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

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60
votes
2answers
50k views

How do VLANs work?

What are VLANs? What problems do they solve? I'm helping a friend learn basic networking, as he's just become the sole sysadmin at a small company. I've been pointing him at various questions/answers ...
50
votes
12answers
4k 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?
9
votes
3answers
9k 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 ...
19
votes
6answers
32k 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?
0
votes
3answers
648 views

What is the difference between a hub and a switch?

I'm sneeking around online store for used stock of hubs, routers and switches for a project I have to build a network infrastructure. So far, I have bought: 1x Cisco 2514 Router; 5x Cisco Serial ...
23
votes
8answers
31k 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 ...
12
votes
5answers
18k 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. ...
5
votes
2answers
5k views

How managed switches handle Broadcast Multicast and Unicast?

Under typical scenarios, a network switch needs to handle broadcast, multicast and unicast messages at the same time. I'd like to understand On a typical managed switch (1Gb Ethernet/10Gb Ethernet), ...
3
votes
1answer
115 views

DNS settings on managed switches in LAN

We have a Windows 2008 server that is connected to a managed switch with about 15 Cat5e connections and three fiber branches that go to different parts of campus. At each of these parts there is ...
3
votes
5answers
5k views

Are Arista SFP Transceivers Compatible with Cisco Switches?

Are the Arista SFP transceivers compatible with Cisco switches? For example, if I go to the CDW site they show multiple transceivers that vary in price. How can I know that they will work in the ...
3
votes
1answer
12k views

How compatible are sfp's really?

How compatible are sfp modules between devices. For example, am I likely to be able to plug something like this into a cisco, hp, or other switch with mini gbic ports? ...
0
votes
1answer
621 views

Configuring a RADIUS server for 802.1x over a Cisco Switch

I am trying to set up RADIUS authentication over a Cisco switch and I have gone through every tutorial they have. I am able to get the RADIUS server to authenticate when I access the CLI of the Cisco ...
0
votes
3answers
353 views

Connecting Linux system to switch from 2 interfaces

To get proper redundancy, we've installed 2 switches in our network and connected them to eachother. We now want to hook our servers to both switches. Since all servers have 2 ethernet ports, this ...
68
votes
1answer
12k 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?
13
votes
7answers
13k 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 ...
13
votes
4answers
12k 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?
29
votes
14answers
70k 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 ...
99
votes
9answers
7k 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 ...
44
votes
6answers
45k 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?
7
votes
3answers
8k 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 ...
17
votes
3answers
2k 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 ...
4
votes
5answers
1k views

Decent 1gb switch (16-24 port) for rack

For a rack containing a smaller nubmer of servers (5 at the moment, going to stay in this area), I am looking to replace the currently aging 100Mbit switch with a 1Gb switch. This is for the backend ...
13
votes
1answer
2k views

What would cause SIP traffic to be seen going into a switch but not coming out?

Background I have been struggling to get my SIP phones to register behind a brand new router and switch in our brand new office. Our PBX is hosted offsite. I have worked with our provider to attempt ...
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 ...
8
votes
1answer
1k views

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

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 switch on all ports? Say for example two ...
7
votes
5answers
11k 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 ...
10
votes
4answers
5k 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 ...
4
votes
6answers
11k views

Does a single LACP channel over multiple switches increase redundancy?

I am curious for opinions, findings, or evidence that having multiple interfaces bonded using LACP to ports in multiple switches can increase redundancy. Previously bonded interfaces have always been ...
3
votes
4answers
9k views

Link bonding across multiple switches?

I've read up a little bit on bonding nics with ifenslave; what I'm having trouble understanding is whether there is special configuration needed in order to split the bonds across two switches. For ...
3
votes
3answers
892 views

How many switches? [closed]

im designing a network for a small business. There are three departments in the business retail sales - 80 employees, sale support - 10 employees, accounts - 15 employees. I've decided to use star ...
3
votes
2answers
540 views

Extending a subnet

We currently have a private IP subnet using the 192.168.1.0/24 range. We are running out of IP addresses and would like to extend this subnet, to something like 192.168.0.0/21. Is it possible to do ...
2
votes
0answers
53 views

HP ProCurve Preventing Loops and Users Plugging in Unauthorized Switches/Access-Points

We have a HP ProCurve 2530-24-PoE (J9773A) switch, recently I had a user who plugged in an Apple wireless hardware device to the network - whenever it was connected I got a ton of broadcast warnings ...
2
votes
3answers
2k views

Is it possible to capture packets of a Router?

I am facing an issue that some packets sent out to internet from inside network were missing. The pattern we are using is like: Client A ←→ Switch A ← Router A:NAT ← .. Network .. → Router ...
2
votes
3answers
468 views

Ethernet: network topology

Consider a standard GigE network switch. In order to do the switching, presumably it needs to maintain a map of MAC addresses of all things that exist on the network to its (switch's) port numbers. ...
1
vote
4answers
4k views

new Catalyst 2950 switch, no console or telnet CLI access

I am connecting a brand-new Catalyst 2950 switch to my LAN. It is on with green lights, and frames successfully go in and out the ports. The switch is on the same LAN has my host PC, and pings are ...
1
vote
2answers
5k views

What is the command to enable 3rd party SFP+ transceivers on Arista switch?

Does anyone know the command that enables the usage of 3rd party SFP+ on an Arista 7148S switch?
1
vote
2answers
4k views

Best practice to trunk two GB switches?

I already read some similar questions but I still have no clue on how to do it the right way. I have a D-Link DGS-1248T 48 port GB-switch with 4 mini GBIC ports and I want to connect it to another ...
9
votes
2answers
7k 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
646 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 ...
6
votes
1answer
626 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 ...
4
votes
1answer
270 views

Can I have a class A and class B on same switch?

Is it possible to have both a class A and a class B network on the same switch?
3
votes
3answers
3k views

Can a Switch be Wall Mounted Using Rack Mounts?

We need a new, fanless, managed 24-port switch for our small office and I'm considering the Cisco SG200-26. The issue is that the network cabling in the office means that the switch must be ...
2
votes
0answers
398 views

Configuring LACP across a IBM B50G switch stack

Is it possible to configure LACP (Link aggregation control protocol) that spans across two IBM B50G stacked switches. Below is an illustration of what I am trying to accomplish. I have currently ...
2
votes
1answer
559 views

Managed switch port-based DHCP allocation - general case?

I saw a strange comment bagging IT departments (i.e. sysadmins) on Slashdot the other day: half the time they cant even do a simple thing like provide a jack with a set IP address for us Reading ...
2
votes
3answers
969 views

Switch eliminated collisions. But what about

Sorry for asking pretty simple question. But I don't understand that there are no collision problem with switch... When 3 PC connected with hub, 2 PC trying to connect to other 1 at the same time ...
2
votes
2answers
12k views

How to connect multiple switches together?

I have 4 "NETGEAR ProSafe GS724T Gigabit Smart Switch" that will need connecting to each other. I am not sure of the best way to go about this. Normally, I would just daisy chain them or hook all ...
2
votes
4answers
121 views

routing tables — dell powerswitch 2724

I was hoping to know if there is a way to direct all traffic to a specific url, to the server it corresponds to on our local network with out having to go out into the internet. It would be way more ...
2
votes
2answers
7k views

Is using the /3GB statup switch in Windows 2008 x64 only running Sql Server 2008 x64, a good thing?

there's plenty of articles that explain the use of the /3GB startup switch. The general explanation is .. Regardless of the amount of physical memory in your system, Windows uses a virtual ...
1
vote
1answer
2k views

Junos: find out each interface's ip

Sorry if my explanation is confusing. I need to get all the ip addresses of a Juniper Switch and Router (different models). On Cisco IOS I can get that with show ip interface brief | exclude ...
1
vote
2answers
5k views

How to interconnect 2 switches (Cisco/Dell) with trunks

In order to migrate to a new rack inside the datacenter I have to replicate the VLAN setup between a Cisco Switch and a Dell PowerConnect Swithch. On the Dell Switch I have 2 VLANs : vlan 10 : WAN ...