Cef is found in almost all cisco routers and catalyst switches, and understanding how cef operates can improve the performance, scalability, and efficiency of your network. Identify cisco express forwarding concepts ccie wiki. Excluding cisco 12000 series internet routers, all cisco devices running cisco ios software that have cisco express forwarding cef enabled can leak information from previous packets that have been handled by the device. This can happen if the packet length described in the ip header is bigger than the physical packet size. Sep 19, 2017 this is the final video of ip forwarding series by arun kumar cisco trainer. Due to this the router is able to perform routing at much lower latency and higher throughput while maintaining low cpu utilization. Although cef is a cisco proprietary protocol other vendors of multilayer switches or highcapacity routers offer a similar functionality where layer3 switching or routing is. Cef seems to be such a big part of cisco networking, just curious if there are alternatives that are also topology based nonroute caching. Cisco express forwarding cef is a packetswitching technique that is the default for many of ciscos router lines over the last ten years. Cef is mainly used to increase packet switching speed by reducing the overhead and delays introduced by other routing techniques best regards, trinh nguyen. Oct 20, 2014 in cisco ios, there are many packet switching methods, but the common ones which we will be discussing in this article are process switching, fast switching and cisco express forwarding cef.
This book addresses common misconceptions about cef and packet switching across various platforms, helping you to improve your. An important consideration for deployment is that cisco express forwarding switching must be enabled for unicast rpf to function. Routing protocols come under the control plane, as this relates to the communication of control traffic. David davis introduces you to cef and its benefits in this article. Introduction to cisco express forwarding cef octa networks. Rob soderbery on the cisco digital network dna architecture duration. Cisco express forwarding afnog 2019 workshop on network. Jun 22, 2017 cisco express forwarding cef is an advanced layer 3 switching technology used mainly in large core networks to enchance the network performance. The cisco express forwarding cef switching mode replaces the traditional cisco routing cache with a data structure that mirrors the entire system routing table. Jan 25, 2018 cisco express forwarding in platforms at the network core provides the performance and scalability that networks need to respond to continued growth and steadily increasing network traffic. In this article, we will be focusing on ip packets although the same concept applies to other protocol packets.
Cisco express forwarding cef is an advanced layer 3 switching technology used mainly in large core networks or the internet to enhance the overall network. Cisco express forwarding, cef is advanced layer 3 ip switching technology used on cisco router and switch. These are automatically updated at the same time as. He was a technical contributor and editor of a number of ieee 802 standards, including 802. Cisco express forwarding cef is advanced, layer 3 ip switching technology. Cef optimizes network performance and scalability for networks with large and. Cisco express forwarding cef issue preamble a couple years ago i managed to get hold of some ancient cisco equipment, probably a pile of rubble to the eyes of professionals, but a little treasure for a young man like me that wanted to learn something about networking. Cisco express forwarding cef is a packetswitching technique used within cisco. Jun 02, 2009 cisco express forwarding cef is advanced, layer 3 ip switching technology. Cef is built around 2 main components the forwarding. May 08, 2020 cisco express forwarding cef, is the evolution of optimizing the router to make it be able to forward more packets faster. Load balancing and cisco express forwarding cef with.
Cisco express forwarding cef provides the ability to switch packets through a device in a very quick and efficient way while also keeping the load on the routers processor low. It provides the ability to switch packets through a device in a very quick efficient way while also keeping the load on the routers processor low. Understanding unicast reverse path forwarding cisco. Prior to cef there were 2 methods for packetswitching process switching. Cisco express forwarding cef is an advanced layer 3 switching technology used mainly in large core networks or the internet to enhance the overall network performance.
In my last post about unicast reverse path forwarding, i made quite a few references to cef. Cisco express forwarding cef switching is a proprietary form. Lets see how we can configure cisco express forwarding cef on cisco devices. If it is not enabled, administrators can enable it with the following global configuration command. The fib is more like a mirror of the routing table but with. Apr 22, 2018 cef cisco express forwarding the forwarding of ip packets is done by the forwarding plane, also called the data plane. In most scenarios the phone would mark the voice stream as e, the switch would honor this. As best i can tell, cef is enabled by default on all these platforms, and can be reenabled with the ip cef orthe ip cef distributed global configuration. Cef cheats a little, by building a forwarding information base fib, and an adjacency table. The main purpose of cef is to optimize the forwarding of packets and increase the packet switching speed. Cisco express forwarding cef issue cisco community. Cef optimizes network performance and scalability for. Cisco express forwarding cef is a packetswitching technique used within cisco routers.
Cisco express forwarding cef is a packetswitching technique that is the default for many of cisco s router lines over the last ten years. This can be done because cef maintains two tables in the data plane. Most of our modern ios devices use cef as the default method. In this video, we cover cisco express forwarding cef, which is one of topics on cisco s encor 350401 exam blueprint.
Cef allows hardware level routing switching to happen without using cpu cycles. This command has been enabled by default as of ios version 12. Ciscos implementation of this architecture is know as cisco express forwarding cef process switching the routermls processes every packet to make a forwarding decision. Specifically, well contrast cef with other packet switching. Packets like these will be expanded to fit the ip length and. Cisco express forwarding cef linkedin learning, formerly. Cef optimizes network performance and scalability for networks with large and dynamic traffic patterns, such as the. It operates at layer 3, and is designed to speed up packet switching, cef supports ethernet, frame relay, ppp, atm, fddi, tunnels and hdlc. Fast switching the initial packets forwarding decision is still derived from the route processor, but that destination is then held in cache for subsequent. Cef cisco express forwarding my internets not working. Cisco express forwarding cef switching is a proprietary form of scalable switching intended to tackle the problems associated with demand. Cisco express forwarding is enabled by default on most cisco platforms running cisco ios software release12. This is the final video of ip forwarding series by arun kumar cisco trainer.
Prior to cef there were 2 methods for packetswitching process switching and fastswitching. In this video, we cover cisco express forwarding cef, which is one of topics on ciscos encor 350401 exam blueprint. So i would check the phones are configured correctly, then on the hp switch i would use the following commands. Cisco express forwarding cef ip with ease ip with ease. Cef cisco express forwarding the forwarding of ip packets is done by the forwarding plane, also called the data plane. Cisco express forwarding demystifies the internal workings of cisco routers and switches, making it easier for you to optimize performance and troubleshoot issues that arise in cisco network environments. The modern and most preferred cisco ios switching process thats in use on ios equipment is called cisco express forwarding, or cef.
Ip switching cisco express forwarding configuration guide. Cef is used on cisco devices to ensure packets can be forwarded without any noticable delays. There are no specific requirements for this document. Cisco express forwarding or cef for short is a layer 3 switching technology propriety to cisco. Oct 11, 2012 cef known as cisco express forwarding is a feature built into every cisco router and is enabled by default its really the feature that makes cisco well cisco. Alternatives to cef cisco express forwarding in terms of multilayer switching, what do other hardware manufactures use. Cisco express forwarding cef the cef switching method goes a step further than fast switching by building the cache in advance even before any packets need to be processed. May 11, 2020 so cisco came up with the idea to cache information to the interface processors. Forwarding information base the fib is used to make layer3 ip destination prefixbased switching decisions. Cef provides the ability to switch packets through advanced, layer 3 ip switching technology via a device in a way that minimises load on routers processor. Cisco express forwarding concepts and challenges in general network. Cef dcef cisco express forwarding cisco ios xe release 2. With cef switching, the information which is conventionally stored in a route cache is split up over several data structures.
Because there is no need to build cache entries when traffic starts arriving for new destinations, cef behaves more predictably when presented with large volumes of traffic addressed. From a 500 foot view cef is a method the router uses to forward packets, without utilizing any cpu cycles. Comware equivalent to cisco express forwarding hewlett. Cef keeps two tables, the fib forwarding information base, and the adjacency table, which contains the layer 2 information for. Cef optimizes routing table lookup by creating a special, easily searched tree structure based on the ip routing table. I figured i would take a little time and discuss cef in a little detail. Cef known as cisco express forwarding is a feature built into every cisco router and is enabled by default its really the feature that makes cisco well cisco. Cef cisco express forwarding also known as topology based switching. Cisco express forwarding by stacia mckee, russ white and nakia stringfield 2007, hardcover at the best online prices at ebay. When using process switching the router will remove the header for each. Get better performance with cisco express forwarding cef. It is a feature that allows a router to quickly and efficiently make a route lookup. Apr 19, 2014 cisco express forwarding cef is advanced, layer 3 ip switching technology. When cisco express forwarding is enabled on a router, the route processor rp performs the express forwarding.
Jan 03, 2007 cisco express forwarding cef can result in faster switching and enable advanced features in the cisco ios. Cisco express forwarding cef is an advanced layer 3 switching technology used mainly in large core networks to enchance the network performance. Cisco express forwarding cef is a packetswitching technique that is the default for many of ciscos router. Cisco express forwarding demystifies the internal workings of cisco routers and switches, making it easier for you to optimize performance and troubleshoot issues that arise. Although cef is a cisco proprietary protocol other vendors of multilayer switches or highcapacity routers offer a similar functionality where layer3 switching or routing is done in hardware in an asic instead of by software and the central cpu. It gets its information from the routing table and maintains a mirror. Cisco express forwarding cef is advanced layer 3 ip switching technology. For these and later cisco ios releases as shown in the table below, the switching path options are cisco express forwarding switched or process switched. Cisco express forwarding paperback networking technology. Cef optimizes network performance and scalability for networks with large and dynamic traffic patterns, such as the internet, on networks characterized by intensive webbased applications, or interactive sessions. Nexus uses its forwarding mechanism which is similar to cef. So cisco came up with the idea to cache information to the interface processors. Somewhere in the 90s cisco realized that fast switching had its limitations, and a new switching technology was developed which led to cef cisco express forwarding. Cisco express forwarding cef in hindi ip forwarding.
It is an advanced one in layer 3 switching technology, which is mainly used in the internet or else core networks to enrich the overall performance of the network. Cisco express forwarding is a distributed switching mechanism that scales linearly with the number of interface cards and the bandwidth installed in the router. Cisco express forwarding cef is a packetswitching technique that is the default for most of cisco routing platforms. Jan 17, 2006 cisco express forwarding cef switching is a proprietary form of scalable switching intended to tackle the problems associated with demand caching. Understanding cisco express forwarding cef introduction. Hello, does comware have any command equivalent to cisco express forwarding cef. This document explains what cisco express forwarding is. Cisco express forwarding cef switching is a proprietary form of scalable switching intended to tackle the problems associated with demand caching. By watching this video you will learn about cisco express forwarding cef mechanism of cisco router. Ef expedited forwarding not express forwarding hence the confussion with cef. Cisco express forwarding cef must be enabled on all.
Cisco express forwarding cef in hindi ip forwarding part. To find out if cisco express forwarding is enabled on your platform, enter the show ip cef command. Feb 27, 20 cisco express forwarding cef is a packetswitching technique that is the default for many of ciscos router lines over the last ten years. Mar 15, 2019 cisco express forwarding or cef for short is a layer 3 switching technology propriety to cisco. Cisco express forwarding overview cisco express forwarding cef is advanced layer 3 ip switching technology. The cef code is able to maintain these data structures in the gigabit. This is the fastest method but there are some limitations. Cisco express forwarding by nakia stringfield, russ white.
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