How many Secondarys can an interface have?

simon.bell · ‎02-13-2009

We're in the process of migrating a site from one big flat network to vlans and were wondering how many secondary IPs an interface can have. All that I find online is "multiple". We might need 20-30...

TIA

Giuseppe Larosa · ‎02-13-2009

Hello Simon,

if you are going to use DHCP to provide ip addresses to users, you can move user ports directly to different Vlans, you can configure the associated SVIs (L3 interfaces if using multilayer switches) and so you can probably skip an intermediary step using secondary ip addresses.

Each VLAN will have its own DHCP scope amd you will be fine.

If not using DHCP you need however to change configuration one device a time and again you can use directly new vlans and new L3 interfaces.

So I would suggest to consider moving few devices to a new vlan at a time after having configured the associated L3 interface.

You need to prepare the infrastructure with all the required L2 trunks to carry all the required vlans from access layer switch to distribution/core

Then when everything is fine you can start your moves directly to definitive Vlans with working L3 services (default gateway may be provided with HSRP or GLBP for redundancy)

Hope to help

Giuseppe

John Blakley · ‎02-13-2009

I would go with what Giuseppe said, but in addition to that, there is no limit on the amount of secondary addresses that you can have.

HTH,

John

HTH, John *** Please rate all useful posts ***

simon.bell · ‎02-13-2009

Thanks john, that's good to know.

simon.bell · ‎02-13-2009

Thanks Giuseppe, we are planning on moving everything to SVIs, this is just part of the migration steps we're taking/discussing.