Second IP on Interface Why?

So as you can see my title pretty much explains it all. I am wondering why someone would set a second ip address to a interface? Is there a special reason being this and has anyone done this and why.

Thanks for the info ahead of time.

Find more posts tagged with

Free for TechExams community: Cybersecurity salary guide

Compare cert salaries and plan your next career move

Button

Comments

mattrgee

There is a few reasons really, the most common you are likely to come across in the near future is for Frame Relay. A physical interface can be divided into multiple sub interfaces indicated with the .x notation, an ip address is then assigned to each sub interface.

mikej412

http://www.cisco.com/en/US/docs/ios/12_2/ip/configuration/guide/1cfipadr.html#wp1001012

https://supportwiki.cisco.com/ViewWiki/index.php/A_network_that_belongs_to_a_secondary_IP_address_is_not_advertised

boostinbadger

You would run into this configuring router on a stick too; configuring one interface with several sub interfaces.

Aaronfb

We do it on one of our routers as a means of seperating two network IP ranges that use the same interface on the router. I work in a retail environment and our Corporate office is next to one of our stores. Our office runs using the private ip range 198.232.234.x while our store runs the private range 10.124.1.x. On our inside interface we have the ip 10.124.1.1 and 198.212.234.1 assigined. Works fine. We treat as two seperate networks - tho really they are the same.

LBC90805

Aaronfb wrote: »

We do it on one of our routers as a means of seperating two network IP ranges that use the same interface on the router. I work in a retail environment and our Corporate office is next to one of our stores. Our office runs using the private ip range 198.232.234.x while our store runs the private range 10.124.1.x. On our inside interface we have the ip 10.124.1.1 and 198.212.234.1 assigined. Works fine. We treat as two seperate networks - tho really they are the same.

Are you sure that is a Private Address???

Gat0rvean

LBC90805 wrote: »

Are you sure that is a Private Address???

The 198.x.x.x is not reserved for private addressing.

Turgon

ULWiz wrote: »

So as you can see my title pretty much explains it all. I am wondering why someone would set a second ip address to a interface? Is there a special reason being this and has anyone done this and why.

Thanks for the info ahead of time.

Useful when migrating from one IP address range to another across a site. Used it for this very same purpose years back.