a device that bridges network segments, operating at the OSI link layer level.

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94
votes
9answers
6k views

Can you mount a network switch upside down?

We just took delivery of a new Avaya 2500 48-port switch, that has 24 PoE ports. The problem is that all the PoE ports are on the left-hand size of the switch, and our PoE device cables can only reach ...
66
votes
1answer
7k views

What happens when you plug two sides of a cable to a single networking device?

What is likely to happen when you plug two ends of a network cable to a single switch/router? Will this create problems on the network, or just be ignored?
45
votes
12answers
3k views

What should I pay attention to when I'm buying a network switch?

Since I'm not a hardware expert, I don't know what features make a network switch a good network switch. What should I pay attention, when I'm comparing the different models from different vendors?
38
votes
6answers
25k views

What is the difference between a managed and unmanaged switch?

I've seen some documentation discussing the use of an unmanaged switch. What is the difference in functionality/performance/etc. between an unmanaged and managed switch?
30
votes
3answers
2k views

What kind of network attack turns a switch into a hub?

I read an article today describing how a penetration tester was able to demonstrate creating a fake bank account with a $14 million balance. However, one paragraph describing the attack stood out: ...
27
votes
14answers
54k views

What is a patch panel?

What is a patch panel? How it is different from (layer 2) switch? EDIT: I think my primary question (and confusion) is this: Why don't network connections go straight to the switch? Don't we still ...
22
votes
8answers
24k views

Does using a single cable to connect two switches create a bottleneck?

I realise this may be a stupid question for some, but it's something I've always wondered about. Let's say we have two gigabit switches and all of the devices on the network are also gigabit. If 10 ...
22
votes
6answers
16k views

What is the minimum ethernet cable length for a CAT6 gigabit connection?

We run a Netgear GS724Tv3 switch and part of the configuration per port is an option for "Lower Power Mode". The documentation for the switch lists this feature as a "Green Ethernet Configuration" ...
19
votes
3answers
3k views

What happens when a consumer switch receives a VLAN-tagged Ethernet frame?

Suppose you connect a trunk port from a VLAN capable network switch to a (VLAN incapable) consumer-grade network switch via a direct cable. Now the former switch send the later switch a 802.1Q-tagged ...
18
votes
5answers
20k views

What are the implications of having two subnets on the same switch?

Can anyone tell me what some of the implications of having two different subnets on the same switch would be if VLANs are not being used?
17
votes
7answers
657 views

Power loss at company

Property management at my organization has informed me that our building will be losing power for 4 hours tomorrow. I need to be prepared for this event (we're a small organization, i'm young, ...
16
votes
3answers
6k views

How do I know if I need a layer 3 switch?

We currently have a flat network with a bunch of unmanaged switches. I would like to use VLANs to segregate certain users like guests and I would like to use 802.1x. However, I'm not sure if what I ...
15
votes
3answers
1k views

How does network sniffing software work over a switch?

We have several of standard non-managed 3com switches in a network. I thought switches were supposed to only send packages between peers of a connection. However it appears network sniffing software ...
13
votes
5answers
6k views

Why do rack switches have their ports on the front?

I've ordered some rack hardware from Dell. A 42U rack, a 3U EqualLogic SAN, two 1U PowerConnect 5424 switches, three 1U PowerEdge servers, and some other stuff such as a tapedrive, firewall, UPS, etc. ...
13
votes
2answers
1k views

How do I ground a network switch?

I read in a lot of places that it's necessary to ground networking equipment. In a small SOHO environment where there are, say, 4-5 systems and each system is grounded, is it also necessary to ground ...
13
votes
3answers
621 views

Prevent administrative users from assigning duplicate static IPs to their workstations

How can I prevent a user that is an administrator on their local machine from manually assigning an IP to their network adapter that is in use on a server? Some users have done this, and it's caused ...
12
votes
3answers
9k views

What's the difference between a switch, a router, and a modem?

What's the difference between a switch, a router, and a modem?
12
votes
3answers
732 views

Improvements for small business network?

My question is more-or-less a newer version of this 3 year old question: Small Business Network Switches/General network configuration Summary Everything is Gigabit and we don't have any real ...
12
votes
7answers
8k views

How do you keep track of what's connected to your switches?

Currently we manually document the connections to the ports of our switches. Of course, maintenance is a chore, and the documentation is out of date as soon as you save it. Are there any tools for ...
12
votes
5answers
2k views

Small Business Network Switches/General network configuration

We just had one of our many 5-port network switches die on us and it took over a day to figure out what was causing our network problems. So now I have $200 to "fix" our network. Our goal is a ...
11
votes
7answers
27k views

Best way to connect multiple switches together

We currently have five 24 port 3com unmanaged switches. Four of them are 100Mb switches with no gigabit port (MDI Uplink port is 100Mb). The fifth is a full gigabit switch which we use for all of ...
11
votes
5answers
12k views

The Job and Monitoring Options of RoboCopy

What does the Job Options of RoboCopy do? And what exactly does the /MON and /MOT switches do? How can I use them? I don't understand them, and can't find any examples on how to use them. ...
9
votes
7answers
634 views

What's a good way to handle multiple devices with the same MAC address on one network?

The devices I'm working with come off the production line all set to the same MAC address. I can set each one to have their own static IP, and I'm wondering if there would be a way to connect them to ...
9
votes
4answers
2k views

Is a Network Switch IP-Aware?

I have some very trivial basic questions about networking, but I find varying information on that, so I just wanted to settle this. As far as I understand a Network Switch handles traffic ...
9
votes
3answers
8k views

Server-to-Switch Trunking in Procurve switch, what does this mean?

I am looking to set up switch redundancy in a new datacenter environment. IEEE 802.3ad seems to be the go-to concept on this, at least when paired with a technology that gets around the "single ...
9
votes
1answer
396 views

Proper method for connecting multiple non-stackable network switches?

I deal with many clients in warehousing and industrial applications who have IT staff or local consultants. Many of these sites are still using a 10/100 Megabit switching backbone... I've managed to ...
9
votes
2answers
600 views

Cable management strategy for a small chassis switch

I'm working with a small site buildout that contains a single HP ProCurve 4200vl chassis switch. The data cabling contractor did not provision for any cable management. I'm looking at the rack ...
9
votes
1answer
2k views

Admin mode on Procurve Switches

Not being a network expert, I spent some time configuring my network, until I found my mistake: On my HP ProCurve Switch 1810G, I thought that "Admin mode" means whether the administrative interface ...
9
votes
2answers
3k views

Is my Cisco switch port bad?

I've been chasing a packet-loss and network stability issue for a handful of end-users on an internal network for the past few days... These issues surfaced last week, however the location was struck ...
8
votes
2answers
2k views

What is serialisation delay? Why does 10GB Ethernet help reduce it?

In the context of a network switch, what exactly is "serialisation delay"? (I've heard this term a few times.) I've also heard that 10Gb Ethernet (as opposed to 1Gb Ethernet) as a transport technology ...
8
votes
3answers
402 views

Cut network cables in Cisco 2960 PoE

We've a Cisco 2960e that services our VoIP phones and other things. I inherited it. The question I have is the cut cables: there are about four network connectors that are cut about 1cm away from the ...
8
votes
3answers
5k views

Is it possible to include switches in traceroute hops?

I was wondering if it's at all possible to make a Dell Powerconnect 2848 switch show when running internal traceroutes. This would help with diagnosing issues and make it far easier to see where ...
8
votes
7answers
2k views

Are VLANs necessary for my environment?

Greetings. I'm the new network manager for a school. I've inherited an environment made up of several Windows servers, about 100 Windows clients, ten printers, one Cisco router, six Cisco switches, ...
8
votes
2answers
410 views

Connecting two devices over 10Base-T Ethernet without a Switch

I am trying to connect two devices one of which is only capable of 10Mbps and does not support auto-negotiation. (The other is a black box, I am unsure how to tell whether it supports ...
7
votes
2answers
1k views

Need a gigabit switch that can be PoE powered [closed]

I'm in need of a gigabit switch that can be powered via PoE. There isn't any A/C power in the area. Suggestions?
7
votes
2answers
2k views

Do switches sometimes need rebooting?

In your opinion, do switches sometimes need a restart? I'm asking this because today our NAS stopped working properly, and was only fixed when we restarted the switch it was attached to.
7
votes
10answers
37k views

Identify machines connected to switch

Our company recently closed down half our office space, which was not being used. We gave back the unused space to the building management and had it walled off. Prior to us closing it off, I jotted ...
7
votes
4answers
1k views

Someone crashed a whole network with a single switch

This might not be a real question, my apologies, but I'm pretty sure it will make your doomsday scenario enjoyment work a little. My company act as a contractor for a larger company. We need to plug ...
7
votes
5answers
7k views

What is the disadvantage to cascading multiple switches?

I have to wire a new office for ethernet and the contractors want to charge atrocious amounts for each line running to each room in the office. It will be much cheaper for me to run a single line to ...
7
votes
2answers
601 views

Architecting your network when you run out of VLANs

This is an entirely hypothetical question, I'm not in this situation now. What happens to your VLAN topology and routing if you run a multi tenant network and you have more than 4096 customers? Do ...
7
votes
4answers
6k views

What happens if you short-circuit a network patch cable?

Today we had some network problems and after some nested-interval trial and error we tracked down a small 4-port hub where someone had connected both ends of a patch cable to the same hub. After ...
7
votes
4answers
1k views

Cooling requirements for POE switches?

Is there any difference between POE switches and normal switches when budgeting for cooling capacity for a network closet? Normally, when I'm thinking about cooling; I can look at the power draw of a ...
7
votes
4answers
5k views

What's the difference between a Layer 2 & Layer 3 switch

What's the difference between a Layer 2 & Layer 3 switch? I've always wondered and never needed to know until now.
7
votes
3answers
7k views

Recommended switch for an iSCSI implementation [closed]

We want to implement an iSCSI SAN and all of our testing has shown that we can implement this quite cheaply (Starwind target, refurbished HP Storage array). What concerns me is the throughput/latency ...
7
votes
2answers
355 views

Is there a network switch with a web interface that reports bandwidth use per port?

I have a number of network enabled devices in the office. I've always wondered how much bandwidth each one is using. I happen to have a 16-port gigabit switch that is dying, so I was wondering if I ...
7
votes
1answer
355 views

Are network switch data transfer speed limits per port or per device?

Sorry in advance for the newbie question! When network switches report speeds of say 100 Mbit or 1 Gbit, are they referring to the maximum speed per Ethernet port or is this the physical limit of the ...
7
votes
2answers
753 views

Linux Router Problem

I have a Linux based router with four interfaces (each with its own private subnet). When I directly connect a device directly (i.e. no switch, just a patch cable) to one interface and another device ...
6
votes
2answers
537 views

What kind of cable is this?

I need to cost out some switching and figure out how to network a PC to this type of network. Clarifying: This is to connect units in a high rise facility. Each unit has the top picture in a ...
6
votes
1answer
452 views

2 ethernet connections between two Switches

I'm setting up servers at our new office and I brought a spare managed switch with 2 Gig ports to run all of our phones(VOIP) and workstations. Now for the servers I've got a separate gigabit ...
6
votes
5answers
7k views

Is it possible to connect a single NIC to two different VLANs?

I know it is possible to assign multiple IP addresses to the same NIC as long as they are on the same sub-net (e.g. server A can be assigned both 192.168.1.1 and 192.168.1.2). However, is it possible ...