Network Working Group W. J
Internet-Draft Y. Liu
Intended status: Informational China Mobile
Expires: January 13, 2022 S. Chen
Huawei
July 12, 2021
Traffic Steering using BGP Flowspec with SRv6 Policy
draft-jiang-idr-ts-flowspec-srv6-policy-04
Abstract
BGP Flow Specification (FlowSpec) [RFC8955] has been proposed to
distribute BGP FlowSpec NLRI to FlowSpec clients to mitigate
(distributed) denial-of-service attacks, and to provide traffic
filtering in the context of a BGP/MPLS VPN service. Recently,
traffic steering applications in the context of SRv6 using FlowSpec
aslo attract attention. This document introduces the usage of BGP
FlowSpec to steer packets into an SRv6 Policy.
Requirements Language
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].
Status of This Memo
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 January 13, 2022.
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Copyright Notice
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definitions and Acronyms . . . . . . . . . . . . . . . . . . 3
3. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Application Example . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Segment Routing IPv6 (SRv6) is a protocol designed to forward IPv6
data packets on a network using the source routing model. SRv6
enables the ingress to add a segment routing header (SRH) [RFC8754]
to an IPv6 packet and push an explicit IPv6 address stack into the
SRH. After receiving the packet, each transit node updates the IPv6
destination IP address in the packet and segment list to implement
hop-by-hop forwarding.
SRv6 Policy [I-D.ietf-spring-segment-routing-policy] is a tunneling
technology developed based on SRv6. An SRv6 Policy is a set of
candidate paths consisting of one or more segment lists, that is,
segment ID (SID) lists. Each SID list identifies an end-to-end path
from the source to the destination, instructing a device to forward
traffic through the path rather than the shortest path computed using
an IGP. The header of a packet steered into an SRv6 Policy is
augmented with an ordered list of segments associated with that SRv6
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Policy, so that other devices on the network can execute the
instructions encapsulated into the list.
The headend of an SRv6 Policy may learn multiple candidate paths for
an SRv6 Policy. Candidate paths may be learned via a number of
different mechanisms, e.g., CLI, NetConf, PCEP, or BGP.
[RFC8955] defines the flow specification (FlowSpec) that allows to
convey flow specifications and traffic Action/Rules associated (rate-
limiting, redirect, remark ...). BGP Flow specifications are encoded
within the MP_REACH_NLRI and MP_UNREACH_NLRI attributes. Rules
(Actions associated) are encoded in Extended Community attribute.
The BGP Flow Specification function allows BGP Flow Specification
routes that carry traffic policies to be transmitted to BGP Flow
Specification peers to steer traffic.
This document proposes BGP flow specification usage that are used to
steer data flow into an SRv6 Policy as well as to indicate Tailend
function.
2. Definitions and Acronyms
o FlowSpec: Flow Specification
o SR: Segment Routing
o SRv6: IPv6 Segment Routing
o SID: Segment Identifier
o SRH: Segment Routing Header
o TE: Traffic Engineering
3. Operations
An SRv6 Policy [I-D.ietf-spring-segment-routing-policy] is identified
through the tuple <headend, color, endpoint>. In the context of a
specific headend, one may identify an SRv6 policy by the <color,
endpoint> tuple. The headend is the node where the SRv6 policy is
instantiated/implemented. The headend is specified as an IPv4 or
IPv6 address and is expected to be unique in the domain. The
endpoint indicates the destination of the SRv6 policy. The endpoint
is specified as an IPv6 address and is expected to be unique in the
domain. The color is a 32-bit numerical value that associates the
SRv6 Policy, and it defines an application-level network Service
Level Agreement (SLA) policy.
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Assume one or multiple SRv6 Policies are already setup in the SRv6
HeadEnd device. In order to steer traffic into a specific SRv6
policy at the Headend, one can use the SRv6 color extended community
and endpoint to map to a satisfying SRv6 policy, and steer traffic
into this specific policy.
[I-D.ietf-idr-flowspec-redirect-ip] defines the redirect to IPv4 and
IPv6 Next-hop action. The IPv6 next-hop address in the Flow-spec
Redirect to IPv6 Extended Community can be used to specify the
endpoint of the SRv6 Policy. When the packets reach to the TailEnd
device, some specific function imformation identifiers can be used
decide how to further process the flows. Several endpoint functions
are already defined, e.g., End.DT6: Endpoint with decapsulation and
IPv6 table lookup, and End.DX6: Endpoint with decapsulation and IPv6
cross-connect. The BGP Prefix-SID defined in [RFC8669] is utilized
to enable SRv6 VPN services [I-D.ietf-bess-srv6-services]. SRv6
Services TLVs within the BGP Prefix-SID Attribute can be used to
indicate the endpoint functions.
This document proposes to carry the Color Extended Community and BGP
Prefix-SID Attribute in the context of a Flowspec NLRI [RFC8955] to
an SRv6 Headend to steer traffic into one SRv6 policy, as well as to
indicate specific Tailend functions.
In this document, the usage of at most one Color Extended Community
in combination at most one BGP Prefix SID Attribute is discussed.
For the case that a flowspec route carries multiple Color Extend
Communities and/or a BGP Prefix SID Attribute, a protocol extension
to Flowspec is required, and is thus out of the scope of this
document.
However, the method proposed in this document still supports load
balancing to the tailend device. To achieve that, the headend device
CAN set up multiple paths in one SRv6 policy, and use a Flowspec
route to indicate the specific SRv6 policy.
4. Application Example
In following scenario, BGP FlowSpec Controller signals the function
imformation (SRv6 SID: Service_id_x) to the HeadEnd device.
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+------------+
| BGP FS |
| Controller |
+------------+
| Flowspec route to HeadEnd:
| NLRI: Filter Rules
| Redirect to IPv6 Nexthop: TailEnd's Address
| Policy Color: C1
| PrefixSID: Service_id_x
| .-----.
| ( )
V .--( )--.
+-------+ ( ) +-------+
| |_( SRv6 Core Network )_| |
|HeadEnd| ( ================> ) |TailEnd|
+-------+ (SR List<S1,S2,S3>) +-------+
'--( )--' Service SID: Service_id_x
( ) (e.g.: End.DT4 or End.DT6 or others)
'-----'
Figure 1: Steering the Flow into SRv6 Policy
When the headend device (as a Flowspec client) receives such
instructions, it will steer the flows matching the criteria in the
Flowspec route into the SRv6 Policy matching the tuple (Endpoint:
TailEnd's Address, Color: C1). And the packets of such flows will be
encapsulated with SRH using the SR List<S1, S2, S3, Service_id_x>.
When the packets reach to the TailEnd device, they will be further
procetssed per the function denoted by the Service_id_x.
For the cases of intra-AS and inter-AS traffic steering using this
method, the usages of Flowspec Color Extended Community with BGP
prefix SID are the same for both scenarios. The difference lie
between the local SRv6 policy configurations. For the inter-domain
case, the operator can configure an inter-domain SRv6 policy/path at
the Headend device. For the intra-domain case, the operator can
configure an intra-domain SRv6 policy/path at the Headend device.
5. IANA Considerations
No IANA actions are required for this document.
6. Security Considerations
This document does not change the security properties of SRv6 and
BGP.
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7. Contributors
The following people made significant contributions to this document:
Yunan Gu
Huawei
Email: guyunan@huawei.com
Shunwan Zhaung
Huawei
Email: zhuangshunwan@huawei.com
Haibo Wang
Huawei
Email: rainsword.wang@huawei.com
Jie Dong
Huawei
Email: jie.dong@huawei.com
8. Acknowledgements
TBD.
9. References
9.1. Normative References
[I-D.ietf-bess-srv6-services]
Dawra, G., Filsfils, C., Talaulikar, K., Raszuk, R.,
Decraene, B., Zhuang, S., and J. Rabadan, "SRv6 BGP based
Overlay Services", draft-ietf-bess-srv6-services-07 (work
in progress), April 2021.
[I-D.ietf-idr-flowspec-redirect-ip]
Uttaro, J., Haas, J., Texier, M., Karch, A., Ray, S.,
Simpson, A., and W. Henderickx, "BGP Flow-Spec Redirect to
IP Action", draft-ietf-idr-flowspec-redirect-ip-02 (work
in progress), February 2015.
[I-D.ietf-idr-segment-routing-te-policy]
Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P.,
Rosen, E., Jain, D., and S. Lin, "Advertising Segment
Routing Policies in BGP", draft-ietf-idr-segment-routing-
te-policy-11 (work in progress), November 2020.
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[I-D.ietf-idr-tunnel-encaps]
Patel, K., Velde, G. V. D., Sangli, S. R., and J. Scudder,
"The BGP Tunnel Encapsulation Attribute", draft-ietf-idr-
tunnel-encaps-22 (work in progress), January 2021.
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-11 (work in progress),
April 2021.
[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>.
[RFC8669] Previdi, S., Filsfils, C., Lindem, A., Ed., Sreekantiah,
A., and H. Gredler, "Segment Routing Prefix Segment
Identifier Extensions for BGP", RFC 8669,
DOI 10.17487/RFC8669, December 2019,
<https://www.rfc-editor.org/info/rfc8669>.
[RFC8955] Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules",
RFC 8955, DOI 10.17487/RFC8955, December 2020,
<https://www.rfc-editor.org/info/rfc8955>.
9.2. Informative References
[RFC4456] Bates, T., Chen, E., and R. Chandra, "BGP Route
Reflection: An Alternative to Full Mesh Internal BGP
(IBGP)", RFC 4456, DOI 10.17487/RFC4456, April 2006,
<https://www.rfc-editor.org/info/rfc4456>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>.
Authors' Addresses
Wenying Jiang
China Mobile
Beijing
China
Email: jiangwenying@chinamobile.com
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Yisong Liu
China Mobile
Beijing
China
Email: liuyisong@chinamobile.com
Shuanglong Chen
Huawei
Beijing
China
Email: chenshuanglong@huawei.com
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