Central & local switching design considerations

[iores]

Hi,

What are Cisco recommendations on maximum client subnet size for central and local switched sites?

What are Cisco recommendations on maximum APs subnet size for central and local switched sites?

What are underlying reasons for such recommendations?

[Haydn Andrews]

I have not seen an official best practice guide from Cisco.

I generally try and keep the size relative to the max number of devices. I generally have no requirement to go over /23 for AP management. Most cases for local switched users im using between /23 and /25 due to the device use cases.

Centrally switched I try and keep it at max /22 and then have multiple VLANs in the VLAN group assigned to the use case if I need more IPs.

[iores]

@Haydn Andrews What are the reasons for doing so? What exactly are you targeting with such approach?

[Haydn Andrews]

Running extremely large company, IPs run out, so firstly its conversation of IP addresses, by ensuring that we are only using subnets applicable to current and expected growth.
For example none of our branch offices have no more than 30 APs, so having a /21 for AP management makes no sense when a /26 will do, yes we could potentially go smaller, but if for some reason we need an additional APs we would be stuck.

For client subnets the same method is used.

When I said I limit the top end, thats more to keep potential broadcast domains low. And generally the additional are added as growth happens.

[iores]

@Haydn Andrews Is there any impact on wireless performance? If you are using VLAN groups or interface grouping, is there any additional reason for this except preventing some subnets being underutilized?