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Questions tagged [udp]

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

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11 views

Port unreachable trying to stream UDP movie with VLC (MacBook to iPhone) [on hold]

I am trying to stream a movie with VLC from my MacBook (192.168.178.23) to my iPhone (192.168.178.26) within my local network with UDP on the port 1234. So I open the streaming window and enter the IP ...
0
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0answers
48 views

why iperf3 UDP throughput is lower than the TCP throughput?

I'm running an iperf3 throughput test from my PC to another one, going through a router. I've tried the same configuration for TCP traffic and for UDP traffic. However, for UDP traffic, I get worse ...
1
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4answers
67 views

Why ICMP Destination Port Unreachable error messeage is generated for unreliable UDP packets?

My doubt is why an icmp destination port unreachable error message generated for udp. Why we can't simply discard the udp packet if the destination port is not reachable by saying udp is connection-...
0
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1answer
38 views

UDP in wifi getting excessively buffered

We are using a wifi-enabled device that receives a stream of UDP packets (30 per second). It is very important for us to receive these messages without lag, that's why we are using UDP and not TCP ...
0
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1answer
1k views

Does Cisco-IPSLA work with Huawei-NQA?

I want to monitor udp-jitter using IP SLA (Cisco Router). The Destination Router was Huawei Router. I'm not sure whether Huawei Router doesn't support IP SLA responder. Is there anyway to use NQA with ...
0
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1answer
57 views

what is the definition of out degree and in degree in computer networks?

in wikipedia we have a good definition for in degree and out degree in a graph: " The degree of a node is the number of connections or edges the node has to other nodes. in-degree is the number of ...
1
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1answer
46 views

How does a DNS response reach a client behind a NAT?

How does a DNS response reach a client behind a NAT? I'm talking about DNS queries using UDP for transport with a server that is not in the same network as the client. Does the NAT correlate the ...
0
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2answers
36 views

Forcing UDP traffic from specific ports [closed]

Is it possible that all traffic from computer 1 towards computer 2 go thru udp port D of computer 1 and received at udp port B of computer 2. Similarly all traffic from computer 2 towards computer 1 ...
0
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0answers
10 views

Can a UDP service and TCP service use one port? [duplicate]

When we open a UDP or TCP connection, there will start a port in server. there I have a question, can a UDP service and TCP service use a same port?
0
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1answer
64 views

If you're behind a firewall and all the ports are blocked, how is your browser able to access the internet?

I'm behind a router and I'm able to run game servers on my home computer after forwarding ports or using the DMZ feature on the router. However, I still don't understand the underlying technology as ...
2
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2answers
97 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 ...
0
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1answer
53 views

Is UDP Hole Punching possible if the network of one peer has multiple external IP addresses?

I've developed an implementation for UDP hole punching that works for most use cases that I've come across. However, one of our offices has a network configuration where we have two ISPs providing us ...
0
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1answer
153 views

How to plot and benchmark UDP response time?

Our application uses UDP protocol in the transport layer. I'm currently filtering the packet trace with the port and then manually checking the RTT by selecting the packet stream and by using " Set ...
0
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1answer
52 views

Avoid bottleneck in UDP multicast

The question is that a server is serving a multicast group with UDP. Lets say that its a file server and it will be serving big files (~10GB). Now we have a multicast group with multiple clients. Some ...
2
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1answer
382 views

IPsec, how to differentiate TCP and UDP

I read a little bit on the Wikipedia IPsec page. I was intrigued by: IPsec is an end-to-end security scheme operating in the Internet Layer of the Internet Protocol Suite I understand this as: ...
25
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7answers
6k views

Why isn't UDP with reliability (implemented at Application layer) a substitute of TCP?

TCP provides reliability at transport layer while UDP does not. So, UDP is fast. But, a protocol at application layer can implement reliable mechanism while using UDP. In this sense, why isn't UDP ...
2
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1answer
66 views

Collect UDP packets lost during iPerf test

I'm testing my network infrastructure where I'm using iPerf and UDP protocol. I'm using the following: On the server side: ubuntu@ip-172-0-1-11:~$ iperf -s -u and the client side: ubuntu@ip-172-2-...
1
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2answers
119 views

How to measure max bandwidth with Wireshark?

I'm trying to measure the max bandwidth usage of my LAN with Wireshark. I´ve done several packet captures but I don't know how to obtain the max bandwidth usage. Any Idea? Thank you in advance
0
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1answer
87 views

Weird Wireshark protocol list (eth:ethertype:ip:data where is the “udp”?)

I am capturing incoming and outgoing WAN to LAN data at a particular host on my LAN (i.e., the one actually receiving/sending the data). Sometimes I get anomalous captured frames that are missing the ...
0
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0answers
18 views

Are there NATs which will block any further incoming packets from a peer after rejecting first one?

I'm attempting to test udp hole punching. Right now I'm simply testing how my computer reacts behind a router. If I send a udp packet from my computer to a server, it can reply back on the same port ...
0
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0answers
47 views

Unable to get NetFlow flow in Cisco CSR1000v on AWS

I'm trying to use NetFlow Traffic Analyzer of SolarWinds or any NetFlow Monitor in my Cisco CSR1000v routers which are deployed on AWS. I am unable to see any NetFlow flows in the NetFlow Traffic ...
2
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1answer
99 views

Setting Destination MAC address for RTP/UDP packets

I have a requirement where I have to send the UDP packet to a destination multicast IPv6 address. In addition to that the packets must also have corresponding destination multicast MAC address set. I ...
-2
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1answer
127 views

How to send data from one PC to another PC over internet? [closed]

I'm basically a developer, and this is the first time i'm trying to develop a chat application over internet without any servers in between. It's easy to send data from PC to server and then to ...
7
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4answers
3k views

Why is a TCP Socket identified by a 4 tuple?

Newbie to networking here. I'm reading the Computer Networking (3rd edition) book, and in section 3.2 they are discussing multiplexing / demultiplexing for both UDP and TCP. In the UDP protocol, a ...
0
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2answers
146 views

How to calculate traffic in bytes from sFlow datagrams?

I want to approximate network traffic in bytes by writing a sFlow collector that receives sFlow datagrams, parses them, extracts key information only and applies a formula that summarizes the traffic ...
4
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2answers
69 views

Is it correct to assume that ordering of frames at switch level is not important?

My understanding is that if the payload of the frame contains any data that needs to be reassembled, at least for TCP payload, it can be done at the OS level, once all the packets are received and ...
1
vote
1answer
130 views

TCP or UDP for Stop & Wait / Go Back N

I'm creating server/client classes for "Stop & Wait" and "Go Back N" (variant of sliding window) protocols, though I'm unsure on whether I should pursue TCP or UDP. From my current understanding I ...
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
39 views

How to know difference between 2 devices connected to the same Wi-Fi hotspot in IPV4?

I am working on a small project to make a client server program to make a connectionless implementation & I want to transmit Information between 2 devices which is connected to the same Wi-Fi ...
6
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2answers
3k views

Why maximum length of IP, TCP, UDP packet is not suit?

From many tutorials, I get follow knowledge(maybe I'm misunderstood) : maximum of an Ethernet packet is about 1500 bytes. maximum of an IP packet is about 65535 bytes. maximum of a UDP packet is ...
0
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0answers
21 views

Why maximum length of IP、TCP、UDP packet is not suit? [duplicate]

From many tutorials, I get follow knowledge(maybe I'm misunderstood) : maximum of an Ethernet packet is about 1500bytes. maximum of an IP packet is about 65535bytes. maximum of a UDP packet is 65515 ...
-3
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2answers
64 views

How can TCP be used in order to implement DHCP and under which circumstances is this preferable?

I am pretty new to the computer networking studies and was learning about the DHCP protocol. It is implemented based on UDP, as I've gathered, but is there a way for it to be implemented over TCP? ...
4
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1answer
147 views

How does the transport layer tell UDP apart from TCP?

So I'm reading Computer Networking: A top down approach (where these images are from) and I was looking at the Transport layer. A generic segment in the transport layer has a pretty simple structure: ...
0
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2answers
112 views

Why do UDP connections only require a socket on one endpoint?

I thought for a long time that sockets were defined as an end point of a two way connection, however UDP sockets can be created without the other end making a socket to keep the connection live. What ...
1
vote
1answer
413 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 ...
0
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1answer
76 views

How is a lost DNS query handled [closed]

If a DNS query gets lost along the way to its destination, is nothing done about it? In my networking class, my lecturer said that DNS runs on UDP. I verified this in Wireshark by doing nslookup for a ...
50
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4answers
262k 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 different results someone says ICMP uses Port 7,...
1
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2answers
750 views

Why do routers (and router firewalls) go through so much effort to make peer-to-peer difficult? [closed]

It is not uncommon for large routers to have unpredictable, random port allocation (which cripples UDP hole punching by making port prediction impossible) and for firewalls (not the software firewall ...
1
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1answer
283 views

Does an EIM-NAT work across both UDP and TCP?

I've read RFC 4787, 5382 and 5128 and I just need a bit of clarification. Assume a NAT has Endpoint Independent Mapping behavior for both UDP and TCP. Although I understand that if a machine would ...
1
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2answers
1k views

UDP Sessions and Ephemeral Port Selection

I would like to ask community to help me finding answers to the following questions: According to RFC 6056 an operating system should pseudo-randomly select ephemeral ports for each transport layer ...
3
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1answer
7k views

VXLAN: how receiver knows that the received packet is VXLAN-encapsulated?

I'm trying to understand how a receiver knows that the received packet is a VXLAN-encapsulated. Looking at the VXLAN RFC, I can't see anything specific that defines that the packet contains VXLAN ...
1
vote
1answer
552 views

UDP checksum calculation on improperly padded packets

Suppose I'm receiving IPv4 UDP packets whose payload is less than 18 octets, so when they are transmitted over Ethernet they have some trailing padding. Between the packets' source and my receiver ...
1
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2answers
1k 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 ...
1
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2answers
288 views

Why is there a difference on the amount of data transferred during a UDP iperf measurement?

I have the following result from a UDP throughput test as measured by iperf3 $ iperf3 -u -t 10 -c 192.168.1.2 -b 100M -V iperf 3.6+ Linux pi-raspberry1 4.4.38-v7+ #938 SMP Thu Dec 15 15:22:21 GMT ...
3
votes
1answer
384 views

How can a UDP Client and a packet sniffer run on the same machine?

In my understanding, if you have a UDP socket client that is bound to a particular port, then a second UDP client on the same machine can't bind to the same port. If this is the case, then how can a ...
5
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2answers
2k 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.
0
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1answer
633 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 ...
2
votes
1answer
106 views

Is there any video streaming online service that actually uses UDP?

We usually hear that UDP is used with data with which a few packets loss/out-of-order can be tolerated like video streaming. And the instructor typically goes on saying "so if you lose a few ...
1
vote
1answer
30 views

Question about output of 'lsof -i' and UDP being connectionless

I'v got a simple setup: Server (IP 10.0.0.33) listening on port 7770 using the command: $ netcat -lup 7770 And a client (IP 10.0.0.2) that communicates with the server using: $ nc -u 10.0.0.33 ...
3
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2answers
52 views

How could a response be sent to the requestor without requestor's address?

I'm reading this talking about the differences between two fire-and-forget message (for example, under UDP) and a request-response communication (for example, under TCP). I came across this: The ...