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Cisco 3802i with 2 GB uplinks Myths

Hello,

 

Can someone explain in detail how does the performance gets affected or improved by having a 3802i with 2GB uplinks rather than with only one GB link to the switch?, is it worth to run and pay for a second cable to be extended for this purpose from the switch to the AP?, have someone deployed a cisco 3802i with two gig uplinks?...Is it really worth it?, how does the lwapp, capwap traffic to the WLC gets affected, now that more traffic is traversing the WLC?

 

And most importantly to what type of clients would you recommend this type setup?

 

8 Replies 8

Leo Laohoo
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All of my 2800/3800 deployment are on a single link.
I have yet to see a 1 Gbps port get over-subscribed.

Leo,

 

Thanks for your response. Would you say this depends on the amount of clients registered to an specific AP as well as the type of traffic being passed via the AP? .

Yes, that is correct. it depends on the clients connected to same AP, and kind of Traffic going in and out via same AP.

 

 

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Balaji,

 

Thanks for your time, but is there any math calculation, or a way to justify the need of a second link? I mean i cant just tell my customer, well you need a second link because of the type of traffic your clients have an the amount of AP's, he will then asked, well what is the math or the formula you use to justify a second link? do you know what I mean? .

Leo,

 

Well if you tell a customer that it will be good for them to install or to run to links/cables to the 3802is from/to the switch. This creates an extra cost. so you need to be able to justify the cost, by saying well, yes mister customer now you have two 1GB uplinks to the switch, and this will be better for the users connected to the AP then he may asked you, well tell me how does 2, 1GB links can help the performance. Another words if an AP can handle 200 clients for basic email, now with 2 links it can handle 400 clients etc etc. 


@bhupenderrawat79 wrote:

Another words if an AP can handle 200 clients for basic email, now with 2 links it can handle 400 clients etc etc. 


I have yet to see >50 wireless clients doing sustained data transmission.   So I can have 200 wireless clients connected to a single AP.  Question is:  How many of the 200 are actually transferring >100 Mbps data?  At a sustained rate?

Let's be honest now.  3800 supports mGIG.  This is Cisco's "selling point" to on-sell the 3850 with mGIG.  Going down the "wave 2" bandwagon is very expensive.  Unlike previous upgrade, like from 802.11 a/b/g to 802.11n, it was as simple as replacing the AP.  That's it. 

For these wave 2 models, one has to swallow hard.  Not only do one have to replace the AP but to ensure that there is enough bandwidth from the switch all the way to the core and WLC.  10 Gbps and 40 Gbps backbone are mandatory. Those things are not cheap either.   So to go down the wave 1/wave 2 fad, it may be necessary to upgrade the access, distro and core switches.  Distro and core must have ample 10- or 40 Gbps optics.  

No, stay with one link. Newer APs, like the 3802, can do mGIG with up to 5 Gbps on a single Cat5e cable over 100 Meters. This does require an mGIG capable switch though. This switch then also requires at least a 10 Gbps connection to the uplink switch, or you loose all the mGIG speed again.
In any case, I'd not do 2 cables, as you will win (barely) nothing.

Nope.
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