IDR Working Group G. Van de Velde, Ed.
Internet-Draft Nokia
Intended status: Standards Track K. Patel
Expires: September 3, 2017 Arrcus
Z. Li
Huawei Technologies
March 2, 2017
Flowspec Indirection-id Redirect
draft-ietf-idr-flowspec-path-redirect-01
Abstract
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 into an
engineered path or into a service plane.
This document defines a new extended community known as redirect-to-
indirection-id (32-bit) flowspec action to provide advanced
redirection capabilities on flowspec clients. When activated, the
flowspec extended community is used by a flowspec client to find the
correct next-hop entry within a localised indirection-id mapping
table.
The functionality present in this draft allows a network controller
to decouple flowspec functionality from the creation and maintainance
of the network's service plane itself including the setup of tunnels
and other service constructs that could be managed by other network
devices.
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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This Internet-Draft will expire on September 3, 2017.
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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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. indirection-id and indirection-id table . . . . . . . . . . . 3
3. Use Case Scenarios . . . . . . . . . . . . . . . . . . . . . 4
3.1. Redirection shortest Path tunnel . . . . . . . . . . . . 4
3.2. Redirection to path-engineered tunnels . . . . . . . . . 5
3.3. Redirection to complex dynamically constructed tunnels . 6
4. Redirect to indirection-id Community . . . . . . . . . . . . 7
5. Redirect using localised indirection-id mapping table . . . . 8
6. Validation Procedures . . . . . . . . . . . . . . . . . . . . 9
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 . . . . . . . . . . . . . . . . . 12
Appendix A. Additional indirection_id types waiting for use-case
description . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
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1. Introduction
Flowspec RFC5575 [2] is an extension to BGP that allows for the
dissemination of traffic flow specification rules. This has many
possible applications, however the primary one for many network
operators is the distribution of traffic filtering actions for DDoS
mitigation.
Every flowspec policy route is effectively a rule, consisting of a
matching part (encoded in the NLRI field) and an action part (encoded
in one or more BGP extended communities). The flow-spec 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
using this technology can be cumbersome when there is need to steer
the traffic onto an engineered traffic path.
This draft proposes a new redirect-to-indirection-id flowspec action
facilitating an anchor point for policy-based forwarding onto an
engineered path or into a service plane. The flowspec client
consuming and utilizing the new flowspec indirection-id extended-
community constructs the redirection information based upon
information found within a localised indirection-id mapping table.
The localised mapping table is a table construct, sequenced by a
table key, providing next-hop information.
The redirect-to-indirection-id flowspec action is encoded in a newly
defined BGP extended community. The type of redirection is
identified as an extended community indirection-id type field.
This draft defines the indirection-id extended-community and a few
wellknown indirection-id types. The specific mechanics to construct
a localised indirection-id mapping table are out-of-scope of this
document.
2. indirection-id and indirection-id table
An indirection-id is an abstract number (32-bit value) used as
identifier for a localised indirection decision. The indirection-id
will allow a flowspec client to redirect traffic into a service plane
or consequently onto an engineered traffic path. For example, when a
BGP flowspec controller signals a flowspec client the indirection-id
extended community, then the flowspec client uses the indirection-id
to make a recursive lookup to find the next-hop information. The
indirection-id is used to find the corresponding next-hop information
within the localised indirection mapping table.
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The indirection-id table is localised on the router. The
indirection-id table is constructed out of table keys, each mapped to
localised redirection information. Each table key is composed by the
combining indirection-id type and an indirection-id 32-bit value.
Each entry in the indirection-table key maps to sufficient
information (parameters regarding encapsulation, egress-interface,
QoS, etc...) to successfully redirect traffic according flowspec
controller expectations.
3. Use Case Scenarios
This section describes use-case scenarios when deploying redirect-to-
indirection-id.
3.1. Redirection shortest Path tunnel
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
o 1 (Node ID): When the intent is to use a Segment Routing based
Indirection-id table on the flowspec client
Description:
The first use-case describes an example where a single flowspec route
(i.e. flowspec_route#1) is sent by a flowspec controller to many BGP
flowspec clients. This single flowspec route will instruct all
Flowspec clients to redirect matching dataflows onto a shortest-path
tunnel pointing towards a single IP destination address.
For this first use-case scenario, each flowspec client receives a
flowspec route (flowspec_route#1) which has the redirect-to-
indirection-id extended community attached. The extended redirect-
to-indirection-id community contains the table key consisting out of
the indirection-id type and indirection-id 32-bit value. The table
key is used on the flowspec client to map to the corresponding next-
hop information within the local indirection-id table. The finite
result of this operation is a remote tunnel end-point IP address
together with accordingly sufficient tunnel encapsulation information
to forward and encapsulate the data-packet accordingly.
Requirements:
For redirect to shortest path tunnel it is required that the tunnel
MUST be operational and allow packets to be exchanged between tunnel
head- and tail-end.
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3.2. Redirection to path-engineered tunnels
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
o 6 (Binding Segment ID): When the intent is to use a Segment
Routing based Indirection-id table on the flowspec client
Description:
The second use-case describes an example where a flowspec controler
injects a single flowspec route which gets distributed to many BGP
flowspec clients. This single flowspec route intends to instruct all
Flowspec clients to redirect corresponding dataflows onto a path
engineered tunnel. It is expected that each of the path engineered
tunnels is instantiated by out-of-band mechanisms. Each used path
engineered tunnel has a unque table key identifier. consequently, the
table key uniquely identifies exactly -one- path engineered tunnel.
In this use-case example, the flowspec controller sends a flowspec
route to each of the flowspec clients and this flowspec route has a
redirect-to-indirection-id extended community attached. The
redirect-to-indirection-id extended community embeds table key
information and hence provides sufficient information to select the
corresponding path-engineered tunnel to redirect the packet according
the flowspec controller expectations.
Segment Routing Example:
A concrete embodiment of a Segment Routing use-case example is found
in networks where path engineered tunnels are created by a Segment
Routing MPLS label stack. In such a deployment, the indirection-id
provides an anchorpoint reference to a Segment Routing Binding SID.
However, the indirection-id type provides a pointer to the Binding
SID semantics to be used. 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 can for example
be setup by a controller using BGP as specified in [I-D.sreekantiah-
idr-segment-routing-te] [5] or by using PCEP as detailed 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 traffic
filtering rule that matches particular packets and redirects them
onto an explicit path associated with the corresponding Binding SID.
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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 and allow packets to be exchanged
between tunnel head- and tail-end.
3.3. Redirection to complex dynamically constructed tunnels
Example: Indirection-ID community types to be used:
o 0 (localised ID) with TID: When the intent is to use a localised
Indirection-id table, then TID (Table-ID) field could be used to
sequence multiple redirect-to-indirection-id actions together to
construct a more complex path engineered tunnel. The order of
sequencing the redirection information may be identified by using
the TID field.
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 flowspec route with multiple 'redirect-
to-indirection-id' communities attached. A recipient flowspec client
may use the Table-ID (TID) field embedded within each 'redirect-to-
indirection-id' community to sequence the redirect information. The
complex dynamically constructed tunnel is the product of
concatenating the available redirect information (i.e. MPLS Segment
Routing Labels).
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 into a Segment Routing Central
Egress Path Engineered tunnel [4]. For this particular complex
dynamic redirect tunnel embodiment, a first redirect-to-indirection-
id (i.e. TID=0) is used to redirect traffic into a tunnel towards a
particlar egress router, while a second redirect-to-indirection-id
(i.e. TID=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 labels. A first MPLS label
(the outer label) to steer the original packet to the egress node
(and hence using a shortest path tunnel), while a second MPLS label
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(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 data-plane principles are documented by
[4].
Requirements:
To achieve redirection towards complex dynamically constructed
tunnels, for each flowspec route, multiple indirection-ids, each
using a unique Tunnel ID may imposed upon a given flowspec policy
rule. It is required that there is synchronisation established
between the data- and control-plane of all relevant devices involved.
Each complex dynamically constructed tunnel MUST be operational and
allow packets to be exchanged between tunnel head- and tail-end
before it should be used to redirect traffic.
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
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.
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0 1
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| RES | TID |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' field identifies a 4 bit Table-id field. This field is
used to provide the flowspec client an indication how and where to
sequence the received indirection-ids to redirecting traffic. TID
value 0 indicates that Table-id field is NOT set and SHOULD be
ignored.
All bits other than the 'C' and 'TID' 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 the redirection information in the
localised indirection-id table.)
1 - Node ID (The flowspec client uses the received indirection-id
as a Segment Routing Node ID to redirect traffic towards)
6 - Binding Segment ID (The flowspec client uses the received
indirection-id as a Segment Routing Binding Segment ID to redirect
traffic towards) [I-D.draft-ietf-spring-segment-routing] [6]
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 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.
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6. Validation Procedures
The validation check described in RFC5575 [2] and revised in [3]
SHOULD be applied by default to received flow-spec routes with 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 invallid combination, it is
possible from a semenatics perspective to have multiple clashing
redirect actions defined within a single flowspec rule. For best and
consistant RFC5575 flowspec redirect behavior the redirect as
documented by RFC5575 MUST not be broken, and hence when a clash
occurs, then RFC5575 based redirect SHOULD 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
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 Agency ID [RFC-To-Be]
3 AS (Autonomous System) ID [RFC-To-Be]
4 Anycast ID [RFC-To-Be]
5 Multicast ID [RFC-To-Be]
6 Tunnel ID (Tunnel Binding ID ) [RFC-To-Be]
7 VPN ID [RFC-To-Be]
8 OAM ID [RFC-To-Be]
9 ECMP (Equal Cost Multi-Path) ID [RFC-To-Be]
10 QoS ID [RFC-To-Be]
11 Bandwidth-Guarantee ID [RFC-To-Be]
12 Security ID [RFC-To-Be]
13 Multi-Topology 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,
<http://www.rfc-editor.org/info/rfc5575>.
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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.
Appendix A. Additional indirection_id types waiting for use-case
description
This section is a placeholder and collection of potential additional
indirection_id types. The current use-cases do not require these
particular indirection types, however at later stage when use-cases
are identified they may be added to the body of teh draft.
2 - Agency ID (The flowspec client uses the received indirection-id
as a Segment Routing Agency ID to redirect traffic towards)
3 - AS (Autonomous System) ID (The flowspec client uses the received
indirection-id as a Segment Routing Autonomous System ID to redirect
traffic towards)
4 - Anycast ID (The flowspec client uses the received indirection-id
as a Segment Routing Anycast ID to redirect traffic towards)
5 - Multicast ID (The flowspec client uses the received indirection-
id as a Segment Routing Multicast ID to redirect traffic towards)
7 - VPN ID (The flowspec client uses the received indirection-id as a
Segment Routing VPN ID to redirect traffic towards)
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8 - OAM ID (The flowspec client uses the received indirection-id as a
Segment Routing OAM ID to redirect traffic towards)
9 - ECMP (Equal Cost Multi-Path) ID (The flowspec client uses the
received indirection-id as a Segment Routing PeerSet ID to redirect
traffic towards)
10 - QoS ID (The flowspec client uses the received indirection-id as
a Segment Routing QoS ID to redirect traffic towards)
11 - Bandwidth-Guarantee ID (The flowspec client uses the received
indirection-id as a Segment Routing Bandwidth-Guarantee ID to
redirect traffic towards)
12 - Security ID (The flowspec client uses the received indirection-
id as a Segment Routing Security ID to redirect traffic towards)
13 - Multi-Topology ID (The flowspec client uses the received
indirection-id as a Segment Routing Multi-Topology ID to redirect
traffic towards)
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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