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2960x stack deployment Questions

Folks:

I am reading through the following document

 

http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-2960-x-series-switches/white_paper_c11-728327.pdf
 

preparing to deploy a few 2960x switch stacks. Some of my stacks will be 4 units, and few of my stacks will max-out at 8 units.

 

Currently – due to simplicity and costs – I am looking at the ‘interwoven’ stack-cable method (page 7). From my understanding, the latter will provide: redundancy and full-bandwidth, while only using 0.5 meter cables. Has anyone deployed this method in production?

 

In addition, I am a little confused as to the placement of my uplink etherchannel connections? On (page 20) it says to place the uplink connections on switches that are NOT directly connected on FlexStack links. This relates to only four member units; however, does it make sense to apply the same concepts to switchstacks that are 4<?

 

Any other pointers, additional information and creative criticism is welcomed.

 

Thank you

JJ

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Super Bronze

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Posting

Don't have any first hand experience, but it shouldn't make any real difference concerning performance or redundancy.

(NB: The method can also can be used with longer cables when "stacking" TOR across multiple cabinets.)

To your last question, perhaps.  What's being done, for a stack of 4, is to insure if a stack member with one of the (two) uplinks fails, the remaining stack member, with uplink, is physically the center switch.  This avoids the need for traffic to transit from one end of the stack to another to get to/from the uplink.

If there are more that 4 switches, it probably makes sense to keep members with two uplinks as far apart as possible, again to avoid needless transit to the remaining uplink switch.

Personally, though, when you consider normal traffic flow, I wonder if it really makes enough of a difference to concern ourselves.

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VIP Super Bronze

Hi,Not sure about your first

Hi,

Not sure about your first question, but as for the second one, if you have stack of 4 switches, the best design is to have one link from each switch to the distro or core in one portchannel. see Figure-1-1

 

HTH

Super Bronze

DisclaimerThe Author of this

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Don't have any first hand experience, but it shouldn't make any real difference concerning performance or redundancy.

(NB: The method can also can be used with longer cables when "stacking" TOR across multiple cabinets.)

To your last question, perhaps.  What's being done, for a stack of 4, is to insure if a stack member with one of the (two) uplinks fails, the remaining stack member, with uplink, is physically the center switch.  This avoids the need for traffic to transit from one end of the stack to another to get to/from the uplink.

If there are more that 4 switches, it probably makes sense to keep members with two uplinks as far apart as possible, again to avoid needless transit to the remaining uplink switch.

Personally, though, when you consider normal traffic flow, I wonder if it really makes enough of a difference to concern ourselves.

New Member

Sorry for such a late follow

Sorry for such a late follow up; however, after working with the stacks I have determined it has do with switch hops along the stacking cables.

In a 4 unit stack - having uplinks on switch 1 and switch 3 enables only 1 hop to uplinked switches. Due to the latter, if only two-uplinks are used - a 4-unit stack is the most effective when looking at the paths to uplinks.

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