Internet DRAFT - draft-vandevelde-idr-flowspec-path-redirect
draft-vandevelde-idr-flowspec-path-redirect
IDR Working Group G. Van de Velde, Ed.
Internet-Draft W. Henderickx
Intended status: Standards Track Alcatel-Lucent
Expires: September 18, 2016 K. Patel
A. Sreekantiah
Cisco Systems
March 17, 2016
Flowspec Indirection-id Redirect
draft-vandevelde-idr-flowspec-path-redirect-02
Abstract
Flow-spec 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,
particular if the redirected traffic needs to be steered into an
engineered path or into a service plane.
This document defines a new redirect-to-INDIRECTION_ID (32-bit or
128-bit) flow-spec action to provide advanced redirection
capabilities. When activated, the flowspec Indirection-id is used to
identify the next-hop redirect information within a router locallized
Indirection-id table. This allows a flowspec controller to signal
redirection towards a next-hop IP address, a shortest path tunnel, a
traffic engineered tunnel or a next-next-hop engineered tunnel
interface.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Van de Velde, et al. Expires September 18, 2016 [Page 1]
Internet-Draft Flowspec Indirection-id Redirect March 2016
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 September 18, 2016.
Copyright Notice
Copyright (c) 2016 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
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 . . . . . . . . . . . . . . . . . . . . . 4
3.1. Redirection shortest Path tunnel . . . . . . . . . . . . 4
3.2. Redirection to path-engineered tunnels . . . . . . . . . 4
3.3. Redirection to Next-next-hop tunnels . . . . . . . . . . 5
4. Redirect to INDIRECTION-ID Communities . . . . . . . . . . . 6
5. Redirect using locallized INDIRECTION_ID Router Mapping . . . 7
6. Validation Procedures . . . . . . . . . . . . . . . . . . . . 8
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
10.1. Normative References . . . . . . . . . . . . . . . . . . 9
10.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
Flow-spec RFC5575 [2] 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.
Van de Velde, et al. Expires September 18, 2016 [Page 2]
Internet-Draft Flowspec Indirection-id Redirect March 2016
Every flow-spec 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 community). 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 for redirecting traffic towards an
alternate destination is useful for DDoS mitigation but using this
technology can be cumbersome when there is need to redirect the
traffic onto an engineered traffic path.
This draft proposes a new redirect-to-Indirection-id flow-spec action
facilitating an anchor point for policy-based forwarding onto an
engineered path or into a service plane. The router consuming and
utilizing the flowspec rule makes a local mapping between the
flowspec signalled redirect Indirection-id and locally available
redirection information referenced by the Indirection-id. This
locally available redirection information is derived from out-of-band
programming or signalling.
The redirect-to-Indirection-id is encoded in a newly defined BGP
extended Indirection_ID community.
The construction of the Indirection-id redirect table and the
technology used to create an engineered path are out-of-scope of this
document.
2. INDIRECTION_ID and INDIRECTION_ID Table
An INDIRECTION_ID is an abstract number (32-bit or 128-bit value)
used as identifier for a localised redirection decision. e.g. When a
BGP flowspec controller intends to redirect a flow using te redirect-
to-INDIRECTION_ID action then it has the ability to redirect the flow
to a destination abstracted as the INDIRECTION_ID. The device
receiving the BGP flowspec rule will use the INDIRECTION_ID to
identify the next-hop and the relevant tunnel encapsulations that
need to be pushed by a localised recursive lookup using information
located within the INDIRECTION_ID table.
The INDIRECTION_ID Table is a router localised table. The table
content is constructed out of INDIRECTION_IDs and corresponding
redirect information which may be of rescursive or non-recursive
nature. When the redirect information is non-recursive, then the
represented information MUST be sufficient to identify the local
egress interface and the corresponding required encapsulations.
However, if the information is recursive, then the represented
information MUST be sufficient to identify the local egress interface
and corresponding encapsulations using additional recursions.
Van de Velde, et al. Expires September 18, 2016 [Page 3]
Internet-Draft Flowspec Indirection-id Redirect March 2016
3. Use Case Scenarios
This section describes use-case scenarios when deploying redirect-to-
INDIRECTION_ID.
3.1. Redirection shortest Path tunnel
A first use-case is allowing a BGP Flowspec controller send a single
flowspec policy message (redirect-to-INDIRECTION_ID#1) to many BGP
flowspec consuming routers. This message is instructing the Flowspec
recipient routers to redirect traffic onto a tunnel to a single IP
destination address.
For this use-case scenario, each flowspec recipient router has a
tunnel configured following the shortest path towards a tunnel IP
destination address. Each tunnel can have its own unique
encapsulation associated. Each tunnel is associated with an
INDIRECTION_ID, and for this example it is on all recipient routers
INDIRECTION_ID#1. Both manual and orchestrated tunnel provisioning
is supported, however for large scale deployment automation is
advisable.
When using this setup, a BGP flowspec controller can send a single
BGP Flowspec NLRI with redirect-to-INDIRECTION_ID#1. This BGP
Flowspec NLRI is received by all recipient routers. Each of the
recipient routers performs a locallised recursive lookup for
INDIRECTION_ID#1 in the INDIRECTION_ID Table and identifies the
corresponding locallised tunnel redirect information. This
locallised tunnel information is now used to redirect traffic
matching the Flowspec policy towards a tunnel, each potentially using
its own unique tunnel encapsulation.
3.2. Redirection to path-engineered tunnels
A second use-case is allowing a BGP Flowspec controller send a single
flowspec policy message (redirect-to-INDIRECTION_ID#2) to many BGP
flowspec consuming routers. This message is instructing the Flowspec
recipient routers to redirect traffic onto a path engineered tunnel.
For this use-case scenario, each flowspec recipient router has a path
engineered tunnel configured. Each tunnel can have its own unique
encapsulation and engineered path associated. Each tunnel is
associated with an INDIRECTION_ID, and for this example it is on all
recipient routers INDIRECTION_ID#2. Both manual and orchestrated
tunnel provisioning is supported, however for large scale deployment
automation is advisable.
Van de Velde, et al. Expires September 18, 2016 [Page 4]
Internet-Draft Flowspec Indirection-id Redirect March 2016
A first example using this setup, is when a BGP flowspec controller
sends a single BGP Flowspec NLRI with redirect-to-INDIRECTION_ID#2.
This BGP Flowspec NLRI is received by all recipient routers. Each of
the recipient routers performs a locallised recursive lookup for
INDIRECTION_ID#2 in the INDIRECTION_ID Table and identifies the
corresponding locallised tunnel redirect information. This
locallised tunnel information is now used to redirect traffic
matching the Flowspec policy towards a path engineered tunnel.
A second example can be found in segment routed networks where path
engineered tunnels can be setup by means of a controller signaling
explicit paths to peering routers. In such a case, the
INDIRECTION_ID references to 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 with a explicit path and can be setup by a controller using
BGP as specified in [I-D.sreekantiah-idr-segment-routing-te] [5] or
using PCE as detailed in draft-ietf-pce-segment-routing [7]. When a
BGP speaker receives a flow-spec route with a 'redirect to Binding
SID' extended community, it installs a traffic filtering rule that
matches the packets described by the NLRI field and redirects them to
the explicit path associated with the Binding SID. The explicit path
is specified as a set/stack of segment identifiers as detailed in the
previous documents. The stack of segment identifiers is now imposed
on packets matching the flow-spec rule to perform redirection as per
the explicit path setup prior. The encoding of the Binding SID value
is specified in section 4, with the indirection field now encoding
the associated value for the binding SID.
3.3. Redirection to Next-next-hop tunnels
A Third use-case is allowing a BGP Flowspec controller send a single
flowspec policy message (redirect-to-INDIRECTION_ID#3) to many BGP
flowspec consuming routers. This message is instructing the Flowspec
recipient routers to redirect traffic onto a shortest or engineered
path to a tunnel end-point and onwards to the next-hop-interface on
this end-point. This type of tunnel is used for example for Segment
Routing Central Egress Path Engineering [4].
For this use-case scenario, each flowspec recipient router constructs
redirect information using two tunnel components. The first
component is a shortest or engineered path towards a network egress
router. The second component is the interface used on this network
egress router to which the redirected traffic needs to be steered
upon. The combination of these two components allows steering
towards the next-hop of the egress router, allowing for example the
Central Egress Path Engineering using BGP Flowspec [4].
Van de Velde, et al. Expires September 18, 2016 [Page 5]
Internet-Draft Flowspec Indirection-id Redirect March 2016
The redirection towards a next-next-hop tunnel can be done by using
either a single INDIRECTION_ID representing the combined path to the
egress router and steering the traffic to the egress interface, or by
using individual INDIRECTION_IDs each representing a tunnel component
(One INDIRECTION_ID value to identify the path towards the egress
router and another INDIRECTION_ID value to identify the egress
interface on this egress router towards the next-next-hop). When
using individual INDIRECTION_IDs it is required to use INDIRECTION_ID
community Tunnel IDs (TID) each identifying a component of the
complete redirect path attached to the NLRI.
i.e. when using next-next-hop tunnels, a BGP flowspec controller can
send a single BGP Flowspec NLRI with redirect-to-INDIRECTION_ID#3.
This BGP Flowspec NLRI is received by all recipient routers. Each of
the recipient routers performs a locallised recursive lookup for
INDIRECTION_ID#3 in the INDIRECTION_ID Table and identifies the
corresponding locallised tunnel redirect information (=path to the
egress router and the next-hop egress interface on this router).
Traffic matching the flowspec policy is redirected towards the
recursively found redirection information.
4. Redirect to INDIRECTION-ID Communities
This document defines a new BGP extended community. The extended
communities have a type indicating they are transitive and IPv4-
address-specific or IPv6-address-specific, depending on whether the
INDIRECTION_ID is 32-bit or 128-bit. The sub-type value [to be
assigned by IANA] indicates that the global administrator and local
administrator fields encode a flow-spec 'redirect to INDIRECTION_ID'
action. In the new extended community the 4-byte or 16-byte global
administrator field encodes the 32-bit or 128-bit INDIRECTION_ID's
providing the INDIRECTION_ID to allow a local to the router mapping
reference to an engineered Path. The 2-byte local administrator
field is formatted as shown in Figure 1.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |B|TID|C|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
In the local administrator field the least-significant bit is defined
as the 'C' (or copy) bit. When the 'C' bit is set the redirection
Van de Velde, et al. Expires September 18, 2016 [Page 6]
Internet-Draft Flowspec Indirection-id Redirect March 2016
applies to copies of the matching packets and not to the original
traffic stream.
The 'TID' field identifies a 2 bit Table-id field. This field is
used to provide the router consuming the flowspec rule an indication
how and where to use the INDIRECTION_ID when redirecting traffic.
Bit 2 is defined to be the 'B' (Binding) bit. When the 'B' bit is
set, the value encoded in the global administrator field is a Binding
Segment Identifier value the use of which is detailed in section 3.2.
All bits other than the 'C', 'TID' and 'B' bits in the local
administrator field MUST be set to 0 by the originating BGP speaker
and ignored by receiving BGP speakers.
5. Redirect using locallized INDIRECTION_ID Router Mapping
When a BGP speaker receives a flow-spec route with a 'redirect to
INDIRECTION_ID' extended community and this route represents the one
and only best path, it installs a traffic filtering rule that matches
the packets described by the NLRI field and redirects them (C=0) or
copies them (C=1) towards the INDIRECTION_ID local recursed Path.
The BGP speaker is expected to do a local INDIRECTION_ID Table lookup
to identify the redirection information.
The router local INDIRECTION_ID table contains a list of
INDIRECTION_ID's each mapped to redirect information. The redirect
information can be non-recursive (i.e. there is only one option
available in the INDIRECTION_ID Table) or recursive (i.e. L3 VPN, L2
VPN, a pre-programmed routing topology, etc... ).
o When the redirect information is non-recursive then the packet is
redirected based upon the information found in the Table.
o In case of a next-hop tunnel, the traffic matching the flowspec
rule is redirected to the next-hop tunnel. This tunnel could be
instantiated through various means (i.e. manual configuration,
PCEP, RSVP-TE, WAN Controller, Segment Routing, etc...).
o In case of redirection to a local next-hop interface, the traffic
matching the flowspec rule is redirected to the local next-hop
interface.
o In case the INDIRECTION_ID Table lookup results in redirect
information identifying an additional layer of recursion, then
this will trigger the flow to be redirected based upon an
additional routing lookup within the realm of the additional layer
of recursion.
Van de Velde, et al. Expires September 18, 2016 [Page 7]
Internet-Draft Flowspec Indirection-id Redirect March 2016
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.
It is possible from a semenatics perspective to have multiple
redirect actions defined within a single flowspec rule. When a BGP
flowspec NLRI has a 'redirect to INDIRECTION_ID' extended community
attached resulting in valid redirection then it MUST take priority
above all other redirect actions emposed. However, 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
'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 an
overflow of traffic being 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. IANA Considerations
This document requests a new sub-type from the "Transitive IPv4-
Address-Specific" extended community registry. The sub-type name
shall be 'Flow-spec Redirect to 32-bit Path-id'.
This document requests a new sub-type from the "Transitive IPv6-
Address-Specific" extended community registry. The sub-type name
shall be 'Flow-spec Redirect to 128-bit Path-id'.
10. References
Van de Velde, et al. Expires September 18, 2016 [Page 8]
Internet-Draft Flowspec Indirection-id Redirect March 2016
10.1. 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>.
10.2. 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)
Alcatel-Lucent
Antwerp
BE
Email: gunter.van_de_velde@alcatel-lucent.com
Van de Velde, et al. Expires September 18, 2016 [Page 9]
Internet-Draft Flowspec Indirection-id Redirect March 2016
Wim Henderickx
Alcatel-Lucent
Antwerp
BE
Email: wim.henderickx@alcatel-lucent.com
Keyur Patel
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
USA
Email: keyupate@cisco.com
Arjun Sreekantiah
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
USA
Email: asreekan@cisco.com
Van de Velde, et al. Expires September 18, 2016 [Page 10]
