No problem.
Thanks for continuing to discuss this.
Here is the recommendation for the PCE-based architecture:
---------------
| --------- | Routing ----------
| | | | Protocol | |
| | TED |<-+----------+-> |
| | | | | |
| --------- | | |
| | | | |
| | Input | | |
| v | | |
---------- Response | --------- | | |
| |Request | | | | | Adjacent |
| SORD |<------->| | PCE | | | Node |
| |Input | | | | | |
---------- | --------- | | |
^ | ^ | | |
| | |Request | | |
| | |Response| | |
Service Order | v | | |
| --------- | | |
Service | | | | Signaling| |
Request | |Signaling| | Protocol | |
------+->| Engine |<-+----------+-> |
| | | | | |
| --------- | ----------
---------------
Here, SORD is the service order reservation database, it contains all
service order requests in terms of ingress and egress points, bandwidth,
service type, time period for the request, etc. When PCE computes a
path,
it could get input from SORD to indicate if there are some network
resource is already blocked out. When a booking order in SORD is
ready to kick off, SORD
will send request to PCE for the path computation, then PCE will send a
service request to signaling engine to establish the LSP.
This would be hugely inefficient, wouldn't it?
Since PCE cannot guess which resources might be blocked out for future
requests, it would have to make this query for every computation.
Further,
if PCE only made the query for resources that satisfied the computation,
it
might have to make repeated recomputations, so it would be more efficient
for it to retrieve information about every future blocking.
So, in fact, it makes more sense for SORD to feed the information into
the
TED and allow PCE to operate on the full database.
But consider: How does SORD know which resources will be reserved and
when?
Presumably, it has consulted PCE as well.
Good point. Thus, even the result is saved in TED, it still needs to
consulted PCE.
Yes. Your SORD becomes just another regular PCC. in fact, it is probably
part of the NMS/OSS.
If you wanted to work on some issue like "Applicability of PCE to
time-scoped service requests" this might be of interest to people. It was
raised in the early days of PCE and of L1VPN, but did not attract
significant interest. I think that the feeling at the time was that it
was
out of scope for PCE, but formed part of a management system. However, it
might be that there would be value in enhancing the PCE protocol to carry
time delimiters for computation requests.
Note that the PCE working group is interested in applications of PCE and
the
protocols involved, but is not so interested in abstract functional
components that are beyond the scope of the working group.
Thank you for the suggestion. Well understand the group interest now. We
will think about the protocol enhancement.
OK.
Thanks,
Adrian
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