilities is a must in todays evolving networks.
Sep 19, 2011 eigrp makes it easy for us the network engineers to make this happen. Before jumping in the ins and out lets run through a few things first when it comes to eigrp load. This tutorial explains how to configure eigrp routing protocol in cisco routers step by step with practical example in packet tracer. Load balancing increases the utilization of network segments, and so increases effective network bandwidth. Many of you have problems finding a comprehensive guide to load balancing for eigrp. Use show and debug commands for the eigrp topology table. It is the only protocol that can have a backup path along with the best path to reach a destination. 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. Pdf simulationbased comparative study of ospf and eigrp. How does unequal cost path load balancing variance.
Reliable transport protocol rtp is used to ensure delivery of most eigrp packets. Dec, 2011 in this lab i will explore equal and unequalcost loadbalancing for eigrp and will explain how eigrp calculates its metric values. Eigrp supports unequal metric load balancing, which allows administrators to better distribute traffic flow in their networks. Every routing protocol supports equal cost path load balancing. Configuring eigrp maximum paths free ccna workbook. Fast reroute means we switch to another next hop, loopfree. Perpacket load balancing can cause problems, so, in general, you should use perdestination load balancing. When there are several routes with an equal metric value, by default all dynamic routing protocols, including eigrp, will used all these routes to forward packet in load balance style. Chapter 2 lab 22, eigrp load balancing topology objectives. In short, cef performs the load balancing once the routing protocol table is calculated.
The multiplier is a variance value, between 1 and 128, used for. Only feasible successors are candidate for load balancing. In addition, interior gateway routing protocol igrp and eigrp also support unequal cost path load balancing. Router takes the ingress packet, hashes source and destination ip addresses and maybe l4 ports and normalizes the result to be, say, in range 116 the result is often called hash bucket. Eigrp stands for enhanced interior gateway routing protocol. But editing is not allowed and commercialization of. Eigrp also supports load balancing across routes with an unequal metric. Eigrp is one of those interior gateway routing protocols that have very rapid convergence. Eigrp unequalcost load balancing eigrp can also balance traffic across multiple routes that have different metricsthis is called unequalcost load balancing. Load sharing occurs only when a route shows up in the forwarding table with multiple paths. The metric calculation for eigrp is based on something called the kvalues. Aug 12, 2012 eigrp allows load distribution among unequal paths which is controlled by the variance command. Nov 22, 2006 bydefault eigrp does equalcost path load balancing upto 4 equal cost paths. Variance 1 in eigrp means unequal load balancing is disabled,it supportequalcost load balancing in eigrp, if the multipoint network has different speeds allocated to the vcs,take the lowest cir and simply multiply it by the number of circuits.
In this lab we will configure rip and will observe load balancing. In this lab, you need to configure equalcost load balancing on per destination or per packet basis. In general, load balancing is the capability of a router to distribute traffic over all the router network ports that are the same distance from the destination address. Topology r1 is the router we will be doing our tests from. Eigrp manual summarization passive eigrp interfaces equalcost load balancing. In the next article, we will consider another solution to the traffic load balancing scenario which deals with policybased routing and ip sla tracking. It has several enhancements to scale the enterprise size network. The unequalcost loadbalancing 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.
Here, the multiplier is the variance value in between 1 and 128 which is used for the. It is inherent to the forwarding process in the router, and it enables. It is inherent to the forwarding process in the router, and it enables a router to use multiple paths to a destination when it forwards packets. Here in this case if you dont use maximumpaths command under the eigrp configuration it. Eigrp is a ciscoproprietary hybrid routing protocol, incorporating features of. The eigrp balance traffic across the multiple routes which have different metrics which is called as unequal cost load balancing. By default, eigrp will automatically loadbalance across equalmetric routes four by default, six maximum. It calculates the best route to a destination using metric value that is based on the link bandwidth and delay. Eigrp introduction to eigrp basic eigrp conguration eigrp packets eigrp neighbor adjacency eigrp neighbor and topology table eigrp unequal load balancing eigrp variance command example eigrp summarization eigrp. We must use the variance command to tell eigrp to loadbalance across these. Here in this case if you dont use maximumpaths command under the eigrp configuration it will take only one path into account. New ways of working, communicating and socializing have been accompanied by new terms.
Eigrp configuration, bandwidth and adjacencies chapter 2. All of our interior gateway protocols can perform equalpath load balancing on up to 4 routes by default. The degree to which eigrp performs load balancing is controlled with the variance command. Routes with equal feasible distance are installed by default in the. Jun, 20 now lets configure unequalcost load balancing to make use of the link via e10. Mar 23, 2020 load balancing is a standard functionality of cisco ios software that is available across all router platforms. By setting the variance to 10 we are telling the router to load balance over routes that have an fd of up to 10 times worse than the fd of the successor route. By default, eigrp will automatically load balance across equalmetric routes four by default, six maximum. In short, cef performs the loadbalancing once the routing protocol table is calculated.
In this lab i will explore equal and unequalcost loadbalancing for eigrp and will explain how eigrp calculates its metric values. Now lets configure unequalcost load balancing to make use of the link via e10. How does unequal cost path load balancing variance work in. The number of paths used is limited by the number of entries that the routing protocol. Eigrp adheres to the following hybrid characteristics. Updates are sent when a change occurs, and include only the change. Eigrp load balancing every routing protocol supports equal cost path load balancing. If you want eigrp to do equal costpath load balancing you can use maximupaths command to set the paths to it. Configuring enhanced interior gateway routing protocol eigrp eigrp autosummarization. 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 successor then traffic will be shared in a 5. The degree to which eigrp performs load balancing is controlled by the variance multiplier router configuration command.
Lets take a look at an example of how eigrp can do load. Layer 3 loadbalancing is similar to loadbalancing used with ethernet portchannels. For equal cost load balancing allboth routes have a metric of 1. On r1, view the routing table and verify that r1 is load balancing to 10. Load balancing is traffic engineering and can be configured manually or au tomatically by mechanisms such as ecmp and eigrp. We can verify this by looking at the output of show ip protocols, it will tell us what the maximum path value is. Configure and verify unequalcost load balancing with eigrp. It is the only protocol that can have a backup path along. In this lab, well go over eigrp unequal cost load balancing theory, and then put that theory into action in a lab with live. Load balancing is a standard functionality of cisco ios software that is available across all router platforms. Then the degree to that eigrp performs the load balancing is. Feb 19, 2020 eigrp can also balance traffic across multiple routes that have different metrics, which is called unequalcost load balancing. Eigrp uses diffusing update algorithm dual to determine the best path among all feasible paths. Verify your configuration by using the show ip route command.
Equal and unequal cost load balancing eigrp support equal and unequal cost load balancing equal cost load balancing is enabled by default. Whenever any new network is added, modified or deleted eigrp only sends incremental updates, reducing the workload on the router and the amount of data that needs to be transmitted. Eigrp has the capability to use unequal cost load balancing in a similar way as that by igrp. Use the variance n command in order to instruct the router to include routes with a metric of less than n times the minimum metric route for that. In addition, interior gateway routing protocol igrp and eigrp also support unequal cost path load. Load balancing is a standard functionality of the cisco ios. Eigrp equal and unequal cost load sharing eric leahy. Cisco ios software supports equal cost load sharing for a default of up to four paths for all routing protocols. Configure and verify equalcost load balancing with eigrp.
You can verify that routers have become neighbors by using the show ip eigrp neighbors command on either router. Eigrp enhanced interior gateway routing protocol eigrp is a ciscoproprietary hybrid routing protocol, incorporating features of both distancevector and linkstate routing protocols. Equalcost means that multiple routes must have the same metric to reach the destination, so that. Building on that knowledge, we have seen how to use eigrp to achieve unequal cost path load balancing through the variance command. 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. Identify successors, feasible successors, and feasible distances. 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. In this lab we will configure rip and will observe load balancing with equal cost load balancing in packet tracer. Eigrp can also balance traffic across multiple routes that have different metrics, which is called unequalcost load balancing. Perpacket load balancing can cause problems, so, in general, you should use perdestination load.
On r1, view the routing table and verify that r1 is loadbalancing to 10. Load balancing in eigrp these videos are free to share and learn and upload in your personal blogs, computers and with your friends. Eigrp routers do not send periodic, fulltable routing updates. How does unequal cost path load balancing variance work. Eigrp can exchange routes for ipv4, ipv6, appletalk and ipxspx.
Jun 06, 2014 building on that knowledge, we have seen how to use eigrp to achieve unequal cost path load balancing through the variance command. Support equal unequal path load balancing eigrp tables neighbor table topology table routing table eigrp routing table terms active state router is trying to find a route. If feasible distance end to end metric for active route variance metric. Configure load balancing on cisco eigrp mustbegeek. Load balancing with ospf routing table cisco certified expert. Eigrp is a ciscoproprietary routing protocol that is based on igrp. These k values are a reference to the entries under vector metric in the screenshot above. Eigrp authentication is used to prevent an attacker from forming the eigrp neighbor relationship with your router and advertising incorrect.
By default, eigrp supports equalcost load balancing over four links. As a senior network engineer, you are considering deploying eigrp in your. The network depicted above consists of only two routers. Nov 06, 2016 for equal cost load balancing allboth routes have a metric of 1. Rip equal cost load balancing on packet tracer networking.
Jul 10, 2014 eigrp introduction video by sikandar shaik dual ccie. Fast reroute means we switch to another next hop, loopfree alternate is an alternative path in the network that is loop free. Eigrp also supports loadbalancing across routes with. Eigrp configuration, bandwidth and adjacencies chapter 2 lab. A comparative study of igp and egp routing protocols, performance evaluation along load balancing and redundancy across different as chapter pdf available march 2016 with 867. Have you ever wondered why among all igps only eigrp supports unequalcost load balancing uclb. Bydefault eigrp does equalcost path loadbalancing upto 4 equal cost paths. During the last decades people have become witnesses to the rapid expansion of data networks.
Eigrp or enhanced interior gateway routing protocol is a cisco proprietary technology for routing. We must use the variance command to tell eigrp to load balance across unequalmetric links. Eigrpintroduction video by sikandar shaik dual ccie. Eigrp makes it easy for us the network engineers to make this happen. It will connect through r2 and r3 to ip address 124. Eigrp administrative distance 5 summary 90 internal 170 exernal eigrp multicast address 224. Pdf a comparative study of igp and egp routing protocols.
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