Flowspec Indirection-id Redirect
draft-ietf-idr-flowspec-path-redirect-03
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (idr WG) | |
|---|---|---|---|
| Authors | Gunter Van de Velde , Keyur Patel , Zhenbin Li | ||
| Last updated | 2018-03-21 (Latest revision 2017-12-20) | ||
| Replaces | draft-vandevelde-idr-flowspec-path-redirect | ||
| Stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-idr-flowspec-path-redirect-03
IDR Working Group G. Van de Velde, Ed.
Internet-Draft Nokia
Intended status: Standards Track K. Patel
Expires: June 23, 2018 Arrcus
Z. Li
Huawei Technologies
December 20, 2017
Flowspec Indirection-id Redirect
draft-ietf-idr-flowspec-path-redirect-03
Abstract
This document defines a new extended community known as flowspec
redirect-to-indirection-id. This extended community triggers
advanced redirection capabilities to flowspec clients. When
activated, this flowspec extended community is used by a flowspec
client to find the corresponding next-hop information within a
indirection-id mapping table.
The functionality detailed in this document allows a network
controller to decouple the BGP flowspec redirection instruction from
the selected redirection path itself.
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 [1].
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
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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 June 23, 2018.
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Copyright Notice
Copyright (c) 2017 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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. indirection-id and indirection-id table . . . . . . . . . . . 3
3. Use Case Scenarios . . . . . . . . . . . . . . . . . . . . . 3
3.1. Redirection shortest Path tunnel . . . . . . . . . . . . 3
3.2. Redirection to path-engineered tunnels . . . . . . . . . 4
3.3. Redirection to complex dynamically constructed tunnels . 5
4. redirect-to-indirection-id Community . . . . . . . . . . . . 6
5. Redirect using localised indirection-id mapping table . . . . 8
6. Validation Procedures . . . . . . . . . . . . . . . . . . . . 8
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
9. Contributor Addresses . . . . . . . . . . . . . . . . . . . . 9
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
11.1. Normative References . . . . . . . . . . . . . . . . . . 11
11.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
Flowspec is an extension to BGP that allows for the dissemination of
traffic flow specification rules. This has many possible
applications but the primary one for many network operators is the
distribution of traffic filtering actions for DDoS mitigation. The
flow-spec standard RFC5575 [2] defines a redirect-to-VRF action for
policy-based forwarding, but this mechanism is not always sufficient,
particularly if the redirected traffic needs to be steered onto an
explicite path.
Every flowspec policy route is effectively a rule, consisting of two
parts. The first part, encoded in the NLRI field, provides
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information about the traffic matching the policy rule. the second
part, encoded in one or more BGP extended communities, provides
policy instructions for traffic handling on the flowspec client. The
flowspec standard RFC5575 [2] defines widely-used filter actions such
as discard and rate limit; it also defines a redirect-to-VRF action
for policy-based forwarding. Using the redirect-to-VRF action to
steer traffic towards an alternate destination is useful for DDoS
mitigation, however using this methodology can be cumbersome when
there is need to steer the traffic onto an explicitely defined
traffic path.
This draft specifies a redirect-to-indirection-id flowspec action
making use of a 32-bit indirection-id using a new extended community.
Each indirection-id serves as anchor point, for policy-based
forwarding onto an explicite path by a flowspec client.
2. indirection-id and indirection-id table
The indirection-id is a 32-bit unsigned number, used as anchor point
on a flowspec client for policy-based forwarding onto an explicite
path by a flowspec client.
The indirection-id table is the table construct of indirection-id
values, ordered by indirection-id type. Each entry in this table
contains policy-based forwarding instructions.
The configuration of the indirection-id table on a flowspec client is
localised on each router and MAY happen out-of-band from BGP
flowspec. For some use-case scenarios the indirection-id type
provides additional (maybe even fully sufficient) context for a
flowspec client for policy based forwarding, making a localized
indirection-id table obsolete. For example, when the indirection-id
refers to a MPLS segment routing node-id [6], then the indirection-id
provides sufficient information for a segment routing lookup on the
flowspec client.
3. Use Case Scenarios
This section describes a few use-case scenarios when deploying
redirect-to-indirection-id.
3.1. Redirection shortest Path tunnel
Description:
The first use-case describes an example where a single flowspec route
is sent from a BGP flowspec controller to many BGP flowspec clients.
This BGP flowspec route carries the redirect-to-indirection-id to all
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flowspec clients to redirect matching dataflows onto a shortest-path
tunnel pointing towards a single remote destination.
In this first use-case scenario, each flowspec client receives
flowspec routes. The received flowspec routes have the extended
redirect-to-indirection-id community attached. Each redirect-to-
indirection-id community embeds two relevant components: (1) 32-bit
indirection-id and (2) indirection-id type. These two components
provide the flowspec client with sufficient information for policy
based forwarding to steer and encapsulate the data-packet accordingly
to a shortest path tunnel to a remote end-point.
Requirements:
For redirect to shortest path tunnel it is required that the tunnel
MUST be operational and allow packets to be steered over the shortest
path between tunnel head- and tail-end.
Example: Indirection-ID community types to be used:
o 0 (localised ID): When the intent is to use a localised
Indirection-id table, configured through out-of-band procedures.
o 1 or 2 (Node ID's): This type can be used when the goal is to use
MPLS based Segment Routing towards a remote destination. In this
use-case scenario the flowspec rule contains a SR (Segment
Routing) node SID to steer traffic towards.
3.2. Redirection to path-engineered tunnels
Description:
The second use-case describes an example where a single flowspec
route is sent from a BGP flowspec controller to many BGP flowspec
clients. This BGP flowspec route carries policy information to steer
traffic upon a path-engineered tunnel. It is assumed that the path
engineered tunnels are configured using out-of-band from BGP
flowspec.
Segment Routing Example:
For this example the indirection-id type points towards a Segment
Routing Binding SID. The Binding SID is a segment identifier value
(as per segment routing definitions in [I-D.draft-ietf-spring-
segment-routing] [6]) used to associate an explicit path. The
Binding SID and corresponding path engineered tunnel may for example
be setup by a controller using BGP as specified in [I-D.sreekantiah-
idr-segment-routing-te] [5] or alternatly by using PCEP as detailed
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in draft-ietf-pce-segment-routing [7]. To conclude, when a BGP
speaker at some point in time receives a flow-spec route with an
extended 'redirect-to-indirection-id' community, it installs a
policy-based forwarding rule to redirect packets onto an explicit
path associated with the corresponding Binding SID. The encoding of
the Binding SID within the redirect-to-indirection-id extended
community is specified in section 4.
Requirements:
For redirect to path engineered tunnels it is required that the
tunnel MUST be operational and allow packets to be steered over the
engineered path between tunnel head- and tail-end.
Example: Indirection-ID community types to be used:
o 0 (localised ID): When the intent is to policy-based steer traffic
using Indirection. The engineered path is configured through out-
of-band procedures and uses the 32-bit Indirection-id as local
anchor point on the local flowspec client.
o 2 or 3 (Binding Segment ID's): This type can be used when the goal
is to use MPLS based Segment Routing towards an out-of-band
configured explicite path.
o 5 (Tunnel ID): When the intent is to policy-based steer traffic
using a global tunnel-id. The engineered path is configured
through out-of-band procedures and uses the 32-bit Indirection-id
as global anchor point on the local flowspec client.
3.3. Redirection to complex dynamically constructed tunnels
Description:
A third use-case describes the application and redirection towards
complex dynamically constructed tunnels. For this use-case a BGP
flowspec controller injects a single flowspec route with two unique
'redirect-to-indirection-id' communities attached, each community
tagged with a different Sequence-ID (S-ID). A flowspec client may
use the Sequence-ID (S-ID) to sequence the flowspec redirect
information. A common use-case scenario would for example be the
dynamic construction of Segment Routing Central Egress Path
Engineered tunnel [4] or next-next-hop tunnels.
Segment Routing Example:
i.e. a classic Segment Routing example using complex tunnels is found
in DDoS mitigation and traffic offload. Suspicious traffic (e.g.
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dirty traffic flows) may be policy-based routed into a purpose built
Segment Routing Central Egress Path Engineered tunnel [4]. For this
complex dynamic redirect tunnel construction, a first redirect-to-
indirection-id (i.e. S-ID=0) may be used to redirect traffic into a
tunnel towards a particular egress router, while a second redirect-
to-indirection-id (i.e. S-ID=1) is used to steer traffic beyond the
particular egress router towards a pre-identified interface/peer.
From data-plane perspective, the principles documented by [4] are
valid for this use case scenario.
Requirements:
To achieve redirection towards complex dynamically constructed
tunnels, various indirection-id communities are imposed upon the
flowspec route and are sequenced using the Sequence ID (S-ID). For
redirect to complex dynamic engineered tunnels it is required that
the tunnel MUST be operational and allow packets to be steered over
the engineered path between tunnel head- and tail-end.
Example: Indirection-ID community types to be used:
o 0 (localised ID) with S-ID: When the intent is to construct a
dynamic engineered tunnel, then a sequence of localised
indirection-ids may be used. The Sequence ID (S-ID) MUST be used
to sequence multiple redirect-to-indirection-id actions to
construct a more complex path engineered tunnel. The construction
of the localised indirection-id table is done out-of-band and is
outside scope of this document.
4. redirect-to-indirection-id Community
This document defines a new BGP extended community known as a
Redirect-to-indirection-id extended community. This extended
community is a new transitive extended community with the Type and
the Sub-Type field to be assigned by IANA. The format of this
extended community is show in Figure 1.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Sub-Type | Flags(1 octet)| Indirection ID|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Generalized indirection_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
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The meaning of the extended community fields are as follows:
Type: 1 octet to be assigned by IANA.
Sub-Type: 1 octet to be assigned by IANA.
Flags: 1 octet field. Following Flags are defined.
0 1
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| RES | S-ID |C|
+-+-+-+-+-+-+-+-+
Figure 2
The least-significant Flag bit is defined as the 'C' (or copy) bit.
When the 'C' bit is set the redirection applies to copies of the
matching packets and not to the original traffic stream.
The 'S-ID' field identifies a 4 bit Sequence ID field. This field is
used to provide a flowspec client an indication how and where to
sequence the received indirection-ids. The Sequence ID value 0
indicates that Sequence ID field is NOT set and SHOULD be ignored. A
single flowspec rule MUST NOT have more as one indirection-id per
S-ID. On a flowspec client the indirection-id with lowest S-ID MUST
be imposed first for any given flowspec entry.
All bits other than the 'C' and 'S-ID' bits MUST be set to 0 by the
originating BGP speaker and ignored by receiving BGP speakers.
Indirection ID: 1 octet value. This draft defines following
indirection-id Types:
0 - Localised ID (The flowspec client uses the received
indirection-id to lookup forwarding information within the
localised indirection-id table. The allocation and programming of
the localised indirection-id table is outside scope of the
document)
1 - Node ID with SID/index in MPLS-based Segment Routing (This
means indirection-id is mapped to an MPLS label using the index as
a global offset in the SID/label space)
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2 - Node ID with SID/label in MPLS-based Segment Routing (This
means indirection-id is mapped to an MPLS label using the label as
global label)
3 - Binding Segment ID with SID/index in MPLS-based Segment
Routing (This means indirection-id is mapped to an MPLS binding
label using the index as a global offset in the SID/label space)
[I-D.draft-ietf-spring-segment-routing] [6]
4 - Binding Segment ID with SID/label in MPLS-based Segment
Routing (This means indirection-id is mapped to an MPLS binding
label using the index as a global offset in the SID/label space)
[I-D.draft-ietf-spring-segment-routing] [6]
5 - Tunnel ID (Tunnel ID is a global value in a network single
administrative domain identifying tunnel information. The
allocation of the Tunnel ID is out of the scope of the document.)
5. Redirect using localised indirection-id mapping table
When a BGP flowspec client receives a flowspec policy route with a
redirect-to-indirection-id extended community attached and the route
represents the best BGP path, it will install a flowspec policy-based
forwarding rule matching the tupples described by the flowpsec NLRI
field and consequently redirects the flow (C=0) or copies the flow
(C=1) using the information identified by the 'redirect-to-
indirection-id' community.
6. Validation Procedures
The validation check described in RFC5575 [2] and revised in [3]
SHOULD be applied by default by a flowspec client, for received
flowspec policy routes containing a 'redirect-to-indirection-id'
extended community. This means that a flow-spec route with a
destination prefix subcomponent SHOULD NOT be accepted from an EBGP
peer unless that peer also advertised the best path for the matching
unicast route.
While it MUST NOT happen, and is seen as invalid combination, it is
possible from a semantics perspective to have multiple clashing
redirect actions defined within a single flowspec rule. For best and
consistant with legacy implementations, the redirect functionality as
documented by RFC5575 MUST NOT be broken, and hence when a clash
occurs, then RFC5575 based redirect MUST take priority.
Additionally, if the 'redirect-to-indirection-id' does not result in
a valid redirection, then the flowspec rule MUST be processed as if
the 'redirect-to-indirection-id' community was not attached to the
flowspec route and MUST provide an indication within the BGP routing
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table that the respective 'redirect-to-indirection-id' resulted in an
invalid redirection action.
7. Security Considerations
A system using 'redirect-to-indirection-id' extended community can
cause during the redirect mitigation of a DDoS attack result in
overflow of traffic received by the mitigation infrastructure.
8. Acknowledgements
This document received valuable comments and input from IDR working
group including Adam Simpson, Mustapha Aissaoui, Jan Mertens, Robert
Raszuk, Jeff Haas, Susan Hares and Lucy Yong.
9. Contributor Addresses
Below is a list of other contributing authors in alphabetical order:
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Arjun Sreekantiah
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
USA
Email: asreekan@cisco.com
Nan Wu
Huawei Technologies
Huawei Bld., No. 156 Beiquing Rd
Beijing 100095
China
Email: eric.wu@huawei.com
Shunwan Zhuang
Huawei Technologies
Huawei Bld., No. 156 Beiquing Rd
Beijing 100095
China
Email: zhuangshunwan@huawei.com
Wim Henderickx
Nokia
Antwerp
BE
Email: wim.henderickx@nokia.com
Figure 3
10. IANA Considerations
This document requests a new type and sub-type for the redirect-to-
indirection-id Extended community from the "Transitive Extended
community" registry. The Type name shall be "Redirect-to-
indirection-id Extended Community" and the Sub-type name shall be
'Flow-spec Redirect to 32-bit Path-id'.
In addition, this document requests IANA to create a new registry for
redirect-to-indirection-id Extended Community INDIRECTION-IDs as
follows:
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Under "Transitive Extended Community:"
Registry: "Redirect Extended Community indirection_id"
Reference: [RFC-To-Be]
Registration Procedure(s): First Come, First Served
Registry: "Redirect Extended Community indirection_id"
Value Code Reference
0 Localised ID [RFC-To-Be]
1 Node ID [RFC-To-Be]
2 Binding ID [RFC-To-Be]
3 Tunnel ID [RFC-To-Be]
Figure 4
11. References
11.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997,
<http://xml.resource.org/public/rfc/html/rfc2119.html>.
[2] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
and D. McPherson, "Dissemination of Flow Specification
Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009,
<https://www.rfc-editor.org/info/rfc5575>.
11.2. Informative References
[3] Uttaro, J., Filsfils, C., Alcaide, J., and P. Mohapatra,
"Revised Validation Procedure for BGP Flow
Specifications", January 2014.
[4] Filsfils, C., Previdi, S., Aries, E., Ginsburg, D., and D.
Afanasiev, "Segment Routing Centralized Egress Peer
Engineering", October 2015.
[5] Sreekantiah, A., Filsfils, C., Previdi, S., Sivabalan, S.,
Mattes, P., and S. Lin, "Segment Routing Traffic
Engineering Policy using BGP", October 2015.
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[6] Filsfils, C., Previdi, S., Decraene, B., Litkowski, S.,
Shakir, R., Bashandy, A., Horneffer, M., Henderickx, W.,
Tantsura, J., Crabbe, E., Milojevic, I., and S. Ytti,
"Segment Routing Architecture", December 2015.
[7] Sivabalan, S., Medved, M., Filsfils, C., Litkowski, S.,
Raszuk, R., Bashandy, A., Lopez, V., Tantsura, J.,
Henderickx, W., Hardwick, J., Milojevic, I., and S. Ytti,
"PCEP Extensions for Segment Routing", December 2015.
Authors' Addresses
Gunter Van de Velde (editor)
Nokia
Antwerp
BE
Email: gunter.van_de_velde@nokia.com
Keyur Patel
Arrcus
USA
Email: keyur@arrcus.com
Zhenbin Li
Huawei Technologies
Huawei Bld., No. 156 Beiquing Rd
Beijing 100095
China
Email: lizhenbin@huawei.com
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