At 3:29 AM -0500 3/22/02, Tom Scott wrote:
>Kent, Irwin,
>
>This is an interesting exchange of perspectives. Could you
>or someone else comment on GMPLS?
GMPLS does many of the things you are describing. It "generalizes"
MPLS setup beyond the current packet/frame oriented paths to paths
that don't have a granularity as fine as packets: optical
wavelengths, multiplex time slots, and specific physical port
sequences on various devices.
I really don't see MPLS/GMPLS as a relevant technology for most
enterprises. Let me throw out an analogy that I just invented -- I
just got up and may not be thinking clearly.
1. ATM was originally intended as a carrier-only technology. FR, ISDN, etc.,
were seen as customer access protocols to the carrier ATM cloud. ATM
UNI specifications came into being due to a market need for a high-speed
access technology.
2. MPLS often is called "ATM without cells." I consider (G)MPLS analogous
to the original carrier role of ATM, and things such as
provider-provisioned
VPNs (PPVPN) at both layer 2 and 3, metro optical Ethernet, 3G wireless,
etc., corresponding to the access protocols in the original ATM model.
3. MPLS is not a panacea, but does have many useful features for traffic
engineering and fault tolerance, especially when dealing with very
large numbers of L2 emulated circuits and L3 private networks/Internet
access/large provider cores. GMPLS provides a smooth path for
integrating
both present (e.g., POS, SONET) and evolving optical technologies.
How many enterprises will have a requirement to manage many fibers
containing many DWDM wavelengths at OC-192 or OC-768?
4. There are enterprise needs that are just starting to get integrated
with MPLS, such as IPsec.
>How does it factor into
>the comparison of MPLS vs. FR? Is there anything about the
>combination of MPLS / GMPLS that gives it an advantage over
>FR?
Some market research I've seen suggests the telcos do not expect to
have the IP-literate staff to do more than deliver the core and
perhaps 10% of their VPNs as L3. L2 VPNs (e.g., frame and virtual
wire emulation) is attractive to them because it significantly
reduces their support costs.
>
>Another issue I'd like to understand in this context is
>native MPLS transport. Do you see a possibility in the
>future for simplifying the transport of MPLS packets? In
>other words, could one replace SONET/SDH with a simple
>transmission layer X (whatever that might be)? The stack
>,might look something like this:
>
> 7 7
> 6 6
> 5 5
> 4 4
> 3 3 3 3
> 2 2 2 2 2 2
> 1 1 1 X 1 1 1
>
> ^ ^
> | |
> +-----+
> native
> MPLS
> core
That's GMPLS, which specifically is intended to be able to transport
SONET, POS, etc.
>
>There in the middle, where the "native MPLS" core would be
>in a greenfield network, is it possible to transport the
>MPLS packets on a fiber medium, possibly on different
>lambdas using GMPLS, but without SONET/SDH? I don't work on
>that layer (physical L1) enough to know the interactions
>between L1/L2, but it seems that simplification is
>desirable. Possibly using MPX (MPLS over PPP over X) instead
>of traditional POS?
>
>There are many reasons to keep SONET/SDH, for example,
>protection switching. Is it possible that MPLS / GMPLS could
>offer similar solutions that would have a competitive
>advantage? Maybe someone at MPLScon will have an answer. See
>you there.
Yes, and probably more advanced protection switching with more
efficient resource use.
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=39155&t=36670
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