Multi-point subinterface vs Multi-point physical interface

[kawarrahaj]

Hi all.

I have been searching for hours regarding the subject above but can't seem to find any. My main question is, why would you prefer to use a multipoint subinterface instead of using a multipoint physical interface? Are there any differences or advantages?

Thank you in advance.

[paul driver]

Hello

Sub-interfaces alows you to defind both multipoint and point-point connections-( full or partial meshed networks)  - however the physical nterface by default is an multipoint interface with inverse-arp enabled and prohbits point-to-point.

http://www.cisco.com/en/US/tech/tk713/tk237/technologies_tech_note09186a008014f8a7.shtml#topic2

res

Paul

Please don't forget to rate any posts that have been helpful.

Thanks.

[kawarrahaj]

Hi Paul.

Sub-interfaces alows you to defind both multipoint and point-point connections-( full or partial meshed networks)  - however the physical nterface by default is an multipoint interface with inverse-arp enabled and prohbits point-to-point.
http://www.cisco.com/en/US/tech/tk713/tk237/technologies_tech_note09186a008014f8a7.shtml#topic2

Thanks for the reply. But, I already know the concept of what you have stated above. What I'm asking is, is there any particular scenario where in you would prefer the use of a multipoint subinterface over a multipoint phyisical interface?

I have read some threads where in using a multipoint subinterface is more ideal than a phyisical interface when it comes to full mesh topologies. But the latter statement is a little bit blurry.

[JohnTylerPearce]

Kawar,

If you do a point-to-multipoint network/interface type, you can use one subnet for all devics within this network. So for instance, let's say you have 10 buidlings around your city, and they are connected via Metro Ethernet. You want as single core network, so you consider them all point-to-multipoint with network, let's say, (10.0.0.0/27).

With point-to-point, each connection would need to be in a separate subnet. For Example, (10.0.0.0/30, 10.0.0.4/30, 10.0.0.8/30) etc etc.

[kawarrahaj]

Hi John. I appreciate the reply. But what you have given is the difference between multipoint and poin-to-point topologies. What I'm asking is about multipoint interfaces only. Point-to-point is off the topic. As you know, we can configure multipoint in two ways.

1.) In the physical interface (which is the default)

2.) In a subinterface

The reason why I'm asking this is because, why would you configure multipoint in the "subinterface" instead of using the "physical" interface if the effect is just the same?

Are there any scenarios where in configuring "multipoint in the subinterface" is more advantageous over "multipoint in physical interface" ?

Thanks.

[kawarrahaj]

Trying to keep this thread alive.

[paul driver · Accepted solution]

Hello

Multipoint interfaces - are muiltaccess, meaning they expect to connect to all devices in one single subnet off that interface .

On a Subinterfaces, you can have muiltaccess interfaces and also a point-point interfaces -  meaning you can have multi-access and  point-to-point networks at the same time -( multiple subnets)

On a physical interface ( multipoint by default) these can use only one ip address meaning one muiltaccess-network..

Interms of the the actual difference when defining either using a physical or sub-interface multipoint interface -  As far as I aware there isn't any apart from the flexibility thats come with a sub-interface stated above.

res

Paul

Please don't forget to rate any posts that have been helpful.

Thanks.

[kawarrahaj]

On a Subinterfaces, you can have muiltaccess interfaces and also a point-point interfaces -  meaning you can have multi-access and  point-to-point networks at the same time -( multiple subnets)

Thanks Paul. Just to clarify your statement above, the fexibility that you are referring to is for example, configuring point-to-pint for some subinterfaces and multipoint for another interface such as

int s0/0.1 point-to-point

int s0/0.2 point-to-point

int s0/0.3 multipoint

Am I right? If so, what type of scenarios would you want to do this type of config?