RE: [nsp] Cisco DS3 Questions..

From: Martin, Christian (cmartin@gnilink.net)
Date: Fri Feb 22 2002 - 15:23:02 EST


> 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



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