Geneve applicability for service function chaining
draft-boutros-nvo3-geneve-applicability-for-sfc-00
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| Authors | Sami Boutros , Dharma Rajan , Philip Kippen | ||
| Last updated | 2017-10-27 | ||
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draft-boutros-nvo3-geneve-applicability-for-sfc-00
INTERNET-DRAFT Sami Boutros
Intended Status: Standard Track Dharma Rajan
Philip Kippen
VMware
Expires: April 30, 2018 October 27, 2017
Geneve applicability for service function chaining
draft-boutros-nvo3-geneve-applicability-for-sfc-00
Abstract
This document describes the applicability of using Generic Network
Virtualization Encapsulation (Geneve), to carry the service function
path (SFP) information, and the network service header (NSH) metadata
(MD) type 1 and type 2. The SFP information and MD types will be
carried in Geneve option TLV(s).
Status of this Memo
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Copyright and License Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Geneve Option TLV(s) . . . . . . . . . . . . . . . . . . . . . 4
4.1 Geneve Service Function List (SFL) Option TLV . . . . . . . 4
4.2 Geneve NSH metadata Option TLV . . . . . . . . . . . . . . . 6
5. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1 Operation at Ingress . . . . . . . . . . . . . . . . . . . . 7
5.2 Operation at each NVE along the service function path . . . 8
5.3 Operation at Egress . . . . . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9.1 Normative References . . . . . . . . . . . . . . . . . . . 11
9.2 Informative References . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
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1. Introduction
The Service Function Chaining (SFC) Architecture [rfc7665] defines a
service function chain (SFC) as (1) the instantiation of an ordered
set of service functions and (2) the subsequent "steering" of traffic
through them.
SFC defines a Service Function Path (SFP) as the exact set of service
function forwarders (SFF)/service functions (SF)s the packet will
visit when it actually traverses the network.
An optimized SFP helps to build an efficient Service function chain
(SFC) that can be used to steer traffic based on classification
rules, and metadata information to provide services for Network
Function Virtualization (NFV). Metadata are typically passed between
service functions and Service function forwarders SFF(s) along a
service function path.
The metadata can be encoded in packets using encapsulation protocols
as per network service header (NSH) [draft-ietf-sfc-nsh] definition
or simply using VLAN or Q-in-Q based encoding.
This document specifies the applicability of using Generic Network
Virtualization Encapsulation (Geneve), to carry the service function
path (SFP) information, and the network service header (NSH) metadata
(MD) types in Geneve option TLV(s).
The SFP will be implemented using a new Geneve Service Function List
option for use strictly between Network Virtualization Edges (NVEs)
performing the service forwarding function (SFF) in the same Network
Virtualization Overlay over Layer 3 NVO3 domain. The NSH Metadata
will be encoded in a new Geneve NSH metadata option TLV.
2. Terminology
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 [RFC2119].
3. Abbreviations
NVO3 Network Virtualization Overlays over Layer 3
OAM Operations, Administration, and Maintenance
TLV Type, Length, and Value
VNI Virtual Network Identifier
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NVE Network Virtualization Edge
NVA Network Virtualization Authority
NIC Network interface card
VTEP Virtual Tunnel End Point
Transit device Underlay network devices between NVE(s).
Service Function (SF): Defined in [RFC7665].
Service Function Chain (SFC): Defined in [RFC7665].
Service Function Forwarder (SFF): Defined in [RFC7665].
Service Function Path (SFP): Defined in [RFC7665].
Metadata: Defined in [[draft-ietf-sfc-nsh]
NFV: Network function virtualization.
VNF: Virtual network function
4. Geneve Option TLV(s)
4.1 Geneve Service Function List (SFL) Option TLV
Geneve Header:
0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver| Opt Len |O|C| Rsvd. | Protocol Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Virtual Network Identifier (VNI) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Geneve Option Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Class | Type |R|R|R| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Option Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option Class = To be assigned by IANA
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Type = To be assigned by IANA
'C' bit set, indicating endpoints must drop if they do not
recognize this option)
Length = variable.
Variable option data:
0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version|Flags |Reserved | SF Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ SF List[0] (32 or 128 bits IPv4/6 address) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
...
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ SF List [n] (32 or 128 bits IPv4/6 address) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// //
// Optional sub-Type Length Value objects (variable) //
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Service Function List (SFL) Option TLV.
Reserved: 12 bits. SHOULD be unset on transmission and MUST be
ignored on receipt.
Flags:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|H| Unused |
+-+-+-+-+-+-+-+-+
Figure 2: SFL flags
H-flag: HMAC flag. If set, the HMAC sub-TLV is present and is
encoded as the last sub-TLV.
SF Index: It contains the service function (SF) index, in SF List, it
is decremented after the packet is inspected by the service function.
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SF List[n]: 32 or 128 bits IPv4/6 addresses representing the nth
service function ip address in the List.
The SF List is encoded starting from the last hop of the path. I.e.,
the first element of the list (SF List [0]) contains the last service
function of the path while the last element of the SF List (SF
List[n]) contains the first service function in the path.
HMAC sub-TLV is optional and contains the HMAC information. The HMAC
sub-TLV has the following format:
0 1 2 3
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 | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HMAC Key ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| //
| HMAC (32 octets) //
| //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: SFL HMAC sub-TLV.
Type: to be assigned by IANA (suggested value 1). Length: 38.
Reserved: 2 octets. SHOULD be unset on transmission and MUST be
ignored on receipt. HMAC Key ID: 4 octets. HMAC: 32 octets. HMAC and
HMAC Key ID usage is described in Operation section.
The Following applies to the HMAC TLV:
When present, the HMAC sub-TLV MUST be encoded as the last sub-TLV.
If the HMAC sub-TLV is present, the H-Flag (Figure 2) MUST be set.
When the H-flag is set, the NVE inspecting the Geneve Service
Function List Option TLV MUST find the HMAC sub-TLV in the last 38
octets of the option TLV.
4.2 Geneve NSH metadata Option TLV
Geneve Option Header:
0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Class | Type |R|R|R| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Variable Option Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: NSH Metadata Option TLV
Option Class = NSH metadata, to be assigned by IANA.
Type = 1 for MD type 1 Type = 2 for MD type 2
'C' bit set, indicating endpoints must drop if they do not
recognize this option)
Length = 4 (16 bytes) for fixed or variable length.
Option data for MD-Type 1 will be a fixed 16 bytes value.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Fixed Length Context Header |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option data for MD-Type 2 will be of variable size.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Variable Length Context Headers (opt.) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5. Operation
5.1 Operation at Ingress
A Source NVE acting as a service function classifier and a service
function forwarder can be any node in an NVO3 domain, originating
based on a classification policy for some customer inner payload an
IP Geneve tunnel packet with the service function list (SFL) option
TLV. The service functions in the SFL represent the IP addresses of
the service functions that the inner customer packets needs to be
inspected by. A controller can program the ingress NVE node to
classify traffic and identify a service function paths i.e the set of
service functions in the path. The mechanism through which an SFL is
derived by a controller or any other mechanisms is outside of the
scope of this document.
The ingress NVE node fills in the list of service functions in the
path, to the Geneve Service Function List option TLV, putting the
first service function ip address as the last element in the list and
the last service function ip address as the first element, setting of
the service function index to the first element. The ingress NVE
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node, then, resolves the service first function ip address, to the
NVE virtual tunnel endpoint node hosting or directly connected to the
service function.
The Geneve tunnel destination is then set to the NVE tunnel endpoint
hosting the first service function, and the service function index is
decremented to n-1 (where n is the number of elements in the SFL),
and set on the SFL option TLV. A metadata option TLV can also be set
on the packet by the NVE ingress node.
The Geneve packet is sent out towards the first NVE.
HMAC optional sub-TLV may be set too.
5.2 Operation at each NVE along the service function path
The NVE node along the service function path corresponding to the
Geneve tunnel destination of the packet, receives the packet, perform
the service function forwarder function and identifies the SFL
option, and locates the service function in the list based on the
service function index.
The Geneve tunnel header and option TLV(s) will be stripped and the
packet will be delivered to the service function or virtual network
function (VNF), possibly along with some metadata that can identify
the SFL option TLV. The NVE maintains state related to the inner
packet, or some metadata association with the SFL option TLV. The
packet passed to the service function can possibly be encaped with
the NSH header, encoding in it a metadata TLV if the metadata
approach is used, and if the SF is NSH aware, other encapsulations
like vlan or q-in-q encap may be used to pass the metadata to the SF
too. The metadata passed to the SF can be associated with the SFL
option TLV.
When the packet comes back from the service function along with the
metadata context, based on the metadata on the packet or based on the
inner packet flow information the NVE acting as the SFF will be able
to locate the SFL option TLV.
If the metadata context indicate (1) that some service functions need
to be bypassed the NVE should bypass in the SFL the service functions
to be skipped and update the service function index accordingly. (2)
A new classification need to be performed on the packet, in that case
the NVE can re-classify the packet or sent it to an NVE node capable
of classification.
The NVE node, then, resolves the next service function ip address, to
the NVE virtual tunnel endpoint node hosting or directly connected to
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the service function.
The NVE then sets the Geneve tunnel destination to the next NVE
tunnel endpoint, and the service function index is decremented by 1
and set on the SFL option TLV, along with other NSH metadata option
TLV.
The Geneve packet is sent out towards the next NVE.
5.3 Operation at Egress
At the last NVE node along the service function path, the NVE locates
the service function in the SFL option TLV based on the service
function index. The service function index received at the last NVE
node will be set to 1.
The Geneve tunnel header and option TLV(s) will be stripped and the
packet will be delivered to the service function, possibly along with
some metadata that can identify the SFL option TLV, the NVE can
maintain state related to the inner packet, or some metadata
association with the SFL option TLV.
When the packet comes back from the service function, based on some
metadata on the packet or based on the inner packet flow information
the NVE will be able to locate the SFL option TLV.
Given that the service function index will be set to 1, the last NVE
will now deliver the packet to the NVE hosting or directly connected
to the inner packet destination.
A packet received with a service function index of 0 MUST be dropped.
6. Security Considerations
Only NVE(s) that are the destinations of the Geneve tunnel packet
will be inspecting the List of Service Function next hops Option. A
Source routing option has some well-known security issues as
described in [RFC4942] and [RFC5095].
The main use case for the use of the Geneve List of Service Function
next hops Option will be within a single NVO3 administrative domain
where only trusted NVE nodes are enabled and configured participate,
this is the same model as in [RFC6554].
NVE nodes MUST ignore the Geneve List of Service Function next hops
Option created by outsiders based on NVA or trusted control plane
information.
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There is a need to prevent non-participating NVE node from using the
Geneve Service Function List option TLV, as described in [draft-ietf-
6man-segment-routing-header], we will use a security sub-TLV in the
Service Function List option TLV, the security sub-TLV will be based
on a key-hashed message authentication code (HMAC).
HMAC sub-TLV will contain:
HMAC Key-id, 32 bits wide;
HMAC, 256 bits wide (optional, exists only if HMAC Key-id is not 0).
The HMAC field is the output of the HMAC computation (per RFC 2104
[RFC2104]) using a pre-shared key identified by HMAC Key-id and of
the text which consists of the concatenation of:
The source IPv4/IPv6 Geneve tunnel address
Version and Flags
HMAC Key-id.
All addresses in the List.
The purpose of the HMAC optional sub-TLV is to verify the validity,
the integrity and the authorization of the Geneve Service Function
List option TLV itself.
The HMAC optional sub-TLV is located at the end of the Geneve Service
Function List option TLV.
The HMAC Key-id field serves as an index to the right combination of
pre-shared key and hash algorithm and except that a value of 0 means
that there is no HMAC field.
The HMAC Selection of a hash algorithm and Pre-shared key management
will follow the procedures described in [draft-ietf-6man-segment-
routing-header] section 6.2.
7. Acknowledgements
8. IANA Considerations
This document makes the following registrations in the "Geneve Option
Class" registry maintained by IANA:
Suggested Description Reference
Value
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----------------------------------------------------------
XX Geneve List of Service Function next hops This document
XX Geneve NSH Metadata This document
In addition, this document request IANA to create and maintain a new
Registry: "Geneve List of Service Function next hops Type-Value
Objects".
The following code-point are requested from the registry:
Registry: Geneve List of Service Function next hops Type-Value
Objects
Suggested Description Reference
Value
-----------------------------------------------------
1 HMAC TLV This document
9. References
9.1 Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
9.2 Informative References
[Geneve] "Generic Network Virtualization Encapsulation", [I-D.ietf-
nvo3-geneve]
[I-D.ietf-sfc-nsh] Quinn, P., Elzur, U., and C. Pignataro, "Network
Service Header (NSH)", draft-ietf-sfc-nsh-16 (work in progress), July
2017.
[RFC4942] Davies, E., Krishnan, S., and P. Savola, "IPv6
Transition/Co-existence Security Considerations", RFC 4942, DOI
10.17487/RFC4942, September 2007, <http://www.rfc-
editor.org/info/rfc4942>.
[RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
Routing Header for Source Routes with the Routing Protocol for Low-
Power and Lossy Networks (RPL)", RFC 6554, DOI 10.17487/RFC6554,
March 2012, <http://www.rfc-editor.org/info/rfc6554>.
[draft-ietf-6man-segment-routing-header] Previdi, S., et all, "IPv6
Segment Routing Header (SRH)", July 20, 2017, draft-ietf-6man-
segment-routing-header-07
[RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation
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of Type 0 Routing Headers in IPv6", RFC 5095, DOI 10.17487/RFC5095,
December 2007, <http://www.rfc-editor.org/info/rfc5095>.
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665, DOI 10.17487/RFC7665, October
2015, <https://www.rfc-editor.org/info/rfc7665>.
Authors' Addresses
Sami Boutros
VMware
Email: sboutros@vmware.com
Dharma Rajan
VMware
Email: drajan@vmware.com
Philip Kippen
VMware
Email: pkippen@vmware.com
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