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 avoid issues with tangential / trivial questions or help vampires.
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On what basis does a router actually install GRE headers and remove them?
I am learning about networks and I have reached the topic of tunnels. At the same time, I have a need to set up a GRE (Generic Routing Encapsulation) tunnel between a remote server (to route addresses ...
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In HDLC, how to recognize bit stuffing?
In framing for the HDLC protocol, assume the receiver receives the following string of bits:
[…] 011111010 […]
How can it realize whether the sequence “011111010” is real data, or the result of a bit ...
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Conflicting opinions for route aggregation [duplicate]
I am a student and I came accross this question:
An ABR in OSPF has in its range networks 10.0.8.9/24 to 10.0.21.0/24. how can it summarise the networks? not necessarily in one prefix.
What we ve ...
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Recognizing the next protocol in MPLS header
How can I know what is the next protocol in MPLS header?
I do know that MPLS header does not provide any information about the next protocol,
But I somehow need to know how to recognize it, as I am ...
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1
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How PoE interacts LLDP and LLDP-MED?
I need to research 802.3at PoE PSE capable equipment for a project in my company's network, but I have some knowledge gaps regarding PoE operation and its reliance on LLDP.
I took a look over 802.3-...
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In MPLS RSVP how would methods of reservations like Wildcard-Filter, Fixed-Filter method, and Shared-Explicit method be explained in simpliest terms?
More specifically I do not understand what is concedered by "transmitter described with wildcard character" in Wildcard-Filter method in RSVP? How is reservation done with this method? What ...
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How can GMPLS unify signalization plain of all telecommunications network technologies?
In what way can GMPLS do that unification of signalization of network technologies, by hardware, like MPLS switches, or by network protocols? And what is the role of optical networks in GMPLS? Are ...
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How is window retraction a "general" problem when segment length is less than the window scale factor?
In the RFC 7323 there is an example about window retraction:
https://datatracker.ietf.org/doc/html/rfc7323#appendix-F
The text also says this:
This is a general problem and can happen any time the ...
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The use of a link local IPv6 address
In a networking course that I'm following, there was a mention of several ways of how IPv6 link local addresses can be used, such as
Assigning the link local address of a router/L3 switch as the ...
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Is there a term for application layer protocols that are responsibilities of network engineers?
In studying network engineering, it is usually taught that network engineers are responsible from physical layer up to transport layer, that is, layer 1-4 only.
Obviously, HTTP or HTTPS are off-topic ...
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Valid uses for IPv4 Options [Community-Wiki]
Engineers building firewall rules often block all IPv4 packets with IPv4 Options set in the header. However, there are a few common and valid use-cases for IPv4 Options.
This Q&A is intended to ...
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Can a BGP speaker records alternative paths to the same destination?
The BGP RFC 4271 reads :
In the context of this document, we assume that a BGP speaker
advertises to its peers only those routes that it uses itself (in
this context, a BGP speaker is said to "...
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How does QUIC encrypt packets containing multiple CRYPTO frames?
TCP is slowly being replaced by QUIC and I'm implementing a component that looks at QUIC packets to extract the server name indication from initial packets. The code is working fine, assuming that: (1)...
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How does QUIC provide delivery guarantee?
I'm struggling to grasp how QUIC implements handshakes in contrast with 3 handshakes in TCP. I came across with this picture on Wikipedia. As QUIC uses UDP, I don't understand how the protocol ensures ...
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How router will send ARP resolve packet when it receive ARP request?
How router will send ARP resolve packet when it receive ARP request ??
Router by default enabled with proxy arp configuration?? If then proxy arp is not configured then what will happen if it receives ...
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Does Network Discovery (rfc2461) preclude ARP sniffing?
I'm debugging a system demonstrating intermittent loss of connection. It's loosing entries from the neighborhood cache while there are active connections.
Does Neighbor Discovery (rfc2461) require ...
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Is the EAP-Request/Identity and EAP-Response/Identity transmitted in the clear in a WPA2 entreprise Wi-Fi setup?
Looking at the WPA2 (Entreprise, let's say PEAP-MSCHAPv2) Wi-Fi protocol, I understand that since WPA2 uses Open System Authentication, and that 802.1X authentication takes place before the 4-way ...
user71928
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What is the point of Wi-Fi Association?
In the 802.11-2020 standard, you can read, regarding 802.11 Association
To deliver an MSDU within an ESS via the DS, the DS needs to know which AP within the ESS to deliver the MSDU, so that the MSDU ...
user71928
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2
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Does window size in tcp header include tcp header size?
Let's say a TCP segments has in the field of "window size" = 1400 bytes.
Does that mean that
we can send 1400 bytes counted in tcp segments = TCP headers + data
or
it does specify only ...
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Size of an ethernet frame carrying an arp request using ip (no options) & ethernet?
OKay so I found that this frame has size 72 bytes with no explanation and I can't seem to be able to figure out why .
Ethernet payload will be : ip header + arp packet
Arp packet with ip & ethrnet ...
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802.11 Protocol on Different Frequency [closed]
Wifi (and the 802.11 protocol) takes place on 2.4Ghz and 5Ghz frequencies. Is it possible to recreate this protocol on a different frequency (say 500Mhz) and create a functional network using a modded ...
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Diffie-Hellman with PSK/PKI in the context of IKEv1
It seems I fail to understand few things about DH's functionality in the context of IKEv1.
A little bit of context first:
During IKE Main Phase, with the 3rd and 4th messages, the peers each exchange ...
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2
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Why two routers connected via PPP don't use ARP but Ethernet requires ARP?
I have read from @Ron Maupin's answer of this question that your two routers are connected via PPP (this is not uncommon), ARP will not be used , but if the two routers are connected via ethernet, ...
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How is P actually chosen in P-persistent CSMA?
I am struggling to understand how the probability value P is chosen for P-persistent CSMA for any particular station, what's the logic behind this.I have read from Wikipedia .
P-persistent
This ...
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2
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Why does IPsec not support Multicast/Broadcast?
Many sources site GRE as supporting broadcast/multicast and IPsec does not. Both GRE and IPsec are merely tunneling protocols. Therefore there is nothing inherent about tunneling protocols which ...
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Does UDP can be exposed to stateful analysis?
From protocol theory we know that TCP is stateful protocol.
Different stateful packet filters do filtration based on connection state. I.e. it can distinguish responses and replies. It's obviously for ...
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Could one call a network protocol an algorithm too
Is protocol - the term that is used in mainly networking contexts is nothing but
an algorithm ? Could we so say like TCP algorithm ?
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Does RIP v1 store next hop in its routing tables?
Does RIP v1 routing protocol store "next hop" field in its routing tables despite not announcing it in the updates? And if yes, how does it do that, simply by storing the address of the node ...
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How Pruning avoids loops in Protocol Independent Mulitcast (PIM- SM)?
I can not think of a scenario, how pruning avoid loops in PIM-SM when a router joins a SPT. I understood that it avoids duplicate messages, but how it avoids loops?
I want a scenario where the router ...
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What happens to the packets in the sender buffer when "eventually a timeout would be reached" for a **delayed ACK** in a AIMD TCP connection?
In a AIMD TCP connection, What happens to the packets in the sender buffer when "eventually a timeout would be reached" for a delayed ACK for a specific packet at the sender side?
Suppose ...
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2
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rules regarding IPV4 fragments and piecing them together
I'm rolling off my own TCP/IP stack for DOS and I have a question on IPV4 packets.
Assuming that a client sends multiple IPV4 fragments, I would predict the MF flag would be set for every fragment ...
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Recommended IPv6 prefix size for PPP to a single host?
I am using PPP to create a IPv6 connection to a remote host.
What is the recommended IPv6 prefix size for a single host at the other end of the PPP connection?
Should it be /128, because there is ...
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Retransmission timer: one per segment or one global timer?
TCP uses various mechanisms to detect packet loss and decide when to retransmit segments. In this question, I am asking about the timeout-based retransmission, wherein a TCP retransmits certain ...
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What would happen if TCP flow control is turned off hypothetically? [closed]
I understand that TCP flow control provides a way for the receiver to backpressure the sender. But what if we eliminated this from the protocol. Of course, the receiver would still ACK everything ...
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Is there any way to send different data packets together over wireline/wireless link? [duplicate]
I would like to know if there is a technology that allow to send many packets (of different data) together and at the same time over communication link (whether in wireline or wireless networks) of ...
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WAN Frames vs. STS-1 and T1 Frames
I am having trouble understanding the need for WAN frames, such as PPP when using the SONET Protocol or T-Carrier System. Since SONET uses STS-1 frames and T-Carrier uses T1 frames, why is there a ...
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I have issue with MSS and window size [duplicate]
I made a short example because I have tried understanding the difference between MSS and window size in tcp header when we consider a sender and a receiver.
So let's say sender and receiver use the ...
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Nature of TCP Timeouts
Are timeouts in TCPs inherently part of sequence numbers, or is it an entirely different component of a TCP packet?
I understand that timeouts provide some level of reliabilty to a data stream, in ...
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Does the destination port change during TCP three-way handshake?
I'm learning networking programming in C and there is a question bothers me a lot, does the destination port change during TCP three-way handshake? Let's say I have a cilent application running on ...
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Do these 2 packets belong to the same tcp socket?
Let's say we have two packets A and B.
A: Has source-IP S1 , destination-IP D1 , source-port SP1 , destination-port DP1
B: Has source-IP S2 , destination-IP D1 , source-port SP2 , destination-port DP1
...
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Does an application implemented using services of layer n necessarily belong to layer n+1 and implement a protocol in layer n+1?
I was wondering what counts a protocol?
When an arbitrary (software or hardware) application is implemented on top of the service of layer n in the Internet Protocol stack or the OSI model,
does ...
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Does the control packets flow into a router/switch through forwarding plane? [duplicate]
I know there are two platforms in any networking device separating the control packets from the traffic, which I call control plane and data plane. My question is, how does the control packets enter ...
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Networks theory: Layers, Services and Interfaces
I want to learn about computer networks from the bottom up.
I don't really understand the nuances of networking layers, with books mentioning that layers provide services to layers above them, but the ...
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Does the first TCP FIN packet (active close) goes with just only FIN bit set?
Suppose we have established TCP connection. The active close process assumes the FIN packet been sent to trigger TCP connection closing.
But I can't figure out, is this first (active close) FIN packet ...
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Is there any other network protocol than tcp/udp that works with ports?
Do you know at least one protocol (any OSI layer) that, like tcp and udp, works with ports ?
Thank you
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Question about the rebooting state of the DHCP protocol [closed]
Taking into account this diagram...
I wonder if a device, after a reboot having a previous known configuration, uses it from the start even tho it's still asking to check if it can continue using ...
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Why is delayed segment prevention (TIME_WAIT) in TCP only done for one side?
One of the reasons for TIME_WAIT is to prevent old packets/duplicates, coming in late, to screw up subsequent connections on the same (src ip, src port, dst ip, dst port) quadruplet.
That makes sense, ...
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ICMP distinguish error messages
Can a Internet Control Message Protocol when an error is sent can it tell which datagram that made the error?
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Does UDP do anything at all?
It's my understanding that TCP has logic for ensuring reliable communication, but UDP just naively sends information along the channel set up for it using IP and things in lower layers.
Does UDP ...
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How does the ARP table know to update if two hosts flop IP addreses?
When hosts on the same local network communicate, they manage their own ARP tables which translate between IP addresses and MAC addresses. Thus when computer A needs to send data to IP address ...
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