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Dilshan De Silva
Dilshan De Silva

Reputation: 1

What are the segments of a packet and parts of a frame in networking?

I have used google for the above questionair but I still couldn't find the answer for the above question. Please help me out on this.

Upvotes: -1

Views: 112

Answers (1)

SupaMaggie70 b
SupaMaggie70 b

Reputation: 356

Networking packets are quite a complicated subject, but I will try to explain them to the best of my ability.

Each packet has a source IP and a destination IP, and a body. That’s all it actually needs. Most packets also have a protocol. I don’t know every major protocol, but the basic ones are ICMP, TCP, and UDP(TCP and UDP might be built on ICMP, not sure). Tcp and UDP packets also have a source port and destination port. Using some Linux trickery, you can define your own protocol, but your router probably won’t know what to do with traffic coming in as it isn’t programmed to know whether it should let it in. TCP gives the illusion of a byte stream, but everything is still split into packets. ICMP is just a simple packet, used for pings and similar things. UDP is the most basic of the 3, and is similar to ICMP but with ports, as far as I can tell.

Back to TCP, it splits into multiple packets, because too large of packets are more likely to get lost. TCP also makes sure all packets arrive and in the right order. A stream is nessesary for this, as if you were to try to send your own packet, it wouldn’t have a check for how large, and could get lost very easily if not done right.

A UDP listener simply tells the OS to listen for UDP packets on that port instead of discarding them. When you send a UDP packet, the router remembers the source and destination, and allows the other end to communicate back for a certain length of time.

A TCP listener accepts packets requesting a UDP connection, and sends them to a different port. The router uses a similar strategy to UDP to know if a packet should be let in. Unfortunately, if one side terminates, there is no way for the other side or the router to know. Thus the router will often continue letting in packets to a stream that was closed, which could pose a risk.

This is my understanding, it is very much flawed. Hope I could help nonetheless!

Upvotes: 0

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