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Diasy-Chain configuration with 3524XL

We currently have a total of 7 Cisco 3524XL switches in a daisy-chain.

6 x Cisco 3524XL switches daisy-chained via Gig Ethernet using fiber and 1 x Cisco 3524XL connected via cross-over cable. There are also 3 or more Nortel Switches daisy-chained via cross-over from one of the Cisco 3524XL. I understand that there is a limitation of 9 cisco switches in a daisy-chain configuration but will this configuration work ?

3 REPLIES

Re: Diasy-Chain configuration with 3524XL

Hi,

are you using GigaStack GBICs to daisy-chain your 6x 3524? (If yes, the stacking cables are metallic, not fiber ones.)

The "9 switches in a daisy-chain" limit is regarding switches using Cisco GigaStack connections only. So don't worry about Nortels and cross-over connected Ciscos.

I would rather check the spanning tree network diameter (less or equal 7 recommended) in this case.

Regards,

Milan

Gold

Re: Diasy-Chain configuration with 3524XL

I agree with Milan, the 9-switch limit is if you're using the GigaStack GBICs, one per switch, and connecting them in the classic GigaStack cascaded configuration.

I also agree, if you are daisy-chaining with point-to-point Gigabit links, a pair of GBICs per link (or a cross-over cable between two 10/100 ports), with a redundant link for Spanning Tree, then watch your network diameter.

Adding to what he said, if no redundant link, just a long string of switches, then you can daisy-chain indefinitely, in theory. But in practice, there will generally be worse performance for the users out on the edge, as they hop their way along the uplinks to the switch with the server they want. Optimum location for the servers, to minimize the congestion, is in the middle of the daisy-chain, not out toward the ends.

A better design is generally to flatten out the network, with each of these switches uplinking to a distribution, core, or aggregation switch (call it what you want). Then users plugged into your access switches have a shorter path to hop, and everyone shares a similar level of access to the servers whether they're on one access switch ("server farm") or connected directly to the distribution/core/aggregation switch.

But there may be a logical reason to daisy-chain. I can think of a campus network design or two that I've seen, where L3 switching was handled in each building. Users in the building were on one or more local VLANs, and got their L3 from the local switch; connections of the L3 switch to adjacent buildings were put on a common backbone VLAN. Seemed to work OK, but I think it would have been better if they had collapsed that pseudo-ring backbone into a centralized switch. They just didn't have enough fiber in place to do it that way, and having evolved their old FDDI network to switched Gigabit Ethernet backbone, weren't inclined to spend any more money to install more fiber just to have an optimized network design. Also didn't want to buy into CWDM or DWDM gear to take advantage of the fiber they had in place, but knew that would probably be the direction they were headed vs. new fiber construction.

Hope this helps.

Community Member

Re: Diasy-Chain configuration with 3524XL

Thank you both for your response I will that into consideration.

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