3750 setup

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May 14th, 2008
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I need to create a new setup using cisco 3750 switches. They will replace 2950 switches which are cascaded using GBIC ports. Need I connect the 3750 switches using stack cables. And in this case therewon't be any requirement to use 10/100 ports to cascade.

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Richard Burts Wed, 05/14/2008 - 17:50
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If you will be using several 3750 switches there are several advantages to connecting them using the stack cables. One advantage is that you do not use any 10/100 ports to create the connections. Other advantages include having much higher bandwidth on the link between switches and a better alternative for managing the stack.



Arvind kumar Sun, 05/18/2008 - 20:27
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I have a total of 7 switches. Now I should connect each switches with the stack cable and as per the earlier setup how could I connect this to the primary/secondary core swtiches for redundance. Please advise

Arvind kumar Tue, 05/20/2008 - 18:09
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My idea is that I should connect all the 7 3750 with stack cables and first one should be connected to the primary switch and last switch in the stack to secondary switch. Both primary and secondary switches are for redundancy. In this case if primary switch goes down traffic could be through the secondary. Now my question is this setup will do in the stacked switches. How STP will run. Please help

srue Tue, 05/20/2008 - 18:25
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no STP will run w/in the 3750's as they will all be one logical unit - in a stacked configuration.

STP will run as normal if you connect them to both core switches.

Also, with etherchannel, STP views this as one logical link.

You also need to verify which of your switches is actually the root switch for each vlan.

show spanning-tree root

Arvind kumar Tue, 05/20/2008 - 19:52
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my question here is onto the 7 stacked switches, how should I connect the primary core switch(Root) and onto which should I connect the secondary switch. Is that STP will be operational and the link on the secondary swithch will be put on blocking state.

vman1976nj Wed, 05/21/2008 - 05:08
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I have this exact setup in all my wiring closets. Its fiber back to the core so Gi1/0/1 goes to core 1, and gi7/0/1 goes to core 2. Core1 is root of the spanning tree, so Core2 is blocking.

Doing a:

sh spanning-tree interface gi1/0/1

Vlan Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

VLAN0001 Root FWD 4 128.1 P2p

VLAN0008 Root FWD 4 128.1 P2p

VLAN0009 Root FWD 4 128.1 P2p


doing a :

sh spanning-tree interface gi7/0/1

Vlan Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

VLAN0001 Altn BLK 19 128.160 P2p

VLAN0008 Altn BLK 19 128.160 P2p

VLAN0009 Altn BLK 19 128.160 P2p

Arvind kumar Tue, 05/27/2008 - 02:53
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one quick question here. I have 7 switches and I would be connecting them with stack cables and will it provide redundancy to each switch and how the first and last swtich will be connected. Thanks

Wantser1981_2 Tue, 05/27/2008 - 02:58
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To connect the first and last switch in the stack you will require a longer stacking cable that will need to be purchased seperately. Depending on how you have spaced your switches (ie with cable management etc) depends on how long a cable you will need.



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