Internet Engineering Task Force J. Lemon, Ed.
Internet-Draft Broadcom
Intended status: Standards Track M. Smith
Expires: November 1, 2019 Cisco
A. Isaac
Juniper
April 30, 2019
Geneve encapsulation for Group Based Policy
draft-lemon-geneve-gbp-03
Abstract
This document describes how a Group Policy Identifier is encapsulated
in Geneve for the purposes of policy enforcement.
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 November 1, 2019.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions . . . . . . . . . . . . . . . . . . . . . . . 2
1.2. Abbreviations used in this document . . . . . . . . . . . 2
2. Treatment By Intermediate Nodes . . . . . . . . . . . . . . . 3
3. Group Based Policy Encapsulation in Geneve . . . . . . . . . 3
4. Use Of Multiple GBP shim headers . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5.1. Genve Option Class Value . . . . . . . . . . . . . . . . 5
5.2. GBP Type Values . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
This document defines the group-based policy (GBP) encapsulation for
Geneve [I-D.ietf-nvo3-geneve]. The GBP shim header carries a group
policy ID that is semantically equivalent to the group policy ID
defined in [I-D.smith-vxlan-group-policy].
Group-based policy provides a more scalable alternative to access
control lists (ACLs) by allowing separation of source marking and
destination enforcement. This allows a decrease in the amount of
information needed at each entry node, rather than a cross product of
every possible source and every possible destination. It also allows
assigning source marking based many different possibilities, not just
the source address. It also allows not having to know where the
packet will end up since whatever the destination is can enforce the
policy specific to the destination service.
1.1. Conventions
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 [RFC2119].
1.2. Abbreviations used in this document
GBP: Group-Based Policy
Geneve: Generic Network Virtualization Encapsulation
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2. Treatment By Intermediate Nodes
Any receiving device may use the group policy information contained
in the Group-Based Policy (GBP) shim header. If an intermediate
device applies policy based upon the GBP shim header, then it must
set the Policy Applied Bit, described below.
Because the group policy information is associated with the payload
(rather than the tunnel or other means by which it is conveyed), if
an intermediate device terminates the Geneve tunnel and
reencapsulates the data in a new tunnel with the ability to convey
the group policy information, it SHOULD propagate the group policy
information and the Policy Applied bit into the new tunnel, unless
there is an explicit policy not to do so. If an intermediate device
can propagate only some of the group policy IDs, it SHOULD propagate
as many as it can, and it MUST select which ones to propagate by the
sequence that the GBP IDs are placed in the Geneve header.
3. Group Based Policy Encapsulation in Geneve
For encapsulating group policy IDs into Geneve [I-D.ietf-nvo3-geneve]
the group policy ID field is included in the Geneve header using
tunnel options. The Group Policy ID field uses a tunnel option class
specific for GBP. In an administrative domain where GBP is used,
insertion of the GBP tunnel option in Geneve is enabled at the Geneve
tunnel endpoints. The Geneve header is defined in
[I-D.ietf-nvo3-geneve]. GBP semantics are described in
[I-D.smith-vxlan-group-policy].
The packet format of the GBP ID when encapsulated in Geneve with a
narrow Group Policy ID is shown in Figure 1.
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 | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Hdr
| Virtual Network Identifier (VNI) | Reserved | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
| Option Class = GBP | Type |R|R|R| Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ GBP
|A| Rsvd |Ver| Reserved | Group Policy ID | ID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
Figure 1: Group Based Policy as a Geneve Option Shim
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The GBP shim header consists of 8 octets, as illustrated in Figure 1.
The first 4 octets are the Geneve Tunnel Option shim header
[I-D.ietf-nvo3-geneve], whose format is as follows:
Option Class: 16-bit unsigned integer that determines the GBP option
class. The value is from the IANA registry setup for Geneve
option classes as defined in [I-D.ietf-nvo3-geneve].
Type: 8-bit unsigned integer defining the GBP ID type. The
following values are defined:
0x00: GBP_Source_ID. A value of 0 indicates that this shim header
carries the Group Policy ID associated with the source of the
packet.
0x01: GBP_Destination_ID. A value of 1 indicates that this shim
header carries the Group Policy ID associated with the end
destination of the packet.
0x02 to 0x7F: Unassigned. For assignment by IANA, as described in
Section 5.
0x80 to 0xFF: Locally Assigned. For local assignment.
If a packet carries a GBP_Destination_ID, it SHOULD also carry a
GBP_Source_ID.
R (3 bits): Option control flags reserved for future use. MUST be
zero on transmission and ignored on receipt.
Length: 5-bit unsigned integer. Length of the GBP HDR in 4-octet
units excluding the option header. The value of this field is 1
for this version.
The next 4 octets are the GBP shim header, whose format is as
follows:
Policy Applied bit (A bit): The A bit MUST be set on a specific GBP
shim header if a frame is returned to a forwarding instance that
it has already visited after having been redirected at a
forwarding instance along the native forwarding path to its
destination by a redirection policy that matched on the value in
that specific GBP shim header. If a GBP option type has the A bit
set, a redirection policy that matches on this GBP option type
MUST not be applied. Redirection policies MAY continue to be
applied so long as they only match on GBP option types that do not
have the A bit set. This procedure is necessary to prevent
forwarding loops. The method that ensures that on returned frames
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the A bit is applied only to GBP option types involved in the
match at the original redirection policy is outside the scope of
this draft. Once an A bit is set on a GBP shim header, it MUST
remain set. Additionally, once a GBP ID is set for a GBP option
type it SHOULD not be changed to avoid redirection related loops.
Rsvd (5 bits): reserved for future use. MUST be zero on
transmission and ignored on receipt.
Ver (2 bits): indicates the Version of the Group Policy shim header.
The initial version is 0.
Reserved (8 bits): When using a 16-bit Group Policy ID, these 8 bits
are reserved for future use and MUST be set to zero on
transmission and ignored on receipt.
Group Policy ID: 16-bit identifier that indicates the Group Policy
ID being encapsulated by this GBP shim header. The Default GBP ID
value is special and indicates that the GBP option was not set.
Packet filters SHOULD be able to match on the Default GBP ID value
as a way to match packets that do not have the GBP option set.
The default Default GBP ID is 0, but MAY be configured to be a
value other than 0. The allocation of Group Policy ID values is
outside the scope of this document.
4. Use Of Multiple GBP shim headers
A tunnel header MAY carry multiple GBP shim headers where each GBP
shim header carries a unique GBP type. There MUST be only one shim
header of a specific GBP type per tunneled packet.
5. IANA Considerations
5.1. Genve Option Class Value
IANA is requested to allocate a Geneve "option class" number for GBP:
+---------------+-------------+---------------+
| Option Class | Description | Reference |
+---------------+-------------+---------------+
| TBD | GBP_ID | This document |
+---------------+-------------+---------------+
5.2. GBP Type Values
IANA is requested to set up a registry of "GBP Type". These are
8-bit values. GBP Type values in the table below are defined in this
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draft. New values in the range of 0x02 through 0x7F are assigned via
Standards Action [RFC5226].
+----------------+--------------------+---------------+
| GBP Type Value | Description | Reference |
+----------------+--------------------+---------------+
| 0x00 | GBP_Source_ID | This document |
+----------------+--------------------+---------------+
| 0x01 | GBP_Destination_ID | This document |
+----------------+--------------------+---------------+
| 0x02 - 0x7F | Unassigned | |
+----------------+--------------------+---------------+
| 0x80 - 0xFF | Local assignment | |
+----------------+--------------------+---------------+
6. Security Considerations
The security considerations of Geneve are discussed in
[I-D.ietf-nvo3-geneve]. The security considerations of GBP are
discussed in [I-D.smith-vxlan-group-policy].
Additionally, the security policy value carried in the GBP shim
header impacts security directly. There is a risk that this
identifier could be altered. Accordingly, the network should be
designed such that this header can be inserted only by trusted
entities, and can not be altered before reaching the destination.
This can be mitigated through physical security of the network and/or
by encryption or validation of the entire packet, including the GBP.
7. Normative References
[I-D.ietf-nvo3-geneve]
Gross, J., Ganga, I., and T. Sridhar, "Geneve: Generic
Network Virtualization Encapsulation", draft-ietf-
nvo3-geneve-13 (work in progress), March 2019.
[I-D.smith-vxlan-group-policy]
Smith, M. and L. Kreeger, "VXLAN Group Policy Option",
draft-smith-vxlan-group-policy-05 (work in progress),
October 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<https://www.rfc-editor.org/info/rfc5226>.
Authors' Addresses
John Lemon (editor)
Broadcom Inc.
270 Innovation Drive
San Jose, CA 95134
USA
Email: john.lemon@broadcom.com
Michael Smith
Cisco Systems
Email: michsmit@cisco.com
Aldrin Isaac
Juniper Networks
1133 Innovation Way
Sunnyvale, CA 94089
USA
Email: aldrin.isaac@gmail.com
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