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.
454
questions
0
votes
0
answers
22
views
Response ARP packets destined for IP addresses ranging from 192.168.0.1 to 192.168.0.255 [closed]
As seen in the image below, I have these many ARP packets going from my wireless adapter to its own local ip address (192.168.0.2), is that a sign of arp spoofing attack?
- 1
0
votes
0
answers
30
views
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 ...
- 101
0
votes
1
answer
39
views
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 ...
3
votes
1
answer
284
views
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-...
- 183
0
votes
0
answers
14
views
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 ...
0
votes
1
answer
16
views
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 ...
0
votes
0
answers
28
views
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 ...
- 31
1
vote
1
answer
394
views
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 ...
- 759
1
vote
1
answer
73
views
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 ...
- 471
3
votes
1
answer
81
views
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 ...
- 29.9k
2
votes
1
answer
45
views
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 "...
- 23
0
votes
0
answers
82
views
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)...
- 465
1
vote
1
answer
214
views
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 ...
- 115
0
votes
1
answer
110
views
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 ...
- 127
3
votes
1
answer
252
views
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 ...
- 133
1
vote
1
answer
99
views
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
0
votes
2
answers
164
views
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
0
votes
2
answers
362
views
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 ...
- 103
0
votes
1
answer
1k
views
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 ...
- 103
-1
votes
1
answer
38
views
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 ...
1
vote
0
answers
190
views
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 ...
4
votes
2
answers
743
views
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, ...
- 358
1
vote
2
answers
1k
views
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 ...
- 358
1
vote
2
answers
2k
views
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 ...
- 127
1
vote
1
answer
65
views
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 ...
- 207
0
votes
1
answer
58
views
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 ?
- 101
1
vote
1
answer
72
views
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 ...
- 13
1
vote
1
answer
77
views
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 ...
- 113
1
vote
1
answer
263
views
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 ...
- 113
1
vote
2
answers
70
views
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 ...
- 11
3
votes
1
answer
131
views
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 ...
- 133
0
votes
1
answer
494
views
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 ...
- 55
1
vote
3
answers
620
views
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 ...
- 153
0
votes
0
answers
12
views
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 ...
- 63
0
votes
0
answers
44
views
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 ...
- 1
1
vote
1
answer
357
views
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 ...
- 113
1
vote
1
answer
44
views
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 ...
10
votes
5
answers
4k
views
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 ...
- 261
3
votes
3
answers
1k
views
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
...
- 133
0
votes
1
answer
56
views
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 ...
- 1,535
0
votes
0
answers
14
views
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 ...
- 581
3
votes
2
answers
214
views
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 ...
- 133
1
vote
1
answer
282
views
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 ...
- 113
1
vote
1
answer
199
views
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
- 13
0
votes
1
answer
141
views
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 ...
- 125
2
votes
2
answers
288
views
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, ...
1
vote
2
answers
73
views
ICMP distinguish error messages
Can a Internet Control Message Protocol when an error is sent can it tell which datagram that made the error?
- 147
44
votes
7
answers
16k
views
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 ...
- 559
1
vote
2
answers
754
views
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 ...
- 157
3
votes
1
answer
319
views
ARP Router issue
I have a question when a Router receives ARP request to a host that dosen't exists on the forwarding table for that router does the.
And this Router is not the next hop either will the Router continue ...
- 147