Very interesting watching this thread, I think LU had a point here
in the world of "dynamic everything". There were lots of interest
from ISPs to do on-line cspf MPLS-TEs, I know two "big" ISPs tried
this(one presented on last nanog i think). I also know some ISPs
are using off-line calculations and then set explicitely the MPLS
LSPs. I personally don't see more ISPs joining this on-line cspf
TE camp.
>How does the headend know there are four paths? You can't use the IGP
>database because, as you point out above, you don't need to use
>MPLS-TE across the entire network, only in some places. Show me a way
>to do this without resorting to explorer packets or crankback.
As in "old" TE with ATM backbones, you can know all the paths
to use. We don't need to debate which one is better here. You
can setup active and standby LSPs(which is the dynamic
portion here).
>
>I think you've missed the difference between verbatim and explicit.
>Explicit still needs a TE DB, and will check the path against the TE
>DB before signalling.
Why it still "needs" a TE DB? why not offer a knob to let user to
decide if it needs to be turned off? to make this check by default
is completely OK, but "have to" check is not very reasonable.
>
>You still haven't answered the question I've been asking - if you
>configure a static path, using no dynamic topology information
>whatsoever, what do you do when a link or node in your static path
>goes down?
its user's decision. Say I want to setup a static MPLS LSP to my
customer, I just want to set it up, there may only be one single
path, why should this TE DB be required? OK, in the backbone,
its not good to just set them up and assume they always work. but
rsvp hellos can be used to indicate status of the lsp, and active
and standby mechanism can be used here. Yes, its not "fast"
convergence, but also users need to make this decision.
So I think it does not matter IOS is the source of the lsp tunnel,
or in the middle of the lsp transit, it should offer a mechanism to
allow user to config this "check TE DB" off if needed. Its very
useful, this is not just school project interest IHMO.
thanks.
george
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This archive was generated by hypermail 2b29 : Sun Aug 04 2002 - 04:13:11 EDT