Geneve encapsulation for Group Based Policy
draft-lemon-geneve-gbp-00

Abstract

This document describes how a Group Policy Identifier is encapsulated in Geneve for the purposes of policy enforcement.

Status of This Memo

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Table of Contents

• 1. Introduction
• 2. Conventions
• 2.1. Requirement Language
• 2.2. Abbreviations
• 3. Group Based Policy Encapsulation in Geneve
• 4. IANA Considerations
• 5. Security Considerations
• 6. Normative References
• Authors' Addresses

1. Introduction

This document defines the group-based policy (GBP) encapsulation for Geneve [I-D.ietf-nvo3-geneve]. The GBP sub-header carries a 16-bit group policy ID that is semantically equivalent to the 16-bit group policy ID defined in [I-D.smith-vxlan-group-policy].

2. Conventions

2.1. Requirement 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 [RFC2119].

2.2. Abbreviations

Abbreviations used in this document:

GBP:

Group-Based Policy

Geneve:

Generic Network Virtualization Encapsulation

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 is defined below.

 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
|            GBP ID             |A|D|    Reserved               | ID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+

Figure 1: Group Based Policy as a Geneve Tunnel Option

The GBP header consists of 8 octets, as illustrated in Figure 1. The first 4 octets are the Geneve Tunnel Option 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. Two values are defined:

GBP_Source_ID:

The Group Policy ID associated with the source of the packet.

GBP_Destination_ID:

The Group Policy ID associated with the end destination of the packet.

Note that if the packet carries a GBP_Destination_ID, it MUST 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.

The next 4 octets are the GBP header, whose format is as follows:

Group Policy ID:

16-bit group policy identifier as as defined in [I-D.smith-vxlan-group-policy].

Policy Applied bit (A bit):

The A bit is set to 0 to indicate that the group policy has not (yet) been applied to this packet. Group policies MUST be applied by devices when the A bit is set to 0 and the destination Group has been determined. Devices that apply the group policy MUST set the A bit to 1 after the policy has been applied. The A bit is set to 1 to indicate that the group policy has already been applied to this packet. Policies that redirect the packet MUST NOT be applied by devices when the A bit is set. Policies that cause the packet to be dropped MAY be applied.

Don't Learn bit (D bit):

The D bit is set to 0 to indicate that the tunnel endpoint MUST NOT learn the source address of the encapsulated frame.

Reserved (14 bits):

reserved for future use. MUST be zero on transmission and ignored on receipt.

4. IANA Considerations

IANA is requested to allocate a Geneve "option class" number for GBP:

              +---------------+-------------+---------------+
              | Option Class  | Description | Reference     |
              +---------------+-------------+---------------+
              | x             | GBP_ID      | This document |
              +---------------+-------------+---------------+

5. 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 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.

6. Normative References

Authors' Addresses