Internet DRAFT - draft-lrss-bess-evpn-group-policy
draft-lrss-bess-evpn-group-policy
BESS WorkGroup W. Lin
Internet-Draft Juniper
Intended status: Standards Track D. Rao
Expires: 5 September 2024 A. Sajassi
M. Smith
Cisco
L. Kreeger
Arrcus
4 March 2024
EVPN Group Policy
draft-lrss-bess-evpn-group-policy-00
Abstract
Group Based Policy can be used to achieve micro or macro segmentation
of user traffic. For Group Based Policy, a Group Policy ID, also
known as Group Policy Tag, is used to represent a logical group that
shares the same policy and access privilege. This document defines a
backward compatible extension to Virtual eXtensible Local Area
Network (VXLAN) that allows a Group Policy ID to be carried for the
purposes of policy enforcement at the egress Network Virtualization
Edge (NVE). It also defines a new BGP Extended Community that can be
used to propagate Group Policy ID through a BGP route advertisement
in the control plane. This is to facilitate policy enforcement at
the ingress NVE when feasible.
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
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 5 September 2024.
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Copyright Notice
Copyright (c) 2024 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 (https://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
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. EVPN Control Plane Extensions . . . . . . . . . . . . . . . . 4
2.1. Group Policy ID Extended Community . . . . . . . . . . . 5
3. VXLAN Header Extension . . . . . . . . . . . . . . . . . . . 6
4. Backward Compatibility . . . . . . . . . . . . . . . . . . . 7
5. Interconnecting multiple EVPN VXLAN domains . . . . . . . . . 8
6. EVPN Interworking with IPVPN . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
8. Security Considerations . . . . . . . . . . . . . . . . . . . 9
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Normative References . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
The Group Based Policy (GROUPPOLICY, GROUPBASEDPOLICY) model defines
an application-centric policy model where the application
connectivity requirements are specified in a manner that is
independent of the underlying network topology. In this model,
Tenant System Interfaces (TSIs) are assigned to Tenant System
Interface (TSI) Groups. Each TSI Group consists of TSIs that share
the same network policies and requirements. Network policies are
defined between the TSI Group of the traffic source and the TSI Group
of the traffic destination. These policies are deployed when the TSI
attaches to the network.
In certain deployment scenarios, the TSI to TSI Group mapping is only
known at the Network Virtualization Edge (NVE) that the TSI is
attached. This implies that the TSI Group of a packet destination
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may not be known until the packet reaches the egress NVE where the
packet destination is attached. This could be a case where no
distribution mechanism is used, or where the mapping cannot be
installed in all NVEs. In such situations, it is required that the
source TSI Group is carried with the packet so that policy can be
applied at the egress NVE.
This document defines a backward compatible extension to VXLAN
[RFC7348] that allows the source TSI Group ID to be carried so that
policy can be applied when the destination TSI Group is determined at
the egress NVE.
In scenarios where the TSI to TSI Group mapping decision can be made
at the ingress NVEs, this document defines extensions to EVPN control
plane for distribution of the destination TSI Group ID to ingress
NVEs so that policy enforcement can be performed at the ingress NVEs.
To accomplish this, this document defines a Group Policy ID BGP
Extended Community to be sent along with EVPN routes to achieve the
propagation of Group Policy ID from an egress node to an ingress
node.
This document does not preclude the VXLAN Group Policy header
extension from being used with other control plane mechanisms, or
without any control plane.
Note: This document is a merged of two IETF documents - one that
defines the VXLAN Group Policy header extensions [VXLAN-GRPPOLICY),
and another one that deinfes the EVPN Extended Community extensions
[EVPN-GPI-EC].
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
* AC: Attachment Circuit
* DCI: Data Center Interconnect
* EVPN: Ethernet VPN, as per [RFC7432]
* GBP : Group Based Policy
* NVE: Network Virtualization Edge
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* NVO: Network Virtualization Overlay
* PE: Provider Edge device
* TSI: Tenant System Interface - equivalent to an attachment circuit
for a given tenant
* Tenant System Interface (TSI) Group: A TSI Group is a collection
of TSIs that share the same network policies and requirements.
* VTEP: Virtual Tunnel Edge
* VXLAN: Virtual Extensible LAN
2. EVPN Control Plane Extensions
In an EVPN VXLAN overlay network, a policy group tag may be assigned
based on the MAC, IP, port, VLAN, etc, or a combination of the above.
Similar to the MAC/IP addresses in the EVPN network, once the Policy
Group ID is known for a local host/server/VM attached to an EVPN
network, its Group Policy ID can be advertised to other Network
Virtualization Edge (NVE) devices in the control plane through the
Group Policy ID Extended Community. The scheme used for
classification and allocation of Policy Group IDs used for GBP in an
EVPN overlay network with VXLAN encapsulation is outside the scope of
this document.
Policy group tag propagation in the EVPN/BGP control plane can be
applied to the EVPN route Type-1 (Ethernet A-D per EVI) [RFC7432],
route Type-2 (MAC/IP Advertisement route) [RFC7432], route Type-3
(Inclusive Multicast Ethernet Tag route - IMET) [RFC7432], or EVPN
route Type-5 (IP Prefix route) [RFC9136]. If Policy Group ID is
allocated for a MAC address, IP host or prefix address through the
GBP classification scheme, then its Group Policy ID can be encoded
through the Group Policy ID Extended Community and be advertised
alongside its corresponding EVPN Type-2 or Type-5 route. If Policy
Group ID is allocated for an Attachment Circuit (AC), then its Group
Policy ID can be encodoed through the Group Policy ID extended
community and be advertised alongside its Ethernet A-D per EVI route.
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For the flows that the ingress VXLAN Tunnel Endpoint (VTEP) has
learned its destination group policy tag through EVPN/BGP control
plane signaling, the policy enforcement can thus be carried out at
the ingress node. Otherwise, policy enforcement can be carried out
at the egress node. If policy enforcement is carried out at the
head-end VXLAN tunnel, the ingress node MUST set the GBP applied bit,
the A-bit as it is specified in Figure 2, to 1 in the VXLAN header
before forwarding the traffic to the VXLAN tunnel. Otherwise, the
ingress node sets the A-bit to 0 in the VXLAN header.
2.1. Group Policy ID Extended Community
The Group Policy ID BGP Extended Community is a new transitive Opaque
Extended Community with a Type value of 0x03. This Extended
Community may be advertised along with an EVPN Type-1, Type-2, Type-
3, or Type-5 route. This new Opaque Extended Community enables the
EVPN route it is attached to, to propagate the Group Policy ID used
for Group Based Policy in the control plane.
When the "Uniformed-Propagation-Mode" is used under the EVPN and
IPVPN interworking use case, the Group Policy ID Extended Community
is carried over by the GW PE when a route for a given IP or IPv6
prefix is propagated from one domain to another with a different
address family.
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=0x03 | Sub-Type | Policy ID Scope |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Group Policy ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Group Policy ID Extended Community
Policy ID Scope: The Policy ID Scope field is 16-bit long, and is an
optional field.
Group Policy ID (GPI): The GPI field is 16-bit long and it encodes
the value of a Group Policy ID.
The reserved fields MUST be set to zero by the sender and ignored by
the receiver.
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If the Policy ID Scope is not set, any EVPN VXLAN NVE node that
receives a route with a Group Policy ID may use the received value as
is. If the Scope is set, a node that has the same locally configured
Scope in the received route may use the received Policy ID value. A
node that has a different local Scope than in the received route may
need to translate the received Policy ID to a locally assigned value.
3. VXLAN Header Extension
This section defines the VxLAN header extension needed for Group
Based Policy (VxLAN-GBP). Although in context of this document this
VxLAN header extension is described with EVPN control plane, this
header extension can be used with other control planes using VxLAN
encapsulation such as [RFC9300] and [RFC9301].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|G|R|R|R|I|R|R|R|R|D|R|R|A|R|R|R| Group Policy ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VXLAN Network Identifier (VNI) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: VXLAN Header Extension for GBP
The following bits are defined in addition to the existing VXLAN
fields:
G Bit: Bit 0 of the initial word is defined as the G (Group Based
Policy Extension) bit.
* G = 1 indicates that the source TSI Group membership is being
carried within the Group Policy ID field as defined in this
document.
* G = 0 indicates that the Group Policy ID is not being carried, and
the G Bit MUST be set to 0 as specified in [RFC7348].
D bit: Bit 9 of the initial word is defined as the Don't Learn bit.
When set, this bit indicates that the egress VTEP MUST NOT learn the
source address of the encapsulated frame.
A Bit: Bit 12 of the initial word is defined as the A (Policy
Applied) bit. This bit is only defined as the A bit when the G bit
is set to 1.
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* A = 1 indicates that the group policy has already been applied to
this packet. Policies MUST NOT be applied by devices when the A
bit is set.
* A = 0 indicates that the group policy has not 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.
Group Policy ID: 16 bit identifier that indicates the source TSI
Group membership being encapsulated by VXLAN. The allocation of
Group Policy ID values is outside the scope of this document.
4. Backward Compatibility
When considering backward compatibility, we need to consider a
network that can have a mix of all the following NVEs:
* NVEs that don't support GBP in either data plane or control plane
* NVEs that support GBP in data plane but not control plane
* NVEs that support GBP in both data plane and control plane
VXLAN [RFC7348] requires reserved fields to be set to zero on
transmit and ignored on receive. This ensures that the G bit will
never be set by VXLAN NVEs and therefore packets received from these
NVEs can be assigned to a default Group Policy ID. It also ensures
that VXLAN NVEs receiving packets with the G bit set will ignore the
Group Policy ID. Due to this defined behavior by VXLAN NVEs, it
allows the extensions described in this document to operate on the
IANA assigned VXLAN UDP port (port 4789).
In some environments, there may be a mix of devices supporting the
VXLAN Group Based Policy Extension and devices that do not. Devices
supporting the VXLAN Group Based Policy Extension SHOULD assign
traffic arriving without the G bit set to a default Group Policy ID
for the purposes of policy enforcement. This guarantees backward
compatibility on the egress NVEs supporting GBP functionality to do
proper egress filtering.
When an ingress NVE receives an EVPN route with Group Policy ID
extended community, if it understands this extended community, it
processes it and adds the Group Policy ID along with the
corresponding MAC/IP route in its forwarding table. If it doesn't
understand this extended community, it processes the EVPN route as
before.
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Now, when a packet from a host arrives on an ingress NVE that can
perform GBP ingress policy enforcement, it looks up the destination
MAC/IP address, retrieves the destination Group Policy ID and takes
the appropriate action based on the pair of Group Policy IDs of the
source and the destination. If the ingress NVE cannot perform the
GBP ingress policy enforcement, it carries out the packet processing
in accordance to the previous paragraph.
The ingress NVE may also use the presence of the Group Policy ID
Extended Community to determine the capability of the advertising NVE
to process the VXLAN Group Based Policy Extension and whether to
include it in packets being sent towards the egress NVE.
5. Interconnecting multiple EVPN VXLAN domains
EVPN VXLAN based deployments may comprise of multiple EVPN networks,
domains or sites.
In such cases, a VXLAN overlay may extend from an ingress node to an
egress node across different domains; or it may be divided into
multiple stitched overlay segments that are interconnected via DCI
through gateway devices.
In this document, we simply refer to each EVPN network or site as a
EVPN domain or domain for short unless it is explicitly specified
otherwise.
From a control plane point of view, border GWs in each domain may
learn routes of other domains either via direct peering sessions or
via a set of external route reflectors.
In such deployments, the allocation and management of Group Policy
IDs may be done independently in different domains, and consequently
the allocated values scoped to each domain. Therefore, when a group
policy tag is signaled with routes to a different domain, the tag
needs to be translated to a value local to the receiving domain
before it can be used in a group based policy at an ingress node in
that domain.
A domain may receive routes from multiple sender domains. In order
to facilitate simpler and flexible application of translation
policies regardless of the deployed overlay design or control plane
peering model, the advertised Policy ID may also carry with it a
Policy ID Scope which identifies the allocation domain. Any suitable
BGP node in the route distribution path can then consistently
translate a received Policy ID based on the scope.
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Scope assignment is done by the administrator or orchestration system
managing the multi-domain deployment. The exact mechanism is out of
the purview of this document.
6. EVPN Interworking with IPVPN
In the EVPN interworking use case as it is specified in the [I-
D.ietf-bess-evpn-ipvpn-interworking], two or more EVPN networks/
domains are interconnected by a layer-3 IP-VPN network with VPN-IPv4/
VPN-IPv6 BGP address families. To support ingress policy
enforcement, the Policy Group ID Extended Community needs to be
propagated by the GW PEs sitting at the border of an EVPN domain and
IP-VPN domain from one domain to another.
For the Uniform-Propagation-Mode defined in the [I-D.ietf-bess-evpn-
ipvpn-interworking], when propagating an EVPN IP prefix route across
the domain boundary to IP-VPN network, the Gateway PE SHOULD
propagate communities, extended communities and large communities
except for all the EVPN extended communities. The Policy Group ID
Extended Community defined in this document is a new transitive
Opaque Extend Community. It is not subject to stripping at the GW PE
when the Uniform-Propagation-Mode is used, and SHOULD be propagated.
7. Acknowledgements
The authors would like to thank Ayan Banerjee, Tom Edsall, Thomas
Graf, Jeffrey Zhang, and Jeff Haas for their careful review and
valuable feedbacks. The authors also would like to thank Prasad
Miriyala and Selvakumar Sivaraj for their contributions.
8. Security Considerations
This document describes an extension to VXLAN to carry the Group
Policy Identifier of the source endpoint. These identifiers must be
distributed to participating VTEPs that are encapsulating traffic
from the endpoints sourcing traffic. The control plane protocol
should ensure that these identifiers are securely distributed to the
network elements participating in the policy enforcement domain.
Additionally, the Group Policy Identifier field being carried in the
packet directly impacts the network policy applied to the traffic.
There is a risk that these identifiers may be spoofed and proper
integrity protection should be put in place to ensure that these
fields can only be populated by trusted entities. Due to the
importance of these fields, confidentiality may also be required to
ensure that traffic cannot be targeted for attack based on the policy
identifiers.
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In some environments, these attacks are mitigated through physical
security. In other environments, traditional security mechanisms
like IPsec that authenticate and optionally encrypt VXLAN traffic
including the bits and fields described in this document.
Furthermore, when EVPN control plane is used, then all the security
considerations in [RFC7432] and [RFC7623] apply directly to this
document because it leverages the control and data plane procedures
described in those documents.
9. IANA Considerations
For the Group Policy ID Extended Community defined in this document,
IANA has allocated the following codepoint in the Sub-type registry
of Type 0x03 Transitive Opaque Extended Community.
Sub-Type Name Reference 0x17 Group Policy ID Extended Community [this
document]
10. References
10.1. Normative References
[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>.
[RFC7348] Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
eXtensible Local Area Network (VXLAN): A Framework for
Overlaying Virtualized Layer 2 Networks over Layer 3
Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
<https://www.rfc-editor.org/info/rfc7348>.
[RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
2015, <https://www.rfc-editor.org/info/rfc7432>.
[RFC7623] Sajassi, A., Ed., Salam, S., Bitar, N., Isaac, A., and W.
Henderickx, "Provider Backbone Bridging Combined with
Ethernet VPN (PBB-EVPN)", RFC 7623, DOI 10.17487/RFC7623,
September 2015, <https://www.rfc-editor.org/info/rfc7623>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
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[RFC9136] Rabadan, J., Ed., Henderickx, W., Drake, J., Lin, W., and
A. Sajassi, "IP Prefix Advertisement in Ethernet VPN
(EVPN)", RFC 9136, DOI 10.17487/RFC9136, October 2021,
<https://www.rfc-editor.org/info/rfc9136>.
10.2. Informative References
[RFC9300] Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A.
Cabellos, Ed., "The Locator/ID Separation Protocol
(LISP)", RFC 9300, DOI 10.17487/RFC9300, October 2022,
<https://www.rfc-editor.org/info/rfc9300>.
[RFC9301] Farinacci, D., Maino, F., Fuller, V., and A. Cabellos,
Ed., "Locator/ID Separation Protocol (LISP) Control
Plane", RFC 9301, DOI 10.17487/RFC9301, October 2022,
<https://www.rfc-editor.org/info/rfc9301>.
Authors' Addresses
Wen Lin
Juniper
Email: wlin@juniper.net
Dhananjaya Rao
Cisco
Email: dhrao@cisco.com
Ali Sajassi
Cisco
Email: sajassi@cisco.com
Michael Smith
Cisco
Email: michsmit@cisco.com
Lawrence Kreeger
Arrcus
Email: lkreeger@gmail.com
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