Experimental Codepoint Allocation for the Path Computation Element communication
Protocol (PCEP)Huawei TechnologiesDivyashree Techno Park, WhitefieldBangaloreKarnataka560066Indiadhruv.ietf@gmail.comLancaster UniversityUKd.king@lancaster.ac.ukJuniper NetworksUKafarrel@juniper.net
Routing
PCE Working GroupPCE, PCEP, IANA, Experimental
IANA assigns values to the Path Computation Element (PCE) communication
Protocol (PCEP) parameters (messages,
objects, TLVs). IANA established a top-level registry to contain all PCEP
codepoints and sub-registries. This top-level registry contains
sub-registries for PCEP message, object and TLV types. The
allocation policy for each of these sub-registries is IETF Review. This document updates RFC 5440 by changing the allocation policies
for these three registries to mark some of the code points as assigned
for Experimental Use.
The Path Computation Element communication Protocol (PCEP) provides
mechanisms for Path Computation Elements (PCEs) to perform path
computations in response to Path Computation Clients (PCCs) requests.Further, in order to support use cases described in ,
specifies a set of
extensions to PCEP to enable stateful control of MPLS-TE and GMPLS
LSPs via PCEP. describes the setup,
maintenance and teardown of PCE-initiated LSPs under the stateful PCE
model.In section 9 of , IANA assigns values to
the PCEP protocol parameters (messages, objects, TLVs).
IANA established a top-
level registry to contain all PCEP codepoints and sub-registries.
This top-level registry contains sub-registries for PCEP message,
object and TLV types. The allocation policy for each of these
sub-registries is IETF Review .
Also, early
allocation provides some latitude for allocation of these
code points, but is reserved
for features that are considered appropriately stable. Recently, there have been rapid advancements in PCE technology, which
has created an enhanced need to experiment with PCEP. It is often necessary
to use some sort of number or constant in order to actually
test or experiment with the new function, even when testing in a
closed environment. In order to run experiments, it is important that
the value won't collide not only with existing codepoints but any
future allocation.
This document updates by changing the allocation policies
for these three registries to mark some of the code points as
assigned for Experimental Use. See for further discussion
of the use of experimental codepoints.
PCEP message types are in the range 0 to 255. This document sets
aside message types 252-255 for experimentation as described in
.
PCEP objects are identified by values in the range 0 to 255. This
document sets aside object identifiers 248-255 for experimentation as
described in .
PCEP TLV type codes are in the range 0 to 65535. This document sets
aside object identifiers 65504-65535 for experimentation as described
in .
A PCEP implementation that receives an experimental PCEP message, that it does not recognize, would react as per section 6.9 of
by sending a PCErr message with Error-value=2 (capability not supported).
If a PCEP speaker does not understand or support an experimental object
then the way it handles this situation depends on the message type.
For example, a PCE handles an unknown object in the Path Computation Request
(PCReq) message according to the rules of . A PCC handles an
unknown object in an Update (PCUpd) message according to the rules of
and, in an LSP Initiate Request (PCInitiate) message, according to the rules of
. Any document that adds a new PCEP message
type must specify how to handle unknown objects on that message.
As per section 7.1 of , unknown experimental PCEP TLV would be ignored.IANA maintains the "Path Computation Element Protocol (PCEP) Numbers"
at <http://www.iana.org/assignments/pcep>.Within this registry IANA maintains a sub-registry for PCEP
Messages (see PCEP Messages at <http://www.iana.org/assignments/pcep>).IANA is requested to change the registration procedure for this
registry to read as follows:
IANA is also requested to mark the values 252-255 in the registry
accordingly.Within this registry IANA maintains a sub-registry for PCEP
Objects (see PCEP Objects at <http://www.iana.org/assignments/pcep>).IANA is requested to change the registration procedure for this
registry to read as follows:
IANA is also requested to mark the values 248-255 in the registry
accordingly.Within this registry IANA maintains a sub-registry for PCEP
TLVs (see PCEP TLV Type Indicators at <http://www.iana.org/assignments/pcep>).IANA is requested to change the registration procedure for this
registry to read as follows:
IANA is also requested to mark the values 65504-65535 in the registry
accordingly.This document does not introduce any new security considerations to
the existing protocol. Refer to for
further details of the specific security measures. asserts that the existence of experimental code points
introduce no new security considerations. However, implementations
accepting experimental codepoints need to take care in how they parse
and process the messages, objects, and TLVs in case they come,
accidentally, from another experiment.The authors would like to thank Ramon Casellas, Jeff Tantsura,
Julien Mueric, Lou Berger,
Michael Shroff, and Andrew Dolganow for their feedback and suggestions. We would like to thank Jonathan Hardwick for shepherding this document and providing comments with text suggestions.
Based on feedback from the PCE WG, it was decided to allocate an
Experimental code point range only in the message, object and TLV
sub-registries. The justification for this decision is that, if
an experiment finds that it wants to use a new code point in
another PCEP sub-registry, it can implement the same function using
a new experimental object or TLV instead.