draft-ietf-teas-pce-native-ip-15.txt   draft-ietf-teas-pce-native-ip-16.txt 
TEAS Working Group A. Wang TEAS Working Group A. Wang
Internet-Draft China Telecom Internet-Draft China Telecom
Intended status: Informational B. Khasanov Intended status: Informational B. Khasanov
Expires: June 12, 2021 Yandex LLC Expires: July 26, 2021 Yandex LLC
Q. Zhao Q. Zhao
Etheric Networks Etheric Networks
H. Chen H. Chen
Futurewei Futurewei
December 9, 2020 January 22, 2021
Path Computation Element (PCE) based Traffic Engineering (TE) in Native Path Computation Element (PCE) based Traffic Engineering (TE) in Native
IP Networks IP Networks
draft-ietf-teas-pce-native-ip-15 draft-ietf-teas-pce-native-ip-16
Abstract Abstract
This document defines an architecture for providing traffic This document defines an architecture for providing traffic
engineering in a native IP network using multiple BGP sessions and a engineering in a native IP network using multiple BGP sessions and a
Path Computation Element (PCE)-based central control mechanism. It Path Computation Element (PCE)-based central control mechanism. It
defines the Central Control Dynamic Routing (CCDR) procedures and defines the Central Control Dynamic Routing (CCDR) procedures and
identifies needed extensions for the Path Computation Element identifies needed extensions for the Path Computation Element
Communication Protocol (PCEP). Communication Protocol (PCEP).
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This Internet-Draft will expire on June 12, 2021. This Internet-Draft will expire on July 26, 2021.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. CCDR Architecture in Simple Topology . . . . . . . . . . . . 4 3. CCDR Architecture in Simple Topology . . . . . . . . . . . . 4
4. CCDR Architecture in Large Scale Topology . . . . . . . . . . 5 4. CCDR Architecture in Large Scale Topology . . . . . . . . . . 5
5. CCDR Multiple BGP Sessions Strategy . . . . . . . . . . . . . 6 5. CCDR Multiple BGP Sessions Strategy . . . . . . . . . . . . . 6
6. PCEP Extension for Critical Parameters Delivery . . . . . . . 8 6. PCEP Extension for Critical Parameters Delivery . . . . . . . 8
7. Deployment Consideration . . . . . . . . . . . . . . . . . . 9 7. Deployment Consideration . . . . . . . . . . . . . . . . . . 9
7.1. Scalability . . . . . . . . . . . . . . . . . . . . . . . 9 7.1. Scalability . . . . . . . . . . . . . . . . . . . . . . . 9
7.2. High Availability . . . . . . . . . . . . . . . . . . . . 9 7.2. High Availability . . . . . . . . . . . . . . . . . . . . 10
7.3. Incremental deployment . . . . . . . . . . . . . . . . . 10 7.3. Incremental deployment . . . . . . . . . . . . . . . . . 10
7.4. Loop Avoidance . . . . . . . . . . . . . . . . . . . . . 10 7.4. Loop Avoidance . . . . . . . . . . . . . . . . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 10 8. Security Considerations . . . . . . . . . . . . . . . . . . . 10
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 11 10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
11.1. Normative References . . . . . . . . . . . . . . . . . . 11 11.1. Normative References . . . . . . . . . . . . . . . . . . 11
11.2. Informative References . . . . . . . . . . . . . . . . . 12 11.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction 1. Introduction
[RFC8283], based on an extension of the PCE (Path Computation [RFC8283], based on an extension of the Path Computation Element
Element) architecture described in [RFC4655] , introduced a broader (PCE) architecture described in [RFC4655] , introduced a broader use
use applicability for a PCE as a central controller. PCEP (PCE applicability for a PCE as a central controller. PCEP Protocol
Protocol) continues to be used as the protocol between PCE and PCC (PCEP) continues to be used as the protocol between PCE and Path
(Path Computation Client). Building on that work, this document Computation Client (PCC). Building on that work, this document
describes a solution using a PCE for centralized control in a native describes a solution using a PCE for centralized control in a native
IP network to provide End-to-End (E2E) performance assurance and QoS IP network to provide End-to-End (E2E) performance assurance and QoS
for traffic. The solution combines the use of distributed routing for traffic. The solution combines the use of distributed routing
protocols and a centralized controller, referred to as Centralized protocols and a centralized controller, referred to as Centralized
Control Dynamic Routing (CCDR). Control Dynamic Routing (CCDR).
[RFC8735] describes the scenarios and simulation results for traffic [RFC8735] describes the scenarios and simulation results for traffic
engineering in a native IP network based on use of a CCDR engineering in a native IP network based on use of a CCDR
architecture. Per [RFC8735], the architecture for traffic architecture. Per [RFC8735], the architecture for traffic
engineering in a native IP network should meet the following engineering in a native IP network should meet the following
skipping to change at page 3, line 32 skipping to change at page 3, line 32
network status. No need for physical links resources reservations network status. No need for physical links resources reservations
to be done in advance. to be done in advance.
Building on the above documents, this document defines an Building on the above documents, this document defines an
architecture meeting these requirements by using a multiple BGP architecture meeting these requirements by using a multiple BGP
session strategy and a PCE as the centralized controller. The session strategy and a PCE as the centralized controller. The
architecture depends on the central control (PCE) element to compute architecture depends on the central control (PCE) element to compute
the optimal path, and utilizes the dynamic routing behavior of IGP/ the optimal path, and utilizes the dynamic routing behavior of IGP/
BGP protocols for forwarding the traffic. BGP protocols for forwarding the traffic.
The related PCEP extensions are provided in draft
[I-D.ietf-pce-pcep-extension-native-ip].
2. Terminology 2. Terminology
This document uses the following terms defined in [RFC5440]: This document uses the following terms defined in [RFC5440]:
o PCE: Path Computation Element o PCE: Path Computation Element
o PCEP: PCE Protocol o PCEP: PCE Protocol
o PCC: Path Computation Client o PCC: Path Computation Client
Other terms are defined in this document: Other terms are used in this document:
o CCDR: Central Control Dynamic Routing o CCDR: Central Control Dynamic Routing
o E2E: End to End o E2E: End to End
o ECMP: Equal-Cost Multipath o ECMP: Equal-Cost Multipath
o RR: Route Reflector o RR: Route Reflector
o SDN: Software Defined Network o SDN: Software Defined Network
3. CCDR Architecture in Simple Topology 3. CCDR Architecture in Simple Topology
Figure 1 illustrates the CCDR architecture for traffic engineering in Figure 1 illustrates the CCDR architecture for traffic engineering in
simple topology. The topology is comprises four devices which are a simple topology. The topology is composed of four devices which
SW1, SW2, R1, R2. There are multiple physical links between R1 and are SW1, SW2, R1, R2. There are multiple physical links between R1
R2. Traffic between prefix PF11(on SW1) and prefix PF21(on SW2) is and R2. Traffic between prefix PF11(on SW1) and prefix PF21(on SW2)
normal traffic, traffic between prefix PF12(on SW1) and prefix is normal traffic, traffic between prefix PF12(on SW1) and prefix
PF22(on SW2) is priority traffic that should be treated accordingly. PF22(on SW2) is priority traffic that should be treated accordingly.
+-----+ +-----+
+----------+ PCE +--------+ +----------+ PCE +--------+
| +-----+ | | +-----+ |
| | | |
| BGP Session 1(lo11/lo21)| | BGP Session 1(lo11/lo21)|
+-------------------------+ +-------------------------+
| | | |
| BGP Session 2(lo12/lo22)| | BGP Session 2(lo12/lo22)|
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In the Intra-AS scenario, IGP and BGP combined with a PCE are In the Intra-AS scenario, IGP and BGP combined with a PCE are
deployed between R1 and R2. In the inter-AS scenario, only the deployed between R1 and R2. In the inter-AS scenario, only the
native BGP protocol is deployed. The traffic between each address native BGP protocol is deployed. The traffic between each address
pair may change in real time and the corresponding source/destination pair may change in real time and the corresponding source/destination
addresses of the traffic may also change dynamically. addresses of the traffic may also change dynamically.
The key ideas of the CCDR architecture for this simple topology are The key ideas of the CCDR architecture for this simple topology are
the following: the following:
o Build two BGP sessions between R1 and R2, via the different o Build two BGP sessions between R1 and R2, via the different
loopback addresses on these routers. loopback addresses on these routers (lo11 and lo12 are the
loopback address of R1, lo21 and lo22 are the loopback address of
R2).
o Using the PCE, set the explicit peer route on R1 and R2 for BGP o Using the PCE, set the explicit peer route on R1 and R2 for BGP
next hop to different physical link addresses between R1 and R2. next hop to different physical link addresses between R1 and R2.
The explicit peer route can be set in the format of a static The explicit peer route can be set in the format of a static
route, which is different from the route learned from the IGP route, which is different from the route learned from the IGP
protocol. protocol.
o Send different prefixes via the established BGP sessions. For o Send different prefixes via the established BGP sessions. For
example, PF11/PF21 via the BGP session 1 and PF12/PF22 via the BGP example, send PF11/PF21 via the BGP session 1 and PF12/PF22 via
session 2. the BGP session 2.
After the above actions, the bi-directional traffic between the PF11 After the above actions, the bi-directional traffic between the PF11
and PF21, and the bi-directional traffic between PF12 and PF22 will and PF21, and the bi-directional traffic between PF12 and PF22 will
go through different physical links between R1 and R2. go through different physical links between R1 and R2.
If there is more traffic between PF12 and PF22 that needs assured If there is more traffic between PF12 and PF22 that needs assured
transport, one can add more physical links between R1 and R2 to reach transport, one can add more physical links between R1 and R2 to reach
the next hop for BGP session 2. In this case, the prefixes that are the next hop for BGP session 2. In this case, the prefixes that are
advertised by the BGP peers need not be changed. advertised by the BGP peers need not be changed.
If, for example, there is bi-directional priority traffic from If, for example, there is bi-directional priority traffic from
another address pair (for example prefix PF13/PF23), and the total another address pair (for example prefix PF13/PF23), and the total
volume of priority traffic does not exceed the capacity of the volume of priority traffic does not exceed the capacity of the
previously provisioned physical links, one need only advertise the previously provisioned physical links, one need only advertise the
newly added source/destination prefixes via the BGP session 2. The newly added source/destination prefixes via the BGP session 2. The
bi-directional traffic between PF13/PF23 will go through the same bi-directional traffic between PF13/PF23 will go through the same
assigned dedicated physical links as the traffic between PF12/PF22. assigned dedicated physical links as the traffic between PF12/PF22.
Such a decoupling philosophy of the IGP/BGP traffic link and the Such a decoupling philosophy of the IGP/BGP traffic link and the
physical link achieves a flexible control capability for the network physical link achieves a flexible control capability for the network
traffic, achieving the needed QoS assurance to meet the application's traffic, satisfying the needed QoS assurance to meet the
requirement. The router needs only support native IP and multiple application's requirement. The router needs only support native IP
BGP sessions setup via different loopback addresses. and multiple BGP sessions setup via different loopback addresses.
4. CCDR Architecture in Large Scale Topology 4. CCDR Architecture in Large Scale Topology
When the priority traffic spans a large scale network, such as that When the priority traffic spans a large-scale network, such as that
illustrated in Figure 2, the multiple BGP sessions cannot be illustrated in Figure 2, the multiple BGP sessions cannot be
established hop by hop, for example, the iBGP within one AS. established hop by hop within one AS. For such a scenario, we
propose using a Route Reflector (RR) [RFC4456] to achieve a similar
For such a scenario, we propose using a Route Reflector (RR) effect. Every edge router will establish two BGP sessions with the
[RFC4456] to achieve a similar effect. Every edge router will RR via different loopback addresses respectively. The other steps
establish two BGP sessions with the RR via different loopback for traffic differentiation are the same as that described in the
addresses respectively. The other steps for traffic differentiation CCDR architecture for the simple topology.
are the same as that described in the CCDR architecture for the
simple topology.
As shown in Figure 2, if we select R3 as the RR, every edge router(R1 As shown in Figure 2, if we select R3 as the RR, every edge router(R1
and R7 in this example) will build two BGP session with the RR. If and R7 in this example) will build two BGP session with the RR. If
the PCE selects the dedicated path as R1-R2-R4-R7, then the operator the PCE selects the dedicated path as R1-R2-R4-R7, then the operator
should set the explicit peer routes via PCEP protocol on these should set the explicit peer routes via PCEP protocol on these
routers respectively, pointing to the BGP next hop (loopback routers respectively, pointing to the BGP next hop (loopback
addresses of R1 and R7, which are used to send the prefix of the addresses of R1 and R7, which are used to send the prefix of the
priority traffic) to the selected forwarding address. priority traffic) to the selected forwarding address.
+-----+ +-----+
+----------------+ PCE +------------------+ +----------------+ PCE +------------------+
| +--+--+ | | +--+--+ |
| | | | | |
| | | | | |
| ++-+ | | +--+---+ |
+------------------+R3+-------------------+ +----------------+R3(RR)+-----------------+
PF12 | +--+ | PF22 PF12 | +--+---+ | PF22
PF11 | | PF21 PF11 | | PF21
+---+ ++-+ +--+ +--+ +-++ +---+ +---+ ++-+ +--+ +--+ +-++ +---+
|SW1+-------+R1+----------+R5+----------+R6+---------+R7+--------+SW2| |SW1+-------+R1+----------+R5+----------+R6+---------+R7+--------+SW2|
+---+ ++-+ +--+ +--+ +-++ +---+ +---+ ++-+ +--+ +--+ +-++ +---+
| | | |
| | | |
| +--+ +--+ | | +--+ +--+ |
+------------+R2+----------+R4+-----------+ +------------+R2+----------+R4+-----------+
+--+ +--+ +--+ +--+
Figure 2: CCDR architecture in large scale network Figure 2: CCDR architecture in large-scale network
5. CCDR Multiple BGP Sessions Strategy 5. CCDR Multiple BGP Sessions Strategy
Generally, different applications may require different QoS criteria, Generally, different applications may require different QoS criteria,
which may include: which may include:
o Traffic that requires low latency and is not sensitive to packet o Traffic that requires low latency and is not sensitive to packet
loss. loss.
o Traffic that requires low packet loss and can endure higher o Traffic that requires low packet loss and can endure higher
skipping to change at page 7, line 4 skipping to change at page 7, line 4
| 1 | Low | Normal | Don't care | | 1 | Low | Normal | Don't care |
+----------------+-------------+---------------+-----------------+ +----------------+-------------+---------------+-----------------+
| 2 | Normal | Low | Don't care | | 2 | Normal | Low | Don't care |
+----------------+-------------+---------------+-----------------+ +----------------+-------------+---------------+-----------------+
| 3 | Normal | Normal | Low | | 3 | Normal | Normal | Low |
+----------------+-------------+---------------+-----------------+ +----------------+-------------+---------------+-----------------+
Table 1. Traffic Requirement Criteria Table 1. Traffic Requirement Criteria
For Prefix Set No.1, we can select the shortest distance path to For Prefix Set No.1, we can select the shortest distance path to
carry the traffic; for Prefix Set No.2, we can select the path that carry the traffic; for Prefix Set No.2, we can select the path that
has end to end under loaded links; for Prefix Set No.3, we can let has end to end under-loaded links; for Prefix Set No.3, we can let
traffic pass over a determined single path, as no Equal Cost traffic pass over a determined single path, as no Equal Cost
Multipath (ECMP) distribution on the parallel links is desired. Multipath (ECMP) distribution on the parallel links is desired.
It is almost impossible to provide an End-to-End (E2E) path It is almost impossible to provide an End-to-End (E2E) path
efficiently with latency, jitter, and packet loss constraints to meet efficiently with latency, jitter, and packet loss constraints to meet
the above requirements in a large scale IP-based network only using a the above requirements in a large-scale IP-based network only using a
distributed routing protocol, but these requirements can be met with distributed routing protocol, but these requirements can be met with
the assistance of PCE, as that described in [RFC4655] and [RFC8283]. the assistance of PCE, as that described in [RFC4655] and [RFC8283].
The PCE will have the overall network view, ability to collect the The PCE will have the overall network view, ability to collect the
real-time network topology, and the network performance information real-time network topology, and the network performance information
about the underlying network. The PCE can select the appropriate about the underlying network. The PCE can select the appropriate
path to meet the various network performance requirements for path to meet the various network performance requirements for
different traffic. different traffic.
The architecture to implement the CCDR Multiple BGP sessions strategy The architecture to implement the CCDR Multiple BGP sessions strategy
is as the follows: is as follows:
The PCE will be responsible for the optimal path computation for the The PCE will be responsible for the optimal path computation for the
different priority classes of traffic: different priority classes of traffic:
o PCE collects topology information via BGP-LS [RFC7752] and link o PCE collects topology information via BGP-LS [RFC7752] and link
utilization information via the existing Network Monitoring System utilization information via the existing Network Monitoring System
(NMS) from the underlying network. (NMS) from the underlying network.
o PCE calculates the appropriate path based upon the application's o PCE calculates the appropriate path based upon the application's
requirements, and sends the key parameters to edge/RR routers(R1, requirements, and sends the key parameters to edge/RR routers(R1,
R7 and R3 in Figure 3) to establish multiple BGP sessions. The R7 and R3 in Figure 3) to establish multiple BGP sessions. The
loopback addresses used for the BGP sessions should be planned in loopback addresses used for the BGP sessions should be planned in
advance and distributed in the domain. advance and distributed in the domain.
o PCE sends the route information to the routers (R1,R2,R4,R7 in o PCE sends the route information to the routers (R1,R2,R4,R7 in
Figure 3) on the forwarding path via PCEP Figure 3) on the forwarding path via PCEP, to build the path to
[I-D.ietf-pce-pcep-extension-native-ip], to build the path to the the BGP next-hop of the advertised prefixes. The path to these
BGP next-hop of the advertised prefixes. BGP next-hop will also be learned via the IGP protocol, but the
route from the PCEP has the higher preference. Such design can
assure the IGP path to the BGP next-hop can be used to protect the
path assigned by PCE.
o PCE sends the prefixes information to the PCC for advertising o PCE sends the prefixes information to the PCC(edge routers that
different prefixes via the specified BGP session. have established BGP sessions) for advertising different prefixes
via the specified BGP session.
o If the priority traffic prefixes were changed but the total volume o The priority traffic may share some links or nodes, if path the
of priority traffic does not exceed the physical capacity of the shared links or nodes can meet the requirement of application.
previous E2E path, the PCE needs only change the prefixed When the priority traffic prefixes were changed but the total
volume of priority traffic does not exceed the physical capacity
of the previous E2E path, the PCE needs only change the prefixed
advertised via the edge routers (R1,R7 in Figure 3). advertised via the edge routers (R1,R7 in Figure 3).
o If the volume of priority traffic exceeds the capacity of the o If the volume of priority traffic exceeds the capacity of the
previous calculated path, the PCE can recalculate and add the previous calculated path, the PCE can recalculate and add the
appropriate paths to accommodate the exceeding traffic. After appropriate paths to accommodate the exceeding traffic. After
that, the PCE needs to update the on-path routers to build the that, the PCE needs to update the on-path routers to build the
forwarding path hop by hop. forwarding path hop by hop.
+------------+ +------------+
| Application| | Application|
+------+-----+ +------+-----+
| |
+--------+---------+ +--------+---------+
+----------+SDN Controller/PCE+-----------+ +----------+SDN Controller/PCE+-----------+
| +--------^---------+ | | +--------^---------+ |
| | | | | |
| | | | | |
PCEP | BGP-LS|PCEP | PCEP PCEP | BGP-LS|PCEP | PCEP
| | | | | |
| +v-+ | | +--v---+ |
+------------------+R3+-------------------+ +----------------+R3(RR)+-----------------+
PF12 | +--+ | PF22 PF12 | +------+ | PF22
PF11 | | PF21 PF11 | | PF21
+---+ +v-+ +--+ +--+ +-v+ +---+ +---+ +v-+ +--+ +--+ +-v+ +---+
|SW1+-------+R1+----------+R5+----------+R6+---------+R7+--------+SW2| |SW1+-------+R1+----------+R5+----------+R6+---------+R7+--------+SW2|
+---+ ++-+ +--+ +--+ +-++ +---+ +---+ ++-+ +--+ +--+ +-++ +---+
| | | |
| | | |
| +--+ +--+ | | +--+ +--+ |
+------------+R2+----------+R4+-----------+ +------------+R2+----------+R4+-----------+
+--+ +--+ +--+ +--+
skipping to change at page 9, line 18 skipping to change at page 9, line 24
PCE [RFC8231] and PCECC [RFC8283] mechanism. PCE [RFC8231] and PCECC [RFC8283] mechanism.
Regarding the BGP session, it is not different from that configured Regarding the BGP session, it is not different from that configured
manually or via NETCONF/YANG. Different BGP sessions are used mainly manually or via NETCONF/YANG. Different BGP sessions are used mainly
for the clarification of the network prefixes, which can be for the clarification of the network prefixes, which can be
differentiated via the different BGP nexthop. Based on this differentiated via the different BGP nexthop. Based on this
strategy, if we manipulate the path to the BGP nexthop, then the path strategy, if we manipulate the path to the BGP nexthop, then the path
to the prefixes that were advertised with the BGP sessions will be to the prefixes that were advertised with the BGP sessions will be
changed accordingly. Details of communications between PCEP and BGP changed accordingly. Details of communications between PCEP and BGP
subsystems in the router's control plane are out of scope of this subsystems in the router's control plane are out of scope of this
draft and will be described in a separate document draft.
[I-D.ietf-pce-pcep-extension-native-ip] .
7. Deployment Consideration 7. Deployment Consideration
7.1. Scalability 7.1. Scalability
In the CCDR architecture, only the edge routers that connect with the In the CCDR architecture, only the edge routers that connect with the
PCE are responsible for the prefixes advertisement via the multiple PCE are responsible for the prefixes advertisement via the multiple
BGP sessions deployment. The route information for these prefixes BGP sessions deployment. The route information for these prefixes
within the on-path routers is distributed via the BGP protocol. within the on-path routers is distributed via the BGP protocol.
For multiple domain deployment, the PCE, or the pool of PCEs For multiple domain deployment, the PCE, or the pool of PCEs
responsible for these domains, needs only to control the edge router responsible for these domains, needs only to control the edge router
to build the multiple EBGP sessions; all other procedures are the to build the multiple EBGP sessions; all other procedures are the
same as within one domain. same as within one domain.
Unlike the solution from BGP Flowspec[I-D.ietf-idr-rfc5575bis], the The on-path router needs only to keep the specific policy routes for
on-path router needs only to keep the specific policy routes for the the BGP next-hop of the differentiated prefixes, not the specific
BGP next-hop of the differentiate prefixes, not the specific routes routes to the prefixes themselves. This lessens the burden of the
to the prefixes themselves. This lessens the burden of the table table size of policy based routes for the on-path routers; and has
size of policy based routes for the on-path routers; and has more more expandability compared with BGP flowspec or Openflow solutions.
expandability compared with BGP flowspec or Openflow solutions. For For example, if we want to differentiate 1000 prefixes from the
example, if we want to differentiate 1000 prefixes from the normal normal traffic, CCDR needs only one explicit peer route in every on-
traffic, CCDR needs only one explicit peer route in every on-path path router, whereas the BGP flowspec or Openflow solutions need 1000
router, whereas the BGP flowspec or Openflow solutions need 1000
policy routes on them. policy routes on them.
7.2. High Availability 7.2. High Availability
The CCDR architecture is based on the use of the native IP protocol. The CCDR architecture is based on the use of the native IP protocol.
If the PCE fails, the forwarding plane will not be impacted, as the If the PCE fails, the forwarding plane will not be impacted, as the
BGP sessions between all the devices will not flap and the forwarding BGP sessions between all the devices will not flap and the forwarding
table remains unchanged. table remains unchanged.
If one node on the optimal path fails, the priority traffic will fall If one node on the optimal path fails, the priority traffic will fall
over to the best-effort forwarding path. One can even design several over to the best-effort forwarding path. One can even design several
paths to load balance/hot-standby the priority traffic to meet a path paths to load balance/hot-standby the priority traffic to meet a path
failure situation. failure situation.
For ensuring high availability of a PCE/SDN-controllers architecture, For ensuring high availability of a PCE/SDN-controllers architecture,
an operator should rely on existing high availability solutions for an operator should rely on existing high availability solutions for
SDN controllers, such as clustering technology and deployment. SDN controllers, such as clustering technology and deployment.
7.3. Incremental deployment 7.3. Incremental deployment
Not every router within the network needs to support the PCEP Not every router within the network needs to support the necessary
extension defined in [I-D.ietf-pce-pcep-extension-native-ip] PCEP extension. For such situations, routers on the edge of a domain
simultaneously. can be upgraded first, and then the traffic can be prioritized
between different domains. Within each domain, the traffic will be
For such situations, routers on the edge of a domain can be upgraded forwarded along the best-effort path. A service provider can
first, and then the traffic can be prioritized between different selectively upgrade the routers on each domain in sequence.
domains. Within each domain, the traffic will be forwarded along the
best-effort path. A service provider can selectively upgrade the
routers on each domain in sequence.
7.4. Loop Avoidance 7.4. Loop Avoidance
A PCE needs to assure calculation of the E2E path based on the status A PCE needs to assure calculation of the E2E path based on the status
of network and the service requirements in real-time. of network and the service requirements in real-time.
The PCE needs to consider the explicit route deployment order (for The PCE needs to consider the explicit route deployment order (for
example, from tail router to head router) to eliminate any possible example, from tail router to head router) to eliminate any possible
transient traffic loop. transient traffic loop.
8. Security Considerations 8. Security Considerations
The setup of BGP sessions, prefix advertisement, and explicit peer The setup of BGP sessions, prefix advertisement, and explicit peer
route establishment are all controlled by the PCE. See [RFC7454] for route establishment are all controlled by the PCE. See [RFC4271] and
BGP security consideration. To prevent a bogus PCE sending harmful [RFC4272] for BGP security considerations. Security consideration
messages to the network nodes, the network devices should part in [RFC5440] and [RFC8231] should be considered. To prevent a
authenticate the validity of the PCE and ensure a secure bogus PCE sending harmful messages to the network nodes, the network
communication channel between them. Mechanisms described in devices should authenticate the validity of the PCE and ensure a
secure communication channel between them. Mechanisms described in
[RFC8253] should be used. [RFC8253] should be used.
The CCDR architecture does not require changes to the forwarding The CCDR architecture does not require changes to the forwarding
behavior of the underlay devices. There will no additional security behavior of the underlay devices. There are no additional security
impacts on these devices. impacts on these devices.
9. IANA Considerations 9. IANA Considerations
This document does not require any IANA actions. This document does not require any IANA actions.
10. Acknowledgement 10. Acknowledgement
The author would like to thank Deborah Brungard, Adrian Farrel, The author would like to thank Deborah Brungard, Adrian Farrel,
Vishnu Beeram, Lou Berger, Dhruv Dhody, Raghavendra Mallya , Mike Vishnu Beeram, Lou Berger, Dhruv Dhody, Raghavendra Mallya , Mike
Koldychev, Haomian Zheng, Penghui Mi, Shaofu Peng, Donald Eastlake Koldychev, Haomian Zheng, Penghui Mi, Shaofu Peng, Donald Eastlake,
and Jessica Chen for their supports and comments on this draft. Alvaro Retana, Martin Duke, Magnus Westerlund, Benjamin Kaduk, Roman
Danyliw, Eric Vyncke, Murray Kucherawy, Erik Kline and Jessica Chen
for their supports and comments on this draft.
11. References 11. References
11.1. Normative References 11.1. Normative References
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006,
<https://www.rfc-editor.org/info/rfc4272>.
[RFC4456] Bates, T., Chen, E., and R. Chandra, "BGP Route [RFC4456] Bates, T., Chen, E., and R. Chandra, "BGP Route
Reflection: An Alternative to Full Mesh Internal BGP Reflection: An Alternative to Full Mesh Internal BGP
(IBGP)", RFC 4456, DOI 10.17487/RFC4456, April 2006, (IBGP)", RFC 4456, DOI 10.17487/RFC4456, April 2006,
<https://www.rfc-editor.org/info/rfc4456>. <https://www.rfc-editor.org/info/rfc4456>.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440, Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009, DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>. <https://www.rfc-editor.org/info/rfc5440>.
[RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations
and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454,
February 2015, <https://www.rfc-editor.org/info/rfc7454>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752, Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016, DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>. <https://www.rfc-editor.org/info/rfc7752>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP) Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231, Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017, DOI 10.17487/RFC8231, September 2017,
skipping to change at page 12, line 17 skipping to change at page 12, line 17
Path Computation Element Communication Protocol (PCEP)", Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017, RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>. <https://www.rfc-editor.org/info/rfc8253>.
[RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An [RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An
Architecture for Use of PCE and the PCE Communication Architecture for Use of PCE and the PCE Communication
Protocol (PCEP) in a Network with Central Control", Protocol (PCEP) in a Network with Central Control",
RFC 8283, DOI 10.17487/RFC8283, December 2017, RFC 8283, DOI 10.17487/RFC8283, December 2017,
<https://www.rfc-editor.org/info/rfc8283>. <https://www.rfc-editor.org/info/rfc8283>.
11.2. Informative References
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC8735] Wang, A., Huang, X., Kou, C., Li, Z., and P. Mi, [RFC8735] Wang, A., Huang, X., Kou, C., Li, Z., and P. Mi,
"Scenarios and Simulation Results of PCE in a Native IP "Scenarios and Simulation Results of PCE in a Native IP
Network", RFC 8735, DOI 10.17487/RFC8735, February 2020, Network", RFC 8735, DOI 10.17487/RFC8735, February 2020,
<https://www.rfc-editor.org/info/rfc8735>. <https://www.rfc-editor.org/info/rfc8735>.
11.2. Informative References
[I-D.ietf-idr-rfc5575bis]
Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules",
draft-ietf-idr-rfc5575bis-27 (work in progress), October
2020.
[I-D.ietf-pce-pcep-extension-native-ip]
Wang, A., Khasanov, B., Fang, S., Tan, R., and C. Zhu,
"PCEP Extension for Native IP Network", draft-ietf-pce-
pcep-extension-native-ip-09 (work in progress), October
2020.
Authors' Addresses Authors' Addresses
Aijun Wang Aijun Wang
China Telecom China Telecom
Beiqijia Town, Changping District Beiqijia Town, Changping District
Beijing 102209 Beijing 102209
China China
Email: wangaj3@chinatelecom.cn Email: wangaj3@chinatelecom.cn
Boris Khasanov Boris Khasanov
Yandex LLC Yandex LLC
Ulitsa Lva Tolstogo 16 Ulitsa Lva Tolstogo 16
Moscow Moscow
Russia Russia
Email: bhassanov@yahoo.com Email: bhassanov@yahoo.com
Quintin Zhao Quintin Zhao
Etheric Networks Etheric Networks
1009 S CLAREMONT ST 1009 S CLAREMONT ST
SAN MATEO, CA 94402 SAN MATEO, CA 94402
USA USA
Email: qzhao@ethericnetworks.com Email: qzhao@ethericnetworks.com
Huaimo Chen Huaimo Chen
Futurewei Futurewei
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