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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1answer
84 views

Configure Nexus N9K-C93180YC-EX

I am configuring a switch for the 1st time (Cisco Nexus N9000 Switch) to do some server performance testing in my lab. I have the serial console working and can log into the switch and run commands. ...
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1answer
52 views

Connecting networks from different states [closed]

Is it possible to connect 5 networks together using one router as a central component even if the networks aren't close to each other? An example would be 2 networks in Houston and 1 in Dallas Texas, ...
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6answers
1k views

Do I need to protect SFP ports and optics from dust/contaminants? If so, how?

I have a used switch with some SFP ports and some SFP modules installed, which I don't use. All new switches come with little rubbery bungs that block up unused SFP ports, but since this old procurve ...
5
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1answer
100 views

Non-HP transceiver and HP switch

Does a non-HP single-mode transceiver work in a HP switch, and does a non-HP single-mode transceiver communicate with a single-mode HP transceiver?
2
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2answers
77 views

Obtaining packet switch-port information via a mirrored port?

When sampling a mirrored port of a switch, is there any means of determining the switch-port information of the packet? Since Ethernet packets do not contain this information, I assume the answer is ...
4
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1answer
173 views

Strange flooding during installing new switch in network

This is very strange issue i am noticing. In our datacenter we have every switch in rack has cisco vPC configured in short whole datacenter running vPC so there is no loop for spanning-tree anywhere ...
2
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1answer
144 views

Duplex mismatch between a Fast Ethernet router and Gigabit Ethernet switch with auto negotiation

i am connecting c3745 router on fast ethernet 0/0 interface with a IOSvL2 switch on gigabit ethernet 0/1 on GNS3. i have set the negotiation on the switch to auto for all interfaces on the switch. ...
0
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1answer
93 views

How does Kismet find WIRED devices when scanning Wi-Fi? [closed]

In an effort to better secure my Wi-Fi network by finding its weaknesses and mitigating them, I have employed the use of Kismet, a well known Wi-Fi security scanning tool. When I use Kismet to scan ...
2
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3answers
79 views

Is it possible that two servers were configured with the same ip under the same switch

I have two physical servers, their configuration as following: ServerI: IPADDR=10.1.1.5 NETMASk=255.255.255.0 ServerII: IPADDR=10.1.1.5 (Same IP) NETMASk=255.255.0.0 (different NETMASK) Because of ...
3
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2answers
237 views

HP switch “No untagged port”

A network engineer showed me the show vlan output of an HP switch. I know tagged ports are trunk and untagged ports are access in Cisco terms. But can anyone explain the "no untagged port"? How is ...
22
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8answers
6k views

Why can't devices on different VLANs, but on the same subnet, communicate?

I have a question about switching. I have two devices connected to a switch with IP addresses 192.168.5.20 and 192.168.5.10. Both devices have the same prefix, /24. That means they are on the same ...
4
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1answer
124 views

Cisco 2960L and ISR 4331 throttled WAN speeds

I have tried finding a solution to this issue and the closest I have found thus far can be found here. https://www.reddit.com/r/networking/comments/8f2sn0/throughput_limited_by_cisco_2960_switch/ My ...
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2answers
110 views

How does pfSense control network traffic when plugged into a switch?

I apologize for this n00b question, but I'm trying to learn networking to help at a non-profit where the old IT guy is no longer there. They have several Cisco switches and one pfSense instance that ...
1
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1answer
59 views

Can't install OS on S6000-ON

I have a Dell Networking S6000-ON. I'm trying to install an OS with ONIE but am running into an issue with the EEROM TLV info. Using some of the onie-syseeprom commands came back with this: ONIE-...
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0answers
58 views

sflow configuration Cisco Nexus 9396PQ

We have Cisco a Nexus switch with M12PQ 12x40G GEM expansion card. Today when i enabled sflow on one of 40G interface i got following error: # sflow data-source interface e2/12 In order to enable ...
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1answer
70 views

Is there a MTBF related to port linking?

During a firmware upgrade, I've noticed one problem: An equipment keeps linking/unlinking on a specific port of a PowerConnect 3548(stp portfast, switchport access mode). I've contacted the local ...
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0answers
30 views

Why does my 1921 Router not bring up its interfaces?

I have the 'no shut' command entered on both interfaces. They work when I enter the command. I copy run start 'wr' Power was cycled for the Router, Switch (3560x-24), Cable modem and AP. They were ...
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2answers
218 views

cisco switch iOS running into problem

I updated Cisco 2960x iOS, but when it started to operate I encountered this error. "Mar 25 12:02:19.878: %ILET-1-AUTHENTICATION_FAIL: This Switch may not have been manufactured by Cisco or with ...
0
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1answer
200 views

Arp Cache Timeout [closed]

I'm trying to poll the arp table from a backbone switch but i want to understand which records are up. I just want to know if there is a specific time for the switch to keep a record on the arp table ...
1
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1answer
65 views

Can a hub be used for sniffing traffic from a device?

My intention is to analyze all network traffic which is coming to and originating from a network connected device I have. From the configurations of the device I am able to proxy all the HTTP traffic ...
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0answers
57 views

Colocation network setup - 2 switches with each 1 uplink - redundant configuration question

I have a question about the network configuration when connecting 2 switches in a colocation rack via 2 uplinks (1 uplink to each switch) to 2 other switches of the datacenter itself. My topology ...
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0answers
48 views

DHCP over Frame Relay [closed]

I have two co-operate buildings. Building A is connected to building B via frame relay. Building A has the main switch server (with VLAN info) and a DHCP server. I need Building B devices to receive ...
3
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1answer
28 views

Access and uplinks ports QoS Queuing model

On an access switch, does the uplinks egress QoS Queuing model (multiple traffic classes and bandwidth reservation), should be different than the access ports egress Queuing model ? Is there a sense ...
4
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2answers
67 views

Is it correct to assume that ordering of frames at switch level is not important?

My understanding is that if the payload of the frame contains any data that needs to be reassembled, at least for TCP payload, it can be done at the OS level, once all the packets are received and ...
1
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1answer
98 views

Switch Configuration for Connecting LAN and WAN

Totally new on networking and on switches, so excuse me if I use some wrong terminology. Problem I have 1 computer and 7 instruments. I would like to form a network setup fulfilling the following ...
5
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1answer
377 views

Assigning a single switchport to different VLANs

I've been trying to figure out how to achieve the outcome below. VLAN Name Status Ports ---- -------------------------------- --------- ------------------------------- ...
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2answers
72 views

How to: Setting up SNMP on various Cisco platforms & Can you recover or configure a switch using SNMP?

How do you setup SNMP on different Cisco switches or routers? Is it possible to limit the IP addresses/subnets, that can access the SNMP communities via access lists? How do you recover or configure ...
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2answers
63 views

How is Ethernet traffic sent between computers with multiple switches in-between? [duplicate]

I've wondered how Ethernet packets sent from Laptop-A to Laptop-B on the local network segment are delivered, when multiple switches are in-between. For hubs, that just replicates the packet on all ...
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0answers
60 views

Wireshark switch ping

I understand that a switch will broadcast to all ports if it doesn't have the destined destination in its mac address table but when I analysed a scenario in wireshark I got confused at what happened. ...
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0answers
10 views

What happens within a switch when a frame is moved from Device A on Switch 1 to Device B on Switch 2? [duplicate]

This might be a noob question but what happens within a switch (regarding mac tables) when a frame is moved from Device A on Switch 1 to Device B on Switch 2? I'm assuming the 2 switches are connected ...
5
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1answer
667 views

Must 40/100G uplink ports on a 10G switch be connected to another switch?

I'm looking at a switch like this: https://www.fs.com/products/29123.html It has 48 10-GbE SFP+ ports and 6 40-GbE uplink ports. I would like to use some of these uplinks to cross-connect to another ...
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0answers
42 views

Is it possible to use FDM and TDM at the same time?

I'm learning about FDM and TDM. And I got the idea that we can use frequency division and time division at the same time, i.e. using TDM for each frequency band. Is it possible? It seems certainly ...
4
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2answers
65 views

Control traffic between two switches

Two catalyst switches connected to each other and all ports of both are in VLAN 2. Ports that connect both switches are access ports (no Trunk) as both switches' ports are in VLAN 2, no any other VLAN....
2
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1answer
72 views

Cannot Ping Firewall After Changing SFP

I am currently working on an issue that has me stumped... I have a network 172.16.144.0/20 which is connected to our fortigate 300D firewall via an Cisco 3850 external switch. Due to hardware ...
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0answers
379 views

Cisco 2960X stacked switches pop up ACL error messages without any ACL configured nor input

I have a few Cisco 2960X with the fiber flexstack modules, when I boot them up, I always got these message: 'Duplicate sequence number. Failed to add ace to access-list' These are brand new switches ...
4
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1answer
765 views

Adding a new switch to a C9300 stack

We currently have a stack of Catalyst 9300, like this : SW1 (master) SW2 SW3 We plan on adding a 4th switch, SW4, but in between SW2 and SW3. This would give: SW1 SW2 SW4 SW3 My question is : ...
2
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4answers
115 views

What happens if I connect several switches together in a loop?

Suppose I want to network a stadium and I have 20 switches connected in a loop. My goal is to be able to connect a laptop to any of the switches and connect to the network and limit my TTL going ...
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0answers
164 views

How Cisco Line Protocol works

How do Cisco Line Protocol works ? I could read this: https://www.cisco.com/c/en/us/support/docs/content-networking/keepalives/118390-technote-keepalive-00.html, about Ethernet Interfaces keepalive ...
3
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1answer
103 views

L3 and L2 interfaces in ACL

What is L3 and L2 interfaces in ACL feature and why ethernet access-lists will not support L3 interfaces
1
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2answers
74 views

802.1X Auth for Clients and Servers

I'm about to introduce 802.1X Authentication to my current network for wifi and wired connections: My Setup: I have a Windows Domain Controller and I wanted to use the Network Policy Service for ...
4
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1answer
634 views

MAC Address learning process

Does a switch learns hosts mac address in these following scenarios: Switch port configured as access and frames received tagged on different VLAN Switch port configured as trunk and frames received ...
2
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1answer
43 views

secure authentication over LAN 802.1X

secure authentication over LAN I have installed FreeRadius Version 3.0.12 server, we debian 9.4.0, and I want to secure my LAN, that means, nobody can connect to the LAN if its MAC address is not ...
1
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1answer
49 views

switch wireshark arp

I connected 4 pcs to a switch, I used pc 1 to ping another pc(pc 3) and used wireshark on all the pc's. The one that sent the ping sent out an arp request and received 4 request and replies from the ...
2
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1answer
87 views

Understanding Vlans

I've started reading about VLans, do vlans always know what port to forward messages to or are the like switches and sometimes they don't know the mac address so they just flood it to all ports? Or ...
1
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1answer
202 views

Disable STP and force port state on a Avaya 4950 switch port

I know how to connect a switch on a router Avaya VSP 7200 by disabling STP with the command : no spanning-tree mstp force-port-state enable but how to force port state on a switch Avaya 4950? ...
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1answer
275 views

Quanta LB6M : how to make trunk port

My hardware is (quanta10g-uha) #show hardware Switch: 1 System Description............................. Quanta LB6M, 1.2.0.14, Linux 2.6.21.7 ...
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1answer
243 views

Ethernet Protocols (Modbus TCP/IP & Ethernet/IP) can be in the same network and in a ring topology without problems?

Ethernet Protocols (Modbus TCP/IP & Ethernet/IP) can be in the same network and in a ring topology without problems? Please, refer to the attached drawing. What are the equivalent Cisco Switches ...
2
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2answers
85 views

InterVLAN routing issue

I've got one L3 Quanta switch. Having a bit of trouble in understanding the right way to configure VLANs and inter-VLAN routing on it. Routing on the switch is enabled. Ports 0/3 - 0/40 are ...
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0answers
61 views

Block internet on a Cisco catalyst 3560 port

Good day Is there a way to block a specific port in a Cisco Catalyst 3560 switch to block the user from accessing the internet but still have full access to the internal corporate resources. The ...
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0answers
40 views

Allied Telesis AT-FS750 MAC authorization with FreeRadius

It is possible to configure mac based authorization with FreeRadius on AT-FS750? We need block device in our network with unknown MAC address. Or set limited access with specify quest VLAN.