At 11:17 PM +0000 2/25/03, Tom Lisa wrote:
>Peter,
>
>The current rumour for the Academy CCNP program is that Cisco is dropping
>the 3 layer model and moving to a 2 layer model with L3 in the core for
At least in the provider space, L3 gets very nuanced between (G)MPLS
and IP, the latter mostly for (G)MPLS path setup. The "3 layer
model" works pretty well for good-sized campus networks, but often is
confusing for WANs.
>the BCMS course. I guess I'll find out for certain at Networkers in
>Orlando, Fla. this June.
Adding to the absurdity of it all, and forgetting that one model
doesn't fit all, Cisco and others have, for some time, used a
four-layer model for service providers:
Core: usually MPLS with a fast IGP for next hops
Distribution:may have levels of internal hierarchy, but
usually where most BGP happens -- either
gateways to other ISPs or customer BGP
Collector: Layer 1/2, but sometimes with IP-based
MPLS/L2TP/etc
tunneling, for broadband aggregation. Media
gateways,
DSLAMs, etc.
Access: Equipment between ISP and customer, such as a BGP
router run by a multihomed customer, a simple
static/default router, broadband modems, etc.
>Peter van Oene wrote:
>
> At 11:05 AM 2/25/2003 +0000, Skarphedinsson Arni V. wrote:
> >In a Core-Distribution-Access Layer design, would you keep the Core
> L2 or
> >with high end L2/L3 switches such as the Cat6500 do you think it
> would be
> >better to do L3 in the core ?
>
> I personally haven't found the need to have a Distribution layer in
> most
> networks. It's a model designed by vendors to sell boxes imho.
>
> Pete
> [EMAIL PROTECTED]
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