Questions tagged [networking]
For questions about networking in general. Any question about all on topic network devices can use this tag.
513
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Unifi Guest Captive Portal for wired connections using UDM-Pro [closed]
In this scenario the UDM-Pro is deployed with direct Internet connectivity on WAN side and on LAN side unifi AP's are deployed. Their are also some wired connections in the network. Unifi guest ...
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2
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85
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What issues can rise from web gui config changes then making other changes from the CLI?
I'm using a 9200L Cisco switch
If I make changes in the CLI, then I make changes in the Web interface and vice versa.
Will there be issues down the road with the config file getting corrupt or ...
- 101
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20
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How to connect single PC with multiple NICs to a another network using OSPF? [closed]
I've 2 networks connected together through CISCO L3 switches using OSPF for some reason Network B have one server only which can have multiple NICs. Can Network B PC configured to connect to Network A ...
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10
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Voip not working in bridge mode [closed]
First device - Pure ont with voice support and no QoS features.
Second device - Wireless Router with no voice support, but QoS features.
First scenario I can configure Voip in android: If i use ont as ...
0
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1
answer
12
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P2P Connection with Aggressive Firewall [closed]
I was testing my P2P app with a particular firewall.
If I originate the packet first, the firewall is letting it through and the peer sees it and then they are able to start communicating.
However, in ...
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1
answer
26
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WOL (Wake on LAN) working only when one PC connected to router via cable [closed]
I have one PC in my LAN that I'd like to start remotely over the internet. It's just a basic server that when booted up runs some important stuff for me without user input needed.
I have enabled Wake ...
- 101
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1
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19
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Do wiremap testers detect split pairs
I was watching a How-to video on Youtube on wiremap testers and the technician said that wiremap testers detect split pairs among other wiring faults. However, I came across a Networking question ...
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6
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Trace Route RTO in two or more hop but next hop works [duplicate]
Today when I was doing tracert,
in the 2nd & 3rd and also 4th Hop I get RTO but my next hop seems to be reachable. How come it works?
Please answer asap.
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1
answer
21
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Why is MPLS label added between layer 2 header and layer 3 header of OSI model and not between headers of layer 3 and 4 of OSI model?
Is there a possibility to use any other two OSI model layers' middle positions? What is the basic concept of switching of packets with MPLS on layer 2.5 of OSI Reference model?
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49
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What is PPP and why does it not have a MAC address?
I just wanted clarification on what exactly PPP is and why it does not have a MAC address due to having seen that under a response to a question of how routers transverse packets to their destinations....
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1
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43
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How should edge switches have their routing configured (when there is a mgmt vlan in the mix)
I'm having trouble with a new network topology we are trying to implement onto our environment. The issue seems to be with the switches. The problem is not relevant to this question but for ...
- 113
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2
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59
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In determining the Hamming distance, how does one know what the list of valid codewords are?
Hamming distance is said to be the number of bits that differ between two codewords. If two code words differ by a distance of d, then up to d-1 bit flips can be detected.
The example given for such ...
- 125
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47
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L2 connection from the simulation network in GNS3 VM to the physical network
GNS3 VM is used to run GNS3 network simulations.
How can I connect from the network in the simulation to the physical network at Layer 2?
For example, create a GNS3 environment with the following ...
- 101
1
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1
answer
65
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Did I get the network ports correctly?
When we enter a URL (for example https://some-url.com) in the address bar of the browser and press Enter, then (simplified version):
when the browser establishes a TCP connection, it sends a SYN ...
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1
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67
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snmpwalk returns hex-string for interfaces without a description
nterfaces with an actual description are returned as a string, for example the interface with Device1ILO
However the interfaces without a description configured, are returned as Hex-STRING 00.
How can ...
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2
answers
92
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Connecting L3 and L2 switches with VLAN settings
I have 1 L3 switch with
Static ip - 192.168.0.252
Two L2 switches
Switch A - 192.168.0.250
Switch B - 192.168.0.251
I have created VLANs in L3 switches with 192.168.1.1 and 192.168.2.2 ips abd set it ...
- 101
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1
answer
36
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How does a client end the TCP connection when SYN+ACK is not received after multiple retransmissions? [closed]
I am trying to establish a TCP connection with a server. I added a firewall rule in the server to drop the TCP packets in order to check how the TCP client terminates.
Client retransmits SYN multiple ...
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2
answers
37
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Are there any ASNs with 0 IP addresses? [duplicate]
Here is the list of all the US ASNs networks ranked by the number of IP addresses: https://ipinfo.io/countries/us
However in the page 10, I can see some ASNs with 0 IP addresses: https://ipinfo.io/...
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0
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20
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Why would TCP ever allow a SYN for a connection in the TIME-WAIT state?
RFC 1122 says this:
When a connection is closed actively, it MUST linger in
TIME-WAIT state for a time 2xMSL (Maximum Segment Lifetime).
However, it MAY accept a new SYN from ...
- 31
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12
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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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1
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111
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What are common network debugging techniques?
I set up our company network several months ago. Some weeks ago, we started having some issues, and I want to find the root cause. How do you debug networking problems in general?
My background is in ...
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48
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Public and Private IP address range confusion [duplicate]
class A private IP range (10.0.0.0 to 10.255.255.255)
class A public IP range (1.0.0.0 to 127.0.0.0)
In these 2 public and private IP ranges, the private IP range is also included into the public ...
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2
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42
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Why is congestion collapse from undelivered packets not possible when there's 1 congested link?
rfc 2914 says this:
The avoidance of congestion collapse from undelivered packets
requires that flows avoid a scenario of a high sending rate, multiple
congested links, and a persistent high packet ...
- 31
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2
answers
41
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Why does the TCP rfc say that there shouldnt be an ACK for the left window edge sequence number?
From rfc 9293:
A TCP implementation MAY send an ACK segment acknowledging RCV.NXT
when a valid segment arrives that is in the window but not at the left
window edge (MAY-13).
But isn't RCV.NXT the ...
- 31
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2
answers
151
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Why are TCP keep-alive messages sent with an already ACKd sequence number?
This is what the TCP rfc says about keep-alive messages:
Implementers MAY include "keep-alives" in their TCP implementations
(MAY-5), although this practice is not universally accepted. ...
- 31
0
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0
answers
12
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How does the client verify its own SYN? [duplicate]
The TCP rfc 9293 says this:
A 3WHS is necessary because sequence numbers are not tied to a global
clock in the network, and TCP implementations may have different
mechanisms for picking the ISNs. The ...
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1
vote
2
answers
31
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Ethernet Frame fields and Physical Frame fields
In L2 Ethernet fields we see [Preamble][SFD][src][dst][tag#][ip/tcp data payload] [FCS] [trailer?]
Does the L1 Physical layer contain [IPG 12octets] field or is that part of L2. What fields sit at L1 ...
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2
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39
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How can I connect two servers using static IPs and two laptops using DHCP
I am currently working with two laptops and two servers which I am trying to link together. For this instance, I do not have a network connection and I will be using a switch as I'm isolating these ...
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2
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68
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Customized IPv6 packet with multiple inner data fragments for multiple destinations
I am studying the possibilities of using IPv6 potentialities to design a customized IPv6 data packet that has the following features:
1. Combines many fragments of different data in one packet.
For ...
- 63
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1
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51
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Can somebody help me understand this static NAT example
I have the following example:
From my understanding of static NAT the client makes a request on the inside global address of a resource, in this case the webserver. (http://209.165.201.5). The request ...
- 189
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38
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TCP and Data field
Need clarification on TCP/UDP DATA field..
Does the Application Layer "Data" go inside the TCP [DATA FIELD] and all of TCP Layer with its Headers sit inside the IP [DATA FIELD], finally the ...
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8
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Question, provisioning divisions of network blocks with differing sizes based on number of hosts required [duplicate]
I was working on this question.
To do this question I used this YT video to help me and I came up with these answers but I wasn't sure about them since there are no answers to the practice questions.
...
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7
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session layer in OSI model
I'm wondering to know how session layer works. In my understanding session layer is to establish active communication sessions between two devices. Based on the OSI layer model, it works layer by ...
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1
answer
68
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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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1
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41
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How to define packet loss
I found that "Packet loss describes lost packets of data not reaching their destination after being transmitted across a network." So, we can say that it is a portion of transmitted packets ...
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1
answer
73
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How to properly configure OSPF protocol?
I have this simple 3 router network that I need to configure the OSPF for, when using two routers every thing works fine and i can ping but when I add the third router nothing works
left router
...
0
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2
answers
263
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How to solve high ping "spikes" to pfSense when ipSec connections are active?
Background information:
We have latency/freeze problems with our pfSense. To be able to answer the question i will first give some general background information:
We run pfSense V2.6.0 on following ...
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11
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3
answers
8k
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Is `0.0.0.0/1` a valid IP address? If so, what does it indicate?
I know that 0.0.0.0/0 represents a default route.
But I would like to understand what does 0.0.0.0/1 represents? Is it even a valid thing in networking?
- 677
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56
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Can't find a device on my network [closed]
I have a device on my network that is at a static address (192.168.3.1). This device is connected to a network switch, that is also connected to the rest of my network. My problem is that I need to be ...
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12
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What's the big deal with "192.168" in ipv4 networking addresses? [duplicate]
What's the big deal with 192.168 in ipv4?
Why can't it be like: 111.473.6946?
Please explain, networking experts.
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2
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31
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Does sharing laptop Wi-Fi cause network noises or network slow down?
We have network (Wifi network) issues in our organization the network is slow and sometimes the access point throw out some connected users. We contacted ISP and they checked our network configuration ...
9
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7
answers
4k
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What is the use of NTP server when devices have accurate time?
Just as the questions says, why there would be an NTP server when the devices already got the internal clock and are accurate.
- 193
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29
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Sonicwall 2650 Set public IP on Transparent (L3 Bridged) [closed]
I'm having problems configuring my Sonicwall 2650.
We have a small range of public IPs on a leased line, most of these are used, via nat, to go to public servers. However we would like to share our ...
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1
vote
1
answer
46
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Does the host need to access the routing table to know if the destination IP address exists in the same network?
It is said that, in the process of building a frame, the host checks if the destination IP address exists in the same network. My question is concerning how the host performs this check. Does the host ...
- 151
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1
answer
63
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Measuring Latency between my local network hops [closed]
I have to measure the latency in my local network and also between each hop. I used the conventional tools like ping, tracert, pathping etc. But the problem is here these tools have there own protocol ...
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2
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266
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Access to systems with the same IP address but various port number in another network?
I have some knowledge of networking but not much, so I appreciate knowing from the experts.
modified part
I have 10 devices(PLCs) with the same IP address "192.168.42.2" that I want to ...
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1
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44
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Routing question
Let’s say I have router A and B and a subnet 192.168.10.0/24. Can I use part of that subnet as a connector between router A and router B (ie. 192.168.10.0/30, .1 on A and .2 on B) and have a route 192....
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1
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44
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Can octet in IP add be a number greater than 127? cuz, each octet can only can have values in range [-128,127], also are -ve no. common in ip add?
Here is the link of website where they say we can have numbers greater than 127 in 1st octet https://www.informit.com/articles/article.aspx?p=433329&seqNum=5#:~:text=10-,128%E2%80%93191,-C
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54
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How do I partition my on-premises network so one part can only access the external (internet)?
Currently, our setup is the following:
I need to make a change so there is no wireless access to our NAS. The Wifi "passthrough" needs to only be able to communicate with the external ...
- 101
1
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1
answer
159
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Test communication of interface using Cat5E loopback
So I need to create a simple process to test a large amount of gigabit network ports. Since I don't want to setup two machines and run software on both the test connection my first thought was to ...
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