Solved: Frame Relay Physical int versus Multipoint interface ?

philipbarker · ‎03-04-2008

Hi,

In my lab I have created a 'Hub & Spoke' network. I want my spokes to reside on the same network address so I can choose between using the physical interface at the hub or a multipoint interface at the hub.

Why would I prefer one technique to the other ? As I see it 'one' physical interface is taken up by both methods !

Also with both techniques I can achieve solutions using inverse arp or static mappings.

What am I missing here ?

Regards,

Phil.

Edison Ortiz · ‎03-04-2008

It could be a migration to point-to-point or just a design requirement.

For instance, per your requirement, you want some spokes to have the same IP subnet as the hub, well - then you configure a multipoint subinterface.

Later on, you want some spokes to have a different subnet, then you configure a point-to-point subinterface along with the multipoint.

That's the flexibility from having that option as opposed of having point-to-point as the only subinterface type available in frame-relay.

HTH,

__

Edison.

View solution in original post

Edison Ortiz · ‎03-04-2008

You can have a multipoint interface for some spokes and a point-to-point interface for other spokes, if needs be.

HTH,

__

Edison.

philipbarker · ‎03-04-2008

Hi ediortiz,

Are you talking here about one physical interface being split such that s0.1 could be multipoint and s0.2 could be point-to-point as a migration from multipoint to point-to-point ?

Regards,

Phil.

Edison Ortiz · ‎03-04-2008

It could be a migration to point-to-point or just a design requirement.

For instance, per your requirement, you want some spokes to have the same IP subnet as the hub, well - then you configure a multipoint subinterface.

Later on, you want some spokes to have a different subnet, then you configure a point-to-point subinterface along with the multipoint.

That's the flexibility from having that option as opposed of having point-to-point as the only subinterface type available in frame-relay.

HTH,

__

Edison.

Richard Burts · ‎03-04-2008

Phil

As far as a lab is concerned I am not sure that you are missing much of anything and both implementations are quite similar. In a live network I might prefer to use the multilink subinterface because it potentially makes things a bit more predictable. Since you have to assign the PVCs/DLCIs to the subinterface you know exactly what is there. If the provider should happen to provision another PVC/DLCI on the connection (perhaps by mistake) Cisco will assign that DLCI to the physical interface. If your multipoint implementation is on the physical interface then there is potential disruption in your network because of the new active connection. If your implementation is on the subinterface then there is no impact.

HTH

Rick

HTH

Rick