wdiff draft-ietf-teas-pce-native-ip-02.txt draft-ietf-teas-pce-native-ip-03.txt

TEAS Working Group A. Wang
Internet-Draft China Telecom
Intended status: Experimental Q. Zhao
Expires: April 24, October 18, 2019 B. Khasanov
H. Chen
Huawei Technologies
R. Mallya
Juniper Networks
October 21, 2018
April 16, 2019

PCE in Native IP Network
draft-ietf-teas-pce-native-ip-02
draft-ietf-teas-pce-native-ip-03

Abstract

This document defines the CCDR framework for traffic engineering within
native IP network, using Dual/Multi-BGP session sessions strategy and
PCE-based PCE-
based central control architecture. The proposed central mode
control framework conforms to the concept that defined in [RFC8283].
The scenario and simulation results of CCDR traffic engineering in Native
IP network is described in draft [I-D.ietf-teas-native-ip-scenarios].

Status of This Memo

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provisions of BCP 78 and BCP 79.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. Dual-BGP CCDR Framework for in Simple Topology . . . . . . . . . . . . . . 3
4. Dual-BGP CCDR Framework in Large Scale Topology . . . . . . . . . . . 4
5. CCDR Multi-BGP Strategy for Extended Traffic Differentiation . . . . . . . . . . . . . . . . . . . 5
6. CCDR Procedures Framework for Multi-BGP Strategy . . . . . . . . . . . . 6
7. PCEP Extension for Key Parameters Delivery . . . . . . . . . 7
8. Deployment Consideration . . . . . . . . . . . . . . . . . . 7 8
8.1. Scalability . . . . . . . . . . . . . . . . . . . . . . . 8
8.2. High Availability . . . . . . . . . . . . . . . . . . . . 8
8.3. Incremental deployment . . . . . . . . . . . . . . . . . 8
9. Security Considerations . . . . . . . . . . . . . . . . . . . 8 9
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9
12. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 9
13. Normative References . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10

1. Introduction

Draft [I-D.ietf-teas-native-ip-scenarios] describes the scenario and scenarios,
simulation results and suggestions for traffic engineering in native
IP network. In
summary, To meet the requirements of various scenarios, the
solution for traffic engineering in native IP network are should have the followings:
followings criteria:

o No complex MPLS signaling procedure. procedures.

o End to End traffic assurance, determined QoS behavior.

o Identical deployment method for intra- intra-domain and inter- domain. inter-domain.

o No influence to existing router forward behavior. forwarding behavior of the router.

o Can utilize exploit the power of centrally control(PCE) control (PCE) and flexibility/
robustness of distributed control protocol.

o Coping with the differentiation requirements for large amount
traffic and prefixes.

o Flexible deployment and automation control.

This document defines the framework for traffic engineering within
native IP network, using Dual/Multi-BGP session strategy, to meet the
above requirements in dynamical and central centrally control mode. mode(Centrally
Control Dynamic Routing, abbreviated as CCDR ). The related PCEP
protocol extensions to transfer the key parameters between PCE and
the underlying network devices(PCC) are provided in draft
[I-D.ietf-pce-pcep-extension-native-ip].

2. Conventions used in this document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119] .

3. Dual-BGP CCDR Framework for in Simple Topology

Dual-BGP

Fig.1 illustrates the CCDR framework for traffic engineering in
simple topology. The topology is illustrated in Fig.1, which
is comprised by four devices which are
SW1, SW2, R1, R2. There are multiple physical links between R1 and
R2. Traffic between IP11 IP11(on SW1) and IP21 IP21(on SW2) is normal traffic,
traffic between IP12 IP12(on SW1) and IP22 IP22(on SW2) is priority traffic
that should be treated differently.

Only native IGP/BGP protocol is deployed between R1 and R2. The
traffic between each address pair may change timely in real time and the
corresponding source/destination addresses of the traffic may also
change dynamically.

The key ideas of the Dual-BGP CCDR framework for this simple topology are the
followings:

o Build two BGP sessions between R1 and R2, via the different
loopback address lo0, lo1 on these routers.

o Send different prefixes via the two established BGP sessions. (For For
example, IP11/IP21 via the BGP pair 1 and IP12/IP22 via the BGP
pair 2). 2.

o Set the explicit peer route on R1 and R2 respectively for BGP next
hop of lo0, lo1 to different physical link address between R1 and
R2.

The

After the above actions, the traffic between the IP11 and IP21, and
the traffic between IP12 and IP22 will go through different physical
links between R1 and R2, each type set of traffic occupy occupies different
dedicated physical links.

If there is more traffic between IP12 and IP22 that needs to be
assured , one can add more physical links between R1 and R2 to reach
the loopback address lo1(also the next hop for BGP Peer pair2). In
this cases the prefixes that advertised by two the BGP peers need not be
changed.

If, for example, there is traffic from another address pair that
needs to be assured (for example IP13/IP23), and the total volume of
assured traffic does not exceed the capacity of the previous
appointed physical links, one need only to advertise the newly added
source/destination prefixes via the BGP peer pair2. The traffic
between IP13/IP23 will go through the assigned dedicated physical
links as the traffic between IP12/IP22.

Such decouple philosophy gives network operator flexible control
ability on the network traffic, achieve the determined QoS assurance
effect to meet the application's requirement. No complex MPLS signal
procedures is introduced, the router need needs only support native IP
protocol.

Fig.1 Design Philosophy for Dual-BGP Framework CCDR framework in simple topology

4. Dual-BGP CCDR Framework in Large Scale Topology

When the assured traffic spans across one the large scale network, as
that illustrated in Fig.2, the dual BGP Dual-BGP sessions cannot be
established hop by hop hop, especially for the iBGP within one AS.

For such scenario, we should consider to use the Route Reflector (RR)
to achieve the similar Dual-BGP effect, select one router which
performs the role of RR (for example R3 in Fig.2), every other effect. Every edge router will establish two
BGP peer sessions with the RR, using their RR via different loopback addresses
respectively. The other two steps for traffic differentiation are same
as that described in the Dual-BGP CCDR framework for simple topology usage case.

For the example topology.

As shown in Fig.2, if we select the R1-R2-R4-R7 R3 as the RR, every edge router(R1
and R7 in this example) will build two BGP session with the RR. If
the PCE calculates select the dedicated path, path as R1-R2-R4-R7, then we the
operator should set the explicit peer routes on these routers
respectively, pointing to the BGP next hop (loopback addresses of R1
and R7, which are used to send the prefix of the assured traffic) to
the actual address of the physical link.

+------------R3--------------+ selected forwarding address.

+----------R3(RR)------------+
| |
SW1-------R1-------R5---------R6-------R7--------SW2
| | | |
+-------R2---------R4--------+

Fig.2 Dual-BGP Framework for Large Scale Network CCDR framework in large scale network

5. CCDR Multi-BGP Strategy for Extended Traffic Differentiation

In general situation, several additional traffic differentiation
criteria exist, including: different applications may require different
QoS criteria, which may include:

o Traffic that requires low latency links and is not sensitive to packet
loss.

o Traffic that requires low packet loss but and can endure higher
latency.

o Traffic that requires lowest jitter path. low jitter.

These different traffic requirements can be summarized in the
following table:

+----------+-------------+---------------+-----------------+
| Flow No. | Latency | Packet Loss | Jitter |
+----------+-------------+---------------+-----------------+
| 1 | Low | Normal | Don't care |
+----------+-------------+---------------+-----------------+
| 2 | Normal | Low | Dont't care |
+----------+-------------+---------------+-----------------+
| 3 | Normal | Normal | Low |
+----------+-------------+---------------+-----------------+
Table 1. Traffic Requirement Criteria

For Flow No.1, we can select the shortest distance path to carry the
traffic; for Flow No.2, we can select the idle path that is comprised by
underloading links to form its from end to end path; end; for Flow No.3, we can let all
assured traffic pass one the determined single path, no ECMP distribution
on the parallel links is required. desired.

It is almost impossible to provide an end-to-end (E2E) path with
latency, jitter, packet loss constraints to meet the above
requirements in large scale IP-based network via the distributed
routing protocol, but these requirements can be solved using with the CCDR
framework since
assistance of PCE controller, because the PCE has the overall network
view, can collect real network topology and network performance
information about the underlying network, select the appropriate path
to meet various network performance requirements of different traffic.
traffics.

6. CCDR Procedures Framework for Multi-BGP Strategy

The procedures framework to implement the CCDR Multi-BGP strategy are the
followings:

o PCE gets topology and link utilization information from the
underlying network, calculates the appropriate link path upon
application's requirements..

o PCE sends the key parameters to edge/RR routers(R1, R7 and R3 in
Fig.3) to build establish multi-BGP peer relations sessions and advertises
different prefixes via them.

o PCE sends the route information to the routers (R1,R2,R4,R7 in
Fig.3) on forwarding path via PCEP, to build the path to the BGP
next-hop of the advertised prefixes.

o If the assured traffic prefixes were changed but the total volume
of assured traffic does not exceed the physical capacity of the
previous end-to-end path, then PCE needs only change the related
information on prefixed
advertised via the edge routers (R1,R7 in Fig.3).

o If the volume of assured traffic exceeds the capacity of previous
calculated path, PCE must can recalculate the appropriate path paths to
accommodate the exceeding traffic via some new end-to-end physical
links. traffic. After that that, PCE needs to
update on-path routers to build
such the forwarding path hop by hop.

+----+
***********+ PCE+*************
* +--*-+ *
* / * \ *
* * *
PCEP* BGP-LS/SNMP *PCEP
* * *
* * \ * /
\ * / * \ */
\*/-----------R3--------------*
| |
| |
SW1-------R1-------R5---------R6-------R7--------SW2
| | | |
| | | |
+-------R2---------R4--------+

Fig.3 PCE based CCDR framework for Multi-BGP deployment

7. PCEP Extension for Key Parameters Delivery

The PCEP protocol needs to be extended to transfer the following key
parameters:

o Peer addresses pair that is used to build the BGP peer address session

o Advertised prefixes and advertised prefixes. their associated BGP session.

o Explicit route information to BGP next hop of advertised prefixes.

Once the router receives such information, it should establish the
BGP session with the peer appointed in the PCEP message, advertise
the prefixes that contained in the corresponding PCEP message, and
build the end to end dedicated path hop by hop.

Details of communications between PCEP and BGP subsystems in router's
control plane are out of scope of this draft and will be described in
separate draft [I-D.ietf-pce-pcep-extension-native-ip] .

The reason that we selected PCEP as the southbound protocol instead
of OpenFlow, is that PCEP is suitable for the changes in control
plane of the network devices, there while OpenFlow dramatically changes the
forwarding plane. We also think that the level of centralization
that requires by OpenFlow is hardly achievable in many today's SP
networks so hybrid BGP+PCEP approach looks much more interesting.

8. Deployment Consideration

8.1. Scalability

In CCDR framework, PCE needs only to influence the edge routers for the
prefixes differentiation advertisement via the multi-BGP deployment. The route
information for these prefixes within the on-path routers were
distributed via the BGP protocol.

Unlike the solution from BGP Flowspec, the on-path router need only
keep the specific policy routes to the BGP next-hop of the
differentiate prefixes, not the specific routes to the prefixes
themselves. This can lessen the burden from the table size of policy
based routes for the on-path routers, and has more scalabilities expandability when
comparing with the solution from BGP flowspec or Openflow.

8.2. High Availability

The CCDR framework is based on the distributed IP protocol. If the
PCE failed, the forwarding plane will not be impacted, as the BGP
session between all devices will not flap, and the forwarding table
will remain the same. unchaned.

If one node on the optimal path is failed, the assurance traffic will
fall over to the best-effort forwarding path. One can even design
several assurance paths to load balance/hot
standby balance/hot-standby the assurance
traffic to meet the path failure situation, as done in MPLS FRR.

For high availability of PCE/SDN-controller, operator should rely on
existing HA solutions for SDN controller, such as clustering
technology and deployment.

8.3. Incremental deployment

Not every router within the network support will support the PCEP extension
that defined in [I-D.ietf-pce-pcep-extension-native-ip]
simultaneously.

For such situations, router on the edge of domain can be upgraded
first, and then the traffic can be assured between different domains.
Within each domain, the traffic will be forwarded along the best-effort best-
effort path. Service provider can selectively upgrade the routers on
each domain in sequence.

9. Security Considerations

Solution described in this draft puts more requirements on the
function of PCE and its communication with the underlay devices.

The PCE should have the capability to calculate the loop-free e2e end to
end path upon the status of network condition and the service
requirements in real time.

The PCE need also to consider the router order during explicit route deployment order (for
example, from tail router to head router) to eliminate the possible
transient traffic loop.

This solution does not require

CCDR framework described in this draft puts more requirements on the change
function of forward behavior on PCE and its communication with the underlay devices, then there will no additional security impact for
the devices.

When deploy the solution on network, service
Service provider should also consider more on the protection of SDN
controller and their communication with the underlay devices, which
is described in document [RFC5440] and [RFC8253]

CCDR framework does not require the change of forward behavior on the
underlay devices, then there will no additional security impact on
the devices.

10. IANA Considerations

This document does not require any IANA actions.

11. Contributors

Penghui Mi and Shaofu Peng contribute the contents of this draft.

12. Acknowledgement

The author would like to thank Deborah Brungard, Adrian Farrel,
Huaimo Chen, Vishnu Beeram, Lou Berger, Dhruv Dhody and Jessica Chen
for their supports and comments on this draft.

13. Normative References

[I-D.ietf-pce-pcep-extension-native-ip]
Wang, A., Khasanov, B., Cheruathur, S., and C. Zhu, C., and S.
Fang, "PCEP Extension for Native IP Network", draft-ietf-pce-pcep-
extension-native-ip-01 draft-ietf-
pce-pcep-extension-native-ip-03 (work in progress), June 2018. March
2019.

[I-D.ietf-teas-native-ip-scenarios]
Wang, A., Huang, X., Qou, C., Li, Z., Huang, L., and P. Mi, "CCDR Scenario,
"Scenario, Simulation and Suggestion", draft-
ietf-teas-native-ip-scenarios-01 Suggestion of PCE in Native IP
Network", draft-ietf-teas-native-ip-scenarios-02 (work in
progress), June October 2018.

[I-D.ietf-teas-pcecc-use-cases]
Zhao, Q., Li, Z., Khasanov, B., Dhody, D., Ke, Z., Fang,
L., Zhou, C., Communications, T., Rachitskiy, A., and A.
Gulida, "The Use Cases for Path Computation Element (PCE)
as a Central Controller (PCECC).", draft-ietf-teas-pcecc-
use-cases-02
use-cases-03 (work in progress), October 2018. March 2019.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.

[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.

[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>.

[RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An
Architecture for Use of PCE and the PCE Communication
Protocol (PCEP) in a Network with Central Control",
RFC 8283, DOI 10.17487/RFC8283, December 2017,
<https://www.rfc-editor.org/info/rfc8283>.

Authors' Addresses

Aijun Wang
China Telecom
Beiqijia Town, Changping District
Beijing 102209
China

Email: wangaj.bri@chinatelecom.cn

Quintin Zhao
Huawei Technologies
125 Nagog Technology Park
Acton, MA 01719
USA

Email: quintin.zhao@huawei.com
Boris Khasanov
Huawei Technologies
Moskovskiy Prospekt 97A
St.Petersburg 196084
Russia

Email: khasanov.boris@huawei.com

Huaimo Chen
Huawei Technologies
Boston, MA
USA

Email: huaimo.chen@huawei.com

Raghavendra Mallya
Juniper Networks
1133 Innovation Way
Sunnyvale, California 94089
USA

Email: rmallya@juniper.net