Group Policy Encoding with VXLAN-GPE and LISP-GPE
draft-lemon-vxlan-lisp-gpe-gbp-01

Abstract

This document defines header companions for the Generic Protocol Extension for Virtual eXtensible Local Area Network (VXLAN-GPE) and for the Locator/ID Separation Protocol (LISP) Generic Protocol Extension (LISP-GPE) that are used to carry a Group Policy Identifier for the purposes of policy enforcement.

Status of This Memo

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Table of Contents

• 1. Introduction
• 1.1. Conventions
• 1.2. Abbreviations used in this document
• 2. Treatment By Intermediate Nodes
• 3. Group Based Policy Sub-header
• 3.1. Common GBP Sub-Header Format
• 4. Use Of Multiple GBP Sub-options
• 5. IANA Considerations
• 6. Security Considerations
• 7. Normative References
• Authors' Addresses

1. Introduction

This document defines the group-based policy (GBP) sub-header for VXLAN-GPE [I-D.ietf-nvo3-vxlan-gpe] and the GBP sub-header for LISP-GPE [I-D.ietf-lisp-gpe]. 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].

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 RFC 2119.

1.2. Abbreviations used in this document

GBP:

Group-Based Policy

LISP-GPE:

Locator/ID Separation Protocol Generic Protocol Extension [I-D.ietf-lisp-gpe]

VXLAN-GPE:

Virtual eXtensible Local Area Network, Generic Protocol Extension [I-D.ietf-nvo3-vxlan-gpe]

2. Treatment By Intermediate Nodes

Any receiving device may use the group policy information contained in the Group-Based Policy (GBP) sub-header. If an intermediate device applies policy based upon the GBP sub-header, then it must set the Policy Applied Bit, described below.

If an intermediate device terminates the VXLAN-GPE or LISP-GPE 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.

3. Group Based Policy Sub-header

In the case of VXLAN-GPE, the Group-Based Policy (GBP) sub-header follows the VXLAN-GPE header, or a previous VXLAN-GPE sub-header. Similarly, in the case of LISP-GPE, the Group-Based Policy (GBP) sub-header follows the LISP-GPE header, or a previous LISP-GPE sub-header.

3.1. Common GBP Sub-Header Format

The format of the GBP sub-header in either a VXLAN-GPE header or a LISP-GPE header is as shown 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Group Policy ID          |A|D|E| Res |Ver| Next Protocol |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           

• Group Policy ID: 16-bit identifier that indicates the Group Policy ID being encapsulated by this GBP sub-header. The allocation of Group Policy ID values is outside the scope of this document.
• 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 1 to indicate that the egress VTEP or the Egress Tunnel Router MUST NOT learn the source address of the encapsulated frame.
• End Destination bit (E bit): The E bit is set to 0 to represent the Group Policy ID associated with the source of the packet. The E bit is set to 1 to represent the Group Policy ID associated with the end destination of the packet. Note that if the packet carryies a destination group sub-header, it MUST also carry a source group sub-header.
• Reserved (Res): The 3-bit field MUST be set to zero on transmission and ignored on receipt.
• Version (Ver): The 2-bit field indicates the Version of the Group Policy sub-header. The initial version is 0.
• Next Protocol: The 8-bit field indicates the protocol header immediately following this sub-header. Next Protocol types are encoded as specified in [I-D.ietf-nvo3-vxlan-gpe] and [I-D.ietf-lisp-gpe].

An example frame format using VXLAN-GPE encapsulation is as shown 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                    Outer Ethernet Header                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Outer IP Header                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       Outer UDP Header                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
|R|R|Ver|I|P|R|O|          Reserved             | NP = GBP      |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ VXLAN
|     Virtual Network Identifier (VNI)          | Reserved      |  -GPE
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
|      Group Policy ID          |A|D|E| Res |Ver| Next Protocol | GBP
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
|                                                               |
:                        Next Protocol                          :
|                                                               |
+---------------------------------------------------------------+

           

An example frame format using LISP-GPE encapsulation is as shown 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                    Outer Ethernet Header                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Outer IP Header                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       Outer UDP Header                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
|N|L|E|V|I|P|K|K|        Nonce/Map-Version      | NP = GBP      |  |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ LISP
|                 Instance ID/Locator-Status-Bits               | -GPE
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
|      Group Policy ID          |A|D|E| Res |Ver| Next Protocol | GBP
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
|                                                               |
:                        Next Protocol                          :
|                                                               |
+---------------------------------------------------------------+

           

4. Use Of Multiple GBP Sub-options

A tunnel header MAY carry multiple GBP option headers where each GBP option header is of a unique GBP type. However, only one header of a specific GBP type is allowed per tunneled packet.

5. IANA Considerations

IANA is requested to add a new value to registry of "Next Protocol", which is defined in [I-D.ietf-nvo3-vxlan-gpe]. The new value of 6 will signify a GBP sub-header as the next protocol.

IANA is requested to add a new value to registry of "Next Protocol", which is defined in [I-D.ietf-lisp-gpe]. The new value of 6 will signify a GBP sub-header as the next protocol.

6. Security Considerations

The same security considerations applied to [I-D.ietf-nvo3-vxlan-gpe], [I-D.ietf-lisp-gpe], and to [I-D.smith-vxlan-group-policy] apply to this document.

Additionally, the security policy value carried in the GBP sub-header impacts security directly. There is a risk that this identifier could be altered. Accordingly, the network should be designed such that this sub-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

Authors' Addresses