Questions tagged [network]

For questions about Networking that includes design, and use of a network, the physical cabling, hub, bridge, switch, router, and so forth. Anything in relation to networking and its technologies.

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Extreme 210 fiber port not connecting

Let me preface my question by saying I'm not a network admin and don't know nearly enough about networking. I have an Extreme 210-12p-GE2 switch. My problem is that the fiber port that was working is ...
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vRack on OVH not letting servers communicate even though i've set the ip addresses [closed]

I don't know if i am missing something, but i have multiple servers with OVH on Ubuntu, and i have them all connected on a vRack. For my post i will just use two of them, i have set the ip addresses ...
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Why shortened version of IP4 exists and it is undocumented but supported everywhere?

For example there is an IP address 192.168.0.1 It is clear that you can use it as the full line, but try that one 192.168.1 It will also work, and it will be automatically converted to 192.168.0.1 ...
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Where do load balancers sit in microservice infrastructure? [closed]

I'm planning on creating a brand new backend with microservices. I've been looking into infrastructure and I'm unsure as to where load balancers come in. Does the API gateway act as a load balancer or ...
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How to create a subnet or secondary network? Do I need VLANs?

I am not new to IT, but in the past, I've always had a Network Admin to handle this type of stuff. That being said I know just enough to be dangerous. What I have is an old hodgepodge of different ...
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In an SDN (OpenFlow), are all switches directly connected to controller?

I found this question how openflow messages get routed from switch to controller? (SDN) And in the answer it says: In SDN networks all OpenFlow switches are directly connected to controllers. But if ...
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How FDB (Filtering Database) is filled out

I would like to understand what is used as a VLAN column in the FDB. For ACCESS port it is PVID if frame untagged or frame VID if frame is tagged, for TRUNK it is allowed VLANs? We can represent the ...
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3 votes
1 answer
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VLAN Ingress filtering process on switch

I read and read the information and somehow it is inconsistent or incomplete. The specification of 802.1Q also read, but to me as a person who has not previously read the specification is difficult. I ...
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2 answers
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unable to ping loopback interface gns3

I have the following gns3 topology I'm unable to ping R1 loopback interface (destination host unreachable) I'm not sure what is wrong R1 configuration are shown below hostname R1 ! boot-start-marker ...
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HP 6120XG switch LACP is blocked - error condition

Folks, I am dealing with very strange issue related LACP and not sure if its bug of 6120XG switch or something else. so let me explain my issue here. Network Diagram: I have two Cisco Nexus 9396PX ...
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How does a computer determine that an Ethernet frame contains an IP packet? [duplicate]

So far as I can tell, there is no "Next Protocol" ID at the Ethernet / data link layer. Nor do IP packets seem to contain any magic numbers for identification purposes. Does the OS bind each ...
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Why does a router need 2 IP address? [duplicate]

Suppose there are 2 PC and 1 router in "LAN1", now if PC1 wants to communicate with PC2, it will need to uniquely identify PC2. So, PC2 gets a private IP that no other PC in LAN1 will have. ...
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GNS3 cant open terminal session in Ubuntu 20.04 LTS

I am having an issue with GNS3 after a recent run of sudo apt upgrade / update. GNS3 can no longer run gnome-terminal to open a session to a router on the VM. The router is working, and if I open ...
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20 votes
5 answers
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Why is Packet Size Limited?

I was reading: this answer to "Maximum packet size for a TCP connection", where it says: The absolute limitation on TCP packet size is 64K (65535 bytes), but in practicality this is far ...
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Can an application on two separate devices share a packet to similar resource?

Can packets requested for an image by an app on a phone be sent to same app on another phone by another user?
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WAP configuration consistency

Simple question, are WAPs always configured from the default gateway's web interface? Do you ever have to go somewhere else?
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How to reset a Default username and password of Allied Telesis AT9000/28 switch using CLI? [duplicate]

How to reset a Default username and password of Allied Telesis AT9000/28 switch using CLI?
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Monitor network link to get bandwidth and/or latency variations

I have a controlled SDN lab scenario where I have a control plane and a data plane. The network is composed by: A switch 2 pc connected to the switch for the data plane A controller pc connected to ...
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3 answers
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Do IDS/IPS/HIDS slow your network down?

Implying I were to use port mirroring, would it increase my network's jitter/ping and other networking matters?
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2 answers
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Why is a switch port a collision domain?

I'm just starting my IT education and this is probably a very basic question but I'm having trouble with it. As far as I understand a collision domain is a part of a network where collisions can occur....
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1 vote
1 answer
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What device(s) I need for connecting two wireless LAN?

IP cameras on ground floor connected to a wireless router, and there is an internet modem on third floor. First of all, I want to extend ground floor wifi signal in order to connect to IP camera LAN ...
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3 votes
1 answer
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Is there an equivalent of the Cisco/ Cisco esque command "ip helper-address a.b.c.d" on Mellanox switches?

Apologies for my newbie question. I have recently had a Mellanox switch added to the mix. I was using an "IP helper-address" to forward DHCP requests in different VLANs to my DHCP server(s) ...
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1 vote
3 answers
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Longest Prefix Matching

I just learnt about this concept and I have a query which was also asked by someone earlier but was grossly misinterpreted. Suppose my Router has Routes for Networks: 192.168.22.0/23 and 192.168.22.0/...
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1 vote
2 answers
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Does a gateway always have to be on the same subnet as the host IP address? [closed]

The obvious answer is yes, I suppose, but my VPS provider doesn't seem to agree. I've just uploaded a Ubuntu 20.04 instance, and the provider is telling me: IP address: 77.xxx.yyy.zzz/32 Gateway: 10....
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Switch: port and NIC relation

I wonder if a switch has one NIC per port? for example, does a switch with 24 ports has 24 NIC? Many thanks in advance for your help.
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Best way to configure layer 2 daisy chain with 2 layer 3 switches/gateways at either end?

I would like to implement a linear daisy chain for the purpose of transmitting internet over a considerable distance. One motivation behind the use of a linear daisy chain for this problem is that ...
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What kind of communication does a switch allow between devices connected to it?

I am a beginner and currently learning network devices and I got a little stuck on switches. Basically, what I've learned is that they connect/provide a wired connection between computers on the same ...
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What are the possible bottlenecks in this design?

I am currently finding myself in a position where I need to design a local network for parallel processing of large amounts of data from multiple sources. Unfortunately I lack the experience to ...
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1 answer
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Cisco Packet Tracer gives "Invalid IP Address" when I assign an address to a router [duplicate]

I was given an exercise where I have an IP address range and I have to configure multiple sub networks from that range. The address is 238.61.192.128 with the mask 255.255.255.128 (/25). I created my ...
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If current IP ranges for PCS are in conflict with a new systems network, how do you re-IP the PCs and the Servers?

I have a question about IP conflicts. Let's say you have a company building full of PCs on a network. Then a firm buys out that company and institutes its new system and new network for that building. ...
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RSVP warning: ID "data" is not configured

I am trying to follow this document: https://www.cisco.com/c/en/us/td/docs/ios/qos/configuration/guide/12_2sr/qos_12_2sr_book/config_rsvp.pdf to configure rsvp, using gns3, for Entering Senders or ...
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9 votes
5 answers
844 views

Different Behaviour of a Router

There are 2 cases that I would like to point out: When the router is directly connected with 2 PCs like this, In this case, PC2 is able to ping PC3. I just configured the IP address of PC2 and PC3 ...
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Is this network configuration possible with Layer 3 switch and ISP routers?

If possible I would like to use a Cisco SF350-24 Layer 3 switch to enable the below network layout. In our office we have 2 internet connections we often use for testing that require an internet ...
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Logs on my Cisco ASA show the public gateway (ISP router) is pinging the internal network, how? [closed]

Im (remotely) working with an issue where the network has intermittent drops. i suspect possible routing loop, but havent confirmed that yet. In the logs of our Cisco ASA 5506, i see that the public ...
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3 answers
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One Missed Point in Data Link Layer Concept?

I see one Course Lecture as follows: I trouble in understanding "source address for the next node’s reply", What is the meaning of next node's reply?
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1 answer
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How do wireless access points work? [closed]

I understand what the intent of wireless access points are but I am struggling to understand them fully on a deeper level. So, do wireless access points have their own network with their own IP ...
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What is the reason behind not returning unused IP addresses? [closed]

There are several companies out there with one or more /8 IP addresses, for example: DoD has more than 200 million, HP has one /8 (>16 million), Apple has one /8, General Electric has one /8, IBM ...
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1 answer
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Is fiber to computer(without the use of any other cables in between) possible?? Are any further developments getting carried out towards this goal? [closed]

All of us know well that the fiber to home(FTTH) connections are a trend nowadays. Every nation is planning to replace the existing metal wires with optical fiber cables. But we also see that the ...
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2 answers
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what is the main function of root bridge and ring master?

When we learn the STP or RSTP,we all learn the election of root bridge, the lowest priority number or MAC address of switch will become the root bridge.So here is my first question: 1.So what can the ...
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1 answer
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Can anyone explain the introduction of Rapid Dual Homing to me?what is the main function of rapid dual homing?

I read some information about Rapid Dual Homing from JetNet 5020G,the figure below is the introduction of Rapid Dual Homing. Honestly,i don't understand why can the rapid dual homing have multiple ...
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1 vote
1 answer
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If one of hub is damaged,will it cause others hub damage too?why can't i enable the rapid dual homing

There is a multi-ring topology, combined with 8 Hubs and 2 switches, i want to ask two questions 1. If H3 is damaged,but the fiber is still ok, will H2 damage too in the future? i have thinking to ...
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1 answer
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questions about queuing delay

I am learning computer network, and confused by the queuing delay. In my textbook, it says that when La/R approaches 1, and with random inter-arrival times, then the average queuing delay is closer to ...
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network IP packet format

i completely understand that why receiver there is 576 bytes but my question is as technology update every after one Minutes then why we can't update that limit [enter link description here][1]
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2 votes
2 answers
390 views

In tunneling, how destination routers identify if a packet is encapsulated?

In tunneling, a packet gets encapsulated in the payload section of another packet. If the router at one end encapsulates the packet, then how the router at another end identifies whether the packet is ...
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How to tell if an ipv4 address is public or private?

I've read the below thing, in a website. According to standards set forth in Internet Engineering Task Force (IETF) document RFC-1918 , the following IPv4 address ranges are reserved by the IANA for ...
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What defines a device as connected to the Internet? [closed]

I recently saw a SO question: Are there global networks other than the Internet? I am aware of other networks such as ATM and the telephone network, which are not part of the Internet. My question is, ...
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Understanding the definition of layer 2

The Wikipedia (and other sources) page about the OSI model explains layer 2 as such: The data link layer provides node-to-node data transfer—a link between two directly connected nodes. ... Let's ...
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why can't my PCs ping each other?

Consider the following network I can ping just fine from PC0 to PC1 and PC2 to PC3, but I can't ping from PC2 to PC1 or PC3 to PC0. Why? I'll share the configuration from the router: Building ...
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0 votes
1 answer
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What is the addressing problem of SLIP? [closed]

In the RFC1055 that describes SLIP, in the DEFICIENCIES section, there is a bullet named "addressing" which says: both computers in a SLIP link need to know each other's IP addresses for ...
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my pfsense is reducing the speed to 40 mbps from 300+ mbps, what can be the issue? [closed]

I have a pfsense system BUSINESS B100 - CELERON DUAL CORE J1800 2.41GHZ 4GB DDR3 SODIMM SSD 60GB HDMI. https://www.amazon.com.br/gp/product/B086M2D8DJ/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&...
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