BGP-LS Advertisement of Segment Routing Service Segments
draft-dawra-idr-bgp-ls-sr-service-segments-06
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Gaurav Dawra
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Clarence Filsfils
,
Ketan Talaulikar
,
Francois Clad
,
Daniel Bernier
,
Jim Uttaro
,
Bruno Decraene
,
Hani Elmalky
,
Xiaohu Xu
,
Jim Guichard
,
Cheng Li
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Last updated |
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2021-08-19
(latest revision 2021-08-17)
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draft-dawra-idr-bgp-sr-service-chaining
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Inter-Domain Routing G. Dawra, Ed.
Internet-Draft LinkedIn
Intended status: Standards Track C. Filsfils
Expires: February 18, 2022 K. Talaulikar, Ed.
F. Clad
Cisco Systems
D. Bernier
Bell Canada
J. Uttaro
AT&T
B. Decraene
Orange
H. Elmalky
Ericsson
X. Xu
Capitalonline
J. Guichard
Futurewei Technologies
C. Li
Huawei Technologies
August 17, 2021
BGP-LS Advertisement of Segment Routing Service Segments
draft-dawra-idr-bgp-ls-sr-service-segments-06
Abstract
Service functions are deployed as, physical or virtualized elements
along with network nodes or on servers in data centers. Segment
Routing (SR) brings in the concept of segments which can be
topological or service instructions. Service segments are SR
segments that are associated with service functions. SR Policies are
used for the setup of paths for steering of traffic through service
functions using their service segments.
BGP Link-State (BGP-LS) enables distribution of topology information
from the network to a controller or an application in general so it
can learn the network topology. This document specifies the
extensions to BGP-LS for the advertisement of service functions along
their associated service segments. The BGP-LS advertisement of
service function information along with the network nodes that they
are attached to, or associated with, enables controllers compute and
setup service paths in the network.
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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 February 18, 2022.
Copyright Notice
Copyright (c) 2021 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 Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. BGP-LS Extensions for Service Chaining . . . . . . . . . . . 4
3. Illustration . . . . . . . . . . . . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
4.1. Service Type Table . . . . . . . . . . . . . . . . . . . 7
4.2. Segment routing function Identifier(SFI) . . . . . . . . 8
5. Manageability Considerations . . . . . . . . . . . . . . . . 8
6. Operational Considerations . . . . . . . . . . . . . . . . . 8
6.1. Operations . . . . . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.1. Normative References . . . . . . . . . . . . . . . . . . 9
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9.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
Segments are introduced in the SR architecture [RFC8402]. Segment
Routing based Service chaining is well described in
[I-D.ietf-spring-sr-service-programming] with an example of network
and services.
This document extend the example to add a Segment Routing Controller
(SR-C) to the network, for the purpose of service discovery and SR
policy [I-D.ietf-spring-segment-routing-policy] instantiation.
Consider the network represented in Figure 1 below where:
o A and B are two end hosts using IPv4.
o S1 is an SR-aware firewall Service.
o S2 is an SR-unaware DPI Service.
SR-C --3--
| / \
| / \
A----1----2----4----5----6----B
| |
| |
S1 S2
Figure 1: Network with Services
SR Controller (SR-C) is connected to Node 1, but may be attached to
any node 1-6 in the network.
SR-C can receive BGP-LS updates to discover topology, and calculate
constrained paths between nodes 1 and 6.
However, if SR-C is configured to compute a constrained path from 1
and 6, including a DPI service (i.e., S2) it is not yet possible due
to the lack of service distribution. SR-C does not know where a DPI
service is nor the SID for it. It does not know that S2 is a service
it needs.
This document proposes an extension to BGP-LS for Service Chaining to
distribute the service information to SR-C. There may be other
alternate mechanisms to distribute service information to SR-C and
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are outside the scope of this document. There are no extensions
required in SR-TE Policy SAFI.
1.1. Requirements Language
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.
2. BGP-LS Extensions for Service Chaining
For an attached service, following data needs to be shared with SR-C:
o Service SID value (e.g. MPLS label or IPv6 address). Service SID
MAY only be encoded as LOC:FUNCT, where LOC is the L most
significant bits and FUNCT is the 128-L least significant
bits[RFC8986]. ARGs bits, if any, MAY be set to 0 in the
advertised service SID.
o Function Identifier (Static Proxy, Dynamic Proxy, Shared Memory
Proxy, Masquerading Proxy, SR Aware Service etc.).
o Service Type (DPI, Firewall, Classifier, LB etc.).
o Traffic Type (IPv4 OR IPv6 OR Ethernet)
o Opaque Data (Such as brand and version, other extra information)
[I-D.ietf-spring-sr-service-programming] defines SR-aware and SR-
unaware services. This document will reuse these definitions. Per
[RFC7752] Node Attributes are ONLY associated with the Node NLRI.
All non-VPN information SHALL be encoded using AFI 16388 / SAFI 71.
VPN information SHALL be encoded using AFI 16388 / SAFI 72 with
associated RTs.
This document introduces new TLVs for the SRv6 SID NLRI
[I-D.ietf-idr-bgpls-srv6-ext] and SR-MPLS SID/Label TLV [RFC9085] to
associate the Service SID value with Service-related Information
using Service Chaining(SC) Sub-TLV.
SRv6 SID Information TLV [I-D.ietf-idr-bgpls-srv6-ext] encodes
behavior along with associated SID Flags.
A Service Chaining (SC) TLV in Figure 2 is defined as:
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+---------------------------------------+
| Type (2 octet) |
+---------------------------------------+
| Length (2 octet) |
+---------------------------------------+
| Service Type(ST) (2 octet |
+---------------------------------------+
| Flags (1 octet) |
+---------------------------------------+
| Traffic Type(1 octet) |
+---------------------------------------+
| RESERVED (2 octet) |
+---------------------------------------+
Figure 2: Service Chaining (SC) TLV
Where:
Type: 16 bit field. TBD
Length: 16 bit field. The total length of the value portion of
the TLV.
Service Type(ST): 16bit field. Service Type: categorizes the
Service: (such as "Firewall", "Classifier" etc.).
Flags: 8 bit field. Bits SHOULD be 0 on transmission and MUST be
ignored on reception.
Traffic Type: 8 Bit field. A bit to identify if Service is IPv4
OR IPv6 OR L2 Ethernet Capable. Where:
Bit 0(LSB): Set to 1 if Service is IPv4 Capable
Bit 1: Set to 1 if Service is IPv6 Capable
Bit 2: Set to 1 if Service is Ethernet Capable
RESERVED: 16bit field. SHOULD be 0 on transmission and MUST be
ignored on reception.
Service Type(ST) MUST be encoded as part of SC TLV.
There may be multiple instances of similar Services that need to be
distinguished. For example, firewalls made by different vendors A
and B may need to be identified differently because, while they have
similar functionality, their behavior is not identical.
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In order for the SDN Controller to identify the categories of
Services and their associated SIDs, this section defines the BGP-LS
extensions required to encode these characteristics and other
relevant information about these Services.
Another Optional Opaque Metadata(OM) TLV of SRv6 SID NLRI may encode
vendor specific information. Multiple of OM TLVs may be encoded.
+---------------------------------------+
| Type (2 octet) |
+---------------------------------------+
| Length (2 octet) |
+---------------------------------------+
| Opaque Type (2 octet) |
+---------------------------------------+
| Flags (1 octet) |
+---------------------------------------+
| Value (variable) |
+---------------------------------------+
Figure 3: Opaque Metadata(OM) TLV
o Type: 16 bit field. TBD.
o Length: 16 bit field. The total length of the value portion of
the TLV.
o Opaque Type: 8-bit field. Only publishers and consumers of the
opaque data are supposed to understand the data.
o Flags: 8 bit field. Bits SHOULD be 0 on transmission and MUST be
ignored on reception.
o Value: Variable Length. Based on the data being encoded and
length is recorded in length field.
Opaque Metadata(OM) TLV defined in Figure 3 may encode propriety or
Service Opaque information such as:
o Vendor specific Service Information.
o Traffic Limiting Information to particular Service Type.
o Opaque Information unique to the Service.
o Propriety Enterprise Service specific Information.
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3. Illustration
In our SRv6 example above Figure 1, Node 5 is configured with an SRv6
dynamic proxy segments (End.AD) C5::AD:F2 for S2.
The BGP-LS advertisement MUST include SRv6 SID NLRI with SRv6 SID
Information TLV in the BGP-LS Attribute:
o Service SID: C5::AD:F2 SID
o Endpoint Behavior: END.AD
The BGP-LS Attribute MUST contain a SC TLV with:
o Service Type: Deep Packet Inspection(DPI)
o Traffic Type: IPv4 Capable.
The BGP-LS Attribute MAY contain a OM TLV with:
o Opaque Type: Cisco DPI Version
o Value: 3.5
In our example in Figure 1, using BGP SR-TE SAFI Update
[I-D.ietf-idr-segment-routing-te-policy], SR Controller computes the
candidate path and pushes the Policy.
SRv6 encapsulation policy < CF1::, C3::, C5::AD:F2, C6::D4:B > is
signaled to Node 1 which has mix of service and topological segments.
4. IANA Considerations
This document requests assigning code-points from the registry "BGP-
LS Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute
TLVs".
4.1. Service Type Table
IANA is request to create a new top-level registry called "Service
Type Table (STT)". Valid values are in the range 0 to 65535. Values
0 and 65535 are to be marked "Reserved, not to be allocated".
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+------------+-----------------------+------------+-------------+
| Service | Service | Reference | Date |
| Value(TBD) | | | |
+------------+-----------------------+------------+-------------+
| 32 | Classifier | ref-to-set | date-to-set |
+------------+-----------------------+------------+-------------+
| 33 | Firewall | ref-to-set | date-to-set |
+------------+-----------------------+------------+-------------+
| 34 | Load Balancer | ref-to-set | date-to-set |
+------------+-----------------------+------------+-------------+
| 35 | DPI | ref-to-set | date-to-set |
+------------+-----------------------+------------+-------------+
Figure 4
4.2. Segment routing function Identifier(SFI)
IANA is request to extend a top-level registry called "Segment
Routing Function Identifier(SFI)" with new code points. This
document extends the SFI values defined in
[I-D.ietf-idr-bgpls-srv6-ext]. Details about the Service functions
are defined in[I-D.ietf-spring-sr-service-programming].
+--------------------------+---------------------------+
| Function | Function Identifier |
| | |
+--------------------------+---------------------------+
| Static Proxy | 8 |
+--------------------------+---------------------------+
| Dynamic Proxy | 9 |
+--------------------------+---------------------------+
| Shared Memory Proxy | 10 |
+--------------------------+---------------------------+
| Masquerading Proxy | 11 |
+--------------------------+---------------------------+
| SRv6 Aware Service | 12 |
+--------------------------+---------------------------+
5. Manageability Considerations
This section is structured as recommended in[RFC5706]
6. Operational Considerations
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6.1. Operations
Existing BGP and BGP-LS operational procedures apply. No additional
operation procedures are defined in this document.
7. Security Considerations
Procedures and protocol extensions defined in this document do not
affect the BGP security model. See the 'Security Considerations'
section of [RFC4271] for a discussion of BGP security. Also refer
to[RFC4272] and[RFC6952] for analysis of security issues for BGP.
8. Acknowledgements
The authors would like to thank Krishnaswamy Ananthamurthy for his
review of this document.
9. References
9.1. Normative References
[I-D.ietf-idr-bgpls-srv6-ext]
Dawra, G., Filsfils, C., Talaulikar, K., Chen, M.,
Bernier, D., and B. Decraene, "BGP Link State Extensions
for SRv6", draft-ietf-idr-bgpls-srv6-ext-08 (work in
progress), June 2021.
[I-D.ietf-spring-sr-service-programming]
Clad, F., Xu, X., Filsfils, C., Bernier, D., Li, C.,
Decraene, B., Ma, S., Yadlapalli, C., Henderickx, W., and
S. Salsano, "Service Programming with Segment Routing",
draft-ietf-spring-sr-service-programming-04 (work in
progress), March 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>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
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[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
(SRv6) Network Programming", RFC 8986,
DOI 10.17487/RFC8986, February 2021,
<https://www.rfc-editor.org/info/rfc8986>.
[RFC9085] Previdi, S., Talaulikar, K., Ed., Filsfils, C., Gredler,
H., and M. Chen, "Border Gateway Protocol - Link State
(BGP-LS) Extensions for Segment Routing", RFC 9085,
DOI 10.17487/RFC9085, August 2021,
<https://www.rfc-editor.org/info/rfc9085>.
9.2. Informative References
[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-13 (work in progress), June 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-13 (work in progress),
May 2021.
[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>.
[RFC5706] Harrington, D., "Guidelines for Considering Operations and
Management of New Protocols and Protocol Extensions",
RFC 5706, DOI 10.17487/RFC5706, November 2009,
<https://www.rfc-editor.org/info/rfc5706>.
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[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
<https://www.rfc-editor.org/info/rfc6952>.
Authors' Addresses
Gaurav Dawra (editor)
LinkedIn
USA
Email: gdawra.ietf@gmail.com
Clarence Filsfils
Cisco Systems
Belgium
Email: cfilsfil@cisco.com
Ketan Talaulikar (editor)
Cisco Systems
India
Email: ketant@cisco.com
Francois Clad
Cisco Systems
France
Email: fclad@cisco.com
Daniel Bernier
Bell Canada
Canada
Email: daniel.bernier@bell.ca
Jim Uttaro
AT&T
USA
Email: ju1738@att.com
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Bruno Decraene
Orange
France
Email: bruno.decraene@orange.com
Hani Elmalky
Ericsson
USA
Email: hani.elmalky@gmail.com
Xiaohu Xu
Capitalonline
Email: xiaohu.xu@capitalonline.net
Jim Guichard
Futurewei Technologies
USA
Email: james.n.guichard@futurewei.com
Cheng Li
Huawei Technologies
China
Email: chengli13@huawei.com
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