ip network design vlan

[sparkclee]

Hello,

We have several C Class on each vlan of our cisco 4510 10.0.30.0/24, 10.0.31.0/24, etc..  (about 8 C class/24 on each vlan)

because we have around 1600 user in some vlan.

I have heard that cisco used to recommend to have only one ip class per vlan.

Is this still true?

Is this realistic to use a A class for example 10.0.0.0/21 SM 255.255.248.0 DG 10.0.7.254 to have 2046 ip address with only one class per VLAN

instead of 8 C CLASS/24?

In term of performance (broadcast!) is this acceptable?

Thanks a lot

an example of what we have.

interface Vlanxx
description ** Vlan xx: production **
ip address 10.0.31.254 255.255.255.0 secondary
ip address 10.0.32.254 255.255.255.0 secondary
ip address 10.0.33.254 255.255.255.0 secondary
ip address 172.28.154.254 255.255.255.0 secondary
ip address 10.0.34.254 255.255.255.0 secondary
ip address 10.0.35.254 255.255.255.0 secondary
ip address 10.0.36.254 255.255.255.0 secondary
ip address 10.0.30.254 255.255.255.0

[Sebastian Fernandez]

James,

Practically this should be avoided as having around 1600 users in single VLAN can be messy if they are impacted with broadcast or multicast storm. Moreover since you have 4500 which is capable of creating good number SVI, I personally dont see a good point in terminating different vlan on same vlan interface.

Regards,

Sebastian

[sparkclee]

Sebastian,

thank you for your answer, so it means that it's better to have serveral  have several C Class /24 on each vlan like we actually have,

than only one A class /21 per vlan to avoid broadcast or multicast storm and about performance?

Thanks a lot
james

[Sebastian Fernandez]

That is correct James. Please rate my post if you find them helpful.

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Sebastian