block design

[carl_townshend]

Hi all, If I wanted to implement the core, dist,access setup in my office builsing, would I say have 2 cores, a distribution on each floor which connected to access switches, then each dist connects to both cores, can anyone give me a good setup for this ? say 4 switches per floor.

thanks

[jheckart]

I think that this depends greatly on the number of floors and users per floor. The campus design model would place two 6500's in the core with something like 4500's in the distribution, and 3560's in the access layer.

You may want to elaborate on what you're trying to design as far as number of users, floors, etc. Much of the time for the smaller environments that would have 6-10 floors with a handfull of access-layer switches per floor, you may be best off with a collapsed core, which could be a couple 6500's or 4500's.

What are the details?

Jeff

[carl_townshend]

thanks for youre help

, basically we have say 80 users per floor, over 6 floors, would we have 1 distribution per floow would you say, and just link the dist switches to both cores ?

[sachinraja]

Hello Carl,

I guess the best and cost effective design in your case is to have a collapsed core with 6500's or 4500's ( i would really prefer 6500) and have Layer 2 distribution switches connected on cascade. with 80 users u might have 2 switches per floor, so u can cascade these two switches and take a trunk from switch 1 to core 1 and switch 2 to core 2. This will give you maximum high availability and scalability. You can run RSTP on the core to have failover trunks to come up quickly than before....

Having a distribution switch on each floor will have the layer 3 terminated on the floor and due to that u might need to have a layer 3 trunk with some routing protocol running on the uplinks. this can give good convergence, but it all depends on ur business requirement. For eg, if u want to extend VLANs between floors, u cannot use this model.

Just to brief, i guess in ur case a two-tier architecture will be really worth, which takes care of all business requirements.

Hope this helps.. all the best.. rate replies if found useful..

Raj

[carl_townshend]

firstly can you tell me what a collapsed core is ? and can you tell me how we would connect each switch then, ie what goes into what,. thanks very much

carl

[jheckart]

I agree with going towards the collapsed core. In answer to your question, the collapsed core merges or collapses the distribution and core layers into one. You then have only the two tier approach with the collapsed core and access layer.

Along with what was said above, I would make certain that you understand how RSTP works, and verify that your root and secondary are the 6500's, so that one of your access layer switches does not become root.

http://www.cisco.com/en/US/tech/tk389/tk621/technologies_white_paper09186a0080094cfa.shtml

In answer to connecting each switch, I would recommend running as much fiber as you can from each floor to the core. Group the access switches in a way that the loss of one switch will not take down an entire floor. For 8 switches per floor, a minimum would be 2 pairs of fiber per floor to maintain a level of redundancy. 4 pairs would be even better.

Jeff