One layer above the physical layer is the data link layer. Typically, the network layer adds its own header to the packets received from the transport layer. Ethernet is a local area network technology with end stations assigned unique 48bit addresses. Switches are layer 2 devices and are therefore relatively easy to configure in. Chapter 2 circuit and packet switching stanford university. The difference between layer 2, 3, and 4 network switches with the rapid development of computer networks over the last decade, highend switching has become one of the most important functions of a network for moving data efficiently and quickly from one place to another. If vlans span across multiple access layer switches, return path traffic can be flooded to all access layer switches and end points. The connection between access and distribution layers was layer2. Data networks lecture 1 introduction mit opencourseware. Murat torlak transport layer is responsible for the endtoend transfer of messages from a process in the source machine to aprocess in the destination machine. Achieving ccnp enterprise certification proves your skills with enterprise networking solutions. Layer 2 is equivalent to the link layer the lowest layer in the tcpip network model. It is a network layer that determines the best available path in the network for communication. Layer 2 foundation services the following are the design recommendations for layer 2 foundation services.
Up to 4094 vlans can be configured on cisco catalyst switches. A layer 2 switch works with mac addresses only and does not care about ip address or any items of higher layers. Lan data transmissions at layer 2 fall into three classifications. Layer 3 has ultimate source, destination layer 2 has next hop source, destination. When comparing the layer 2 switch to a layer 3 switch the first thing to look at is what additional software functionality you are getting. Portland is a single logical layer 2 data center network fabric that scales to millions of endpoints modify network fabric to work with arbitrary operating systems and virtual machine monitors maintain the boundary between network and endhost administration scale layer 2 via network modifications. Layer 2 switching or data link layer switching is the process of using devices mac addresses to decide where to forward frames. Unfortunately this means if one layer is hacked, communications are compromised without the other layers being aware of the problem. Within the discussion of content networking, we will.
Basically what i am going to explain in this article is, how intercommunication happens in data network between two devices at layer 2 switching. Extension of layer 2 vlans across multiple switches using spanning tree protocol stp prevents looping across the network. A guide for it professionals is the first systematic guide to this new technology. Before a user can make a call, a virtual path between caller and callee is established over the network. First, the switch loads a poweron selftest post program stored in rom. Spanning treeenabled switches go through a root election process based on bridge p rotocol data unit. If the switches at the layer2 dont follow any routing table then how they. Protocol analyzer ensures proper decoding along with call and session analysis. They break up one large collision domain into multiple smaller ones in a typical lan, all hosts are connected to. If this cannot be avoided, then tune the arp aging timer so that it is less than the cam aging timer.
This header provides the information needed for routing e. Basics of tcpip, switching, routing and firewalling. Of course, the main example of its use is the phone. Perform layer 2 functions like switching, physical addressing etc. When data is to be sent from one ethernet station to another, the data is first arranged in frames as shown in figure 2. Catalyst switches use hash to place mac in cam table 1 2 3. Layer 2 network design network startup resource center. If you need the switch to aggregate multiple access switches and do intervlan routing, then a layer 3 switch is needed. Routing operates at layer 3, where packets are sent to a specific nexthop ip address. Understanding the 5g nr physical layer understanding the 5g nr physical layer 3 low latency minislots cbg retransmissions frontloaded dmrs future proof forward compatible bandwidth parts reduced alwayson signals no fixed time relationship between channels waveforms and frame structure scalable numerology numerology multiplexing dynamic tdd. To enable multilayer switching, lan switches must use storeandforward techniques because the switch must receive the entire frame before it performs any protocol layer operations, as illustrated in figure 612. The performance of this class of switch is aimed at the core of large enterprise networks.
Because static routing allows traffic to be routed between vlans. Spanning tree protocol overview the plugandplay spanning tree protocol stp, a layer 2 protocol that ensures a loopfree topology in bridged lans, has been around for decades. Layer 3 switches the layer 3 switch functions at the network layer and performs the multiport, virtual lan, data pipelining functions of a standard layer 2 switch. By default, only vlan 1 is configured on the switch, so if you connect hosts on an outofthebox switch they all belong to the same layer 2 continue reading. This thesis will just focus on the digital version of circuit switching. Additional references for layer 2 switching cli version 21. In a network, when a switch receives a frame, the frame is first checked for the errors using cyclic redundancy check crc and forwarded. Stp spanning tree protocol explained with examples.
Switches may not bridge any traffic between vlans, as this would. How computers connected to a layer 2 switch communicate with each other, explained in detail stepbystep. You can configure layer 2 switching ports as access or trunk ports. Although this is a layer 2 ethernet switching course, networks always use higher layers as well. Switch configuration by the end of this session, you will be able to. It uses hardware based switching techniques to connect and transmit data in a local area network lan. What you will learn on completing this chapter, you will be able to. In the last step of the previous task, you configured the hostname. Trunks carry the traffic of multiple vlans over a single link and allow you to extend vlans. The phrase the network is as fast as its slowest link comes to mind. For protocol testing, you need protocol analyzer and simulator.
Mar 03, 2015 understanding basic layer 2 switching concepts. This tutorial is the second and last part of the article layer 2 switching loop. Layer 2 overview although nxos is a single operating system for the nexus line of switches, the hardware architecture of the switches might differ slightly. For example, the catalyst 6500 is not the only layer 3 layer 2 switching device, but it has the most features and highest switching performance on the market today. Layer 2, also known as the data link layer, is the second level in the seven layer osi reference model for network protocol design. In this beginners networking training series, our previous tutorial briefed us about subnetting and network classes in detail we will learn the various features and application of switches at layer2 and layer3 of the osi reference model. The layer 3 packet cant use layer 2 mac addresses, so the ip address scheme was created for layer 3. Layer3 or multilayer forwarding traffic filtering and qos scalable, redundant links to the core and access layers historically, the distribution layer was the layer3 boundary in a hierarchical network design. To earn ccnp enterprise certification, you pass two exams. Basics layer 2 known attacks attacks described below are applicable to any ethernet switch based network and are based on common and basic switching functions. A layer 2 switch can assign vlans to specific switch ports, which in turn are in different layer 3 subnets, and therefore in different broadcast domains. Traditional switching operates at layer 2 of the osi model, where packets are sent to a specific switch port based on destination mac.
Layer 3 switching is the next generation of lan routing and switching technologycapable of transmission speeds up to ten times as fast at onetenth the cost of current systems. How computers connected to a layer 2 switch communicate with each other, explained in detail. Percy dias slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. In a typical lan, all hosts are connected to one central device. Understanding basic layer 2 switching part 2 youtube. This article discusses the difference between layer 2 and layer 3 switches and the appropriate use cases for each. Fun with ethernet switches sean convery, cisco systems. Combining the packet handling of routers and the speed of switching, these multilayer switches operate on both layer 2 and layer 3 of the osi network model. The main difference between layer 2 and layer 3 is the routing function. Differentiate among unicast, multicast, and broadcast transmission methods describe storeandforward, cutthrough, and fragmentfree switch ing mechanisms describe layer 2 and layer 3 switching operation 1003fmf. If you continue browsing the site, you agree to the use of cookies on this website. These addresses are called media access control mac addresses. Tcpip networks, access the transport layer setting up and releasing connections across the network ee4367 telecom. You can manage access control and policy, create separate collision domains, and implement port security at this layer.
It can also perform basic routing functions between virtual lans. Difference between layer 2 and layer 3 switches in computer networking system. A layer 2 switch is a type of network switch or device that works on the data link layer osi layer 2 and utilizes mac address to determine the path through where the frames are to be forwarded. Switches and bridges are used for layer 2 switching. The layer 3 interface vlan feature is explained in the ip configuration guide. Layer 2 concepts layer 2 protocols basically control access to a shared medium copper, fiber, electromagnetic waves ethernet is the defacto wiredstandard today reasons. They break up one large collision domain into multiple smaller ones. Layer2 is the network layer used to transfer data between adjacent network nodes in a wide area network or between nodes on.
Although this is a layer 2 ethernet switching course, networks always use higher. For this tutorial, i assume that you know what the layer 2 switching loop is and what problems it creates in the network. Understanding basic layer 2 switching part 1 youtube. This is usually called access layer in a network topology.
Although a different frame at least as far as mac addresses are concerned is sent hopbyhop through the network, the data content of the frame, called the layer 3 packet, remains intact from source host to destination host. Switch configuration introduction to ethernet switching v1. Distribution serves as the communication point between the access layer and the core. A pure layer 2 domain is where the hosts are connected, so a layer 2 switch will work fine there. Spanning tree protocol in layer 2layer 3 environments. Jun 05, 2014 module 4 layer 2 switching fundamentals by dr. When it comes to networking, layer 2 can be a very weak link physical links mac addresses ip addresses protocolsports application stream application.
Set various ethernetswitchingoptions such as voice vlan, l2 security dhcp snooping, dynamic arp inspection, etc, or other layer 2specific features. Simple cheap manufacturers keep making it faster wireless 802. The first comprehensive, objective guide to layer 3 switching. Ipx, or appletalk, but only with where the mac address of the recipient end. Layer 2 switching exceptions on srx series devices 48.
A switch is a bridge that uses frames with special tags called virtual lans vlans, to forward traffic. The lowest layer is the physical layer that defines the basic signalling on the medium. This layer usually incorporates layer 2 switches and access points that provide connectivity between workstations and servers. Ethernet transmits symbols representing logic ones or zeros across the medium to another station that decodes the symbols to extract the data. When it comes to networking, layer 2 can be a very weak link. This post will deal with creating layer 2 vlans on cisco switches and performing all relevant configurations. From the html or pdf version of the manual, copy a configuration example into a. This can be easily avoided by not spanning vlans across access layer switches. Layer 2 covers protocols like ethernet and sonet, which can carry ip packets, but only over simple lans or pointtopoint wans. When it comes to networking, layer 2 can be a very weak link physical links mac addresses ip addresses protocolsports application stream.
The network basics of bridging, routing, and switching. Chapter 2 basic switching concepts and configuration 2. Telephone is the best suitable example of circuit switching. Circuit switching was designed for voice applications. But layer 3 packets are placed inside layer 2 frames, and a network node that only looks at frames is called a bridge. Configure basic ip connectivity and elements to enable remote access. These days layer 3 engines are no longer bottlenecks and can keep pace with layer 2 engines. Vlans allow for greater flexibility by allowing different layer 3 networks to be sharing the same layer 2 infrastructure. This technique was somewhere in middle of circuit switching and packet switching. When a switch supports dynamic routing protocols, its no longer a strictly layer 2 switch. Set various ethernet switching options such as voice vlan, l2 security dhcp snooping, dynamic arp inspection, etc, or other layer 2 specific features.
Describe storeandforward, cutthrough, and fragmentfree switch ing mechanisms. Mar 02, 2015 understanding basic layer 2 switching concepts. Multilayer switching is a switching technique that switches at both the data link osi layer 2 and network osi layer 3 layers. In a properly designed network, lan switches are responsible for directing and controlling the data the flow at the access layer to networked resources. The switch behaves as several virtual switches, sending traffic only within vlan members. The data link layer in system a, for example, communicates with the network layer of system a, the physical layer of system a, and the data link layer in system b.
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