Posts8 Link layer packet (frame) transfer This is a more in-depth overview of what happens in link layer when a host wants to send a message from a host to another host. The last post covered how error detection works in Link Layer, so I won't bother about the details of error detection in this post. Rather, I will focus more on keywords like MAC, LAN, ethernet, switches, ARP. I know, lots of buzzwords, but that's network :0 Each host h.. 2021. 10. 12. Link layer Error Detection Code (EDC) Link layer is the second layer in the five layer model of network. Link layer packet is called 'frame', and the purpose of link layer is to put datagram (from network layer) into a frame. Frame = [headers, EDC(error detection code), datagram, trailers] Out of services that link layer provides, error detection and correction are two things that we will focus our discussion on. Error detection and.. 2021. 10. 10. Hierarchical routing (iBGP, eBGP, OSPF, RIP) Motivation We communicate from our house to somewhere distant. In order for this to happen, we need to determine exactly which routers have to be trodden to get from our host to the other host. Routing algorithm determines the path. We also want the algorithm to provide the most efficient path to get from one host to another. The easiest way to do this is to see the network as a single, giant gr.. 2021. 10. 9. When everyone wants to say something - MAC (Medium Access Control) Recall the issue of deadlock? That's when many people wants to access a resource at the same time - we impose concurrency control at different isolation levels and reduce concurrency issues that could occur. There's a very similar issue in networks. It's multiple access problem. Let me outline the context, and the key problem that MAC (Medium Access Control) has to solve. There's a central hub c.. 2021. 10. 5. Building multiroom chatting app in python (PyQT5, pure TCP socket) I'd like to share what I had to consider while building a chatting application. This is for an assignment where you have to build a chat application where you can connect to a server (by specifying ip address) and chat 1:1 with other people that are connected or create a group chat to talk to others. At the start, I was a little bit frustrated by the requirement - you have to use pure TCP socket.. 2021. 10. 3. Authentication, Email, SSL Authentication (uses symmetric key system) If A wants to prove its identity to B, that's authentication. Or more precisely, it's an End-point authentication. If A was able to visit B, then it would be super easy to prove its identity. But in the network, the only way that authentication can be done is via packets sent over the network. Authentication of A to B: A sends 'hello' to B. A receives n.. 2021. 9. 30. How do we guarantee confidentiality and integrity of message over the network? (ft. symmetric key, public key, hash, digital signature, certification authority) Network is always vulnerable to attacks. In particular, the existence of packet sniffing means that whatever is being transferred across the internet can be read, bit by bit. So rather than denying the potential for leaking the packets, network engineers have come up with several very robust, mathematical solutions that even if you know what the bits that are being transferred are, you cannot de.. 2021. 9. 29. How is IP address allocated to a host/router? What is a subnet? Network layer deals with transmission of network-level packets called IP datagrams. Network layer is present on every router and end systems (hosts). Network layer is not concerned with the abstracted, end-to-end communication between two hosts (as in transport layer). It's concerned with the communication that happens between every pair of routers and hosts. That was abstract enough. Here's whe.. 2021. 9. 25. 이전 1 다음
