A layer 3 switch is a specialized hardware device used in network routing. The funny thing about arp is that it actually provides service to two different layers of the osi model. The r first bytes r 1,2,3 correspond to the network address. The network layer is interested in getting messages to the corresponding network. Vmware virtual san layer 2 and layer 3 network topologies deployments. In the sevenlayer osi model of computer networking, the network layer is layer 3. Network protocols and vulnerabilities dan boneh cs 155 spring 2010. With source specific multicast, shortestpath trees are built and are rooted in just one source, offering a more secure and scalable model for a limited amount of applications mostly broadcasting of. The network layer is responsible for packet forwarding including routing through intermediate routers, since it knows the address of neighboring network nodes, and it also manages quality of service qos, and recognizes and forwards local host domain messages to. 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. Exchange ipx are examples of network layer protocols. Introductiona network can be defined as a group of computers and other devices.
Ip is the standard for routing packets across interconnected networkshence, the name internet. Almost all linklayer protocols encapsulate each networklayer datagram within a networklayer datagram is inserted, and a number of header fields. Lecture 2 protocol stacks and layering last time todays lecture. Ftp data ftp header tcp data tcp header ip data ip. Notice that the bottom layer is identified as the first layer. Traditional internet routers operate at the network layer by. Note that network layer addresses can also be referred to as logical addresses. This book excerpt is from chapter 2 of optimizing network performance with content switching. The common protocols at this layer are ip which is paired with tcp at the transport layer for internet network and ipx which is paired with spx at the transport layer for some older macintosh, linus, unix, novell and windows networks. Within the service layering semantics of the osi network architecture, the network layer responds to service requests from the transport layer and issues service requests to the data link layer. Layer 3 network pim source specific mode communication flow. Layer2 network design a good network design is modular and hierarchical, with a clear separation of.
Mx series router architecture techlibrary juniper networks. Network layer protocol configuration phase after the link is established and lcp negotiates optional facilities as needed, ppp must send ncp packets to choose and configure one or more network layer protocols. Knowing your layer 2 and layer 3 protocols biztech. Network 1 network 2 global internet address 123 246 subnetwork attachment point address logical connection e. 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.
Presentation application session transport network data link physical layer 7 layer 6 layer 5 layer 4 layer 3 layer 2 layer. The top layer in the stack, the application layer is where the enduser applica tion resides. Network ip link layer application message data tcp data tcp data tcp data tcp header ip tcp data ip header eth ip tcp data etf link ethernet. Many of these protocols are originally based on the internet protocol suite. Layer 2 concepts layer 2 protocols basically control access to a shared medium copper, fiber, electromagnetic waves ethernet is the defacto wiredstandard today. Mpls operates at a layer that is generally considered to lie between traditional definitions of layer 2 data link layer and layer 3 network layer, and. How useful is a layer 3 switch for network routing. Metro ethernet forum layer 2 control protocol handling. The network layer is in charge of routing network messages data from one computer to another.
Mpls makes it easy to create virtual links between distant nodes. This requires stripping off the datalink layer frame information. Optimizing network performance with content switching chapter 2. A layer 3 switch is a highperformance device for network routing. The basic function of spanningtree is to prevent bridge loops allowing a network to have redundant links and failover paths to a single destination. Ssi, 2006 cse 123a lecture 2 protocols and layering21 the osi layering model application presentation session transport network datalink physical end host application presentation. This article lists protocols, categorized by the nearest layer in the open systems interconnection model. The most significant protocol at layer 3 also called the network layer is the internet protocol, or ip. Network layer protocols 2015 jens andersson etsf05etsf10 internet protocols. Within the discussion of content networking, we will.
L3 is responsible to get it from source to destination by deciding the path, and using l2 for each step along the path. Network protocols acronyms and abbreviations list of network protocols with abbreviations order by index. Arp rfc 826 is used to translate layer 3 ip addresses into layer 2 mac addresses, thus allowing devices such as switches and routers to determine where other devices are located on each port. Lan layer 2 qoscos protocol for traffic prioritization205. Spanningtree is a layer 2 protocol developed to avoid any layer 2 loops in the network when you have different paths to one or more destination. Provides connectivity and path selection between two host systems routes data packets selects best path to deliver data the network layer prioritizes data known as quality of service qos. Data link layer protocols the data link layer provides service to the network layer above it. This list is not exclusive to only the osi protocol family. Version ihl type of service total length identification flags fragment offset ttl protocol header checksum source address destination address options padding figure 3.
Internet network layer protocols 14 network layer protocols in the internet ip main protocol, responsible for best effort hosttohost delivery arp maps ip address of next hop to its macphysical address used when passing packets to lower datalink layer rarp maps macphysical address to ip. The network layer provides the means of transferring variablelength network packets from a source to a destination host via one or more networks. It is an encapsulating protocol similar to the way ethernet is an encapsulating protocol. Network data link physical application presentation session transport network data link. Data link layer, layer 2 in the tcpipbased layered network, layer 2 is the data link layer. Tcpip tutorial and technical overview ibm redbooks. Chapter 1 introduction to networking and the osi model. A layer 3 protocol, in a packet switched network such as the internet, is that protocol providing sufficient functionality to move a packet from one network to another.
A datalink protocol specifies the structure of the frame, as well as a channel access protocol that specifies the rules by which a frame is transmitted onto the link. Along with the transmission control protocol tcp, ip represents the heart of the internet protocols. Protocol encapsulation chart a pdf file illustrating the relationship between common protocols and the osi reference model. For now, network managers should plan on mstp for at least the next five years. While layer 2 protocols such as stp operate within a lan environment, routing between subnets requires layer 3 dynamic routing to minimize management costs. Chapter 3 network layerinternet protocols 63 figure 3. The services provided by the network layer should be independent of the subnet topology. Internet protocols 303 ip packet format figure 302 fourteen.
Vmware virtual san layer 2 and layer 3 network topologies. The key components of the juniper networks mx series 5g universal routing platforms are. Fun with ethernet switches sean convery, cisco systems. The transport layer should be shielded from the number, type and topology of the subnets present. Most tcpip application layer protocols were developed before pcs, guis and. Describe the function and operation of layer 2 switching.
Think of the application layer as the browser application or email client for a user sur. Network layer protocol an overview sciencedirect topics. Layer 3 networks are built to run on on layer 2 networks. In an ip layer 3 network, the ip portion of the datagram has to be read.
If we view the original check as a unit of data needed to be sent, we now have two envelopes required. In the internet suite of protocols called tcpip, it is the ip layer. It can encapsulate packets of various network protocols. Nth layer control info is passed as n1th layer data. Both can support the same routing protocols, inspect incoming packets and make dynamic routing decisions based on the source and destination addresses inside. Identify the seven layers of the osi model identify the function of each layer of the osi model identify the layer at which networking devices function identify the function of various networking protocols. Router 3layer physical, datalink, network device, with 3 key functions. A router works with ip addresses at layer 3 of the model. Principles, protocols and practice, release techniques allow to create pointtopoint links while radiobased techniques, depending on the directionality of the antennas, can be used to build networks containing devices spread over a small geographical area. Layer 3 the network layer layer 3, the network layer of the osi model, provides an endtoend logical addressing system so that a packet of data can be routed across several layer 2 networks ethernet,token ring, frame relay, etc. While a protocol that affects the configuration or operation of a layer 2 network can use any type of frame with ordinary unicast or multicast addresses, the protocols that are considered layer 2 control protocols with the reserved addresses above can take advantage of special. Layer 3 switches technically have a lot in common with typical routers, and not just in physical appearance. It can also perform basic routing functions between virtual lans. The actual protocols encompassed in the link layer are numerous, and the implementation details can be found in various documents throughout the internet and in trade texts.
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