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LAN design

I am working on a LAN design. The total users are 26000. It is multifloor single building. I would like to know what architecture should I propose - 3tier or 2-tier. Also what should be there in core?

Hall of Fame Super Silver

Re: LAN design

Hello Satheesh,

using powerful switches at access layer modular C4506 you should be able to use a two layers network.

C4500 has 48 10/100/1000 linecards


WS-X4648-RJ45V-E (24 Gbps/linecard)

the chassis can be 4510R-E with sup6-E

that should be able to host 8 48GE linecards

384 ports/device

67 devices required

a 3 tier may be needed if you want to give 10GE uplinks to the access layer switches.

(reduced port density for 10GE ports)

Or even you can think to used C6500 also on the access layer to have greater port density.

How many users per floor ? this can be a parameter to decide what switch to use on the access layer.

On the core two C6500 with Sup720 3B should do the work.

the distribution layer if needed (if 10GE uplinks) can be done with c6500 with sup720 3B too.

You may also consider to use a L3 access layer if deploying multilayer switches at access layer.

In this case each client vlan will be within a single access layer multilayer switch that will act as the router for it.

Hope to help


Super Bronze

Re: LAN design

With current equipment, you could provide 26,000 ports with just two layers. Many of the chassis devices support 48 port cards providing hundreds of ports per device. Some also support 10 gig port cards providing up to over a hundred ports per device. Cisco's stackable switches can also provide a large number of ports per logical device; comparable port numbers vs. large chassis, at least for copper ports.

"Also what should be there in core?" That would depend much on whether you go with 3 or 2 tier, required performance, other features needed, etc. For a 2 tier approach, you'll likely want a powerful large chassis, 6509 might be a good choice, or perhaps with a focus on 10 gig, the Nexus 7000 series. For a 3 tier approach, a smaller chassis or high performance non-chassis device may work. Examples of the latter, again if working with 10 gig, might be the 4900M or Nexus 5000 series (NB: the Nexus 5000 series, I believe, is only be L2).

Hall of Fame Super Blue

Re: LAN design


There really isn't enough information to suggest either really.

26000 users in a single building is a big building and this raises any number of questions

1) How many floors

2) Are you thinking of a routed or switches access-layer to distribution layer. This can make a big difference to whether you use 3 or 2 tier model

3) Do you have any servers in this building that users need access to. If so what type of applications are running on these servers in terms of data volumes.

4) How are the users in the building organised eg. by floor/dept etc. And are some users more important than others.

5) Are you going to be using VOIP/Video or do any of your other applications require traffic prioritisation.

6) Do you security requirements such as internal firewalling.

7) Do you have requirements for load-balancing.

The list could go on and on and without answers to these questions it's difficult to choose between one or the other. As Giuseppe pointed out what speed links are you looking to have as uplinks and what speed are you looking to deliver to the desktop as these again could have a huge impact on 2 vs 3 tier design.

Key thing is to know exactly what will be running across the network in terms of apps and then you can start to design a solution.