LAN Switching

[himanshubhalla]

Hi All,

If i stack of 4 x 48 port 3750x switches, with one gig links going to desktop for each switch. What bandwidth would i need to connect it back to the distribution layer so that there is no contention?    

any help will much appreciated.

Thanks

[vmiller]

So 4x48 1 gig ports comes out to 192 Gig.

40 Gig is just getting started.......

You may need to re think things.

[Reza Sharifi]

Hi,

You can get a 10Gig module for the 3750x series. Each module will give you 2 10gig ports.  You can use them for your uplinks.

HTH

[hobbe]

Hi

What is the average bandwith of each of the desktops ?

1-10 Mbit ?

How many will be "maxing out" at the same time ? I am guessing 3-400 Mbit per pc when reinstalling the computer or something similar and max throughput from the server would be 10Gbit ? right ?

The max bandwith you can get is 64Gbit since thats the stackwise+ speed.

My guess would be that you would need 1, but I would buy 2 c3k-nm-10g etherchannel all 4 10Gbit ports.

That will give you max 40Gbit to the dist.

Good luck

HTH

[himanshubhalla]

Hi Guys,

Thanks for your replies, your help is much appreciated.

I am using 4506 x 2 for resiliency and with 3 x  6 port 10 gig Linecard. I know all the switches comes out at 192 gig, can i use all the SFP ports on each switch to give me 10 gig uplinks to the distribution layer?

This will come out to 80 gig, but the contention issue will still be there because it is just over 2:1 over subscription.

Like before, any help is much appreciated.

Thanks

[Freihafener]

Never had to try it, but basically it should be possible to build a channel with all 8 ports. I guess you wolud have to connect them to a single 4506, for dividing connections of a channel you need some nexus switches - as far a I know.

But you are right - 80G is still less than 192G. But I do not see your point with that. A higher bandwith is not possible in this configuration. Theoretically you could take a 48 port switch and divide it in 24 port client connection and 24 port uplink channel (if 24 ports in a portchannel are possible). In this case connection clients to the core switch directly would be easier, I guess.Or you have to take 24 port switches with a 20G uplink.

Are you sure that each of your clients need 1G bandwith permanently? At an average environment clients rarely need full bandwith as mentioned above. We often used 48 port gigabit switches with an 2x1G fiber uplink - no problem.

Greets FH

[himanshubhalla]

Hi FH

Thanks a lot for your answer.

I think going for 24 ports switch with 2 10 gig links could resolve the contention issues. I think SFP ports can be aggregated to create one channel on 3750x but i guess 24 ports switches is the right way forward. Unless there is another way to approach this.

I need to desgin a LAN for 625 seats, spread scross 5 floors. 125 users on each floor and some hot desks. Trying to find whats the best way forward. I am using a two teir architecture.

Thansk

[Leo Laohoo]

10 Gb on a 4500?  I wouldn't even bother unless you are thinking about a 4500E+ paired with a Sup7.

[vmiller]

Were your intentions to run one big VLAN? (i hope not).

I'd suggest carving the user community up logically and run a pair of access switches on one uplink (or something like that) and use

layer 3 to reduce the broadcast domain and keep things tidy.

I understand your concern regarding oversubscription, so I'd suggest try it first, get some numbers regarding performance,

then look at QOS to meter the flow.

All of us here at one point have had users insist that they need the absolute maximum bandwidth 7x24. In reality, it rarely works out that way.

2 to 1 oversubscription is well within reason.