[nsp] Cisco DS3 Questions..

Fri Feb 22 20:23:02 UTC 2002

> link in a controlled way.  Not saying that's a particularly 
> good use, just
> that that's the most common reason I've seen it deployed on otherwise
> simple point-to-points.  The idea behind frame relay is that 
> it gives you
> a multipoint layer-2 protocol to use on a more complicated network of
> circuits.
> 
>                                 -Bill

It can also be used to 'equalize' two links of different speeds in such a
way that you can do reasonable equal-cost load-balancing.  For example, if
you have a DS3 and an OC3, you can create 3 FR subinterfaces on the OC3 and
add the DS3 to the mix to give you essentially 4 DS3s.  There is a slight
speed difference, but it is minimal.  This can be done for 2 OC-12s and an
OC-48, for example.

Another reason for virtualizing a ptp circuit is for differentiate billing
in a MPLS VPN environment with an Internet offload component.  You can
direct VPN traffic on one VC and Internet on the other, and then take
advantage of basic MIB-II stats for billing and per-(sub)interface CAR for
enforcement of contract and reclassification, etc.

regards,
chris