300 people LAN advice

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thehacker

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Aug 22, 2011
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Hi

We are trying to set up a medium sized lan for our hostels. There will be around 300 users.

The plan of the hostel (3 floors) is as follows :



We have access to a few gigabit switches and some 100mbps switches

(all are L2 switches DGS1008D and DES1008D)

We have something like the following setup.



We get 1 wire for internet coming from the campus which needs to be distrbuted to everyone.

Requirement is maximum file transfer speeds followed by LAN latencies for LAN gaming.

Last year what we did was connect the gigabit switches in a line (bus) and then connect the 100 mbps switches to the gigabits and the users were connected to the 100mbps switches (the high usage users to the gigabits directly where possible)

Is there a better / more optimum solution possible?

Would it be better to have a star topology with a better switch at the center and the gigabits connected to it in a star?

What equipment would be required for such purpose?

Please keep in mind that we would like it as cheap as possible since we already have most of the gigabit switches and 100mbps switches on hand and have approx 300USD equivalent in INR for additional equipment.

Your inputs and feedback would be highly appreciated.

Thanks a lot in advance

Shubhangam
NIT Calicut, India
 
I'd recommend a more star-ish design as you mentioned. The bus design is going to cause a lot of latency problems in high usage situations, especially if devices towards the end of the chain need to talk to devices on another end.

Assuming you don't need a router as your gateway, you can go with any cheap HP/Cisco switch you can find.

I think your biggest problem is going to be users hogging bandwidth. If the software on your switches allows for it, you may want to use some form of QoS or bandwidth limiting.
 
Agree that bus design is asking for problems and will also limit your bandwidth a lot.

Without more information on where your closets are and the length of runs etc, it's hard to really make any recommendations, but I'd say a good middle ground might be to have several stars that are trunked together. Whether you have two stars per floor (6 cores linked), or one per floor (3), or two stars eg if your building is east to west, an east and west core to trunk together.

I'd personally lean toward having fewer stars, or even 2 levels of stars, and use solid switches for distribution that support link aggregation so you will have a lot of internal switching bandwidth. Though just going to star will improve that from your current design.

All IMHO. There are far more experienced network designers around these parts than me. :)
 
Thanks for your quick responses.

The hostel length will be 80 mtrs and width around 40 mtrs.

We have more or less settled for a star design

Now the thing is we have around 10 8-port gigabit switches.

What I'd like to know is that should we use one of these as the main star centre or buy a 16 port gigabit switch?

The problem is that we cannot find any 8, 12 or 16 port switch with (l2+) routing facilites or link aggregation within 200~250$ and our max spare budget atm is around 300~350$.

So what would you guys recommend to do? Are there any cheap switches available which would fit the bill? Please understand that we are in India, and as such do not have a lot of options available.

Is there a problem going for a un-managed regular gigabit 8 or 12 port at the centre of the star? How much difference in performance is it going to have? Especially because we have lot of traffic on the LAN.

Thanks for you valuable time.
Shubhangam
 
I don't think you need link aggregation unless you are really pumping data. The only reason you'd need an L3 switch is to limit broadcasts which may get intense with 300 or more nodes on the network.

However, as long as the folks on the other end of your internet wire are cooperative and have taken care of things for you, or even better are offering services to you like DHCP, you're in good shape.

The biggest issue for the center of your star is going to be total throughput of the switch. Since this switch will likely see the highest utilization, make sure that it is as close to non-blocking as possible.
 
thehacker said:
Thanks for your quick responses.

The hostel length will be 80 mtrs and width around 40 mtrs.

We have more or less settled for a star design

Now the thing is we have around 10 8-port gigabit switches.

What I'd like to know is that should we use one of these as the main star centre or buy a 16 port gigabit switch?

The problem is that we cannot find any 8, 12 or 16 port switch with (l2+) routing facilites or link aggregation within 200~250$ and our max spare budget atm is around 300~350$.

So what would you guys recommend to do? Are there any cheap switches available which would fit the bill? Please understand that we are in India, and as such do not have a lot of options available.

Is there a problem going for a un-managed regular gigabit 8 or 12 port at the centre of the star? How much difference in performance is it going to have? Especially because we have lot of traffic on the LAN.

Thanks for you valuable time.
Shubhangam
Click to expand...

Very nice - doing a single star simplifies things a lot. You only would really benefit from link aggregation if you had multiple stars that you were going to join. If everything goes to a single central switch, your load is reasonably well spread and there's no need to link ag to each switch.

For your purposes, you could use an unmanaged switch at the core, however there are benefits to getting a managed switch for that purpose, for example to monitor port bandwidth via SNMP or rate-limit/disable ports, or set up VLANs. Check out a Cisco SG300-20.
 
That's quite a lot of 8 port switches you have there! My preference would be to just wire the whole thing from a couple of chassis switches, given that you have stated distances <100m. But big switches cost $$$.
 
Sounds pretty good I guess

We are thinking of using a 16port Gigabit at the centre

What exactly is a smart switch?

http://www.netgear.com/business/products/switches/smart-switches/gs716t.aspx is available for 300USD equivalent.

What would be the benefits of using this over a regular un-managed 16 port gigabit switch (can get one for around 200USD equivalent)?

The SG300-20 is 400$ on US Amazon, will be around 500$ here -- way out of our budgets :)

I guess link-aggregation will not be needed for a single star so that's one problem out :)

Thanks again for you time
Shubhangam

Edit:


brons2 said:
That's quite a lot of 8 port switches you have there! My preference would be to just wire the whole thing from a couple of chassis switches, given that you have stated distances <100m. But big switches cost $$$.
Click to expand...

The cash is becoming a problem as all of this is student funded instead of being university funded... Also we already have the 100mbps switches left over from last year's config. So much for being in a "National Institute of Technology" :(


Volcanon said:
However, as long as the folks on the other end of your internet wire are cooperative and have taken care of things for you, or even better are offering services to you like DHCP, you're in good shape.
Click to expand...

No, and no - no dhcp - we have to use static IPs. And FWIW we have per stream bandwidth limitation and a lot of other limitations :)
 
Last edited:
Smart or managed switches allow you to run Cacti, MRTG (both free) or pretty much any SNMP monitoring software against the switch to see how much bandwidth each port is using. And you can log into the switch to turn on or off a port, or to put bandwidth limits on the port, if a port is known for saturating the network. Smart switches can also provide some security and QoS features that could come in handy, plus they allow you to set up monitoring ports so you can run a sniffer to troubleshoot your network or to install an IDS. Useful.

The reason I recommended the SG300 is because it's the first Cisco that offers a console access, however, I'd recommend you also price the SG100 and SG200 lines. They're web-console only, but I feel they'd probably be something I'd go with over a Netgear. But for what it's worth, the Netgear you linked isn't too bad, and it's definitely an improvement over an unmanaged switch, as it does support at least a lot of the basic things you might want to do. I've used the GS108T and it's been a decent standin for the price where I've needed extra features....

Edit: .... but I'd still recommend going for a Cisco in a larger installation.
 
Okay I shall enquire about the availability and pricing of the Cisco switches here.

Do the smart switches have the routing facilities i.e. will they send data only to the proper nodes instead of flooding the network? (From what I understand, un-managed switches have this problem of flooding)

Thanks
Shubhangam
 
All switches (managed, smart, unmanaged) will direct the traffic to the appropriate port for regular unicast traffic, unlike a hub. Of course some traffic is designed/intended to be sent to all ports.

However, unmanaged switches are prone to layer 2 attacks like MAC flooding (dsniff), rogue DHCP servers, and STP security issues. While I'm not fully versed in these things, I do know that the better managed switches have protections from these things like port security, dhcp snooping, and root guard.
 
I would highly recommend a DHCP server. People will be stepping on each others IPs if you don't.

You can throw any old PC on the network running an appliance (pfSense, etc) to provide the service.
 
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