Re: [Ieprep] Re: WG Review: Recharter of Internet Emergency Preparedness (ieprep)

What you're describing, in general terms, is MPLS TE. Yes, MPLS TE  
will allow you to use your capacity a little more efficiently.

As I said, not all networks are MPLS, and not all MPLS networks do  
traffic engineering.

The scenario in question is *after* those things have been done.

On Nov 16, 2006, at 7:13 PM, Curtis Villamizar wrote:

>
> In message <5512B961-3280-4EBD-8A0B-275AD43358DE@cisco.com>
> Fred Baker writes:
>>
>> On Nov 16, 2006, at 4:02 PM, Curtis Villamizar wrote:
>>> Preemption in MPLS can be soft preemption (setting aside
>>> differences of opinion about how signaling of soft preempt should
>>> be done for the moment)...
>>>
>>> Even for hard preemption, there is at worst a fall back to IP and
>>> reroute...
>>
>> Those are both options, but IMHO have issues. One can't, for example,
>> fall back and reroute to a different path if the bottleneck where
>> preemption is occurring is the only path to the destination. [...]
>
> One vendor, lets call them vendor A, has solved this using a feature
> they call metric-bias which is a better alternative to soft
> preemption.  MPLS CSPF is influenced so that an effort is made to
> avoid highly utilized links.  If there is no other way, thats where it
> goes.  If there is other traffic (BE) thats what gets clobberred.
>
> But we're way off topic so I won't go into details.
>
>> [big snip]
>>
>> Yes, I'm being extreme, but this topic is about the end cases. And
>> yes, adding more bandwidth is always helpful. It isn't always an
>> option, and under the scenarios in question (in some cases, just say
>> "Armageddon") might be pretty difficult to predict in detail.
>
> Plain IP solutions based on queueing alone work fine if allowing  
> the ETS
> traffic to take the shortest IGP path never congests the ETS traffic
> and never gets too painful for the BE traffic.
>
> Generally MPLS shines relative to plain IP where there is a network
> fault, or many network faults, and capacity remains but may be quite
> limited in part of the topology.  That would be expected to be the
> case in certain situation where an ETS is most needed.
>
> For example, multiple faults occurred and capacity was very
> substantially reduced during and for quite a while after Katrina.
> Some automatic means of best using whatever capacity is available at
> any give time (such as MPLS does) would be a good thing IMHO.
>
> Do you disagree?
>
> Curtis

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