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Questions tagged [protocol-theory]

For questions about network protocols published in a Standard or RFC. Do not use this tag merely because the question mentions a networking protocol in it. Questions with this tag *could* be closed if they do not explain why the question is relevant and important to answer; this is necessary to ...

0
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1answer
49 views

A new version of RIPv2 using different keys for each router

There's a problem in a textbook that is really stumping me. How would you enhance the RIPv2 protocol to provide a (more) secure and scalable schema for distributing the updates? Describe the ...
0
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1answer
44 views

TCP errors explain

Could anyone explain these errors: TCP ACKed unseen segment TCP Dup ACK TCP Previous segment not captured TCP Out-Of-Order TCP Retransmission
2
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2answers
70 views

NAT Translation Table Port Number

I had a practice question about a NAT-enabled router with outside address 24.34.112.235 and inside network 192.168.1/24 and three inside hosts .1, .2 and .3. The three hosts all open two connections ...
2
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2answers
189 views

tcp connection and stream flow question

Could anyone explain the main principe of tcp flow when making a session ? I have take a tcp dump when i'm trying to browse a site. when I analyse the packet by wireshark, i have found many Three way ...
0
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1answer
21 views

Is it possible to implement virtual network based on MAC in IP instead of MAC in UDP?

We know that flannel use MAC in UDP to create a overlay network. My question is: UDP header only provides an extra port number fields, let's suppose that one physical machine only run one flanneld ...
3
votes
1answer
29 views

Quagga router advertisement messages are wrong after an address change

I have a problem with Quagga OSPFv3 implementation. I have a Mininet topology with a host connected to a router. I assigned an IPv6 address to the router interface. And I enabled IPv6 ...
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0answers
36 views

Simulating TCP/IP Illustrated Test Network [closed]

I just recently bought TCP/IP Illustrated volume 1 first edition for cheap and I see that they reference a test network throughout the book that looks like the following Now I'm not the sharpest tool ...
1
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1answer
18 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 ...
6
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2answers
97 views

What Cisco will discard TTL=1 packets for own interface?

There have been a number of questions about router behaviour with IPv4 packets with TTL=1 and apparently contradictory answers. This question is not about what should a host or router do, it is a ...
3
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1answer
21 views

Why is retransmission delayed when the RTO is long?

I am new to networking and learning about TCP Timer Management and read this in my textbook: "If the value of time-out (RTO) is too small then unnecessary re-transmission will take place. If time-out ...
3
votes
1answer
30 views

Why are the Address and Control fields constant in PPP protocol?

I saw that address and control fields are constant in PPP protocol. What is the need for even having a field that has constant value in it if we had not have this field then wouldn't it have saved ...
3
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2answers
209 views

How does the Transport Layer construct the Pseudo-Header for TCP checksum?

THE TCP Psuedo Header needs sender and destination IP Address and protocol type. All of this informations is present in the network layer/IP header. Since the transport layer cannot access the data ...
3
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2answers
36 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 ...
3
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2answers
37 views

Do protocols ever have standards that affect multiple layers of networking?

I'm reading about higher-level protocols such as HTTP and SOAP (concerning the application layer at the highest level) in addition to lower-level ones such as TCP. So far these protocols concern only ...
1
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0answers
40 views

Processing received SACK information in case of reordering

I would like to understand how TCP receiver in established state should treat SACK information of out-of-order and fully within receive window segments, where rcv_nxt < seq_no < rvc_nxt + ...
4
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1answer
65 views

Features of ICMP

I'm taking a Network class and learned ICMP, but I cannot understand the reason why below arguments are applied. ICMP message is not generated on header checksum errors If a datagram carrying an ICMP ...
3
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1answer
37 views

Packet with wrong source MAC address

When I send a UDP packet with wrong source MAC address but with right source IP address, assuming a reply is sent, will I get the reply because I have right source IP address, or I will not get the ...
1
vote
1answer
250 views

Are Protocols written in programming languages?

The protocols such as HTTP, IP, BGP are written in programming languages or simply plain English text ? If it is written in plain English, then how it is communicated with web browser, switches/...
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3answers
265 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 ...
2
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1answer
183 views

Is There an Indication in Protocol Stack showing that the End Host is Mobile?

Suppose you are using the Web from your mobile phone. Is there any indication in the internet backbone, when you look at the traffic that shows that the end host is a mobile device? I am sure there ...
1
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1answer
53 views

Questions about TCP packets

I am currently in college learning about networks, and I just wanted to make sure that I understood part of the TCP correctly. The question is "What does TCP use to reassemble packets in the correct ...
1
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1answer
28 views

Are there any advantage of using multiple threads for a file upload, for an internet connected node? [closed]

I got asked in an intervew recently to design a file upload feature. After initial discussion, The interviewer asked if I can design for multiple threads. My thought was, As the network bandwidth is ...
1
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2answers
60 views

How do you know which layer-2 protocol is in action?

We know that the packet contains an IPv4 header, by reading the EtherType field. My question is, how does the NIC know the Layer 2 protocol is Ethernet to begin with? If there are two different Layer ...
0
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1answer
41 views

Whether every TCP packet have a Ack Reply?

The TCP Acknowledgements you see in the diagram's green arrows, have ACK numbers separated by 3000(two 1500 bytes). I have a question, why the Ack number is separated by two packets? Or is it just ...
7
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2answers
2k views

Where is Ping's “round-trip time” stored in the IP header?

If we use ICMP's ping, we know the TTL and round-trip time are stored in the IP header. In the below IP header map we know TTL's location, but where is the round-trip time? Is it stored in Options?
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2answers
33 views

Where is the data fragmented into pieces, and based on what rule?

When data from the application layer pass to transport layer: data may be fragmented into pieces of data, and then the transport layer will be added to the transport layer header (may be TCP header, ...
3
votes
1answer
193 views

Linux TCP stack repeatedly sends “TCP window update” without acknowledging any data

My company is developing its own TCP stack for low-latency purposes and one of the tests involves running 128 instances of ncat on Linux 4.11 to listen to ports 55000 through 55127 and sending data in ...
2
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2answers
29 views

How to understand the `Data in the Network Access Layer, it will be break up into smaller units.`?

Today when I read a book, there is a sentence: Data in the Network Access Layer(TCP/IP's layer 1/4), it will be break up into smaller units. I can not understand this statement, does it mean the ...
1
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1answer
136 views

How IP datagram know its upper layer protocol?

Hi I'm a newbie in networking, I just want to know how IP datagram know its upper layer protocol is TCP or UDP? I know there is protocol field inside the IP datagram header that can tell the layer ...
0
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1answer
73 views

Iterative queries of a default DNS server

I have just started to study networks and I have a confusion about what happens when a default DNS server does iterative queries to other DNS servers to resolve a name in an IP address. I am very ...
1
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2answers
47 views

How does the server know how to respond to a UDP packet? [closed]

As far as I know, UDP ports and OS sockets are mapped only by the (local port, local address) pair. In other words, the receiver side's OS does not keep a state of (remote port, remote address) pair (...
3
votes
1answer
319 views

Why are DHCP ACK and REQ messages broadcast in Link Layer?

When I look at the protocol, I see that DHCP Request and Acknowledgement are both broadcast in the link layer. However at that point, both sides actually know each other's MAC addresses. Why do they ...
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3answers
73 views

Why do we need an ethernet MAC address? [duplicate]

Don't think it's a duplicate. I've searched really many articles and couldn't find the satisfying answer. I understand : how ARP works MAC address is an unique address for each NIC IP is network ...
0
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2answers
35 views

Network Packet that allows maximum throughput

I created a basic wireless system between two microcontrollers. Each uses the on-chip UART and an HM-TRP radio module to communicate with each other. Eventually I'll have a master-slave setup where ...
2
votes
2answers
132 views

If the IPv6 address will be strictly based on EUI-64 logic then is there any real need of Neighbour Discovery Protocol?

I am building my fundamentals on IPv6 and have realised the multicast group is nothing but FF02::1:FFXX:XXXX. Here xxx is nothing but 24-bits of Mac-address (48 bits) with simple 7th bit magic. ...
0
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3answers
116 views

Do OSI and TCP/IP models use the same protocols?

OSI is known for using hundreds of protocols to do its job. Both OSI and TCP/IP have Transport and Network(Internet) layers where TCP and IP protocols work respectively. It is clear that TCP/IP model ...
0
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1answer
63 views

What Are the Advantages of Static IP Addresses?

As there are two types of IP addresses, why static addresses are harder to maintain, and if they are so what is their advantage to have one instead of dynamic IP adresses?
4
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1answer
146 views

Internet Protocol version 4 (IPv4) padding?

Where is ip padding insert in ip data-gram format, after payload?
3
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3answers
97 views

Do TCP implementations retransmit bytes or segments?

The sequence number and acknowledgement number in the TCP header is specified to contain byte counts. However, a lot of resources, including RFCs, say that "lost segments are retransmitted" instead ...
6
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4answers
718 views

Why is the Ethernet Connection Symmetric?

I know that cable connection (DSL) is asymmetric, there is a certain bandwidth on the channel, and for a better user experience, they allocate a bigger portion to the downstream. I suppose Ethernet ...
4
votes
1answer
606 views

Do we send ack frames in ethernet? if not then how does a router know if its neighbors are down or not?

So first off, do ethernet sends ack frames or not? if it doesn't : then how does a router know whether its neighbors are down or not? if it does : then is it cumulative ack with an ack timer or one ...
2
votes
1answer
84 views

Ethernet's frame format, length or EtherType?

Ethernet defines a 2 byte header for the payload's length in its frame format. This header has an ambiguous meaning: if smaller than or equal to 1500 it represents the payload length. if ...
0
votes
1answer
111 views

How do ICMP packets travel in a networks?

Questions: I'd like to know how ICMP packets travel in a network? Are they encapsulated within IP datagram? The RFC 792 doesn't explicitly states the layer of ICMP. Are ICMP messages sent using a ...
0
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1answer
64 views

Computer networking dwdm [closed]

Why do we use digital cross connects, which define permanent cross connect between source and destination in core network while the PSTN allocated circuits dynamically as both are types of circuit ...
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1answer
53 views

What is Ether? is it the same meaning with Ethernet?

What is Ether? is it the same meaning with Ethernet?
3
votes
1answer
99 views

How does SDN Controller know the IP address from a packet?

We've always said that SDN Controllers are "Protocol-less", they don't need to know the packet's encoding to switch it or, controllers can be routed packets by the IP Address and the IP Address used ...
4
votes
3answers
738 views

How is tcp/ip implemented

Well, first of all I am new to networking. And I have studied the layered structure of tcp/ip protocol stack. I know that the layered structure is an abstract model, but I didn't know how the ...
4
votes
1answer
469 views

How do data packets travel without merging?

I have been very interested in networking for quite a while, and I have been wondering this question. I've been thinking about this in complete binary, meaning how does a 0 of a data packet not get ...
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0answers
239 views

Selective Repeat protocol's window size

Hi I'm a newbie to networking, I can understand the differences between Go-Back-N and Selective Repeat protocol on transport layer.I'm confused with Selective Repeat, I know receiver might not be able ...
-1
votes
1answer
551 views

What is the EtherType of a BPDU frame sent by a switch which runs Spanning Tree Protocol

I want to know what is the EtherType field of a BPDU frame in various versions and variants of the Spanning Tree Protocol.