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ip address of a port

when configuring the ip address of a port on a router , we can use the "secondary address" command to configure more than one ip address to the port , my question is what's the purpose of using another address on the port , and is there any limiations of numbers of the ip address on the port

thanks advance


Re: ip address of a port

The use of a secondary address (also called multinetting) lets you share multiple IP subnets per physical network segment. This is usually used for when your migrating from 1 address scheme to another address space and old address removed after moved over to new addressing.

Some folks do thie extensively for some reason (give different departments different IP space yet use same wire, etc). this really isn't good design. Can't think of any reasons for doing this on a long-term basis, especially in todays world with VLANs, dot1q/isl, etc.

You can have as many as the routers memory can handle... their probably is a limit of 255 but maybe not.

Routing protocols and other services running on router use the primary IP address to source packets from. This can be changed for a few things but not all.

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