Carrying Binding Label/Segment
Identifier (SID) in PCE-based Networks.Ciena Corporationmsiva282@gmail.comCisco Systems, Inc.Pegasus ParcDe kleetlaan 6aDIEGEMBRABANT 1831BELGIUMcfilsfil@cisco.comMicrosoft Corporationjefftant.ietf@gmail.comHuawei Technologiesstefano@previdi.netHuawei TechnologiesHuawei Campus, No. 156 Beiqing Rd.Beijing100095Chinac.l@huawei.com
Routing Area
PCE Working GroupIn order to provide greater scalability, network confidentiality, and
service independence, Segment Routing (SR) utilizes a Binding Segment
Identifier (SID) (called BSID) as described in RFC 8402. It is possible
to associate a BSID to an RSVP-TE-signaled Traffic Engineering Label
Switched Path or an SR Traffic Engineering path. The BSID can be used by
an upstream node for steering traffic into the appropriate TE path to
enforce SR policies. This document specifies the concept of binding
value, which can be either an MPLS label or Segment Identifier. It
further specifies an extension to Path Computation Element (PCE)
communication Protocol(PCEP) for reporting the binding value by a Path
Computation Client (PCC) to the PCE to support PCE-based Traffic
Engineering policies.A Path Computation Element (PCE) can compute Traffic Engineering
paths (TE paths) through a network where those paths are subject to
various constraints. Currently, TE paths are set up using either the
RSVP-TE signaling protocol or Segment Routing (SR). We refer to such
paths as RSVP-TE paths and SR-TE paths respectively in this
document.As per SR allows a head-end node to steer a
packet flow along a given path via a Segment Routing Policy (SR Policy).
As per , an SR
Policy is a framework that enables the instantiation of an ordered list
of segments on a node for implementing a source routing policy with a
specific intent for traffic steering from that node.As described in , a Binding Segment
Identifier (BSID) is bound to a Segment Routing (SR) Policy,
instantiation of which may involve a list of Segment Identifiers (SIDs).
Any packets received with an active segment equal to a BSID are steered
onto the bound SR Policy. A BSID may be either a local (SR Local Block
(SRLB)) or a global (SR Global Block (SRGB)) SID. As per Section 6.4 of
a BSID can also
be associated with any type of interface or tunnel to enable the use of
a non-SR interface or tunnel as a segment in a SID list. In this
document, the term 'binding label/SID' is used to generalize the
allocation of binding value for both SR and non-SR paths. describes the PCEP for communication between
a Path Computation Client (PCC) and a PCE or between a pair of PCEs as
per . specifies
extensions to PCEP that allow a PCC to delegate its Label Switched Paths
(LSPs) to a stateful PCE. A stateful PCE can then update the state of
LSPs delegated to it. specifies a mechanism
allowing a PCE to dynamically instantiate an LSP on a PCC by sending the
path and characteristics. This document specifies an extension to PCEP
to manage the binding of label/SID that can be applied to SR, RSVP-TE,
and other path setup types. provides a mechanism for a PCE (acting as a
network controller) to instantiate SR-TE paths (candidate paths) for an
SR Policy onto a head-end node (acting as a PCC) using PCEP. For more
information on the SR Policy Architecture, see .A binding label/SID has local significance to the ingress node of
the corresponding TE path. When a stateful PCE is deployed for setting
up TE paths, a binding label/SID reported from the PCC to the stateful
PCE is useful for the purpose of enforcing end-to-end TE/SR policy. A
sample Data Center (DC) and IP/MPLS WAN use-case is illustrated in
with a multi-domain PCE. In the IP/MPLS WAN,
an SR-TE LSP is set up using the PCE. The list of SIDs of the SR-TE
LSP is {A, B, C, D}. The gateway node 1 (which is the PCC) allocates a
binding SID X and reports it to the PCE. In the MPLS DC network, an
end-to-end SR-TE LSP is established. In order for the access node to
steer the traffic towards Node-1 and over the SR-TE path in WAN, the
PCE passes the SID stack {Y, X} where Y is the node SID of the gateway
node-1 to the access node and X is the BSID. In the absence of the
BSID X, the PCE would need to pass the SID stack {Y, A, B, C, D} to
the access node. This example also illustrates the additional benefit
of using the binding label/SID to reduce the number of SIDs imposed by
the access nodes with a limited forwarding capacity.Using the extension defined in this document, a PCC could report to
the stateful PCE the binding label/SID it allocated via a Path
Computation LSP State Report (PCRpt) message. It is also possible for
a stateful PCE to request a PCC to allocate a specific binding
label/SID by sending a Path Computation LSP Update Request (PCUpd)
message. If the PCC can successfully allocate the specified binding
value, it reports the binding value to the PCE. Otherwise, the PCC
sends an error message to the PCE indicating the cause of the failure.
A local policy or configuration at the PCC SHOULD dictate if the
binding label/SID needs to be assigned.To implement the needed changes to PCEP, in this document, we
introduce a new OPTIONAL TLV that a PCC can use in order to report the
binding label/SID associated with a TE LSP, or a PCE to request a PCC
to allocate any or a specific binding label/SID value. This TLV is
intended for TE LSPs established using RSVP-TE, SR-TE, or any other
future method. In the case of SR-TE LSPs, the TLV can carry a binding
label (for SR-TE path with MPLS data-plane) or a binding IPv6 SID
(e.g., IPv6 address for SR-TE paths with IPv6 data-plane). Throughout
this document, the term "binding value" means either an MPLS label or
a SID.As another way to use the extension specified in this document, to
support the PCE-based central controller
operation where the PCE would take responsibility for managing some
part of the MPLS label space for each of the routers that it controls,
the PCE could directly make the binding label/SID allocation and
inform the PCC. See for details.In addition to specifying a new TLV, this document specifies how
and when a PCC and PCE can use this TLV, how they can allocate a
binding label/SID, and associated error handling.The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP 14
when, and only when,
they appear in all capitals, as shown here.The following terminologies are used in this document: Binding Segment Identifier.a generic term used for the binding
segment for both SR and non-SR paths.a generic term used for the binding
segment as it can be encoded in various formats (as per the binding
type(BT)).Label Switched Path.Path Computation Client.Path Computation Element communication
Protocol.Resource ReserVation Protocol-Traffic
Engineering.Segment Identifier.Segment Routing.The new optional TLV called "TE-PATH-BINDING TLV" (whose format is
shown in ) is defined to carry
the binding label/SID for a TE path. This TLV is associated with the LSP
object specified in . This TLV can also be
carried in the PCEP-ERROR object in case of
error. Multiple instances of TE-PATH-BINDING TLVs MAY be present in the
LSP and PCEP-ERROR object. The type of this TLV is 55 (early allocated
by IANA). The length is variable.[Note to RFC Editor: Please remove "(early allocated by IANA)" before
publication]TE-PATH-BINDING TLV is a generic TLV such that it is able to carry
binding label/SID (i.e. MPLS label or SRv6 SID). It is formatted
according to the rules specified in . The value
portion of the TLV comprises:Binding Type (BT): A one-octet field that identifies the type of
binding included in the TLV. This document specifies the following BT
values: BT = 0: The binding value is a 20-bit MPLS label value. The TLV
is padded to 4-bytes alignment. The Length MUST be set to 7 (the
padding is not included in the length, as per Section 7.1) and the first 20 bits are used to
encode the MPLS label value.BT = 1: The binding value is a 32-bit MPLS label stack entry as
per with Label, TC , S, and TTL values encoded. Note that the
receiver MAY choose to override TC, S, and TTL values according to
its local policy. The Length MUST be set to 8.BT = 2: The binding value is an SRv6 SID with the format of a
16-octet IPv6 address, representing the binding SID for SRv6. The
Length MUST be set to 20.BT = 3: The binding value is a 24 octet field, defined in , that contains the SRv6 SID as well as
its Behavior and Structure. The Length MUST be set to 28. defines the IANA registry used to maintain
all these binding types as well as any future ones. Note that multiple
TE-PATH-BINDING TLVs with same or different Binding Types MAY be present
for the same LSP. A PCEP speaker could allocate multiple TE-PATH-BINDING
TLVs (of the same BT), and use different binding values in different
domains or use-cases based on a local policy.Flags: 1 octet of flags. The following flag is defined in the new
registry "TE-PATH-BINDING TLV Flag field" as described in :where: R (Removal - 1 bit): When set, the requesting PCEP peer requires
the removal of the binding value for the LSP. When unset, the PCEP
peer indicates that the binding value is added or retained for the
LSP. This flag is used in the PCRpt and PCUpd messages. It is
ignored in other PCEP messages.The unassigned flags MUST be set to 0 while sending and ignored
on receipt.Reserved: MUST be set to 0 while sending and ignored on receipt.Binding Value: A variable-length field, padded with trailing zeros to
a 4-octet boundary. When the BT is 0, the 20 bits represent the MPLS
label. When the BT is 1, the 32 bits represent the MPLS label stack
entry as per . When the BT is 2, the 128 bits
represent the SRv6 SID. When the BT is 3, the Binding Value also
contains the SRv6 Endpoint Behavior and SID Structure, defined in . In this document, the TE-PATH-BINDING TLV
is considered to be empty if no Binding Value is present. Note that the
length of the TLV would be 4 in such a case.This section specifies the format of the Binding Value in the
TE-PATH-BINDING TLV when the BT is set to 3 for the SRv6 Binding SIDs
. The format is shown in .The Binding Value consists of:SRv6 Binding SID: 16 octets. The 128-bit IPv6 address,
representing the binding SID for SRv6.Reserved: 2 octets. It MUST be set to 0 on transmit and ignored
on receipt.Endpoint Behavior: 2 octets. The Endpoint Behavior code point
for this SRv6 SID as per the IANA subregistry called "SRv6
Endpoint Behaviors", created by . When the
field is set with the value 0, the endpoint behavior is considered
unknown. defines an SRv6 SID as consisting of
LOC:FUNCT:ARG, where a locator (LOC) is encoded in the L most
significant bits of the SID, followed by F bits of function
(FUNCT) and A bits of arguments (ARG). A locator may be
represented as B:N where B is the SRv6 SID locator block (IPv6
prefix allocated for SRv6 SIDs by the operator) and N is the
identifier of the parent node instantiating the SID called locator
node. The following fields are used to advertise the length of
each individual part of the SRv6 SID as defined in :LB Length: 1 octet. SRv6 SID Locator Block length in
bits.LN Length: 1 octet. SRv6 SID Locator Node length in
bits.Function Length: 1 octet. SRv6 SID Function length in
bits.Argument Length: 1 octet. SRv6 SID Arguments length in
bits.The total of the locator block, locator node, function, and
argument lengths MUST be lower or equal to 128 bits. If this condition
is not met, the corresponding TE-PATH-BINDING TLV is considered
invalid. Also, if the Endpoint Behavior is found to be unknown or
inconsistent, it is considered invalid. A PCErr message with
Error-Type = 10 ("Reception of an invalid object") and Error-Value =
37 ("Invalid SRv6 SID Structure") MUST be sent in such cases.The SRv6 SID Structure could be used by the PCE for ease of
operations and monitoring. For example, this information could be used
for validation of SRv6 SIDs being instantiated in the network and
checked for conformance to the SRv6 SID allocation scheme chosen by
the operator as described in Section 3.2 of .
In the future, PCE could also be used for verification and the
automation for securing the SRv6 domain by provisioning filtering
rules at SR domain boundaries as described in Section 5 of . The details of these potential applications are
outside the scope of this document.The binding value is usually allocated by the PCC and reported to a
PCE via a PCRpt message (see where PCE does the
allocation). If a PCE does not recognize the TE-PATH-BINDING TLV, it
would ignore the TLV in accordance with . If a
PCE recognizes the TLV but does not support the TLV, it MUST send a
PCErr with Error-Type = 2 (Capability not supported).Multiple TE-PATH-BINDING TLVs are allowed to be present in the same
LSP object. This signifies the presence of multiple binding SIDs for the
given LSP. In the case of multiple TE-PATH-BINDING TLVs, the existing
instances of TE-PATH-BINDING TLVs MAY be included in the LSP object. In
case of an error condition, the whole message is rejected and the
resulting PCErr message MAY include the offending TE-PATH-BINDING TLV in
the PCEP-ERROR object.If a PCE recognizes an invalid binding value (e.g., label value from
the reserved MPLS label space), it MUST send a PCErr message with
Error-Type = 10 ("Reception of an invalid object") and Error Value = 2
("Bad label value") as specified in .For SRv6 BSIDs, it is RECOMMENDED to always explicitly specify the
SRv6 Endpoint Behavior and SID Structure in the TE-PATH-BINDING TLV by
setting the BT (Binding Type) to 3. This can enable the sender to have
control of the SRv6 Endpoint Behavior and SID Structure. A sender MAY
choose to set the BT to 2, in which case the receiving implementation
chooses how to interpret the SRv6 Endpoint Behavior and SID Structure
according to local policy.If a PCC wishes to withdraw a previously reported binding value, it
MUST send a PCRpt message with the specific TE-PATH-BINDING TLV with R
flag set to 1. If a PCC wishes to modify a previously reported binding,
it MUST withdraw the former binding value (with R flag set in the former
TE-PATH-BINDING TLV) and include a new TE-PATH-BINDING TLV containing
the new binding value. Note that other instances of TE-PATH-BINDING TLVs
that are unchanged MAY also be included. If the unchanged instances are
not included, they will remain associated with the LSP.If a PCE requires a PCC to allocate a (or several) specific binding
value(s), it may do so by sending a PCUpd or PCInitiate message
containing a TE-PATH-BINDING TLV(s). If the value(s) can be successfully
allocated, the PCC reports the binding value(s) to the PCE. If the PCC
considers the binding value specified by the PCE invalid, it MUST send a
PCErr message with Error-Type = TBD2 ("Binding label/SID failure") and
Error Value = TBD3 ("Invalid SID"). If the binding value is valid, but
the PCC is unable to allocate the binding value, it MUST send a PCErr
message with Error-Type = TBD2 ("Binding label/SID failure") and Error
Value = TBD4 ("Unable to allocate the specified binding value"). Note
that, in case of an error, the PCC rejects the PCUpd or PCInitiate
message in its entirety and can include the offending TE-PATH-BINDING
TLV in the PCEP-ERROR object.If a PCE wishes to request the withdrawal of a previously reported
binding value, it MUST send a PCUpd message with the specific
TE-PATH-BINDING TLV with R flag set to 1. If a PCE wishes to modify a
previously requested binding value, it MUST request the withdrawal of
the former binding value (with R flag set in the former TE-PATH-BINDING
TLV) and include a new TE-PATH-BINDING TLV containing the new binding
value. If a PCC receives a PCUpd message with TE-PATH-BINDING TLV where
the R flag is set to 1, but either the binding value is missing (empty
TE-PATH-BINDING TLV) or the binding value is incorrect, it MUST send a
PCErr message with Error-Type = TBD2 ("Binding label/SID failure") and
Error Value = TBD6 ("Unable to remove the binding value").In some cases, a stateful PCE may want to request that the PCC
allocate a binding value of the PCC's own choosing. It instructs the PCC
by sending a PCUpd message containing an empty TE-PATH-BINDING TLV,
i.e., no binding value is specified (bringing the Length field of the
TLV to 4). A PCE can also request a PCC to allocate a binding value at
the time of initiation by sending a PCInitiate message with an empty
TE-PATH-BINDING TLV. Only one such instance of empty TE-PATH-BINDING
TLV, per BT, SHOULD be included in the LSP object and others ignored on
receipt. If the PCC is unable to allocate a new binding value as per the
specified BT, it MUST send a PCErr message with Error-Type = TBD2
("Binding label/SID failure") and Error-Value = TBD5 ("Unable to
allocate a new binding label/SID").As previously noted, if a message contains an invalid TE-PATH-BINDING
TLV that leads to an error condition, the whole message is rejected
including any other valid instances of TE-PATH-BINDING TLVs, if any. The
resulting error message MAY include the offending TE-PATH-BINDING TLV in
the PCEP-ERROR object.If a PCC receives a TE-PATH-BINDING TLV in any message other than
PCUpd or PCInitiate, it MUST close the corresponding PCEP session with
the reason "Reception of a malformed PCEP message" (according to ). Similarly, if a PCE receives a TE-PATH-BINDING TLV
in any message other than a PCRpt or if the TE-PATH-BINDING TLV is
associated with any object other than an LSP or PCEP-ERROR object, the
PCE MUST close the corresponding PCEP session with the reason "Reception
of a malformed PCEP message" (according to ).If a TE-PATH-BINDING TLV is absent in the PCRpt message and no
binding values were reported before, the PCE MUST assume that the
corresponding LSP does not have any binding. Similarly, if
TE-PATH-BINDING TLV is absent in the PCUpd message and no binding values
were reported before, the PCC's local policy dictates how the binding
allocations are made for a given LSP.Note that some binding types have similar information but different
binding value formats. For example, BT=(2 or 3) is used for the SRv6 SID
and BT=(0 or 1) is used for the MPLS Label. In case a PCEP speaker
receives multiple TE-PATH-BINDING TLVs with the same SRv6 SID or MPLS
Label but different BT values, it MUST send a PCErr message with
Error-Type = TBD2 ("Binding label/SID failure") and Error-Value = TBD7
("Inconsistent binding types").In PCEP messages, LSP route information is carried in the Explicit
Route Object (ERO), which consists of a sequence of subobjects. defines the "SR-ERO subobject" capable of carrying a
SID as well as the identity of the node/adjacency (NAI) represented by
the SID. The NAI Type (NT) field indicates the type and format of the
NAI contained in the SR-ERO. In case of binding SID, the NAI MUST NOT be
included and NT MUST be set to zero. Section
5.2.1 specifies bit settings and error handling in the case when NT=0.
defines the
"SRv6-ERO subobject" for an SRv6 SID. Similarly to SR-ERO (), the NAI MUST NOT be included and the NT MUST be set
to zero. Section 5.2.1 specifies bit settings
and error handling in the case when NT=0. already includes the scenario where a PCE
requires a PCC to allocate a specified binding value by sending a PCUpd
or PCInitiate message containing a TE-PATH-BINDING TLV. This section
specifies an OPTIONAL feature for the PCE to allocate the binding
label/SID of its own accord in the case where the PCE also controls the
label space of the PCC and can make the label allocation on its own as
described in . Note that the act of requesting a
specific binding value () is different from
the act of allocating a binding label/SID as described in this
section. introduces the architecture for PCE as a
central controller as an extension of the architecture described in
and assumes the continued use of PCEP as the
protocol used between PCE and PCC. specifies
the procedures and PCEP extensions for using the PCE as the central
controller. It assumes that the exclusive label range to be used by a
PCE is known and set on both PCEP peers. A future extension could add
the capability to advertise this range via a possible PCEP extension as
well (see ).When PCECC operations are supported as per ,
the binding label/SID MAY also be allocated by the PCE itself. Both
peers need to exchange the PCECC capability as described in before the PCE can allocate the binding label/SID on
its own.A new P flag in the LSP object is introduced
to indicate that the allocation needs to be made by the PCE. Note that
the P flag could be used for other types of allocations (such as path
segments ) in future. P (PCE-allocation): If the bit is set to 1, it indicates that the
PCC requests PCE to make allocations for this LSP. The
TE-PATH-BINDING TLV in the LSP object identifies that the allocation
is for a binding label/SID. A PCC MUST set this bit to 1 and include
a TE-PATH-BINDING TLV in the LSP object if it wishes to request for
allocation of binding label/SID by the PCE in the PCEP message. A
PCE MUST also set this bit to 1 and include a TE-PATH-BINDING TLV to
indicate that the binding label/SID is allocated by PCE and encoded
in the PCEP message towards the PCC. Further, if the binding
label/SID is allocated by the PCC, the PCE MUST set this bit to 0
and follow the procedure described in .Note that - A PCE could allocate the binding label/SID of its own accord for
a PCE-initiated or delegated LSP, and inform the PCC in the
PCInitiate message or PCUpd message by setting P=1 and including
TE-PATH-BINDING TLV in the LSP object.To let the PCC allocate the binding label/SID, a PCE MUST set P=0
and include an empty TE-PATH-BINDING TLV ( i.e., no binding value is
specified) in the LSP object in PCInitiate/PCUpd message.To request that the PCE allocate the binding label/SID, a PCC
MUST set P=1, D=1, and include an empty TE-PATH-BINDING TLV in PCRpt
message. The PCE will attempt to allocate it and respond to the PCC
with PCUpd message including the allocated binding label/SID in the
TE-PATH-BINDING TLV and P=1, D=1 in the LSP object. If the PCE is
unable to allocate, it MUST send a PCErr message with Error-Type =
TBD2 ("Binding label/SID failure") and Error-Value = TBD5 ("Unable
to allocate a new binding label/SID").If one or both speakers (PCE and PCC) have not indicated support
and willingness to use the PCEP extensions for the PCECC as per
and a PCEP peer receives P=1 in the LSP
object, it MUST: send a PCErr message with Error-Type=19 (Invalid Operation)
and Error-value=16 (Attempted PCECC operations when PCECC
capability was not advertised) andterminate the PCEP session.A legacy PCEP speaker that does not recognize the P flag in the
LSP object would ignore it in accordance with .It is assumed that the label range to be used by a PCE is known and
set on both PCEP peers. The exact mechanism is out of the scope of or this document. Note that the specific BSID could
be from the PCE-controlled or the PCC-controlled label space. The PCE
can directly allocate the label from the PCE-controlled label space
using P=1 as described above, whereas the PCE can request the allocation
of a specific BSID from the PCC-controlled label space with P=0 as
described in .Note that, the P-Flag in the LSP object SHOULD NOT be set to 1
without the presence of TE-PATH-BINDING TLV or any other future TLV
defined for PCE allocation. On receipt of such an LSP object, the P-Flag
is ignored. The presence of TE-PATH-BINDING TLV with P=1 indicates the
allocation is for the binding label/SID. In the future, some other TLV
(such as one defined in )
could also be used alongside P=1 to indicate allocation of a different
attribute. A future document should not attempt to assign semantics to
P=1 without limiting its scope that both PCEP peers could agree on.[Note to the RFC Editor - remove this section before publication, as
well as remove the reference to RFC 7942.]This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in . The description of implementations in this section
is intended to assist the IETF in its decision processes in progressing
drafts to RFCs. Please note that the listing of any individual
implementation here does not imply endorsement by the IETF. Furthermore,
no effort has been spent to verify the information presented here that
was supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.According to , "this will allow reviewers and
working groups to assign due consideration to documents that have the
benefit of running code, which may serve as evidence of valuable
experimentation and feedback that have made the implemented protocols
more mature. It is up to the individual working groups to use this
information as they see fit".Organization: HuaweiImplementation: Huawei's Router and ControllerDescription: An experimental code-point is used and will be
modified to the value allocated in this document.Maturity Level: ProductionCoverage: FullContact: c.l@huawei.comOrganization: Cisco SystemsImplementation: Head-end and controller.Description: An experimental code-point is used and will be
modified to the value allocated in this document.Maturity Level: ProductionCoverage: FullContact: mkoldych@cisco.comThe security considerations described in ,
, , , and are applicable to this
specification. No additional security measure is required.As described in and , SR intrinsically involves an entity (whether
head-end or a central network controller) controlling and instantiating
paths in the network without the involvement of (other) nodes along
those paths. Binding SIDs are in effect shorthand aliases for longer
path representations, and the alias expansion is in principle known only
by the node that acts on it. In this document, the expansion of the
alias is shared between PCC and PCE, and rogue actions by either PCC or
PCE could result in shifting or misdirecting traffic in ways that are
hard for other nodes to detect. In particular, when a PCE propagates
paths of the form {A, B, BSID} to other entities, the BSID values are
opaque, and a rogue PCE can substitute a BSID from a different LSP in
such paths to move traffic without the recipient of the path knowing the
ultimate destination.The case of BT=3 provides additional opportunities for malfeasance,
as it purports to convey information about internal SRv6 SID structure.
There is no mechanism defined to validate this internal structure
information, and mischaracterizing the division of bits into locator
block, locator node, function, and argument can result in different
interpretation of the bits by PCC and PCE. Most notably, shifting bits
into or out of the "argument" is a direct vector for affecting
processing, but other attacks are also possible.Thus, as per , it is RECOMMENDED that these
PCEP extensions only be activated on authenticated and encrypted
sessions across PCEs and PCCs belonging to the same administrative
authority, using Transport Layer Security (TLS) , as per the recommendations and best current
practices in BCP195 (unless explicitly set
aside in ).All manageability requirements and considerations listed in , , and apply to PCEP protocol extensions defined in this
document. In addition, requirements and considerations listed in this
section apply.A PCC implementation SHOULD allow the operator to configure the
policy the PCC needs to apply when allocating the binding
label/SID.If BT is set to 2, the operator needs to have local policy set to
decide the SID structure and the SRv6 Endpoint Behavior of the
BSID.The PCEP YANG module will
be extended to include policy configuration for binding label/SID
allocation.The mechanisms defined in this document do not imply any new
liveness detection and monitoring requirements in addition to those
already listed in .The mechanisms defined in this document do not imply any new
operation verification requirements in addition to those already
listed in ,
, and .The mechanisms defined in this document do not imply any new
requirements on other protocols.The mechanisms defined in , , and also apply to the
PCEP extensions defined in this document.IANA maintains the "Path Computation Element Protocol (PCEP) Numbers"
registry. This document requests IANA actions to allocate code points
for the protocol elements defined in this document.This document defines a new PCEP TLV; IANA is requested to confirm
the following early allocations from the "PCEP TLV Type Indicators"
subregistry of the PCEP Numbers registry, as follows:ValueDescriptionReference55TE-PATH-BINDINGThis documentIANA is requested to create a new subregistry "TE-PATH-BINDING
TLV BT field" to manage the value of the Binding Type field in the
TE-PATH-BINDING TLV. Initial values for the subregistry are given
below. New values are assigned by Standards Action .ValueDescriptionReference0MPLS LabelThis document1MPLS Label Stack EntryThis document2SRv6 SIDThis document3SRv6 SID with Behavior and StructureThis document4-255UnassignedThis documentIANA is requested to create a new subregistry "TE-PATH-BINDING
TLV Flag field" to manage the Flag field in the TE-PATH-BINDING TLV.
New values are to be assigned by Standards Action . Each bit should be tracked with the following
qualities:Bit number (count from 0 as the most significant bit)DescriptionReferenceBitDescriptionReference0R (Removal)This document1-7UnassignedThis documentIANA is requested to confirm the early allocation for a new
code-point in the "LSP Object Flag Field" sub-registry for the new P
flag as follows:BitDescriptionReference0PCE-allocationThis documentThis document defines a new Error-type and associated Error-Values
for the PCErr message. IANA is requested to allocate new error-type
and error-values within the "PCEP-ERROR Object Error Types and Values"
subregistry of the PCEP Numbers registry, as follows:Error-TypeMeaningError-valueReferenceTBD2Binding label/SID failure 0: UnassignedThis documentTBD3: Invalid SIDThis documentTBD4: Unable to allocate the specified binding valueThis documentTBD5: Unable to allocate a new binding label/SIDThis documentTBD6: Unable to remove the binding valueThis documentTBD7: Inconsistent binding typesThis documentWe would like to thank Milos Fabian, Mrinmoy Das, Andrew Stone, Tom
Petch, Aijun Wang, Olivier Dugeon, and Adrian Farrel for their valuable
comments.Thanks to Julien Meuric for shepherding. Thanks to John Scudder for
the AD review.Thanks to Theresa Enghardt for the GENART review.Thanks to Martin Vigoureux, Benjamin Kaduk, Eric Vyncke, Lars Eggert,
Murray Kucherawy, and Erik Kline for the IESG reviews.