BGP Flow Specification by ClassID
draft-song-idr-flowspec-classid-filter-01
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Jian Song , Changwang Lin , Ran Chen , Jinming Li | ||
| Last updated | 2026-07-06 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
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| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
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draft-song-idr-flowspec-classid-filter-01
IDR Working Group J. Song
Internet Draft China Mobile
Intended status: Standards Track C. Lin
Expires: January 08, 2027 New H3C Technologies
R. Chen
ZTE Corporation
J. Li
China Mobile
July 06, 2026
BGP Flow Specification by ClassID
draft-song-idr-flowspec-classid-filter-01
Abstract
BGP Flowspec mechanism (BGP-FS) [RFC8955] [RFC8956] propagates both
traffic Flow Specifications and Traffic Filtering Actions by making
use of the BGP NLRI and the BGP Extended Community encoding formats.
This document specifies a new BGP-FS component type named ClassID to
support ClassID filtering.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 08 January 2027.
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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respect to this document. Code Components extracted from this
document must include Simplified BSD License text as described in
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warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction...................................................2
2. Requirements Language..........................................4
3. The Flow Specification Encoding for ClassID....................4
4. Use Cases......................................................5
5. IANA Considerations............................................6
5.1. FSv2 IP Basic TLV Components..............................6
6. Security Considerations........................................7
7. Informative References.........................................7
Authors' Addresses................................................9
1. Introduction
BGP Flowspec mechanism (BGP-FS) [RFC8955] [RFC8956] propagates both
traffic Flow Specifications and Traffic Filtering Actions by making
use of the BGP NLRI and the BGP Extended Community encoding formats.
As shown in Figure 1, PE2 advertises routes Prefix21, Prefix22, ...,
Prefix2n, and PE3 advertises routes Prefix31, Prefix32, ...,
Prefix3n. The server sends Flow-Spec rules to PE1 to redirect the
traffic for routes Prefix2x and Prefix3x respectively.
When there are a large number of routes, a significant amount of BGP
Flow-Spec rules need to be deployed.
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+---------+
| BGP FS |
| Server |
+--/------+
/
+----+
/
/
+----+ +---+ +----+Prefix 21
+PE1 +-------+ P +---------+PE2 |Prefix 22
+----+ +-+-+ +----+...
|
|
| +----+Prefix 31
+-----------+PE3 |Prefix 32
+----+...
Figure 1
To address this issue, when PE2 and PE3 advertise routes, they can
include specific routing attributes.
For the included routing attributes, various combinations of BGP
properties can be used, such as:
BGP Standard Community
BGP Large Community
Extended Community
Color
AS Path, etc.
By extending the BGP-FS component type, filtering of various BGP
route attributes can be supported. However, the following issues
exist:
* Various attributes need to be planned on the device, transmitted
across devices, and then traffic steering must be performed using
BGP-FS rules on the corresponding devices.
* Due to the large number of BGP attributes, extending corresponding
BGP-FS component types for each attribute may generate a large
volume of BGP FS routes.
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*BGP needs to update these attributes to the forwarding table. The
extensive attribute content results in the forwarding table
maintaining a complex BGP attribute list.
This document specifies a new BGP-FS component type named ClassID to
support ClassID filtering. The device maps various attributes into
ClassIDs and updates the corresponding ClassIDs to the forwarding
table. The match field is the ClassID of the destination IP address
encoded in the Flowspec NLRI.
2. 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 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when,
they appear in all capitals, as shown here.
3. The Flow Specification Encoding for ClassID
[I-D. draft-ietf-idr-fsv2-ip-basic] defines the Components in the IP
Basic TLV. This document proposes a new Component for ClassID
information.
When filtering using FlowSpec rules, the condition can be specified
as the ClassID.
This is primarily used for traffic diversion based on the ClassID.
Sub-TLV Definition
-------- ---------------------
TBD - ClassID
The ClassID Components has following format:
+-------------------------------+
| SubTLV type = TBD (1 octet) |
+-------------------------------+
| length (1 octet) |
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+ ------------------------------+
| value (variable) |
+-------------------------------+
Type: ClassID(TBD)
Filter defines: match for ClassID
length: variable
value: [numeric_op, value]+
where the value following each numeric_op is a two octets ClassID.
4. Use Cases
As shown in Figure 2, on the ingress PE, Route-Policy is configured
to map various route attributes into ClassID. These route attributes
include Community, Large Community, Extended Community, Color, etc.
The BGP Flow-Spec Server deploys BGP Flow-Spec rules by specifying
ClassID as the matching condition and Redirect as the action.
For traffic steering:
First, route attributes are mapped to a unified ClassID through
Route-Policy based on traffic characteristics.
Then, traffic is redirected to the specified destination router by
matching the ClassID against BGP Flow-Spec rules.
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|Input:
|filter = destip + ClassID
|Action = redirect
V
+----------+
|Controller|
+----------+
|BGP FS:
|NLRI
| Filter: ClassID
|Action=redirect
V
+----------+
|Device |
+----------+
Route-Policy: (Color, Community, ...)
Remark ClassID
Flow-Spec: ClassID->redirect
Figure 2
5. IANA Considerations
5.1. FSv2 IP Basic TLV Components
[I-D. draft-ietf-idr-fsv2-ip-basic] defines the Components in the IP
Basic TLV.
This document requested to assign a new type code point from "FSv2
IP Basic TLV Components" registry for ClassID.
Sub-TLV Definition
-------- ---------------------
0 - Reserved
1 - IP Destination prefix
2 - IP Source prefix
3 - IPv4 Protocol /
IPv6 Upper Layer Protocol
4 - Port
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5 - Destination Port
6 - Source Port
7 - ICMPv4 type / ICMPv6 type
8 - ICMPv4 code / ICPv6 code
9 - TCP Flags
10 - Packet length
11 - DSCP
12 - Fragment
13 - Flow Label
TBD1- ClassID This document
14-255 Reserved
6. Security Considerations
TBD
7. Informative References
[I-D. ietf-idr-flowspec-v2] Hares, S., Eastlake, D. E., Yadlapalli,
C., and S. Maduschke, "BGP Flow Specification Version 2",
Work in Progress, Internet-Draft, draft-ietf-idr-flowspec-
v2-04, 28 April 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
flowspec-v2-04>.
[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>.
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[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>.
[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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Authors' Addresses
Song Jian
China Mobile
China
Email: songjianyjy@chinamobile.com
Changwang Lin
New H3C Technologies
China
Email: linchangwang.04414@h3c.com
Ran Chen
ZTE Corporation
Nanjing
China
Email: chen.ran@zte.com.cn
Jinming Li
China Mobile
China
Email: lijinming@chinamobile.com
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