Questions tagged [udp]

For questions about User Datagram Protocol, a Transport Layer protocol.

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2
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1answer
943 views

TCP error recovery

Consider two machines A and B, machine A sends 3 packets to B of sequence number 1, 2, 3 during transmission only packets 1 and 3 are received by B. Now B requests for packet 2, and machine A sends ...
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2answers
610 views

How does data encapsulation work in the TCP/IP stack?

As a UDP segment traverses down the stack, each layer adds a header. What occurs for this to happen? Does the kernel do a bunch stuff then add the header? I am particularly interested in the ...
1
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1answer
911 views

How does address resolution work with multicast, specifically IPv6?

If I want to send an IPv6 UDP multicast message, how does L3 to L2 address resolution occur? I think I understand ARP and how this same idea applies to unicast, but I am struggling to grasp the idea ...
65
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5answers
405k views

PING port number?

Yesterday interviewer ask me what is port number for ping and which protocol ping use TCP/UDP. After interview I search on internet and found different results someone says ICMP uses Port 7, someone ...
18
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4answers
19k views

What does a UDP connection timeout really mean?

Since UDP is a connectionless protocol, I'm confused by the setting on my Sonicwall Firewall for "UDP Connection Timeout". It's set at a default of 30 seconds -- but what exactly times out after 30 ...
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2answers
2k views

How does the TCP/IP stack handle UDP checksum errors?

RFC 2460, Internet Protocol, Version 6 (IPv6) Specification, Section 8.1 Upper-Layer Checksums, states the UDP checksum is mandatory and any IPv6 receivers must discard UDP packets containing a zero ...
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3answers
55 views

Understanding the ways of communication in IP networks

I am trying to check my understanding about the ways of communication in IP networks. I would classify the ways of communication in IP networks into three generic types: The source requests name ...
0
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1answer
130 views

Looking for a lightweight reliable protocol directly built upon Ethernet utilizing jumbo frames? [closed]

I am looking for a lightweight reliable protocol utilizing Ethernet jumbo frames (for instance up to 9 KBytes). One side will be implemented on an FPGA without a CPU core (so simplicity needed) and ...
1
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1answer
559 views

UDP hole punching. How to listen to a port that is busy?

Good day everyone! I am developing a network application that is extremely time sensitive and having an intermediary server is not an option. Therefore, I decided to implement a udp hole punching ...
0
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1answer
853 views

Is UDP used in every TCP/IP connection?

I am confused on whether UDP and TCP work together, or are they completely separate protocols. So, UDP is used to allow multiplexing of different services on the same machine. So, essentially, for ...
1
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1answer
437 views

SNMP protocol MIBs & OIDs

I am trying to understand SNMP protocol. I have clear understanding how SNMP works on network level. We can send UDP request to device, but on this device snmpd should listen for incoming requests. ...
4
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2answers
3k views

IPERF TCP vs UDP

I had to determine UDP performance over multi-hop network , I used MAC Air over gigabit ethernet ( Thunderbolt). As is customary, TCP was tested and the gig over link was saturated ~900mbps, but ...
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4answers
1k views

Do subnet masks hinder the ability to listen to a UDP multicast?

I have a device connected to an ethernet switch, and my PCs NIC is connected to that switch as well. The device is sending multicast messages to 239.255.255.251 to which I am able to listen. My ...
1
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2answers
619 views

Types of packet loss

I am used to the term ICMP Ping Packet Loss but recently, I came across this other term UDP Jitter Packet loss I will like to know the difference between the two, and of what importance it is to ...
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2answers
256 views

The meaning of TCP port in the network context

When talking about ports, sometimes I read articles that state TCP port while others just say port. Are there some features that make TCP port different from other ports in the OS?
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1answer
41 views

How the hops and the subnets are influencing NATs and ports ?

I'm a beginner with networking, specifically linux networking, I have a question that I'll split into 2 parts : If I have an x number of hops inside the same subnet ( namely 192.168.1.x ) and my goal ...
4
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2answers
18k views

How to find out TCP/UDP latency of your network? [closed]

Many people often suggest you to use ping command to find out your network latency. But it is false and a myth you often find in articles on Internet. ICMP ping was never designed to find out latency ...
1
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1answer
519 views

UDP and fragmentation calculation

Assume we have a ethernet link with an MTU of 1300 bytes, while an application want to send 5200 bytes of data. How many fragments do we transmitted ? i would say 5, to send 5200 bytes over a link ...
1
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1answer
2k views

How TCP hole punching works?

Is TCP Hole Punching similar to UDP hole punching?How it is established between "Peer A" and "Peer B" when both the peers are behind NAT? You can use Peer A and Peer B as example to make it easy to ...
0
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2answers
373 views

Do MSS/MTU violate the protocol stack layers independence?

We studied that the beauty of internet protocol suite layers is that each layer is responsible for a piece of the communication process. These layers provide services to adjacent layers and operate ...
2
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4answers
1k views

Is a unique TCP/UDP port assigned to a user?

I know that a user is assigned a routable IP to access internet so I was wondering if user is also assigned with TCP/UDP port too? I mean just like there is a specific IP of the destination server ...
2
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1answer
163 views

When last was the OSI model layer updated

since reading about the OSI model, which was created since 1984. My question is has there been any revision on the model. Or did the delegate who design the OSI model made it for everlasting. Thanks
1
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6answers
12k views

When would one use UDP over TCP? [closed]

It seems TCP is quite a reliable service with error checking, end-to-end delivery assurance etc/, while UDP is a connectionless unreliable service. In what occasion would application engineers use ...
5
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2answers
5k views

How does a layer-2 switch work with UDP?

If UDP and/or TCP send packets via IP to an Internet Protocol Address, how can a layer-2 switch forward these? Is this possible or do you need a layer-3 switch?
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1answer
374 views

Firewall seems to damage/delay packages

I have two networks communicating with each other through a transparent firewall. My problem is that the software using these networks is reporting that it's losing packages. The number of lost ...
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2answers
20k views

What is the transport protocol used in wget?

wget is basically to retrieve HTTP contents from web servers. I want to know if wget is based on TCP or UDP? I did a search but some resources said it is TCP while others said UDP.
1
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1answer
974 views

How to calculate the data rate in 802.11g? [closed]

I know this is not the community to discuss my homework problem but I cam confused because I cannot find a formula that can find data rate for 802.11g standard given modulation, coding rate and ...
1
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2answers
784 views

Does UDP multicast overwhelm the network?

I am curious as to whether udp multicast creates a lot of unnecessary traffic on an internal LAN. I assume the obvious answer to me is yes, but is it enough to congest the switch and slow down all ...
0
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1answer
726 views

Blocking vs Non blocking IO? [closed]

I have just started network programming and I am a bit confused Does the read and write operations behavior {in regards to blocking or not} change depending if we have a regular file descritpor or a ...
5
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2answers
3k views

Why does IKE use UDP instead of TCP?

Why does IKE use UDP, and handle any retransmission itself? (Larger IKE packets may cause UDP fragmentation and are dropped by some ISPs: IKE over TCP.
2
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3answers
9k views

Can two different applications bind the same port on a host if they use different protocols?

So my question is quite clear I think. If two applications use different transport layer protocols (e.g. TCP and UDP or something else) can they open the same port number? How does the OS do the ...
3
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1answer
201 views

Satellite Internet Connection - Faster Speed?

I acknowledge the fact that satellite internet maybe quite slow and have high latency. This is generally true for TCP applications like HTTP, FTP etc. If a UDP VPN connection was to be setup between ...
2
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2answers
235 views

Using as many multicast groups as transmitting devices

We have a set of ~40 embedded devices, each one equipped with a wifi module. All the devices are connected to the same wireless network. All the devices send packets to the same "master" computer. ...
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1answer
1k views

HPE 1920-8G-PoE+ multicast filtering

I have a switch HPE 1920-8G-PoE+ that is connected to two computers and two access points: Ubiquiti UniFi AP-Pro n450. The access points receive data from many devices. The two computers send UDP ...
2
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2answers
2k views

Multicast doesn't get forwarded correctly [closed]

I have a problem with UDP-Multicast with Kubernetes: I have to Kubernetes-Nodes each of them running a pod: Kubernetes-Node-1: - eth0: 192.168.0.2/24 - docker0: 10.1.1.1/24 Pod1 on Kubernetes-...
4
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3answers
8k views

Why do i only see QUIC and not UDP during capture in wireshark?

I've been using wireshark and noticed that I no longer see UDP but QUIC, why is this the case?
18
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3answers
8k views

What do TCP/UDP add to “raw ip”?

I know that both TCP and UDP are built on top of IP, and I know the differences between TCP & UDP, but I'm confused about what exactly "raw ip" is. Would it be fair to say that TCP & UDP both ...
2
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3answers
1k views

Sending raw IP packets over UDP

Can we send raw IP packets over UDP? What are raw IP Packets? UDP is a connectionless and unreliable protocol, is it?
15
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3answers
89k views

How to verify that a UDP port is open? [closed]

I have here a dilemma. I have a device that communicates to another remote device but there is a firewall between them. It's a UDP connection, so TCP utilities don't work to test if the specific port ...
2
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2answers
127 views

Could long sequences of consecutive zeros cause Ethernet link problems?

I am in the process of debugging an Ethernet communication issue. Basically using Wireshark to monitor the source data the stream was intermittent when the cable was removed and subsequently ...
2
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2answers
3k views

Where are UDP packets lost during iPerf test?

I'm testing a 802.11 wireless link using iPerf and the UDP protocol. Using the -b command at the client, I can set the bandwidth to an arbitrary number (e.g. 1 Gbps) that's much higher than the link ...
2
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2answers
80 views

Performance of a socket [closed]

What is the difference between the following scenario's. And is there any performance differ due to this. Consider a server provide 5 services like web, mail, file, app and ssh : Each service and ...
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2answers
600 views

Connecting to a remote computer over cell network with flaky connection using VPN over UDP? [closed]

I was wondering if someone could provide some networking guidance. Any ideas/suggestions are welcome. I am trying to figure out how to reliably connect from my office computer to a computer on-board ...
6
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2answers
2k views

What is the reason for the different order of the Source and Destination in a L2 header?

A TCP/UDP header (Layer 4) lists the Source Port, then the Destination Port: An IP header (Layer 3) lists the Source IP, then the Destination IP: An Ethernet header (L2) and a WiFi Header (L2) lists ...
1
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1answer
140 views

UDP protocol that can't be used for DDOS?

I'm designing a protocol similar to the DNS protocol but that may return more data. I have the option to use UDP or TCP. UDP is attractive because it is stateless, but it can also be used for DDOS. ...
1
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1answer
638 views

why does my openVPN client work over udp, given that i am behind several firewalls [closed]

this is been puzzling me for months now, i tried to google this, but results are often irrelevant, like questions about why is something not working for someone and how to deal with firewall problems. ...
2
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1answer
331 views

Linux routing: routing between 2 local interfaces depends on source address? [closed]

The setup is this: The linux system (debian 7 as a VBox guest) has the following interfaces: $ ip addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/...
2
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3answers
139 views

Is there a way to build a functional (sub)network with devices that have the same MAC Address?

I have a series of modules (similar to a RPi) that run a Linux flavor each having an Ethernet NIC. I have 4 of these and I want to connect them to a switch to be able to send UDP packets to each one ...
0
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2answers
1k views

Real time traffic explanation

What is the difference between Best effort traffic and Real time traffic? Is TCP means best effort traffic and UDP means real time traffic? Or anything else?
3
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2answers
4k views

Very slow TCP speed and throughtput in contast to UDP

I have been monitoring a 1 Gbps OM2 fiber connection to one switch we have with Smokeping... There seems to be an avg loss of 3-4% for a few days now.. Started troubleshooting using iperf, having set ...