Questions tagged [switch]

For questions about network switches, the term commonly refers to a multi-port network bridge that processes and routes data at the data link layer (layer 2) of the OSI model.

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What if a host makes an ARP request for an IP outside its subnet?

I have read other similar question on the forum and none have completely answered my question. But to understand my confusion, you would need to know what else I'm confused about. Is ARP a layer-2 or ...
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What are non-learning and learning VLANs?

I was going through some IEEE standards for switches (IEEE 802.1aq and IEEE 802.1Qca), and came upon a terminology of learning and non-learning VLANs. I read that learning VLANs are used in Shortest ...
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Configure VEPA on Mellanox MLNX-OS MSN2700

Can anyone please help me with configuring reflective relay on Mellanox MLNX-OS MSN2700 (Mellanox switch)? This is to enable configuration of VEPA(Virtual Ethernet Port Aggregator). I was able to find ...
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SSH Key Generation

I have an issue where I can't SSH into to switch due to a connection refused fatal error after a switch rebooted. One of the rsa key that is in the switch that I think is used in the switch is : Key ...
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2 answers
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Write command for only saving the config to power memory

I'm confused on what command to use on a cisco switch where if the power is unplugged from the switch, I lose the configuration I saved and it reverts back to the previous config. I've been ...
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How do layer-2 devices (bridges/switches) join a multicast MAC address?

I was going through the IEEE 802.1Q (2018) standard on my own. The standard speaks about group addresses, and how these group addresses are learned by transit bridges, which is all fine. But how do ...
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Multiple IP address on an unmanaged switch

Sorry if this question have been already asked. My ISP is providing multiple public IP's on an interface. Can I use an unmanaged switch to conect to ISP's interface and then connect this switch to ...
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If 10/100 ports means the ports can be connected as ethernet and fast ethernet, why show interface status command only show fast ethernet? [closed]

How come the answer for question no. 5 is C? If 10/100 ports means the ports can be connected as ethernet and fast ethernet, why show interface status command only show fast ethernet? Figure-1: ...
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Do switches send their own extra traffic? [closed]

Doing a packet capture I noticed some unknown extra packets that might have come from the switch. Is this what happens and why? Did not see an answer from a quick search. I was under the impression ...
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3 answers
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Does duplex depend on the cable or the interface?

I wanted to know what made a Duplex system work? I always thought it was the Switch that made it work. But I just read on my Cisco course 2 things that made me question it. It said this, and made me ...
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Is it possible to configure Cisco ASR901 as a layer 2 VLAN switch?

I have been fiddling with a Cisco ASR901 for a while now, but I can't wrap my head around configuring it as a layer 2 VLAN switch. Is it not possible to configure one of its Gigabit Ethernet ports as ...
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How can network switch recognize the connected device is on? [closed]

I was just using a unmanaged switch and IoT devices, and I noticed that the LINK/ACT LED turned on and blink during the boot sequence of device. Then I wondered how network switch recognized this ...
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Troubleshooting ethernet->fiber->ethernet with media converters

I'm trying to get the following setup to work: ethernet switch <---> media converter <---> fiber cable <---> media converter <---> ethernet switch The switches are identical tp-...
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2 answers
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Why are ISPs arranged in hierarchies?

ISPs are organised in a hierarchy where the Tier 3 ISPs are connected to Tier 2, and Tier 2 ISPs are connected to Tier 1 ISPs. Why are they organised in a hierarchy? Is it because if all devices were ...
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transfer vlan from one cisco switch to an other through a central cisco switch

I can't figure out how to pass one vlan from one switch to an other: Let's say, I have 2 valns: Vlan 1 and Vlan 2 3 cisco switches: Cisco Catalyst 3560g (central switch) Cisco SG-300 (with native ...
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1 vote
1 answer
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HP ProCurve Switch 4100 series - Checking PSU status & S/N from the CLI

Do you know if there is any CLI command available on the very old HPE Procurve 4108gl/J4865A switches where you can see how many PSUs are installed in the chassis, what's their current status and ...
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Open Switch (OPX): Accessing SFP EEPROMs via I2C on a Dell S4112F-ON

The S4112F-ON switch has 12 SFP+ ports; we are using several of them. My goal is to access the EEPROM on ALL the SFPs on the switch via their i2c interface with i2c-tools (linux) and ultimately open ...
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How do switches learn the neighbour MAC address? [duplicate]

According to the CCNA Official Guide a switch learns the new MAC address by checking the source MAC address of a new frame. Here is the quote: Switches build the address table by listening to ...
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1 answer
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How to connect to different VLANs through VPN

I have the following setup: I have setup a Layer 3 Switch with multiple VLANs Multiple devices are connected to it on different VLANs via untagged access ports There is also a router connected to the ...
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Download ExtremeXOS

I need to update the extreme switch, I found a lot of instructions but I don't know where to download the latest version of extremeXOS. Thanks a lot in advance for your help.
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1 vote
1 answer
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Working with credentials encrypted credentials on Aruba / HP switches

I come more from a cisco back ground and there when i show the running configuration i can see the encrypted / hased local user password. This makes it more secure to have in a automation tool where I ...
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1 vote
2 answers
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Proxy-ARP when the destination device is connected to the same layer-2 switch, but belongs to a different subnet

I have recently learned about Proxy-ARP and am slightly confused about what would happen in the following scenario. Let's say I have two host devices A (IP: 10.0.0.10/24) and B (IP: 10.0.1.10/24) that ...
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Dropping packets when mirroring a switch trunk port

I'm building a test lab to support a networking monitoring application I'm developing. I have written a simple UDP packet generator and receiver, and I use iperf3 to create some bulk background ...
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1 answer
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How does a switch decide what mac to use for Root election in STP?

I know that for the STP a root switch or bridge is to be elected based on the BID that consists of a priority value and the MAC address of a switch if the priority is the same then the MAC is the ...
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2 answers
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Tagging a VLAN or not

I want to create a wi-fi network for guests using access points. I asked to the IT provider a dedicated network with its VLAN and it is: 172.16.0.0/24 VLAN ID 344 The above network is configured on ...
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2 answers
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How does a switch know when and how to forward traffic to a router

I generally understand how L2 switching works. I want to understand how a switch and router work together to send traffic to a device off the L2 network. For example. Computer A tries to send ...
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1 answer
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N routers but only one valid dynamic gateway

I'm not able to figure out a good strategy for this situation. There's one router per client and all the routers are in the same network. Each router is able to connect to an external router in a ...
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3 votes
2 answers
250 views

Is it possible get fragmented if the packet size is less then MTU?

I'm writing a socket application that is running on Linux. My server machine is connected to a switch that is connected to a network. There are also other servers connected to the switch. My client ...
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1 vote
2 answers
1k views

How to populate ARP table without having to ping every device individually through the console on a Brocade ICX 7750 switch

I need to make a port-IP diagram and so far the best way to do this seems to be through show arp after consoling into the brocade switch. The arp table is empty however, and the only way I have been ...
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L3 Switch acting both as a router and as a switch for the same packets

I am trying to figure out if an L3 switch is able to act as a switch and as a router at the same time for the same packets. Consider the following architecture: I would like to set up VRRP for both ...
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2 answers
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Why Ping Reply Succcess from different subnet IPs

In the university lab, i manually added IP in two ubuntu machines. PC1 IP 10.129.2.33 255.255.0.0 and PC2 IP 10.129.2.165 255.255.255.0. I connected first both computers with direct ethernet cable ...
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1 answer
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What is the difference between these two different network security devices?

I have a choice between these two network security appliances, however the only difference I can see is the year and I don't know what that year means. SONICWALL TZ300 WIRELESS-AC SECURE UPGRADE PLUS ...
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2 answers
76 views

Can port mirroring be used to convert single video stream to multiple video streams?

I am new in networking and had a basic query regarding port-mirroring. A video stream is taken from camera-based software system and is being fed to a distribution system. For high availability (...
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1 answer
553 views

Computers in an unmanaged switch cannot communicate with one another [closed]

TL;DR: I have > 2 computers in an un-managed switch which can't communicate with one another i.e. can't ping or ssh among one another. Long story: As per the diagram my router can reach the ...
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1 answer
173 views

Non [R]STP switches in LAN ring topology

I am revamping a simple network, which is based on cascaded, standard, unmanaged PoE switches. I am also adding a redundant loop closing wire, from the last switch to the first one, which at the ...
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0 votes
1 answer
86 views

What prevents a device from receiving its own multicast stream, and can it be turned off?

I know that it is normally not possible for a device to receive its own multicast stream on the same network interface where it transmitted said stream. I also understand why this is sensible, and ...
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1 answer
522 views

Aruba 2930M - the NTP server is unreachable

My Aruba 2930M switch cant reach the NTP servers. Below is the following conf: ##################### OOBM IP Address 192.168.90.34 IP Version IPV4 IP Mode Manual Subnet Mask 255.255.255.0 ...
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2 votes
2 answers
222 views

Connecting two HP 2910al Switches using SFP to get 2Gb/s speed

I would like to Connect my two HP 2910al switches using SFPs to get a maximum of 2G links. is this possible, and how? I want to make both of them to use the IP address (ex 192.168.2.xxx). I have the ...
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1 vote
1 answer
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How to block telnet access for one particular network from all networks except one using Extended ACL

Scenerio is given in the picture. I want to block all the networks except 192.168.5.128/25 from doing telnet of 192.168.5.0/25.
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2 answers
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Do DSLAM and OLT function like a switch?

Let's say for example we have the following hypothetical topology: In each network, can each user communicate with each other? For example, can User 1 ping User 2?
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2 answers
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Where are ATM switches located in real life?

Consider the following diagram from this link: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/bbdsl/configuration/xe-3s/bba-xe-3s-book/bba-ppoe-atm-xe.html If I am correct, here's how I see it ...
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6 votes
2 answers
2k views

How do I know the switch is layer 2 or layer 3?

Is it possible to find the switch is Layer3 or Layer2 in (Switch)CLI? Is there any command to check whether the switch Layer(Layer 3 or 2) in CLI?
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2 votes
1 answer
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Port only in trunk mode vs encapsulating the frame

A network with 2 switches, each switch has 2 vlan, one called vlan 10 and another vlan 20. A port-channel with 2 uplinks (trunk). Why in a layer 2 scenario I don't need to configure the trunks with ...
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1 vote
2 answers
968 views

How to Change the Date on Cisco Catalyst 3750x Switch

We are using cisco catalyst 3750x 24 port switch series How to Change the Exact Date(Singapore) on a Switch ASW-G-L09-001#show running-config Building configuration... Current configuration : 11883 ...
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0 votes
1 answer
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Linux networking + mix of auto-negotiation of yes/no [closed]

we have 10 servers with Advertised auto-negotiation: yes as the machines with driver driver: i40e driver: i40e version: 2.3.2-k firmware-version: 10.51.5 expansion-rom-version: bus-info: 0000:12:00.0 ...
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1 vote
1 answer
44 views

Where can one find how much memory is currently allocated to logbuffer?

Do you know where it can be checked, how much memory is currently being used by the logbuffer? some-switch#show log | i Buffer|Trap|udp Buffer logging: level debugging, 2268 messages logged, xml ...
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1 vote
1 answer
252 views

How to route incoming UDP Unicast traffic to multiple computers

I have a Ubiquiti ES-16-150W and I must somehow route incoming UDP Unicast traffic to multiple computers. Ideally I would change the Unicast to Multicast but unfortunately the device which is sending ...
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2 votes
1 answer
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Trex not receiving any packets

This is my setup to benchmark my server Diagram Trex version v2.88 Trex server MAC ens2f0: f8:f2:1e:5c:bf:78 ens2f1: f8:f2:1e:5c:bf:79 DUT server MAC eth0: fa:16:3e:1c:be:82 eth1: fa:16:3e:d5:37:b1 ...
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4 votes
1 answer
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GNS3 switches vs Real switches performance

I want to emulate the performance of switches in GNS3, and the focus is not the configuration of switches. My questions are: Do emulated switches perform worst than actual switches? Are emulated ...
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Using GNS3 to Sniffing Packets on Siemens RuggedCom RS900

I am using GNS3 to simulate an environment. I have 4 docker containers which all host Python programs. Three of the devices communicate with each other via the programs (Program 1, Program 2, Program ...
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