wdiff draft-ietf-idr-flowspec-path-redirect-02.txt draft-ietf-idr-flowspec-path-redirect-03.txt

IDR Working Group G. Van de Velde, Ed.
Internet-Draft Nokia
Intended status: Standards Track K. Patel
Expires: March 3, June 23, 2018 Arrcus
Z. Li
Huawei Technologies
August 30,
December 20, 2017

Flowspec Indirection-id Redirect
draft-ietf-idr-flowspec-path-redirect-02
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 correct corresponding next-hop information within a localised
indirection-id mapping table.

The functionality detailed in this document allows a network
controller to decouple the BGP flowspec redirection instruction from
the actual selected redirection path selected. 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.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. indirection-id and indirection-id table . . . . . . . . . . . 3
3. Use Case Scenarios . . . . . . . . . . . . . . . . . . . . . 4 3
3.1. Redirection shortest Path tunnel . . . . . . . . . . . . 4 3
3.2. Redirection to path-engineered tunnels . . . . . . . . . 5 4
3.3. Redirection to complex dynamically constructed tunnels . 6 5
4. Redirect to indirection-id redirect-to-indirection-id Community . . . . . . . . . . . . 7 6
5. Redirect using localised indirection-id mapping table . . . . 8
6. Validation Procedures . . . . . . . . . . . . . . . . . . . . 9 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 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 a
matching part (encoded two
parts. The first part, encoded in the NLRI field) and an action part (encoded field, provides
information about the traffic matching the policy rule. the second
part, encoded in one or more BGP extended communities). communities, provides
policy instructions for traffic handling on the flowspec client. The flow-spec
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 but
mitigation, however using this technology methodology can be cumbersome when
there is need to steer the traffic onto an explicitely defined
traffic path.

This draft proposes specifies a new redirect-to-indirection-id flowspec action
making use of a 32-bit indirection-id within using a new extended community.
Each indirection-id serves as anchor point, for policy-
based policy-based
forwarding onto an explicite path on by a flowspec client.

A flowspec based indirection service plane can be create when a
single 32-bit flowspec indirection-id maps towards a pool of
explicite paths.

2. indirection-id and indirection-id table

The indirection-id is a 32-bit unsigned number, used as anchor point
on a flowspec client. The indirection-id is on a flowspec client the
lookup key-value within a localised list of potential indirection
paths. The indirection-id will allow the flowspec client to steer
traffic to a particular path or into for policy-based forwarding onto an indirection service plane explicite
path by
doing a recursive key-value lookup. flowspec client.

The indirection-id table is the table containing an ordered list construct of indirection-id key-values,
values, ordered by indirection-id type; where each
key-value maps towards a particular path or set of paths. The
indirection-id type MAY provide additional context about the
indirection-id 32-bit value. The flowspec client MUST use the
indirection-id as key-value within the indirection-id type
corresponding indirection-id type. Each entry in this table to locate the explicite path and
corresponding next-hop information.
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 and is a localised construct
on each router.
flowspec. For some use-case scenarios the indirection-id type
provides additional (maybe even fully sufficient) context towards for a
flowspec client to deduct automatic, without explicite out-of-band
configuration, the for policy based forwarding, making a localized
indirection-id table. table obsolete. For example, when the indirection-id
refers to a MPLS segment routing node-id [6], then
indirection-id type can provide the flowspec client the awareness
that the indirection-id is
provides sufficient information for a segment routing node-id. For this
example the indirection-id type allows the flowspec clients to do a
recursive lookup using traditional segment routing technology.

To summarise, each indirection-id key-value entry in on the indirection-
table maps recursively to sufficient next-hop information (parameters
regarding encapsulation, egress-interface, QoS, etc...) to
successfully indirect traffic according
flowspec controller
expectations. client.

3. Use Case Scenarios

This section describes a few use-case scenarios when deploying redirect-to-
indirection-id.
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
flowspec clients to redirect matching dataflows onto a shortest-path
tunnel pointing towards a single remote destination.

For

In this first use-case scenario, each flowspec client receives
flowspec routes. The received flowspec routes have the extended redirect-to-
indirection-id
redirect-to-indirection-id community attached. Each redirect-to-indirection-id redirect-to-
indirection-id community embeds two relevant components: (1) 32-bit
indirection-id
key-value and (2) indirection-id type. The indirection-id type is
used to identify the corresponding indirection-id table, and the
actual 32-bit indirection-id key-value is used within the
indirection-id table to locate These two components
provide the corresponding next-hop
information. The finite result of this operation is flowspec client with sufficient
tunnel encapsulation information for policy
based forwarding to forward steer and encapsulate the data-
packet data-packet accordingly
to a remote shortest path tunnel to a remote end-point.

Requirements:

For redirect to shortest path tunnel it is required that the tunnel
MUST be up-and-running operational and allow packets to be unidirectional
exchanged 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 on the flowspec client. This requires out-
of-band configuration of the indirection-id table table, configured through out-of-band procedures.

o 1 or 2 (Node ID): When ID's): This type can be used when the intent goal is to use a Segment Routing
MPLS based
Indirection-id table on the flowspec client. This requires that Segment Routing is enabled on towards a remote destination. In this
use-case scenario the flowspec client. 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 the redirect-to-
indirection-id extended community to all flowspec clients with
instructions policy information to redirect matching dataflows onto steer
traffic upon a path engineered path-engineered tunnel. It is expected assumed that each of the path
engineered tunnels is
instantiated by out-of-band configuration and can be uniquely
identified by the combination of (1) indirection-id 32-bit key-value
and (2) indirection-id type.

For this second use-case scenario, each flowspec client receives
flowspec routes. The flowspec routes have the extended redirect-to-
indirection-id community attached. Each redirect-to-indirection-id
community embeds two relevant components similar as explained in
previous use-case. However the finite result of this operation is
sufficient tunnel encapsulation information to forward and
encapsulate the data-packet accordingly to a remote tunnel end-point are configured using a path engineered tunnel construction. out-of-band from BGP
flowspec.

Segment Routing Example:

For this example the indirection-id type informs the flowspec client
that the indirection-id 32-bit key-value references 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] [I-D.draft-ietf-spring-
segment-routing] [6]) used to associate an explicit path. The
Binding SID and corresponding path engineered tunnel can may for example
be setup by a controller using BGP as specified in [I-D.sreekantiah-idr-segment-
routing-te] [I-D.sreekantiah-
idr-segment-routing-te] [5] or alternatly by using PCEP as detailed
in draft-ietf-pce-
segment-routing 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' 'redirect-to-indirection-id' community, it installs a traffic filtering
policy-based forwarding rule that
matches particular to redirect packets and redirects them 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
engineered
tunnel MUST be active operational and allow packets to be
unidirectional exchanged 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 use a localised policy-based steer traffic
using Indirection. The engineered path is configured through out-
of-band procedures and uses the 32-bit Indirection-id table as local
anchor point on the local flowspec client. This requires out-
of-band configuration of the indirection-id table.

o 6 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 use policy-based steer traffic
using a Segment
Routing based global tunnel-id. The engineered path is configured
through out-of-band procedures and uses the 32-bit Indirection-id table
as global anchor point on the local flowspec client. This
requires out-of-band configuration of the Binding Segment IDs.

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 'redirect-to-
indirection-id' unique
'redirect-to-indirection-id' communities attached, each community
tagged with a different
Table-ID (TID). Sequence-ID (S-ID). A flowspec client may
use the Table-ID (TID) 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.

dirty traffic flows) may be steered 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 redirect-to-
indirection-id (i.e. TID=0)
is S-ID=0) may be used to redirect traffic into a
tunnel towards a particlar particular egress router, while a second redirect-to-indirection-id redirect-
to-indirection-id (i.e. TID=1) S-ID=1) is used to steer traffic beyond the
particular egress router towards a pre-identified interface/peer.

For this DDoS use-case, in its simplest embodiment, the flowspec
client must dynamically append 2 MPLS Segment Routing labels. A
first MPLS Segment Routing label (the outer label) to steer the
packet to the egress node (and hence use a shortest path tunnel),
while a second MPLS label (matching redirect-to-indirection-id with
TID=1), the inner label, to steer on the egress router the original
packet to a pre-defined interface/peer. The basic
From data-plane perspective, the principles are documented by [4]. [4] are
valid for this use case scenario.

Requirements:

To achieve redirection towards complex dynamically constructed
tunnels, for each flowspec route, multiple indirection-ids, each
using a unique Tunnel ID various indirection-id communities are pushed imposed upon a given the
flowspec policy
rule. It route and are sequenced using the Sequence ID (S-ID). For
redirect to complex dynamic engineered tunnels it is required that there is synchronisation established
between
the data-plane and control-plane of all relevant devices
involved. Each complex dynamically constructed tunnel MUST be operational and allow packets to be unidirectional exchanged steered over
the engineered path between
tunnel head- and tail-end before it can be used to redirect traffic. tunnel head- and tail-end.

Example: Indirection-ID community types to be used:

o 0 (localised ID) with TID: S-ID: When the intent is to use construct a localised
Indirection-id table,
dynamic engineered tunnel, then the TID (Table-ID) 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 order construction
of sequencing
the redirection information MUST be identified by using the TID
field.

4. Redirect to 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.

Figure 1

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 | TID 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 'TID' 'S-ID' field identifies a 4 bit Table-id Sequence ID field. This field is
used to provide the a flowspec client an indication how and where to
sequence the received indirection-ids to redirecting traffic. TID indirection-ids. The Sequence ID value 0
indicates that Table-id 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 TID S-ID MUST
be processed imposed first for a any given flowspec route. entry.

All bits other than the 'C' and 'TID' '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
indirection-id Types:

0 - Localised ID (The flowspec client uses the received
indirection-id to lookup the redirection forwarding information in within the
localised indirection-id table. The allocation and programming of
the localised indirection-id table.) table is outside scope of the
document)

1 - Node ID (The flowspec client uses the received with SID/index in MPLS-based Segment Routing (This
means indirection-id is mapped to an MPLS label using the index as
a Segment Routing global offset in the SID/label space)
2 - Node ID with SID/label in MPLS-based Segment Routing (This
means indirection-id is mapped to redirect traffic towards)

6 an MPLS label using the label as
global label)

3 - Binding Segment ID (The flowspec client uses the received with SID/index in MPLS-based Segment
Routing (This means indirection-id is mapped to an MPLS binding
label using the index as a Segment Routing 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 redirect
traffic towards) 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 traffic
filtering policy-based
forwarding rule matching the IP 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 to by a flowspec client, for received flow-spec
flowspec policy routes with containing a
'redirect to indirection-id' '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 invallid invalid combination, it is
possible from a semenatics semantics perspective to have multiple clashing
redirect actions defined within a single flowspec rule. For best and
consistant RFC5575 flowspec redirect behavior with legacy implementations, the redirect functionality as
documented by RFC5575 MUST not NOT be broken, and hence when a clash
occurs, then RFC5575 based redirect SHOULD MUST take priority.
Additionally, if the 'redirect to indirection-id' 'redirect-to-indirection-id' does not result in
a valid redirection, then the flowspec rule must MUST be processed as if
the 'redirect to indirection-id' 'redirect-to-indirection-id' community was not attached to the
flowspec route and MUST provide an indication within the BGP routing
table that the respective 'redirect to indirection-id' '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:

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 redirect-to-
indirection-id Extended community from the "Transitive Extended
community" registry. The Type name shall be "Redirect to "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
redirect-to-indirection-id Extended Community INDIRECTION-IDs as
follows:

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]
6 Tunnel ID (Tunnel
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.

[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