2/15/2024 0 Comments Youtube radia perlman recital![]() In a routing loop, a packet is passed continuously between routers. The packet traverses multiple networks, with IP protocols guiding it towards the destination, ensuring error checking and congestion handling. ![]() It passes through routers that consult their routing tables to forward the packet. A packet reaches its destination through routing. *"How does a packet get to the destination?"* It uses IP addresses, routing tables, and algorithms to determine the best path for packet forwarding, connecting different network types and managing traffic between internal and external networks.ģ. A router is a device that forwards data packets between networks, operating at the network layer. Packets enable efficient routing and reassembly at the destination in network communication. ![]() It contains both the payload (actual data) and control information such as source and destination IP addresses. A packet is a data unit sent over a network, encapsulated within protocols like IP and TCP/UDP. What do you think of these answers? Would chatgpt pass the interview? I asked chatgpt to give me answers to these questions as I'm also in the process of learning these things. But that's more in line with what you call "using it to troubleshoot", which is not "how it works."īut "how traceroute works" is simple: First you send a packet with TTL=1, then you send a packet with TTL=2, and so on. But these are not inherent or necessary to perform a traceroute.Īnd understanding why different protocols exhibit different behavior / observe different metrics, or why some nodes don't send ICMP TTL expired, is important. Sure, there's lots you can do to enrich the data you receive (e.g, reverse DNS and geolocation), or sending multiple sequences to identify equal cost multipath. None of that is relevant to the fact that all traceroute implementations make use of very basic networking fundamentals: in particular, by sending out a series of packets with artificially limited TTL, to receive ICMP type 11 code 0 "TTL expired" packets from the hops along the path to your target. Your linked 1+ hour video includes things like IATA airport codes for geolocation and such. I still think being able to figure it out is a reasonable problem solving question. Also, Linux/Unix traceroute by default use UDP to a high numbered (and usually closed) port for probe packets instead since UDP historically is less likely to be dropped/filtered than ICMP.Īside: asking how traceroute works is one of my interview questions, most people don't know (if they do the question is no good) and many are unable to figure it out from first principles no matter how many questions I answer about TCP/IP. That said, your site has a very nice presentation.īTW, ipv4 TTL is dejure seconds even though it's defacto hop count since no router takes more than a second and the minimum decrement is 1 (except middleboxes which wish to remain hidden won't decrement at all). One of the first CGI programs I wrote nearly three decades ago (ugh.) was a Perl script that wrapped traceroute and streamed the results via server push. Search for: "looking glass bgp" and you'll find some. > I realized I had never seen this sort of thing on the web before. (Side note: why Rust? I don’t think programming language choice matters that much, but I wanted to quickly write a very dependable low-level program, and I really like Rust’s error handling primitives. I'm still hacking on this and I'm sure my code will manage to break somehow, so please let me know if you have any suggestions! :) In the process, I learned some really interesting things about how BGP and the structure of The Internet, so I melted the traceroute tool with an article sharing that knowledge. I realized I had never seen this sort of thing on the web before, and it was actually a kind of cool and novel way of visualizing the structure of the Internet, so I polished it up and built a pretty site around it. So I just hacked away on personal projects and, through some coincidental learning on how the Internet works, ended up hacking together a traceroute program that could live stream to a website from scratch! After cpu.land, I felt a lot of pressure to make another Big Giant Thing but didn't really have anything compelling. I'm 17, and one of the things I'm interested in right now is gaining a deeper understanding of how computers work and showing that in new ways.Ī few months ago I published (discussion: ).
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