Planning for a Core Switch Deployment

[ranjit123]

Hello All,

I am planning for a core switch requirement is it should connect 2000 access ports in the distribution / access layer and scale in future.

I have the option for using 9500-48 port ( in SVL ) which has 6.3 Tbps of switching capacity and 9404R ( in SVL ) which has switching capacity of 9 Tbps..

considering the future expansion and requirement which model should i go for..

As if i choose 9500 i will get 12.6 Tbps aggregated throughput

and

if i choose 9404R i will get 18 Tbps aggregated throughput

[balaji.bandi]

CAt 9500 or Cat 9600(bit expensive here) for core deployment,)

The distribution you can use Cat 9400 or Cat 9600(again as Collapsed Core - to save cost)

Since the high volume of access switches, I suggest having modular distribution or collapsed core here.

use the distributed model to split the access switches based on the area.

here are some good resources :

https://www.cisco.com/c/en/us/td/docs/solutions/CVD/Campus/cisco-campus-lan-wlan-design-guide.html

https://www.cisco.com/c/en/us/solutions/enterprise/design-zone-campus/design-guide-listing.html

[ranjit123]

Thanks a lot Balaji for your feedback.. budget is a constraint here ..

I will am planning for 9200 switches in the distribution / access in stack for aggregated port density

Also the end user count can also increase so for that purpose i am planning for 9404 modular chassis switches in core

so if in future is the end user count increases i can buy another line cards on the switches and connect them to distribution / access layer

Please update me can 9404 be used in the core layer also will it increase my aggregate throughput ( 19 Tbps ) for consolidated B/W from the distribution / access layer

As if the the network grows in the future to 3000 to 4000 users 9500 i think will not be able to handle it with its 6.3 Tbps throughput limitation per switch.

Kindly guide me on the same..... 

[Scott Hodgdon]

Ranjit,

How many stacks will you have ? The number of ports is not the concern so much as the number of switch stacks if you are using stacking as you indicated. 2000 ports is 42 switches of 48 ports each.

What do you plan for uplink bandwidth from these stacks ? 

Do you have a design diagram you can share?

Cheers,
Scott Hodgdon

Senior Technical Marketing Engineer

Enterprise Networking and Cloud Group

[ranjit123]

Hi Scott,

I am planning for initially 1000 users with 4 switches maximum in a stack ( 9200-48)

Like this 8 stacks in the access layer

[balaji.bandi]

There are a couple of things that need to be addressed here :

If cat 9200 as access that is deployed as Layer 2

Your Collapsed Core should be good enough to hand all the Layer 2 traffic of your Access switches.

Cat 9400 ( i will step back here - but I believe good candidate but i will not recommend as core here)

But you can go Cat 9600 good chassis with your Long-term plan, so you no need to change anything, except adding Access layer switch and new modules blades on Collapsed Core Switch.

If you calculate another side, Cat 9500 X 4 will give you more capacity less cost compare to Cat 9600 here ( which can accommodate your requirements of 42 switched as per the calculation) - when you adding new users, you can add new Cat 9500 along with access switch order, this gives the business some buffer for to invest rather Capex cost high at the beginning.

You need to split the load between Cat 9500 for the Access switches to meet the throughput (this is cost vs performance debate ?)

if the "budget is a constraint here" I stay away from SD-Access for now (but if cisco gives free - I got one free to play ) you can take free to play DNAC environment,(its free appliance there is no support added bare that in mind).

in this case any of the solutions you need only the essential License for Access, Network Advantage for  Collapsed Core.

[ranjit123]

Hi Balaji,

Thanks a lot for your detailed update

how about 9606 in the core ( With Network Advantage license)

9200 switch stack in the access ie 8 switch stack of 4 switches each ( 48 ports ) ( with network essential license )

Also for a 4 switch stack of 48 ports ie 192 ports will 40 G uplink for this switch stack be sufficient so that will be a ratio of 192:40

will this subscription ratio work..

Please guide me..

[balaji.bandi]

Yes Cisco 9600 is good Candidate for Core, (since you mentioned budged i was pushing towards Cat 9500, if you can can able to accomidate Cat 9600, its good have good capacity.

I would Advise 4 switch per stack, rather 8 per stack, (in terms of maintenance and failure scenarios)

192:40 will this subscription ratio work..

Do you really see 100% utilisatiom, since this access switches, you may not reach that level, as per my deployment models should be good, but wait for other suggestions.

[Scott Hodgdon · Accepted solution]

Ranjit,

The oversubscription is really up to what you think your users will require. They will be connected at 1Gbps, but I doubt any will run at that speed for any length of time (if ever). What is the bandwidth needed now ? What kind of applications do they use ? What is the expected growth ?

With 2 x 40G uplinks from a stack , that means only  8 of 32 ports used on 9500-32QC. So you could easily double the number of stacks with no worries of running out of ports. The 9500-32QC is line rate, so even if you used all 32 ports at 40G, you would not have blocking.

Cheers,
Scott Hodgdon

Senior Technical Marketing Engineer

Enterprise Networking and Cloud Group

[ranjit123]

Thanks a lot Balaji, Scoot & Leo...

[Leo Laohoo]

Talk to your Cisco AM/SE and ask about the Catalyst 9600.

You just might get a free Cisco DNA Appliance with the purchase.

[ranjit123]

Thanks leo.. i will also check with them

[Leo Laohoo]

Or ask your Cisco AM/SE about the newly announced 9300X.