![]() It works pretty simple: an additional header with a VLAN-tag is added to the frame, and it determines which network the frame belongs to.Īnother device is a bridge. ![]() You can implement it, say, using a switch. But what if we want to establish a network of servers located physically in different places? Or, say, we want to logically separate servers connected to one switch in one location into different networks?įor such cases a VLAN (virtual local area network) is created. Of course, a bunch of servers connected to one switch is quite an obvious way to create a network. A lot of devices connected to one switch form a local area network(LAN). The task of L2 switch (there are more advanced ones, concerning 元 and even L7) – to forward frames from MAC sender to MAC receiver. A network needs additional devices for its organization.Ī switch is a device which builds up the network and which all our machines are connected to via ports. You have already noticed that your computer has billions of cables connected directly to all computers in the world. Thanks to lo, local applications can communicate with each other even without a network connection. Lo is a loopback device, a specific virtual interface, which system uses to communicate with itself. In this case, an interface used for communicating with the world via network is eth0, which has the MAC-address 52:54:00:05:36:e6. Let's look at the interfaces using the ip ~]$ ip link showġ: lo: mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT Of course, a machine can have multiple NIC's. NIC has a MAC-address – a unique address usually embedded in a hardware or generated by a virtualization system. This is a piece of hardware (or virtual hardware), which is responsible for sending and receiving frames. This address is called MAC-address.įirst of all, every device (including your laptop) has NIC - Network Interface Controller. ![]() Data is transmitted in frames, a frame contains the physical address of the sender and the receiver. Data link layerĭata link layer is responsible for the transmission of data between two devices in one network. Examples of protocols: Wi-Fi, Bluetooth, DSL. The very transmission of data by wire (or wireless) is described in this layer. The protocols of this layer are responsible for hardware communication on the lowest level. You will hear things like "it happens on the 3rd layer" a lot. OSI divides the communication into 7 layers, each one having its protocols. This model standardizes the communication between network protocols. We'll be thrilled to be your guides on any part of this journey.įirst of all, we need to get familiar with the OSI model. Don't be lazy, click all the links and read everything.īut in this text we will focus on a network structure, its basic components and see how they are used in practice with the help of virtual machines and libvirt/KVM in particular, which we have become familiar with in the previous article.ĭevOps consulting: DevOps is a cultural and technological journey. ![]() Inside of the article and in the end of it, I will give a lot of links to the sources, which can help you deepen the knowledge you've gained. The goal of this article is not to give a comprehensive guide on networks. No part of the infrastructure should remain a blackbox neither for developers nor for administrators nor, of course, for you, the future DevOps engineer. It doesn't matter how many frameworks you have learned, without the networking knowledge you won't be taken seriously. Such an attitude is not only incorrect, but also wrong for every self-respecting IT engineer's career. It often happens with us: we use words like IP and DNS every day, but there's no understanding how it all works, and how to try it on. Even programmers most often take networks for granted and don't think about how they work. All the used technologies, protocols and best practices are pretty old, they have been surrounding us and ensuring the communication between millions of devices around us for a long time. The subject of networking, unfortunately, is boring for the most of our colleagues. ![]()
0 Comments
Leave a Reply. |