Cisco hierarchy question

Nov 23, 2006 7 Replies
S

Hi



I'm trying to visualise the Cisco hierarchy of access-distribution-core.



So far, I understand that the access layer is where the users are connected to (e.g. 2960 switches), the distribution is where ACLS's, VLAN routing etc takes places (e.g 3750 switches) and the core layer is simply for fast thoroughput of data (e.g. Cisco 5000 switch).



As below;



5000
3750 3750 I I I I
2960-2960-2960-2960

What I don't understand then is why do Core switches such as the 4000.



5000, and 6000 Cat switches have so many ports? Surely it should be the access layer switches with most ports, then the distribution and finally the core with the least (as in the diagram above, since the core switch there only connects the two 3750's together).

To help me, I've built a little home lab with three 2950 switches, a



2620 router (intervlan routing), and an old 5000 switch. Would the optimum method be for all to be connected to the 5000 switches ports, as below


5000



2950 2950 2950 2620

or should it be


5000
2620
2950 2950 2950

Very confused, and could appreciate some advise from others!



Thanks!



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D

when a network requires the core dist access layout it is because they have many users, probably 1000's and more, so when they have a big cat switch at the core, all of those ports will be trunking to another switch(dist), or they will bundle many ports together through etherchannel to proivde enough bandwidth, and all those ports on the dist switch trunk to smaller switches which users plug into, that gives an idea on the bandwidth and speed the core switches need.. i understand you are just testing it, but with 5 switches you wouldn't use a 3 tier layout like this.

Flamer.

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X

A lot of small and middle networks don't have the distribution layer,it is merged to the core layer.Also,many servers may be connected to the core layer.So,the core maybe have a lot of ports.Now,the switches are all moduler,if you do not need may ports,you can select the right module.

On 11=D4=C224=C8=D5, =C9=CF=CE=E73=CA=B143=B7=D6, snipped-for-privacy@googlemail.com wr= ote:

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S

Thanks for the replies.

Just one final question, in my home lab of the 2950's, 2620 (intervlan routing) and 5000 switch, what would be the most effecient setup?

Thanks again.

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M

Suggested setup would be

2620 | 5000 / | \\ 2950 2950 2950
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S

Thanks....out of curiosity, if I had a bunch of 2950's and a layer 3 switch, such as a 3550 (but with no spare gigabit ports), where should the server block be connected? To the 2950's, the 3550, or does it not matter?

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M

Lets assume your setup is emulating a business network and that the

3550 is located in a central location ( computer room?). For this type of setup one would connect the server to the 3550 because usually the computer room would be air-conditioned and access closet are gnerallly not.

This topology would also result in users being equidistant from the server in terms of the number of switch hops.

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