| Internet-Draft | PCEP Extensions for Native IP Networks | November 2023 |
| Wang, et al. | Expires 18 May 2024 | [Page] |
This document defines the Path Computation Element Communication Protocol (PCEP) extension for Central Control Dynamic Routing (CCDR) based applications in Native IP networks. It describes the key information that is transferred between Path Computation Element (PCE) and Path Computation Clients (PCC) to accomplish the End to End (E2E) traffic assurance in the Native IP network under PCE as a central controller.¶
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.¶
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.¶
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."¶
This Internet-Draft will expire on 18 May 2024.¶
Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved.¶
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
Generally, Multiprotocol Label Switching Traffic Engineering (MPLS-TE) requireHs the corresponding network devices to support Resource ReSerVation Protocol (RSVP)/Label Distribution Protocol (LDP) protocols to assure the End-to-End (E2E) traffic performance. But in native IP network scenarios described in [RFC8735], there will be no such signaling protocol to synchronize the action among different network devices. It is necessary to use the central control mode described in [RFC8283] to correlate the forwarding behavior among different network devices. [RFC8821] describes the architecture and solution philosophy for the E2E traffic assurance in the Native IP network via multi Border Gateway Protocol (BGP) session-based solution. It requires only the PCE send the instructions to the PCCs, to build multiple BGP sessions, distribute different prefixes on the established BGP sessions and assign the different paths to the BGP nexthops.¶
This document describes the corresponding Path Computation Element Communication Protocol (PCEP) extensions to transfer the key information about BGP peer, peer prefix advertisement, and the explicit peer route on on-path routers.¶
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 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
This document uses the following terms defined in [RFC5440]: PCE, PCEP¶
The following terminology is used in this document:¶
During the PCEP Initialization Phase, PCEP Speakers (PCE or PCC) advertise their support of Native IP extensions.¶
This document defines a new Path Setup Type (PST) [RFC8408] for Native-IP, as follows:¶
A PCEP speaker MUST indicate its support of the function described in this document by sending a PATH-SETUP-TYPE-CAPABILITY TLV in the OPEN object with this new PST included in the PST list.¶
[RFC9050] defined the PCECC-CAPABILITY sub-TLV to exchange information about their PCECC capability. A new flag is defined in PCECC-CAPABILITY sub-TLV for Native IP:¶
N (NATIVE-IP-TE-CAPABILITY - 1 bit - 30): If set to 1 by a PCEP speaker, it indicates that the PCEP speaker is capable of TE in a Native IP network as specified in this document. The flag MUST be set by both the PCC and PCE to support this extension.¶
If a PCEP speaker receives the PATH-SETUP-TYPE-CAPABILITY TLV with the newly defined path setup type, but without the N bit set in PCECC-CAPABILITY sub-TLV, it MUST:¶
PCECC Native IP TE solution utilizing the existing PCE Label Switched Path (LSP) Initiate Request message (PCInitiate) [RFC8281], and PCE Report message (PCRpt) [RFC8281] to accomplish the multi BGP sessions establishment, E2E TE path deployment, and route prefixes advertisement among different BGP sessions. A new PST for Native-IP is used to indicate the path setup based on TE in Native IP networks.¶
The extended PCInitiate message described in [RFC9050] is used to download or remove central controller's instructions (CCIs). [RFC9050] specifies an object called CCI for the encoding of the central controller's instructions. This document specifies a new CCI object-type for Native IP. The PCEP messages are extended in this document to handle the PCECC operations for Native IP. Three new PCEP Objects (BGP Peer Info (BPI) Object, Explicit Peer Route (EPR) Object, and Peer Prefix Advertisement (PPA) Object) are defined in this document. Refer to Section 7 for detailed object definitions. All PCEP procedures specified in [RFC9050] continue to apply unless specified otherwise.¶
The PCInitiate Message defined in [RFC8281] and extended in [RFC9050] is further extended to support Native-IP CCI.¶
The format of the extended PCInitiate message is as follows:¶
<PCInitiate Message> ::= <Common Header>
<PCE-initiated-lsp-list>
Where:
<Common Header> is defined in [RFC5440]
<PCE-initiated-lsp-list> ::= <PCE-initiated-lsp-request>
[<PCE-initiated-lsp-list>]
<PCE-initiated-lsp-request> ::=
(<PCE-initiated-lsp-instantiation>|
<PCE-initiated-lsp-deletion>|
<PCE-initiated-lsp-central-control>)
<PCE-initiated-lsp-central-control> ::= <SRP>
<LSP>
(<cci-list>|
(<BPI>|<EPR>|<PPA>))
<cci-list> ::= <CCI>
[<cci-list>]
Where:
<cci-list> is as per [RFC9050]
<PCE-initiated-lsp-instantiation> and <PCE-initiated-lsp-deletion> are as per [RFC8281].
The LSP and SRP objects are defined in [RFC8231].
¶
When PCInitiate message is used for Native IP instructions, the SRP, LSP and CCI objects MUST be present. The error handling for missing SRP, LSP or CCI object is as per [RFC9050]. Further only one object among BPI, EPR, or PPA object MUST be present. The PLSP-ID within the LSP object should be set by PCC uniquely according to the Symbolic Path Name TLV that is included in the CCI object. The Symbolic Path Name is used by the PCE/PCC to uniquely identify the E2E native IP TE path. It MUST be set the same value with the related BPI, EPR and PPA object.¶
If none of the BPI, EPR, or PPA object are present, the receiving PCC MUST send a PCErr message with Error-type=6 (Mandatory Object missing) and Error-value=19 (Native IP object missing). If there are more than one instance of BPI, EPR or PPA object present, the receiving PCC MUST send a PCErr message with Error-type=19 (Invalid Operation) and Error-value=22 (Only one BPI, EPR or PPA object can be included in this message).¶
To cleanup the existing Native IP instructions, the SRP object must set the R (remove) bit.¶
The PCRpt message is used to acknowledge the Native-IP instructions received from the central controller (PCE) as well as during the State Synchronization phase.¶
The format of the PCRpt message is as follows:¶
<PCRpt Message> ::= <Common Header>
<state-report-list>
Where:
<state-report-list> ::= <state-report>[<state-report-list>]
<state-report> ::= (<lsp-state-report>|
<central-control-report>)
<lsp-state-report> ::= [<SRP>]
<LSP>
<path>
<central-control-report> ::= [<SRP>]
<LSP>
(<cci-list>|
(<BPI>|<EPR>|<PPA>))
Where:
<path> is as per [RFC8231] and the LSP and SRP object are also defined in [RFC8231].
¶
The error handling for missing CCI object is as per [RFC9050]. Further only one object among BPI, EPR, or PPA object MUST be present.¶
If none of the BPI, EPR, or PPA object are present, the receiving PCE MUST send a PCErr message with Error-type=6 (Mandatory Object missing) and Error-value=19 (Native IP object missing). If there are more than one instance of BPI, EPR or PPA object present, the receiving PCE MUST send a PCErr message with Error-type=19 (Invalid Operation) and Error-value=22 (Only one BPI, EPR or PPA object can be included in this message).¶
The detail procedures for the TE in native IP environment are described in the following sections.¶
The PCInitiate and PCRpt message pair is used to configure the parameters for a BGP peer session. This pair of PCEP messages is exchanged between a PCE and each BGP peer (acting as PCC) which needs to be configured. After the BGP peer session has been configured via this pair of PCEP messages, the BGP session establishes and operates in a normal fashion. The BGP peers can be configured for External BGP (EBGP) peers or Internal BGP (IBGP) peers. For IBGP connection topologies, the Route Reflector (RR) is required.¶
The PCInitiate message should be sent to PCC which is acting as BGP router and/or RR.¶
The RR topology for a single AS is shown in Figure 1. The BGP routers R1, R3, and R7 are within a single AS. R1 and R7 are BGP RR clients, and R3 is a RR. The PCInitiate message should be sent only the BGP routers that need to be newly configured R1, R3 and R7.¶
PCInitiate message creates an auto-configuration function for these BGP peers by providing the indicated Peer AS and the Local/Peer IP Address.¶
When PCC receives the BPI and CCI object (with the R bit set to 0 in SRP object) in PCInitiate message, the PCC should try to establish the BGP session with the indicated Peer as per AS and Local/Peer IP address.¶
During the establishment procedure, PCC should report periodically to the PCE the status of the BGP session via the PCRpt message, with the status filed in the BPI object set to the appropriate value and the corresponding SRP and CCI object included.¶
When PCC receives this message with the R bit set to 1 in SRP object in PCInitiate message, the PCC should clear the BGP session that is indicated by the BPI object.¶
When PCC clears successfully the specified BGP session, it should report the result via the PCRpt message, with the BPI object included, and the corresponding SRP and CCI objects.¶
+------------------+
+-----------> PCE <----------+
| +--------^---------+ |
| | |
| PCInitiate/PCRpt |
| | |
| +----v--+ |
+---------------+ R3(RR)+-----------------+
| +-------+ |
PCInitiate/PCRpt PCInitiate/PCRpt
| |
+v-+ +--+ +--+ +-v+
|R1+----------+R5+----------+R6+---------+R7|
++-+ +-++ +--+ +-++
| | |
| +--+ +--+ |
+------------+R2+----------+R4+-----------+
+--+ +--+
Figure 1: BGP Session Establishment Procedures(R3 act as RR)
¶
The message peers, message type, message key parameters and procedures in the above figures are shown in below:¶
+-------+ +-------+
|PCC | | PCE |
|R1 | +-------+
+------| | |
| PCC +-------+ |
| R3 | | |
+------| | |<--PCInitiate,CC-ID=X1(Symbolic Path Name=Class A)------------|
| | | BPI Object(Peer AS, Local_IP=R1_A, Peer_IP=R3_A)|(For R1/R3 BGP Session on R1 )
|PCC +--------+ | |
|R7 | | |----PCRpt,CC-ID=X1(Symbolic Path Name=Class A)--------------->|
| | | | BPI Object(Peer AS, Local_IP=R1_A, Peer_IP=R3_A)|
+--------+ | |
| |<--PCInitiate,CC-ID=X1(Symbolic Path Name=Class A)------------------|(For R1/R3 BGP Session on R3 )
| | BPI Object(Peer AS, Local_IP=R3_A, Peer_IP=R1_A) |
| |----PCRpt,CC-ID=X1(Symbolic Path Name=Class A)--------------------->|
| | BPI Object(Peer AS, Local_IP=R3_A, Peer_IP=R1_A) |
| | |
| |<--PCInitiate,CC-ID=X1(Symbolic Path Name=Class A)------------------|(For R3/R7 BGP Session on R3 )
| | BPI Object(Peer AS, Local_IP=R3_A, Peer_IP=R7_A) |
| |----PCRpt,CC-ID=X1(Symbolic Path Name=Class A)--------------------->|
| | BPI Object(Peer AS, Local_IP=R3_A, Peer_IP=R7_A) |
| |
|<--PCInitiate,CC-ID=X1(Symbolic Path Name=Class A)--------------------------|(For R3/R7 BGP Session on R7)
| BPI Object(Peer AS, Local_IP=R7_A, Peer_IP=R3_A) |
|---PCRpt,CC-ID=X1(Symbolic Path Name=Class A)------------------------------>|
| BPI Object(Peer AS, Local_IP=R7_A, Peer_IP=R3_A) |
Figure 2: Message Information and Procedures
¶
The Local/Peer IP address MUST be dedicated to the usage of native IP TE solution, and MUST NOT be used by other BGP sessions that established by manual or other ways. If the Local IP Address or Peer IP Address within BPI object is used in other existing BGP sessions, the PCC should report such error situation via a PCErr message with:¶
3) Error-type=33 and Error-value=1, Local IP is in use, or¶
4) Error-type=33 and Error-value=2, Remote IP is in use.¶
The detailed Error-Types and Error-Values are defined in Section 8¶
If the established BGP session is broken, the PCC should report such information via PCRpt message with the status filed set to "BGP session disabled" in associated BPI Object. In future, when the BGP session is up again, the PCC should report that as well via the PCRpt message with status field set to "BGP Session Established".¶
The explicit route establishment procedures can be used to install a route via PCE on the PCC, using PCInitiate and PCRpt message pair. Such explicit routes operate the same as static routes installed by network management protocols(NETCONF/YANG). The procedures of such explicit route addition and remove must be controlled by the PCE in an specific order so that the pathways are established without loops.¶
The PCInitiate message should be sent to the on-path routers respectively. In the example, for explicit route from R1 to R7, the PCInitiate message should be sent to R1, R2 and R4, as shown in Figure 3. For explicit route from R7 to R1, the PCInitiate message should be sent to R7, R4 and R2, as shown in Figure 5.¶
When PCC receives the EPR and the CCI object (with the R bit set to 0 in SRP object) in PCInitiate message, the PCC should install the explicit route to the peer.¶
When PCC install successfully the explicit route to the peer, it should report the result via the PCRpt messages, with EPR object and the corresponding SRP and CCI object included.¶
When PCC receives the EPR and the CCI object with the R bit set to 1 in SRP object in PCInitiate message, the PCC should clear the explicit route to the peer that indicated by the EPR object.¶
When PCC clear successfully the explicit route that indicated by this object, it should report the result via the PCRpt message, with the EPR object included, and the corresponding SRP and CCI object.¶
+------------------+
+----------> PCE +
| +----^-----------^-+
| | |
| | |
| | +------+ |
+---------------|-+R3(RR)+--|-------------+
PCInitiate/PCRpt | +------+ | |
| | | |
+v-+ +--+ | | +--+ +--+
|R1+------+R5+---+-----------|---+R6+----+R7|
++-+ +--+ | | +--+ +-++
| PCInitiate/PCRpt PCInitiate/PCRpt |
| | | |
| +--v--+ +--v-+ |
+------------+- R2 +-----+ R4 +-----------+
+--+--+ +--+-+
Figure 3: Explicit Route Establish Procedures(From R1 to R7)
¶
The message message peers, message type, message key parameters and procedures in the above figures are shown in below:¶
+-------+ +-------+
|PCC | | PCE |
|R1 | +-------+
+------| | |
| PCC +-------+ |
| R2 | | |
+------| | |<--PCInitiate,CC-ID=X1(Symbolic Path Name=Class A)------------|
| | | EPR Object(Peer Address=R7_A, Next Hop=R2_A) |(EPR route on R1 )
|PCC +--------+ | |
|R4 | | |----PCRpt,CC-ID=X1(Symbolic Path Name=Class A)--------------->|
| | | | EPR Object(Peer Address=R7_A, Next Hop=R2_A) |
+--------+ | |
| |<--PCInitiate,CC-ID=X1(Symbolic Path Name=Class A)------------------|(EPR route on R2 )
| | EPR Object(Peer Address=R7_A, Next Hop=R4_A) |
| |----PCRpt,CC-ID=X1(Symbolic Path Name=Class A)--------------------->|
| | EPR Object(Peer Address=R7_A, Next Hop=R4_A) |
| | |
| |
|<--PCInitiate,CC-ID=X1(Symbolic Path Name=Class A)--------------------------|(EPR route on R4)
| EPR Object(Peer Address=R7_A, Next Hop=R7_A) |
|---PCRpt,CC-ID=X1(Symbolic Path Name=Class A)------------------------------>|
| EPR Object(Peer Address=R7_A, Next Hop=R7_A) |
Figure 4: Message Information and Procedures
¶
+------------------+
+ PCE <-----------+
+----^-----------^-+ |
| | |
| | |
| +------+ | |
+-----------------+R3(RR)+--|-------------+
| | +------+ | PCInitiate/PCRpt
| | | |
+--+ +--+ | | +--+ +-v+
|R1+------+R5+---+-----------|---+R6+----+R7|
++-+ +--+ | | +--+ +-++
| PCInitiate/PCRpt PCInitiate/PCRpt |
| | | |
| +--v--+ +--v-+ |
+------------+- R2 +-----+ R4 +-----------+
+--+--+ +--+-+
Figure 5: Explicit Route Establish Procedures(From R7 to R1)
¶
The message message peers, message type, message key parameters and procedures in the above figures are shown in below:¶
+-------+ +-------+
|PCC | | PCE |
|R7 | +-------+
+------| | |
| PCC +-------+ |
| R4 | | |
+------| | |<--PCInitiate,CC-ID=X1(Symbolic Path Name=Class A)------------|(EPR route on R7 )
| | | EPR Object(Peer Address=R1_A, Next Hop=R4_A) |
|PCC +--------+ | |
|R2 | | |----PCRpt,CC-ID=X1(Symbolic Path Name=Class A)--------------->|
| | | | EPR Object(Peer Address=R1_A, Next Hop=R4_A) |
+--------+ | |
| |<--PCInitiate,CC-ID=X1(Symbolic Path Name=Class A)------------------|(EPR route on R4 )
| | EPR Object(Peer Address=R1_A, Next Hop=R2_A) |
| |----PCRpt,CC-ID=X1(Symbolic Path Name=Class A)--------------------->|
| | EPR Object(Peer Address=R1_A, Next Hop=R2_A) |
| | |
| |
|<--PCInitiate,CC-ID=X1(Symbolic Path Name=Class A)--------------------------|(EPR route on R2)
| EPR Object(Peer Address=R1_A, Next Hop=R1_A) |
|---PCRpt,CC-ID=X1(Symbolic Path Name=Class A)------------------------------>|
| EPR Object(Peer Address=R1_A, Next Hop=R1_A) |
Figure 6: Explicit Route Establish Procedures(From R7 to R1)
¶
In order to avoid the transient loop while deploying the explicit peer route, the EPR object should be sent to the PCCs in the reverse order of the E2E path. To remove the explicit peer route, the EPR object should be sent to the PCCs in the same order of E2E path.¶
To accomplish ECMP effects, the PCE can send multiple EPR objects to the same node, with the same route priority and peer address value but different next hop addresses.¶
The PCC should verify that the next hop address is reachable. Upon the error occurs, the PCC SHOULD send the corresponding error via PCErr message, with an error information:¶
1) Error-type=33, Error-value=3, Explicit Peer Route Error.¶
When the peer info is not the same as the peer info that indicated in BPI object in PCC for the same path that is identified by Symbolic Path Name TLV, an PCErr message should be reported, with an error information:¶
2) Error-type=33, Error-value=4, EPR/BPI Peer Info Mismatch. Note that the same error is received in case no BPI is received at the PCC.¶
If the PCE needs to update the path, it should first instruct new CCI with updated EPR corresponding to the new nexthop to use and then instruct the removal of older CCI.¶
The detail procedures for BGP prefix advertisement are shown below, using PCInitiate and PCRpt message pair.¶
The PCInitiate message should be sent to PCC that acts as BGP peer edge router only. In the example, it should be sent to R1 and R7 respectively.¶
When PCC receives the PPA and the CCI object (with the R bit set to 0 in SRP object) in PCInitiate message, the PCC should send the prefixes indicated in this object to the appointed BGP peer via the corresponding BGP session [RFC4271].¶
When PCC sends successfully the prefixes to the appointed BGP peer, it should report the result via the PCRpt messages, with PPA object and the corresponding SRP and CCI object included.¶
When PCC receives the PPA and the CCI object with the R bit set to 1 in SRP object in PCInitiate message, the PCC should withdraw the prefixes advertisement to the peer that indicated by this object.¶
When PCC withdraws successfully the prefixes that indicated by this object, it should report the result via the PCRpt message, with the PPA object included, and the corresponding SRP and CCI object.¶
+------------------+
+----------> PCE <-----------+
| +------------------+ |
| +--+ |
+------------------+R3+-------------------+
PCInitiate/PCRpt +--+ PCInitiate/PCRpt
| |
+v-+ +--+ +--+ +-v+
|R1+----------+R5+----------+R6+---------+R7|
++-+ +--+ +--+ +-++
(BGP Router) (BGP Router)
| |
| |
| +--+ +--+ |
+------------+R2+----------+R4+-----------+
+--+ +--+
Figure 7: BGP Prefix Advertisement Procedures
¶
+-------+ +-------+
|PCC | | PCE |
|R1 | +-------+
+------| | |
| PCC +-------+ |
| R7 | | |
| | |<--PCInitiate,CC-ID=X1(Symbolic Path Name=Class A)------------|(Instruct R1 to advertise Prefix 1_A to R7 )
| | | PPA Object(Peer IP=R7_A, Prefix=1_A) |
+--------+ | |
| |----PCRpt,CC-ID=X1(Symbolic Path Name=Class A)--------------->|
| | PPA Object(Peer IP=R7_A, Prefix=1_A) |
| |
|<--PCInitiate,CC-ID=X1(Symbolic Path Name=Class A)------------------|(Instruct R7 to advertise Prefix 7_A to R1 )
| PPA Object(Peer IP=R1_A, Prefix=7_A) |
|----PCRpt,CC-ID=X1(Symbolic Path Name=Class A)--------------------->|
| PPA Object(Peer IP=R1_A, Prefix=7_A) |
| |
Figure 8: Message Information and Procedures
¶
The allowed AFI/SAFI for the IPv4 BGP session should be 1/1 (IPv4 prefix) and the allowed AFI/SAFI for the IPv6 BGP session should be 2/1 (IPv6 prefix). If mismatch occur, an error:¶
1) Error-type=33, Error-value=5, BPI/PPA address family mismatch should be reported via PCErr message.¶
When the peer info is not the same as the peer info that is indicated in the BPI object in PCC for the same path that is identified by Symbolic Path Name TLV, an error:¶
2) Error-type=33, Error-value=6, PPA/BPI peer info mismatch should be reported via the PCErr message. Note that the same error is received in case no BPI is received at the PCC.¶
Normally, when the above procedures are finished, the user traffic will be forwarded via the appointed path, but the forwarding will be based soley on the destination of user traffic. If there are traffic from different attached point to the same destination come into the network, they may share the priority path which may not be the initial desire. For example, as illustrated in Figure 1, the initial aim is to assure traffic that enter into the network via R1, and exit the network at R7. If some traffic enter into the network via the R2 router to router R5, they may share the priority path among R5-R6-R7, which is not the desired effect.¶
The above normal traffic forwarding behaviour are clarified as Raw mode forwarding strategy. Such mode can achieve only the moderate traffic path control effect. In order to achieve the strict traffic path control effect, the entry point should tunnel the user traffic from the entry point of the network to the exit point of the network, which is also between the BGP peer that established via Section 6.1. Such forwarding behavior are called Tunnel mode forwarding strategy.¶
The selection of Raw mode and Tunnel mode forwarding strategy are controlled via the "T" bit in BPI Object that is defined in Section 7.2¶
In order to delete the Native-IP state from the PCC, the PCE MUST send explicit CCI cleanup instruction for PPA, EPR, and BPI object with R flag set in the SRP object. If the PCC receives a PCInitiate message but does not recognize the Native-IP information in the CCI, the PCC MUST generate a PCErr message with Error-Type=19 (Invalid operation) and Error-value=TBD (Unknown Native-IP Info) and MUST include the SRP object to specify the error is for the corresponding cleanup (via a PCInitiate message).¶
The handling of the state synchronization, redundant PCEs, re-delegation and clean up is the same as other CCIs as specified in [RFC9050].¶
One new CCI Object type and three new PCEP objects are defined in this document. All new PCEP objects are as per [RFC5440].¶
The Central Control Instructions (CCI) Object (defined in [RFC9050]) is used by the PCE to specify the forwarding instructions. This document defines another object-type for Native-IP.¶
CCI Object-Type is 2 for Native-IP as below:¶
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CC-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |
+---------------------------------------------------------------+
| |
// Optional TLV //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: CCI Object for Native IP¶
The field CC-ID is as described in [RFC9050]. Following fields are defined for CCI Object-Type 2¶
The Symbolic Path Name TLV [RFC8231] MUST be included in the CCI Object-Type 2 to identify the E2E TE path in Native IP environment and MUST be unique.¶
The BGP Peer Info object is used to specify the information about the peer with which the PCC should establish the BGP session. This object should only be included and sent to the source and destination router of the E2E path in case there is no Route Reflection (RR) involved. If the RR is used between the source and destination routers, then such information should be sent to source router, RR and destination router respectively.¶
By default, the Local/Peer IP address SHOULD be dedicated to the usage of native IP TE solution, and SHOULD NOT be used by other BGP sessions that established by manual or non PCE initiated configuration.¶
BGP Peer Info Object-Class is 46¶
BGP Peer Info Object-Type is 1 for IPv4 and 2 for IPv6¶
The format of the BGP Peer Info object body for IPv4 (Object-Type=1) is as follows:¶
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peer AS Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETTL | Status | Flag |T|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local IP Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peer IP Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Optional TLVs //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: BGP Peer Info Object Body Format for IPv4¶
The format of the BGP Peer Info object body for IPv6 (Object-Type=2) is as follows:¶
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peer AS Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ETTL | Status | Error Code | Flag |T|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Local IP Address (16 bytes) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Peer IP Address (16 bytes) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Optional TLVs //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: BGP Peer Info Object Body Format for IPv6¶
Peer AS Number: 4 Bytes, to indicate the AS number of Remote Peer.¶
ETTL: 1 Byte, EBGP Time To Live, to indicate the multihop count for EBGP session. It should be 0 and ignored when Local AS and Peer AS is same.¶
Status: 1 Byte, Indicate BGP session status between the peers. It's values are defined below:¶
0: Reserved¶
1: BGP Session Established¶
2: BGP Session Establishment In Progress¶
3: BGP Session Disabled¶
4-255: Reserved¶
Error Code: 1 Byte, Indicate the reason that BGP session can't be established.¶
0: Reserved¶
1: ASes does not match, BGP Session Failure¶
2: Peer IP can't be reached, BGP Session Failure¶
3-255: Reserved¶
Flag: 1 Byte. Currently only bit 0 (T bit) is defined. When T bit is set, the traffic should be sent in IPinIP tunnel (Tunnel source is Local IP Address, tunnel destination is Peer IP Address). When T bit is cleared, the traffic is sent via its original source and destination address. The Tunnel mode(T bit is set) is used when the operator want to assure only the traffic from the specified (entry, exit) pair, the Raw mode(T bit is clear) is used when the operator want to assure traffic from any entry to the specified destination.¶
Local IP Address(4/16 Bytes): IP address of the local router, used to peer with other end router. When Object-Type is 1, length is 4 bytes; when Object-Type is 2, length is 16 bytes.¶
Peer IP Address(4/16 Bytes): IP address of the peer router, used to peer with the local router. When Object-Type is 1, length is 4 bytes; when Object-Type is 2, length is 16 bytes;¶
Optional TLVs: TLVs that associated with this object, can be used to convey other necessary information for dynamic BGP session establishment. No TLVs are currently defined.¶
When PCC receives BPI object, with Object-Type=1, it should try to establish BGP session with the peer in AFI/SAFI=1/1.¶
When PCC receives BPI object with Object-Type=2, it should try to establish the BGP session with the peer in AFI/SAFI=2/1.¶
The Explicit Peer Route object is defined to specify the explicit peer route to the corresponding peer address on each device that is on the E2E assurance path. This Object should be sent to all the devices on the E2E assurance path that is calculated by the PCE.¶
It is RECOMMENDED that the path established by this object should have higher priority than the other paths calculated by dynamic IGP protocol, but should have lower priority than the static route configured by manual or NETCONF or any other means.¶
Explicit Peer Route Object-Class is 47.¶
Explicit Peer Route Object-Type is 1 for IPv4 and 2 for IPv6¶
The format of Explicit Peer Route object body for IPv4 (Object-Type=1) is as follows:¶
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Priority | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peer IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Hop IPv4 Address to the Peer IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Optional TLVs //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: Explicit Peer Route Object Body Format for IPv4
¶
The format of Explicit Peer Route object body for IPv6 (Object-Type=2) is as follows:¶
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Priority | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Peer IPv6 Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Next Hop IPv6 Address to the Peer IPv6 Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Optional TLVs //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: Explicit Peer Route Object Body Format for IPv6
¶
Route Priority: 2 Bytes; the priority of this explicit route. The higher priority should be preferred by the device. This field is used to indicate the backup path at each hop.¶
Reserved: is set to zero while sending, ignored on receipt.¶
Peer (IPv4/IPv6) Address: Peer Address for the BGP session(4/16 Bytes).¶
Next Hop (IPv4/IPv6) Address to the Peer Address: To indicate the next hop address (4/16 Bytes) to the corresponding peer address.¶
Optional TLVs: TLVs that associated with this object, can be used to convey other necessary information for explicit peer path establishment. No TLVs are currently defined.¶
The Peer Prefix Advertisement object is defined to specify the IP prefixes that should be advertised to the corresponding peer. This object should only be included and sent to the source/destination router of the E2E path.¶
The prefixes information included in this object MUST only be advertised to the indicated peer, MUST NOT be advertised to other BGP peers.¶
Peer Prefix Advertisement Object-Class is 48¶
Peer Prefix Advertisement Object-Type is 1 for IPv4 and 2 for IPv6¶
The format of the Peer Prefix Advertisement object body is as follows:¶
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Peer IPv4 Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | No. of Prefix | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 Prefix #1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Prefix #1 Len | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | : | | : | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 Prefix #n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Prefix #n Len | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // Optional TLVs // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 14: Peer Prefix Advertisement Object Body Format for IPv4¶
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Peer IPv6 Address | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | No. of Prefix | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 Prefix #1 | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Prefix #1 Len | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | : | | : | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 Prefix #n | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Prefix #n Len | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // Optional TLVs // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 15: Peer Prefix Advertisement Object Body Format for IPv6¶
Peer IPv4 Address: 4 Bytes. Identifies the peer IPv4 address that the associated prefixes will be sent to.¶
No. of Prefix: 1 Byte. Identifies the number of prefixes that are advertised to the peer in the PPA object.¶
Reserved: 3 Bytes. MUST be set to zero while sending and MUST be ignored on receipt.¶
IPv4 Prefix: 4 Bytes. Identifies the prefix that will be sent to the peer identified by Peer IPv4 Address.¶
Prefix Len: 1 Byte. Identifies the length of the prefix.¶
Optional TLVs: TLVs that associated with this object, can be used to convey other necessary information for prefixes advertisement. No TLVs are currently defined.¶
For IPv6:¶
A PCEP-ERROR object is used to report a PCEP error and is characterized by an Error-Type that specifies that type of error and an Error-value that provides additional information about the error. An additional Error-Type and several Error-values are defined to represent the errors related to the newly defined objects that are related to Native IP TE procedures.¶
+============+===============+=====================================+
| Error-Type | Meaning | Error-value |
+============+===============+=====================================+
| 33 | Native IP | |
| | TE failure | |
+------------+---------------+-------------------------------------+
| | |0:Unassigned |
+------------+---------------+-------------------------------------+
| | |1:Local IP is in use |
+------------+---------------+-------------------------------------+
| | |2:Remote IP is in use |
+------------+---------------+-------------------------------------+
| | |3:Explicit Peer Route Error |
+------------+---------------+-------------------------------------+
| | |4:EPR/BPI Peer Info mismatch |
+------------+---------------+-------------------------------------+
| | |5:BPI/PPA Address Family mismatch |
+------------+---------------+-------------------------------------+
| | |6:PPA/BPI Peer Info mismatch |
+------------+---------------+-------------------------------------+
Figure 16: Newly defined Error-Type and Error-Value
¶
This document defines the procedures and objects to create the BGP sessions and advertise the associated prefixes dynamically. Only the key information, for example peer IP addresses, peer AS number are exchanged via the PCEP protocol. Other parameters that are needed for the BGP session setup should be derived from their default values, as described in Section 7.2.¶
When the PCE sends out the PCInitiate message with BPI object embedded to establish the BGP session between the PCC peers, PCC should report the BGP session status. For instance, the PCC could respond with "BGP Session Establishment In Progress" initially and on session establishment send another PCRpt message with state updated to "BGP Session Established". If there is any error during the BGP session establishment, the PCC should indicate the reason with the appropriate status value set in the BPI object.¶
Upon receiving such key information, the BGP module on the PCC should try to accomplish the task appointed by the PCEP protocol and report the successful status to the PCEP modules after the session is setup.¶
There is no influence on current implementation of BGP Finite State Machine (FSM). The PCEP focuses only on the success and failure status of BGP session, and acts upon such information accordingly.¶
The error handling procedures related to incorrect BGP parameters are specified in Section 6.1, Section 6.2, and Section 6.3.¶
The information transferred in this document is mainly used for the BGP session setup, explicit route deployment and the prefix distribution. The planning, allocation and distribution of the peer addresses within IGP should be accomplished in advanced and they are out of the scope of this document.¶
[RFC8232] describes the state synchronization procedure between stateful PCE and PCC. The communication of PCE and PCC described in this document should also follow the same procedures, treat the three newly defined objects (BPI, EPR, PPA) associated with the same symbolic path name as the attribute of the same path in the LSP-DB (LSP State Database).¶
When PCE detects one or some of the PCCs are out of its control, it should recompute and redeploy the traffic engineering path for native IP on the currently active PCCs. The PCE should assure the avoidance of possible transient loop in such node failure when it deploys the explicit peer route on the PCCs.¶
In case of a PCE failure, a new PCE can gain control over the central controller instructions as described in [RFC9050].¶
As per the PCEP procedures in [RFC8281], the State Timeout Interval timer is used to ensure that a PCE failure does not result in automatic and immediate disruption for the services. Similarly, as per [RFC9050], the central controller instructions are not removed immediately upon PCE failure. Instead, they could be re-delegated to the new PCE before the expiration of this timer, or be cleaned up on the expiration of this timer. This allows for network clean up without manual intervention. The PCC supports the removal of CCI as one of the behaviors applied on expiration of the State Timeout Interval timer.¶
A PCE or PCC implementation SHOULD allow the PCECC NATIVE-IP-TE-CAPABILITY capability to be enabled/disabled as part of the global configuration.¶
[RFC7420] describes the PCEP MIB; this MIB can be extended to get the PCECC NATIVE-IP-TE-CAPABILITY capability status. The PCEP YANG [I-D.ietf-pce-pcep-yang] module could be extended to enable/disable the PCECC NATIVE-IP-TE-CAPABILITY capability.¶
Mechanisms defined in this document do not imply any new liveness detection and monitoring requirements in addition to those already listed in [RFC5440]. The operator relies on existing IP liveness detection and monitoring.¶
Verification of the mechanisms defined in this document can be built on those already listed in [RFC5440], [RFC8231] and [RFC9050]. Further, the operator needs to be able to verify the status of BGP sessions and prefix advertisements.¶
Mechanisms defined in this document requires the interaction with BGP. Section 9 describes in detail the considerations regarding to the BGP. During BGP session configuration , implementation MUST NOT allow the use local/remote IP address already sent tin the BPI object.¶
[RFC8821] describes the various deployment considerations in CCDR architecture and their impact on network operations.¶
[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 [RFC7942]. 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 [RFC7942], "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".¶
At the time of posting the -26 version of this document, there are no known implementations of this mechanism. A proof of concept for the overall design has been verified using another SBI protocol on the Open DayLight (ODL) controller.¶
ZTE is preparing an implementation of this document as the time of posting the -26 version of this document.¶
In this setup, the BGP sessions, prefix advertisement, and explicit peer route establishment are all controlled by the PCE. See [RFC4271] and [RFC4272] for BGP security considerations. Security considerations in [RFC5440] and [RFC8231] should be considered. To prevent a bogus PCE from sending harmful messages to the network nodes, the network devices should authenticate the validity of the PCE and ensure a secure communication channel between them. Thus, the mechanisms described in [RFC8253] and [RFC9050] should be used.¶
[RFC8408] created a sub-registry within the "Path Computation Element Protocol (PCEP) Numbers" registry called "PCEP Path Setup Types". IANA is requested to allocate a new code point within this sub-registry, as follows:¶
Value Description Reference 4 Native IP TE Path This document¶
[RFC9050] created a sub-registry within the "Path Computation Element Protocol (PCEP) Numbers" registry to manage the value of the PCECC-CAPABILITY sub-TLV's 32-bits Flag field. IANA is requested to allocate a new bit position within this registry, as follows:¶
Bit Name Reference 30 NATIVE IP This document¶
IANA is requested to allocate new codepoints in the "PCEP Objects" sub-registry as follows:¶
Object-Class Value Name Reference
44 CCI Object This document
Object-Type
2: Native IP
46 BGP Peer Info This document
Object-Type
1: IPv4 address
2: IPv6 address
47 Explicit Peer Route This document
Object-Type
1: IPv4 address
2: IPv6 address
48 Peer Prefix Advertisement This document
Object-Type
1: IPv4 address
2: IPv6 address
¶
IANA is requested to allocate new error types and error values within the "PCEP-ERROR Object Error Types and Values" sub-registry of the PCEP Numbers registry for the following errors:¶
Error-Type Meaning Error-value Reference
6 Mandatory Object missing
19:Native IP object missing This document
10 Reception of an invalid object
39:PCECC NATIVE-IP-TE-CAPABILITY bit is not set This document
19 Invalid Operation
22:Only one BPI,EPR or PPA object can be included in this message This document
33 Native IP TE failure This document
1:Local IP is in use
2:Remote IP is in use
3:Explicit Peer Route Error
4:EPR/BPI Peer Info mismatch
5:BPI/PPA Address Family mismatch
6:PPA/BPI Peer Info mismatch
¶
IANA is requested to create a new registry within the "Path Computation Element Protocol (PCEP) Numbers" and assign the code points for the following status codes of the BPI Object:¶
Status Code Meaning Reference
0 Reserved This document
1 BGP Session Established This document
2 BGP Session Establishment In Progress This document
3 BGP Session Disabled This document
4-255 Reserved This document
¶
IANA is requested to create a new registry within the "Path Computation Element Protocol (PCEP) Numbers" and assign the code points for the following status codes of the BPI Object:¶
Status Code Meaning Reference
0 Reserved This document
1 ASes does not match, BGP Session Failure This document
2 Peer IP can't be reached, BGP Session Failure This document
3-255 Reserved This document
¶
IANA is requested to create a new registry within the "Path Computation Element Protocol (PCEP) Numbers" and assign the code points for the following Flag field values of the BPI Object:¶
Bit Position Meaning Reference
0 T (IPnIP) bit This document
1-7 Reserved This document
¶
Dhruv Dhody has contributed to this document.¶
Thanks Mike Koldychev, Susan Hares, Siva Sivabalan, Adam Simpson for his valuable suggestions and comments.¶