BDI interface

What is BDI interface and why we use it ???

Hello Muhammad

Under normal circumstances, when you configure a router, each interface is assigned an IP address, and each interface must be on a separate subnet. If you try to assign IP addresses of the same subnet on two interfaces, the router will inform you of the error and not allow you to do so.

There are circumstances where you would want two or more interfaces of a router to be on the same subnet. More accurately, you would want two or more interfaces of a router to function as layer 2 switch ports, without any IP addresses assigned to the specific interfaces. Such interfaces on a router are called bridged interfaces. It is essentially a way to modify a layer 3 port on a router to function like a layer 2 port on a switch.

Now all of these bridged ports need a layer 3 port to correspond to them, so that devices connected to these ports can access other subnets. This is where a Bridge Domain Interface (BDI) comes in. It is a layer 3 virtual interface that corresponds to these bridged interfaces and is used as a default gateway for devices connected to the bridged interfaces.

Such a virtual port is known as a BDI for platforms using IOS-XE while it is known as a Bridge-Group Virtual Interface (BVI) for IOS devices.

You can find more information about these concepts at the following Cisco documentation:

I hope this has been helpful!

Laz

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The thing I got , same like SVI on layer 3 switch.

Hello Muhammad.

Yes, in a sense it is converting the participating ports of the router to function as layer 2 ports on a layer 3 switch with an SVI as the default gateway for all devices connected to these. That’s a good way of looking at it.

Laz

Hi Rene
Kindly can you make one Lab on BDI and service instance , i can’t truely understand the concept after searching on internet .will be thankful

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Hello Muhammad

Thanks for the suggestion for new topics. In order to have your suggestion recorded and considered for topics, feel free to go to the Lesson Ideas page whose link you’ll see below:


There you can state your idea and it can be considered for publication.

I hope this has been helpful!

Laz