Internet DRAFT - draft-li-idr-flowspec-srv6
draft-li-idr-flowspec-srv6
Network Working Group Z. Li
Internet-Draft L. Li
Intended status: Standards Track Huawei
Expires: February 26, 2022 H. Chen
Futurewei
C. Loibl
Next Layer Communications
G. Mishra
Verizon Inc.
Y. Fan
Casa Systems
Y. Zhu
China Telecom
L. Liu
Fujitsu
X. Liu
Volta Networks
August 25, 2021
BGP Flow Specification for SRv6
draft-li-idr-flowspec-srv6-07
Abstract
This document proposes extensions to BGP Flow Specification for SRv6
for filtering packets with a SRv6 SID that matches a sequence of
conditions.
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 BCP 14
[RFC2119][RFC8174] when, and only when, they appear in all capitals,
as shown here.
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/.
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This Internet-Draft will expire on February 26, 2022.
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 . . . . . . . . . . . . . . . . . . 4
3. The Flow Specification Encoding for SRv6 . . . . . . . . . . 4
3.1. Type TBD1 - Some Parts of SID . . . . . . . . . . . . . . 5
3.2. Encoding Examples . . . . . . . . . . . . . . . . . . . . 7
3.2.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
[RFC8955] describes in details about a new BGP NLRI to distribute a
flow specification, which is an n-tuple comprising a sequence of
matching criteria that can be applied to IP traffic. [RFC8956]
extends [RFC8955] to make it also usable and applicable to IPv6 data
packets. [I-D.ietf-idr-flowspec-l2vpn] extends the flow-spec rules
for layer 2 Ethernet packets. [I-D.hares-idr-flowspec-v2] specifies
BGP Flow Specification Version 2.
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Segment Routing (SR) for unicast traffic has been proposed to cope
with the usecases in traffic engineering, fast re-reroute, service
chain, etc. SR architecture can be implemented over an IPv6 data
plane using a new type of IPv6 extension header called Segment
Routing Header (SRH) [I-D.ietf-6man-segment-routing-header]. SRv6
Network Programming [RFC8986] defines the SRv6 network programming
concept and its most basic functions. An SRv6 SID may have the form
of LOC:FUNCT:ARG::.
LOC: Each operator is free to use the locator length it chooses.
Most often the LOC part of the SID is routable and leads to the node
which instantiates that SID.
FUNCT: The FUNCT part of the SID is an opaque identification of a
local function bound to the SID. (e.g. End: Endpoint, End.X, End.T,
End.DX2 etc.).
ARG: A function may require additional arguments that would be placed
immediately after the FUNCT.
This document specifies one new BGP Flow Specification (FS) component
type to support Segment Routing over IPv6 data plane (SRv6) filtering
for BGP Flow Specification Version 2. The match field is destination
address of IPv6 header, but it's a SRv6 SID from SRH rather than a
traditional IPv6 address (refer to Figure 1). To support these
features, a Flowspec version that is IPv6 capable (i.e., AFI = 2)
MUST be used. These match capabilities of the features MAY be
permitted to match when there is an accompanying SRH.
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+-----------------------------+
IPv6 Header| SA | DA |<--Match field of this document
+--------------------^--------+
|
+--------------------|--------+
| +-------------+ | +-------------------+
| | Segment[0] +-------> Loc | Func | Arg |
| +-------------+ | +-------------------+
| | Segment[1] | |
| +-------------+ |
| | ... | |
SR Header| +-------------+ |
| | Segment[n] | |
| +-------------+ |
| +-------------+ |
| ~ Option TLV ~ |
| +-------------+ |
+-----------------------------+
Figure 1: Match Field
2. Definitions and Acronyms
o FS: Flow Specification
o BGP-FS: Border Gateway Protocol (BGP) Flow Specification (FS)
o SR: Segment Routing
o SRH: SR Header.
o SRv6: IPv6 Segment Routing, SRv6 is a method of forwarding IPv6
packets on the network based on the concept of source routing.
o SID: Segment Identifier
o BSID: Binding SID
3. The Flow Specification Encoding for SRv6
The Flow Specification NLRI-type consists of several optional
components, each of which begins with a type field (1 octet) followed
by a variable length parameter. 13 component types are defined in
[RFC8955] and [RFC8956] for IPv4 and IPv6. This document defines one
component type for SRv6.
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3.1. Type TBD1 - Some Parts of SID
[RFC8986] defines the format of SID is LOC:FUNCT:ARG::. In some
scenarios, traffic packets can just match Locator, Function ID,
Arguments or some combinations of these different fields. In order
to match a part of SID, its prior parts need to be examined and
matched first. For example, in order to match the Function ID
(FUNCT), the Locator (LOC) needs to be examined and matched first.
The new component type TBD1 defined below is for matching some parts
of SID.
Encoding: <type, LOC-Len, FUNCT-Len, ARG-Len, [op, value]+>
o type (1 octet): This indicates the new component type (TBD1, which
is to be assigned by IANA).
o LOC-Len (1 octet): This indicates the length in bits of LOC in
SID.
o FUNCT-Len (1 octet): This indicates the length in bits of FUNCT in
SID.
o ARG-Len (1 octet): This indicates the length in bits of ARG in
SID.
o [op, value]+: This contains a list of {operator, value} pairs that
are used to match some parts of SID.
The total of three lengths (i.e., LOC length + FUNCT length + ARG
length) MUST NOT be greater than 128. If it is greater than 128, an
error occurs and Error Handling is applied according to [RFC7606] and
[RFC4760].
The operator (op) byte is encoded as:
0 1 2 3 4 5 6 7
+---+---+---+---+---+---+---+---+
| e | a | field type|lt |gt |eq |
+---+---+---+---+---+---+---+---+
where the behavior of each operator bit has clear symmetry with that
of [RFC8955]'s Numeric Operator field.
e - end-of-list bit. Set in the last {op, value} pair in the
sequence.
a - AND bit. If unset, the previous term is logically ORed with the
current one. If set, the operation is a logical AND. It should be
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unset in the first operator byte of a sequence. The AND operator has
higher priority than OR for the purposes of evaluating logical
expressions.
field type:
000: SID's LOC
001: SID's FUNCT
010: SID's ARG
011: SID's LOC:FUNCT
100: SID's FUNCT:ARG
101: SID's LOC:FUNCT:ARG
For an unknown type, Error Handling is applied according to [RFC7606]
and [RFC4760].
lt - less than comparison between data' and value'.
gt - greater than comparison between data' and value'.
eq - equality between data' and value'.
The data' and value' used in lt, gt and eq are indicated by the field
type in a operator and the value field following the operator.
The value field depends on the field type and has the value of SID's
some parts rounding up to bytes (refer to the table below).
+-----------------------+------------------------------+
| Field Type | Value |
+=======================+==============================+
| SID's LOC | value of LOC bits |
+-----------------------+------------------------------+
| SID's FUNCT | value of FUNCT bits |
+-----------------------+------------------------------+
| SID's ARG | value of ARG bits |
+-----------------------+------------------------------+
| SID's LOC:FUNCT | value of LOC:FUNCT bits |
+-----------------------+------------------------------+
| SID's FUNCT:ARG | value of FUNCT:ARG bits |
+-----------------------+------------------------------+
| SID's LOC:FUNCT:ARG | value of LOC:FUNCT:ARG bits |
+-----------------------+------------------------------+
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3.2. Encoding Examples
3.2.1. Example 1
An example of a Flow Specification NLRI encoding for: all SRv6
packets to LOC 2001:db8:3::/48 and FUNCT {range [0100, 0300]}.
Some Parts of SID
|
length v LOC==20010db80003 FUN>=100 FUN<=300
0x12 0f 30 10 40 01 2001 0db8 0003 4b 0100 bd 0300
^ ^ ^
| | |
Length of LOC FUN ARG
Decoded:
Value
0x12 length 18 octets (if len<240, 1 octet)
TBD1(0x0f) type type TBD1(0x0f) - Some Parts of SID
0x30 LOC Length = 48 (bits)
0x10 FUNCT Length = 16 (bits)
0x40 ARG Length = 64 (bits)
0x01 op LOC ==
0x2001 value LOC's value = 2001:db8:3
0x0db8
0x0003
0x4b op "AND", FUNCT >=
0x0100 value FUNCT's value = 0100
0xbd op end-of-list, "AND", FUNCT <=
0x0300 value FUNCT's value = 0300
4. Security Considerations
No new security issues are introduced to the BGP protocol by this
specification over the security considerations in [RFC8955] and
[RFC8956].
5. IANA Considerations
Under "Flow Spec Component Types" registry, IANA is requested to
assign the following values:
+-----------+------------+-------------------+----------------+
| Value | IPv4 Name | IPv6 Name | Reference |
+-----------+------------+-------------------+----------------+
| TBD1 | Unassigned | Some Parts of SID | This Document |
+-----------+------------+-------------------+----------------+
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6. Acknowledgments
The authors would like to thank Joel Halpern, Jeffrey Haas, Ketan
Talaulikar, Aijun Wang, Dhruv Dhody, Shunwan Zhuang and Rainsword
Wang for their valuable suggestions and comments on this draft.
7. References
7.1. Normative References
[I-D.hares-idr-flowspec-v2]
Hares, S. and D. Eastlake, "BGP Flow Specification Version
2", draft-hares-idr-flowspec-v2-02 (work in progress),
July 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>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<https://www.rfc-editor.org/info/rfc4760>.
[RFC7153] Rosen, E. and Y. Rekhter, "IANA Registries for BGP
Extended Communities", RFC 7153, DOI 10.17487/RFC7153,
March 2014, <https://www.rfc-editor.org/info/rfc7153>.
[RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
Patel, "Revised Error Handling for BGP UPDATE Messages",
RFC 7606, DOI 10.17487/RFC7606, August 2015,
<https://www.rfc-editor.org/info/rfc7606>.
[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>.
[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>.
[RFC8956] Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed.,
"Dissemination of Flow Specification Rules for IPv6",
RFC 8956, DOI 10.17487/RFC8956, December 2020,
<https://www.rfc-editor.org/info/rfc8956>.
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7.2. Informative References
[I-D.ietf-6man-segment-routing-header]
Filsfils, C., Dukes, D., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", draft-ietf-6man-segment-routing-header-26 (work in
progress), October 2019.
[I-D.ietf-idr-flowspec-l2vpn]
Hao, W., Eastlake, D. E., Litkowski, S., and S. Zhuang,
"BGP Dissemination of L2 Flow Specification Rules", draft-
ietf-idr-flowspec-l2vpn-17 (work in progress), May 2021.
[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>.
Authors' Addresses
Zhenbin Li
Huawei
156 Beiqing Road
Beijing, 100095
P.R. China
Email: lizhenbin@huawei.com
Lei Li
Huawei
156 Beiqing Road
Beijing 100095
P.R. China
Email: lily.lilei@huawei.com
Huaimo Chen
Futurewei
Boston, MA
USA
Email: Huaimo.chen@futurewei.com
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Christoph Loibl
Next Layer Communications
Mariahilfer Guertel 37/7
Vienna 1150
AT
Email: cl@tix.at
Gyan S. Mishra
Verizon Inc.
13101 Columbia Pike
Silver Spring MD 20904
USA
Phone: 301 502-1347
Email: gyan.s.mishra@verizon.com
Yanhe Fan
Casa Systems
USA
Email: yfan@casa-systems.com
Yongqing Zhu
China Telecom
109, West Zhongshan Road, Tianhe District
Guangzhou 510000
China
Email: zhuyq8@chinatelecom.cn
Lei Liu
Fujitsu
USA
Email: liulei.kddi@gmail.com
Xufeng Liu
Volta Networks
McLean, VA
USA
Email: xufeng.liu.ietf@gmail.com
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