Difference between interface and controller interface ?

[abhdivak]

Hello all,

What is the difference between interface and controller interface?  I observed interfaces as serial 1/0 and serial 2/0:0 (Controller E1 2/0). What is this exactly mean ?

Thanks,

Abhijith

[Peter Paluch · Accepted solution]

Abhijith,

Certain interface types have several modes of operation that need to be configured before the interface becomes operable. These modes are configured for the entire interface hardware - that is the interface controller - and they in turn determine how the individual interfaces driven by this controller operate. For example, an ISDN PRI controller can be configured either for US T-carrier or European E-carrier operation, and based on that, it provides you with either 23 or 30 resulting Serial interfaces, one for each B-channel. Without configuring the controller, the Serial interfaces would not even be available, because their count depends on what mode (T-carrier or E-carrier) is the controller working in.

This is the basic logic: The controller represents the hardware of the interface module whose configuration affects all interfaces on the module. Configuring the controller is typical for ISDN or selected DSL interface modules. Ethernet interfaces or plain Serial interfaces do not have similar configurable properties, and so there is no controller configuration available for them.

Best regards,
Peter

[abhdivak]

Hello Peter,

Thank you so much for the valuable information. I have one more question, Are cisco devices come with Controller by default or do we need to buy it separately ?  I am not taking about higher end device like 4500 or 6500 where we can select line cards as per our needs (Lets take ASR1004 or ISR 4451 or 3945 router). What about Ethernet interfaces or plain Serial interfaces ? In short what i am trying to ask is if i purchase one cisco device, how many interfaces will be available by default ?

Thanks,

Abhijith

[Peter Paluch]

Hi Abhijith,

Let me put it this way: Every network interface has a controller - a hardware chip that implements the necessary operations required to send and receive frames. However, not every interface type has a configurable controller, simply because the particular interface type does not have multiple modes of operation.

As for the default number of available interfaces, this really depends on the particular type of the Cisco box, as each can be different. For example, old 800 series routers came with built-in Serial interface and one or two routed Ethernet interfaces, newer 800 series routers come with DSL interface and a couple of switched Ethernet interfaces. With modular router types like 1800, 1900, 2800, 2900 series, they usually have at least two built-in routed Ethernet interfaces. As I mentioned, it depends very much on the particular type of the device, and there is no universal default.

Best regards,
Peter