Title: PCEP Requirements and Extensions for the support of Wavelength Switched Optical Networks (WSON)
1PCEP Requirements and Extensions for the support
of Wavelength Switched Optical Networks (WSON)
draft-lee-pce-WSON-routing-wavelength-01.txt
Young Lee ylee_at_huawei.com Huawei Greg
Bernstein gregb_at_grotto-networking.com Grotto
Networking
2Outline
- Applicability of PCE to WSON/RWA
- PCEP Requirements
- Summary Next Step
3Wavelength Constraints in WSON Path Computation
- The path in WSON is referred to as a lightpath.
- A lightpath may span multiple fiber links and the
path should be assigned a wavelength for each
link. - Two lightpaths that share a common fiber link
cannot be assigned the same wavelength. To
prevent this a signaling system must block setup
requests that could result in this condition. - Therefore, assigning the proper wavelength on a
lightpath is an essential requirement in the
optical path computation process. - In a transparent optical network, a lightpath
must operate on the same wavelength across all
fiber links that it traverses. This constraint is
known as the wavelength continuity constraint.
4Illustration wavelength constraints
D
E
C
B
A
5PCEP Requirements
- PCE Computation Options
- Wavelength Assignment and Wavelength Set
information - Optimization Degree
- Lightpath Route Parameters
- Wavelength Selection Preference (optional)
- Timeliness Characteristics (optional)
- Duration of lightpath (optional)
6PCE Computation Options
- The following RWA computation options should be
conveyed in the PC Request - The request is for Wavelength Assignment (WA)
only. - The request is for both Routing and Wavelength
Assignment (RWA). - The request is for Routing (R) only.
- The request is for Routing (R) with the
suggested/restricted wavelength set.
PC Request RP object RC bits
PCC
PCE
PC Reply RP object RC bits
7Wavelength Assignment and Wavelength Set
information
- The PCE MUST specify the wavelength assignment
and/or wavelength set information in response to
the wavelength assignment/wavelength set Request
made by the PCC in the PCReq message. - Note Wavelength assignment is the part of path
computation in a transparent optical network that
chooses a wavelength that meets the wavelength
continuity constraint.
8Optimization Degree
- The PC Request Message should indicate the degree
of optimization associated with lightpath
computation. - Concurrent Optimization multiple lightpaths
requested at one time. - Lightpath(s) and backup lightpath(s) requested at
one time. - Sequential Optimization single lightpath
requested at a time. - The PC Reply Message should include the original
optimization degree associated with the request
when replying the path computation results.
9Lightpath Route Parameters
- The following Lightpath Route Parameters should
be indicated - Bidirectional Assignment of wavelengths for a
bidirectional LSP request. This means that the
same wavelength should be assigned in both
directions on each hop. - Simultaneous assignment of the same wavelength to
primary and backup paths. - The PC Reply Message should include the
original lightpath route parameter associated
with the request when replying the path
computation results.
10Wavelength SelectionPreference - optional
- The PC Request may indicate the Wavelength
Selection Preference to which a path computation
request is applied. The Wavelength Selection
Preference to be supported at the minimum is - Random
- First Fit
- Most Used
- Least Loaded
- Dont Care
- The PC Reply should indicate which wavelength
selection preference has actually been applied.
11Timeliness Characteristics - optional
- The request may indicate specific timeliness
characteristics of lightpath. - Time Critical this type of request is useful for
those lightpath establishment requests used for
restoration of service or other high priority
real time services. - Soft Time Bound this type of request is a more
typical new connection request. While expected
to be responsive, there should be more time to
take into account network optimization. - Scheduled this type of request is useful when
the requested lightpath connections are not time
critical (i.e., the request is significantly
ahead of their intended "in-service" time.
12Duration of lightpath - optional
- The request may indicate specific lightpath
duration information associated with the request.
This may be useful to the PCE since it is not
worthwhile to optimize lightpaths with relatively
short duration as compared to pseudo-static
paths.
13Summary Next Step
- Lightpath provisioning in WSON requires a routing
and wavelength assignment (RWA) which is a
routing constraint in WSON path computation -gt So
it is within PCE WG charter. - Continue to refine PCEP requirements and encoding
details.