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Network Design Questions

I am finalizing the design of our new corporate network. It will consist of the following:

Work Station Access - 3548 XL Switches - 2 per floor (one East / one West) ; total of 14 for seven floors. Each side of a floor will be a separate VLAN (Subnet). Switches will have 2 1000Base-SX GBICs. One GBIC will connect to fiber running to opposite closet/3548 Switch on that floor for redundancy. Other will terminate into a Catalyst 3508 XL Concentrator switch at the Core..

Server and WAN access: Other 3548 's will be "Giga Stacked" to form access stacks for Servers, Firewalls, WAN, and Internet access. These stacks will be connected to the Core 2948G-L3 's via

802.1Q "Channel Group" VLAN trunks. (groups of 2 to 4 FE ports)

Distribution/Core: Consist of 3 3508XL Switches to aggregate the GE fiber from the 3548''s. First Question: Should these 3508's be connected together via GigStack Modules or just plain 1000B-SX ?

Also connected to the 3508's will be 2 2948G-L3 Switches for routing function.

Current plan is to assign one 2948G-L3 to "West" subnets, and other to "East" subnets. Each 2948G-L3 attached to 3508's via one fiber GB Ethernet. Other GB Ethernet will connect the two 2948's together to keep inter-Server traffic off backbone.


1) Planing to utilize Spanning Tree for the East-to-West recovery link (if link to 3508 is lost) Is this sound? Better design?

2) What is best way to link the 3508's together - GigaStack modules or 1000B-SX, and why?

3) Will one GBE link from each 2948G-L3 to 3508 be OK or should I use 2 and connect the 2948's together with FE Channel groups?

4) Is splitting "east" and "west" Subnets (VLANS) between 2948s a sound idea? Can I use HSRP and secondary IP addresses to back one another up?

Better design?

Any other comments welcome. TIA.


Re: Network Design Questions

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