Using a switch at a college campus

[adamone11]

Up here we play alot of Counterstrike, most of the time me serving. Lots of people don't have LAN access, but they do have souped up laptops. So...would it be possible to put a switch in between the serving computer and the port on the wall, and then connect the switch to the wall, without any change in IP address or how the network would see it? The LAN recoginizes MAC addresses and only allows bandwidth at certain rooms, so would the switch somehow change that? (The switch would be moved to different people's rooms, depending on who's serving) This way the laptop people could get some smackdown.

Thanks,
Yo

 

[HaVoC]

Not exactly sure what you are trying to do. If you think that just adding a switch and connecting the UPLINK port of the switch will give your the server computer more bandwidth FROM the dorm LAN, you are mistaken. Most likely your dorm network admin has a managed switch/hub that is limiting bandwidth per port based on MAC addresses. Now, if you set up a lan in the server's dorm room, then the switch will allow the computers to communicate with each other faster as long as they are connected to the same switch.

Your concern here is latency more than bandwidth anyway. If you have a hub for the whole floor and a lot of people playing counterstrike, the collisions on the shared network will increase and latency will get worse. Theres not much you can do about that.

 

[adamone11]

Objective: Abiliity to have 3 laptops in a room, connected to the CS server. No internet access through dorm-wide LAN necessary or requested for the extra laptops; however the cs server is connected dorm-wide.

Materials: One 5 port switch, with the fifth shared as uplink; 15 foot of cat5 + 15 foot of cat5/laptop (Linksys 5-port workgroup switch model #EZXS55W rev2.0)

Question: If I connect my computer to the switch, then the switch to the wall, will the LAN see me any differently than before.

Reasoning: CS server might not be in the same room every time, so it would be a hassle to reregister if the switch changed something.

Thanks
Yo

 

[huesmann]

I suspect you'd need to have an individual IP for each machine on the network. If your ethernet port is assigned a number, then you wouldn't be able to just plug a switch into it and plug the laptops in as they wouldn't be able to all have the assigned IP at the same time.

 

[adamone11]

Okay, forget the laptops. If my ethernet works now, and I plugged in a switch (just me, no other computers on the switch) between me and the wall port, would it work?

I KNOW that the laptops would be able to connect to any other computer on MY switch, which is all I needed. I just need to know if _I_ will be able to get on the internet.

 

[Possum]

I also use a switch in my school dorm room to connect my own computer as well as a server to the single wall jack I get in my room (roommate gets the other jack). The school network assigns me a static IP address based on the MAC address of my ethernet card (OS is set to use DHCP). If I place a switch between my computer and the wall jack, nothing is changed in terms of my network settings and assignments.

But when I hook up my 2nd computer, I have to register the MAC address of the ethernet card in that system for a 2nd IP address in order for it to be recognized on the rest of the dorm/school network.

So if it's just you on the switch, and the switch to the wall, I think your connection should work as before. But if you were to add a 2nd computer to the switch, you might have to request for a 2nd IP address, depending on your school's policy. I'd check with your school's network services department.

 

[ktwebb]

I think the point they are trying to make is that you have an IP assigned by the college you attend. Either dynamic or static, really makes no difference. If you assigned a private IP to the NIC in your machine and then assigned like IP's (read same network ID's) then you would be cool, but if you tried to give IP's to your buddies that had the same network ID as the college you would have problems. In other words, you need one of the private IP ranges locally. They are 10.X.X.X, 172.16.X.X, and 192.168.X.X. Probably best just to buy the switch, and plug everybody's PC into that and just forget about the RJ-45 jack on the wall while you do your thing with counterstrike.

 

[adamone11]

<< If I place a switch between my computer and the wall jack, nothing is changed in terms of my network settings and assignments. >>

Thanks possum, thats exactly what I wanted to hear. I'm not sure about asking for extra ip addresses. From what I've heard from the dsl crowd you need a router to split bandwidth w/o the extra IP, so if I ever get a second computer I'd have to remember that. Problem with that is if your roommate didn't buy access; how would they know he wasn't feeding off you. I guess that's legal though, like SE's ICS, the bw would be half for each.

 

[bhuie]

<< Question: If I connect my computer to the switch, then the switch to the wall, will the LAN see me any differently than before >>



In all likelyhood and for all practical purposes, there won't be any difference to the network if you do this.

If you want to be nit-picky: (sort-of in-depth networking details follow)

But, there is is possiblility that you could cause a short (~1 min)loss of connectivity in the switched segment of the network that you are connected to when you plug the switch in or take it out. A number of things would need to be true for this to happen, but it is possible. For this to be true:

- spanning tree must be enabled on your switch
- there must be some redundancy (ie. some sort of loops) in the switches that lead up to the router that serves your port
- the bridge priority of your switch is lower than the current root switch of the spanning tree OR all the bridge priorities are the same and your switch's mac address is the lowest of all the switches

What happens in that case is that spanning tree (the layer 2 protocol that prevents loops among a group of switches) will detect that your switch should be the &quot;head&quot; of the spanning tree. It then causes every other switch to block all their ports while they recalculate the new topology of the network. This may take up to a minute or so, depending on what options are configured on the switches.

So, the moral of the story is that if everyone else on your floor/building starts complaining of losing their network connection whenever you add/remove your switch, then you need to set the bridge priority of your switch to greater than 32768.

But I would be seriously shocked if this actually happened.