Fully redundant Switches meaning

[moh123321]

                   Hi Everyone,

Could you pls let me know the exact meaning of attach ( yellow marked one)? the contractor was saying "it doesn't mean two switches as there is a built in redundancy in Cisco switch)"

I don't think he is correct as I never heard about built in redundancy in Cisco Router/switch

Any comment as this will affect the numbers from 55 (3750 v2) to 110....he is trying to save as you know.

Thanks

M

[Bilal Nawaz]

There is no true redundancy at the access layer unless PC's Destops Phones Printers etc... have two connections.

This is my personal opinion.

With regards to 3750 stackwise etc... the switches are resilient in that they can have redundant uplinks to the distribution/core that are etherchanneled. If one switch fails in the stack one of the uplinks in the etherchannel goes down, other one continues with the uplink in the etherchannel.

You just have degraded bandwidth and service, and several hosts not being on the network.

Same with chassis, 6500 or the 4500, dual SUPs is true redundancy in switch/router, but still does not provide resilence to access hosts. It will do with uplinks as long as you have pairs of chassis or running VSS (note, even a linecard could go bust!). Similar way with 3750's.

By redundant, I think this means the 'UPLINKs' to Core/Distribution - that should be the main worry here, and you can create resiliency. There is no resilience within one single physical 3750. Not that Im aware of anyway.

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[moh123321]

Thanks Bilal,

Regarding the 3750 stacking, the plan is as follow :

every floor ( total are 40) will have an IT room (closet), all will be connected via fiber to the core switch on level 27,

my question, can we implement etherchannel for all the casced switches even if they are located in differnt floor?

or the stacking can be on each floor between the two redundant switches?

BTW, you didn't answer me about your reading for the paragraph I attached, is this mean one or two switches per floor?

Thanks

M

[Bilal Nawaz]

Since the total is 40 on each floor, and the requirement is to have 24 port 10/100 PoE, you need 2 switches in a stack per floor.

From these two switches you can have:

• single link for each switch to the core's if you have two core switches (meaning 1gb connection each to the core)
• etherchanneled link from switch to one core switch (bundled etherchannel to single core switch)
• 2 links for each etherchannel, 1 etherchannel per core if you have two core's. (this is the best option - etherchannel from each switch to two cores)

Hope this helps

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[moh123321]

40 here meaning the number of the floors in the building NOT the number of network points per floor...just to clarify

so, from your reading the yellow part, is it meaning two physical switches cascaded or just a single one per floor?

Thanks

M

[Bilal Nawaz]

2 or more are required most definitely - how many people per floor? - (how else will you have redundacy with one switch, its a single point of failure!) Just wait for Leo's reply to my post for confirmation - he probably has more experience and knowledge with 3750's than me

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[Leo Laohoo]

Are you doing Layer 3?

If you're not, then purchasing a 3750 purely for Layer 3 is a sure waste of money.

Have you heard of the 2960S? 

[Bilal Nawaz]

Leo - is this statement correct?

"it doesn't mean two switches as there is a built in redundancy in Cisco switch"

With regards to 3750... (I dont know of anything within a single unit with redundancy features - as far as im aware, if its dead... its dead)

At least Mohamed can have a peace of mind that this statement is incorrect and he'll need a stack of some sort to provide resilience.

(I think its just for layer 2 - requirement was for access switch)

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[Leo Laohoo]

it doesn't mean two switches as there is a built in redundancy in Cisco switch

Hi Bilal,

This is a "trick question".

And this depends entirely on "who" is talking:  A SALES engineer or an engineer.

If this was spoken by a sales engineer, then it's correct.  How?  Chassis-based unit with dual supervisor card.  Ok, ok, ok, we'll debate later when you have a backplane failure.  LOL

If I was the engineer, then you are absolutely right.  Rubbish.  Once the unit is dead, it's dead.

My opinion. 

[moh123321]

Yes I heard about it, but specwise I think 3750 is higher than 2960S

I like your idea of having two bundled etherchannel fiber link for each group of Access switches, I think there is a limitation of the number of etherchannled switches ( the total will be 110 distributed as follows :

- Each floor 2 (3750 V2) Access Switches X 55 IT rooms

- Two core switches on 27th floor ( 6513)

Can I get a draft drawing for how the network will looks like ? should I have to use VISIO or there is a template can be used...

Thanks

M

[Bilal Nawaz]

2Gb etherchannels to each core. (2Gb from one switch to core 1 and 2G from second switch to core 2)
Both stacked.

We are not touching limitations here, unless there's limitation on line cards you're using in the 6500's. (128 ether channels 6500 12.2SX and other IOS)

Visio is probably best.

Sent from Cisco Technical Support iPhone App

[moh123321]

Let us take one floor as a typical,

- we have two Access switches, both cascaded

-  each one will be eitherchannled with the similar on on next floor connected to the core1 switch

- the eithechannel is limited to 8 aggregated Access switches

I it correct?

Thanks

M

[Bilal Nawaz]

No, this is not a limit in our case (we're not hitting anywhere near the 8 active links).

We have one floor....

• x2 24port 3750 in a stack

Switch 1 has etherchannel 1 on gi1/0/1 and 1/0/2 that goes back to Core 1 (2 each only, not 8)

Switch 2 has etherchannel 2 on gi2/0/1 and 2/0/2 that goes back to Core 2 (2 each only, not 8)

You are not hitting the limit on 8 ports bundled in an etherchannel

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[Leo Laohoo]

Bilal,

I presume you haven't heard of this:  2960-X

[moh123321]

Got it,

then the eitherchannel will be between two ports for each access switch to the core switch and because both access switches are  stacked, if one goes down the other switch will take over.

Thanks

M