Secure EVPN
draft-sajassi-bess-secure-evpn-00
The information below is for an old version of the document.
| Document | Type |
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|---|---|---|---|
| Authors | Ali Sajassi , Ayan Banerjee , Samir Thoria , David Carrel , Brian Weis | ||
| Last updated | 2018-10-21 | ||
| Replaced by | draft-ietf-bess-secure-evpn | ||
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draft-sajassi-bess-secure-evpn-00
BESS Workgroup A. Sajassi, Ed.
INTERNET-DRAFT A. Banerjee
Intended Status: Standards Track S. Thoria
D. Carrel
B. Weis
Cisco
Expires: May 20, 2019 October 20, 2018
Secure EVPN
draft-sajassi-bess-secure-evpn-00
Abstract
The applications of EVPN-based solutions ([RFC7432] and [RFC8365])
have become pervasive in Data Center, Service Provider, and
Enterprise segments. It is being used for fabric overlays and inter-
site connectivity in the Data Center market segment, for Layer-2,
Layer-3, and IRB VPN services in the Service Provider market segment,
and for fabric overlay and WAN connectivity in Enterprise networks.
For Data Center and Enterprise applications, there is a need to
provide inter-site and WAN connectivity over public Internet in a
secured manner with same level of privacy, integrity, and
authentication for tenant's traffic as IPsec tunneling using IKEv2.
This document presents a solution where BGP point-to-multipoint
signaling is leveraged for key and policy exchange among PE devices
to create private pair-wise IPsec Security Associations without IKEv2
point-to-point signaling or any other direct peer-to-peer session
establishment messages.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
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and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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Copyright and License Notice
Copyright (c) 2014 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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Tenant's Layer-2 and Layer-3 data & control traffic . . . . 7
2.2 Tenant's Unicast & Multicast Data Protection . . . . . . . . 7
2.3 P2MP Signaling for SA setup and Maintenance . . . . . . . . 7
2.3 Granularity of Security Association Tunnels . . . . . . . . 7
2.4 Support for Policy and DH-Group List . . . . . . . . . . . . 8
3 Solution Description . . . . . . . . . . . . . . . . . . . . . 8
3.1 Distribution of Public Keys and Policies . . . . . . . . . 9
3.1.1 Minimum Set . . . . . . . . . . . . . . . . . . . . . . 9
3.1.2 Single Policy . . . . . . . . . . . . . . . . . . . . . 10
3.1.3 Policy-list & DH-group-list . . . . . . . . . . . . . . 10
3.2 Initial IPsec SAs Generation . . . . . . . . . . . . . . . 11
3.3 Re-Keying . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.4 IPsec Databases . . . . . . . . . . . . . . . . . . . . . . 11
4 Encapsulation . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1 Standard ESP Encapsulation . . . . . . . . . . . . . . . . . 12
4.2 ESP Encapsulation within UDP packet . . . . . . . . . . . . 13
5 BGP Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1 ESP Notify Sub-TLV . . . . . . . . . . . . . . . . . . . . . 14
5.2 ESP Key Exchange Sub-TLV . . . . . . . . . . . . . . . . . . 15
5.3 ESP Nonce Sub-TLV . . . . . . . . . . . . . . . . . . . . . 15
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5.3 ESP Proposals Sub-TLV . . . . . . . . . . . . . . . . . . . 16
6 Applicability to other VPN types . . . . . . . . . . . . . . . 17
7 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18
8 Security Considerations . . . . . . . . . . . . . . . . . . . . 18
9 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 18
10 References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.1 Normative References . . . . . . . . . . . . . . . . . . . 18
10.2 Informative References . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20
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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
AC: Attachment Circuit.
ARP: Address Resolution Protocol.
BD: Broadcast Domain. As per [RFC7432], an EVI consists of a single
or multiple BDs. In case of VLAN-bundle and VLAN-based service models
(see [RFC7432]), a BD is equivalent to an EVI. In case of VLAN-aware
bundle service model, an EVI contains multiple BDs. Also, in this
document, BD and subnet are equivalent terms.
BD Route Target: refers to the Broadcast Domain assigned Route Target
[RFC4364]. In case of VLAN-aware bundle service model, all the BD
instances in the MAC-VRF share the same Route Target.
BT: Bridge Table. The instantiation of a BD in a MAC-VRF, as per
[RFC7432].
DGW: Data Center Gateway.
Ethernet A-D route: Ethernet Auto-Discovery (A-D) route, as per
[RFC7432].
Ethernet NVO tunnel: refers to Network Virtualization Overlay tunnels
with Ethernet payload. Examples of this type of tunnels are VXLAN or
GENEVE.
EVI: EVPN Instance spanning the NVE/PE devices that are participating
on that EVPN, as per [RFC7432].
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EVPN: Ethernet Virtual Private Networks, as per [RFC7432].
GRE: Generic Routing Encapsulation.
GW IP: Gateway IP Address.
IPL: IP Prefix Length.
IP NVO tunnel: it refers to Network Virtualization Overlay tunnels
with IP payload (no MAC header in the payload).
IP-VRF: A VPN Routing and Forwarding table for IP routes on an
NVE/PE. The IP routes could be populated by EVPN and IP-VPN address
families. An IP-VRF is also an instantiation of a layer 3 VPN in an
NVE/PE.
IRB: Integrated Routing and Bridging interface. It connects an IP-VRF
to a BD (or subnet).
MAC-VRF: A Virtual Routing and Forwarding table for Media Access
Control (MAC) addresses on an NVE/PE, as per [RFC7432]. A MAC-VRF is
also an instantiation of an EVI in an NVE/PE.
ML: MAC address length.
ND: Neighbor Discovery Protocol.
NVE: Network Virtualization Edge.
GENEVE: Generic Network Virtualization Encapsulation, [GENEVE].
NVO: Network Virtualization Overlays.
RT-2: EVPN route type 2, i.e., MAC/IP advertisement route, as defined
in [RFC7432].
RT-5: EVPN route type 5, i.e., IP Prefix route. As defined in Section
3 of [EVPN-PREFIX].
SBD: Supplementary Broadcast Domain. A BD that does not have any ACs,
only IRB interfaces, and it is used to provide connectivity among all
the IP-VRFs of the tenant. The SBD is only required in IP-VRF- to-IP-
VRF use-cases (see Section 4.4.).
SN: Subnet.
TS: Tenant System.
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VA: Virtual Appliance.
VNI: Virtual Network Identifier. As in [RFC8365], the term is used as
a representation of a 24-bit NVO instance identifier, with the
understanding that VNI will refer to a VXLAN Network Identifier in
VXLAN, or Virtual Network Identifier in GENEVE, etc. unless it is
stated otherwise.
VTEP: VXLAN Termination End Point, as in [RFC7348].
VXLAN: Virtual Extensible LAN, as in [RFC7348].
This document also assumes familiarity with the terminology of
[RFC7432], [RFC8365] and [RFC7365].
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1 Introduction
The applications of EVPN-based solutions have become pervasive in
Data Center, Service Provider, and Enterprise segments. It is being
used for fabric overlays and inter-site connectivity in the Data
Center market segment, for Layer-2, Layer-3, and IRB VPN services in
the Service Provider market segment, and for fabric overlay and WAN
connectivity in the Enterprise networks. For Data Center and
Enterprise applications, there is a need to provide inter-site and
WAN connectivity over public Internet in a secured manner with the
same level of privacy, integrity, and authentication for tenant's
traffic as used in IPsec tunneling using IKEv2. This document
presents a solution where BGP point-to-multipoint signaling is
leveraged for key and policy exchange among PE devices to create
private pair-wise IPsec Security Associations without IKEv2 point-to-
point signaling or any other direct peer-to-peer session
establishment messages.
EVPN uses BGP as control-plane protocol for distribution of
information needed for discovery of PEs participating in a VPN,
discovery of PEs participating in a redundancy group, customer MAC
addresses and IP prefixes/addresses, aliasing information, tunnel
encapsulation types, multicast tunnel types, multicast group
memberships, and other info. The advantages of using BGP control
plane in EVPN are well understood including the following:
1) A full mesh of BGP sessions among PE devices can be avoided by
using Route Reflector (RR) where a PE only needs to setup a single
BGP session between itself and the RR as opposed to setting up N BGP
sessions to N other remote PEs; therefore, reducing number of BGP
sessions from O(N^2) to O(N) in the network. Furthermore, RR
hierarchy can be leveraged to scale the number of BGP routes on the
RR.
2) MP-BGP route filtering and constrained route distribution can be
leveraged to ensure that the control-plane traffic for a given VPN is
only distributed to the PEs participating in that VPN.
For setting up point-to-point security association (i.e., IPsec
tunnel) between a pair of EVPN PEs, it is important to leverage BGP
point-to-multipoint singling architecture using the RR along with its
route filtering and constrain mechanisms to achieve the performance
and the scale needed for large number of security associations (IPsec
tunnels) along with their frequent re-keying requirements. Using BGP
signaling along with the RR (instead of peer-to-peer protocol such as
IKEv2) reduces number of message exchanges needed for SAs
establishment and maintenance from O(N^2) to O(N) in the network. be
increased from O(N) to O(N^2).
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2 Requirements
The requirements for secured EVPN are captured in the following
subsections.
2.1 Tenant's Layer-2 and Layer-3 data & control traffic
Tenant's layer-2 and layer-3 data and control traffic SHALL be
protected by IPsec cryptographic methods. This implies not only
tenant's data traffic SHALL be protected by IPsec but also tenant's
control and routing information that are advertised in BGP SHALL also
be protected by IPsec. This in turn implies that BGP session SHALL be
protected by IPsec.
2.2 Tenant's Unicast & Multicast Data Protection
Tenant's layer-2 and layer-3 unicast traffic SHALL be protected by
IPsec. In addition to that, tenant's layer-2 broadcast, unknown
unicast, and multicast traffic as well as tenant's layer-3 multicast
traffic SHALL be protected by IPsec when ingress replication or
assisted replication are used. The use of BGP P2MP signaling for
setting up P2MP SAs in P2MP multicast tunnels is for future study.
2.3 P2MP Signaling for SA setup and Maintenance
BGP P2MP signaling SHALL be used for IPsec SAs setup and maintenance.
The BGP signaling SHALL follow P2MP signaling framework per
[CONTROLLER-IKE] for IPsec SAs setup and maintenance in order to
reduce the number of message exchanges from O(N^2) to O(N) among the
participant PE devices.
2.3 Granularity of Security Association Tunnels
The solution SHALL support the setup and maintenance of IPsec SAs at
the following level of granularities:
1) Per pair of PEs: A single IPsec tunnel between a pair of PEs to be
used for all tenants' traffic supported by the pair of PEs.
2) Per tenant: A single IPsec tunnel per tenant per pair of PEs. For
example, if there are 1000 tenants supported on a pair of PEs, then
1000 IPsec tunnels are required between that pair of PEs.
3) Per subnet: A single IPsec tunnel per subnet (e.g., per VLAN/EVI)
of a tenant on a pair of PEs.
4) Per pair of IP addresses: A single IPsec tunnel per pair of IP
addresses of a tenant on a pair of PEs.
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5) Per pair of MAC addresses: A single IPsec tunnel per pair of MAC
addresses of a tenant on a pair of PEs.
2.4 Support for Policy and DH-Group List
The solution SHALL support a single policy and DH group for all SAs
as well as supporting multiple policies and DH groups among the SAs.
3 Solution Description
This solution uses BGP P2MP signaling where an originating PE only
send a message to Route Reflector (RR) and then the RR reflects that
message to the interested recipient PEs. The framework for such
signaling is described in [CONTROLLER-IKE] and it is referred to as
device-to-controller trust model. This trust model is significantly
different than the traditional peer-to-peer trust model where a P2P
signaling protocol such as IKEv2 [RFC7296] is used in which the PE
devices directly authenticate each other and agree upon security
policy and keying material to protect communications between
themselves. The device-to-controller trust model leverages P2MP
signaling via the controller (e.g., the RR) to achieve much better
scale and performance for establishment and maintenance of large
number of pairwise Security Associations (SAs) among the PEs.
This device-to-controller trust model first secures the control
channel between each device and the controller using peer-to-peer
protocol such as IKEv2 [RFC7296] to establish P2P SAs between each PE
and the RR. It then uses this secured control channel for P2MP
signaling in establishment of P2P SAs between a pair of PE devices.
Each PE advertised to other PEs via the RR the information needed in
establishment of pair-wise SAs between itself an every other remote
PEs. These pieces of information are sent as Sub-TLVs of IPSec tunnel
type in BGP Tunnel Encapsulation attribute. These Sub-TLVs are
detailed in section 5 and they are based on IKEv2 specification
[RFC7296]. The IPsec tunnel TLVs along with its Sub-TLVs are sent
along with the BGP route (NLRI) for a given level of granularity.
If only a single SA is required per pair of PE devices to multiplex
user traffic for all tenants, then IPsec tunnel TLV is advertised
along with IPv4 or IPv6 NLRI representing loopback address of the
originating PE. It should be noted that this is not a VPN route but
rather an IPv4 or IPv6 route.
If a SA is required per tenant between a pair of PE devices, then
IPsec tunnel TLV can be advertised along with EVPN IMET route
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representing the tenant or can be advertised along with a new EVPN
route representing the tenant.
If a SA is required per tenant's subnet (e.g., per VLAN) between a
pair of PE devices, then IPsec tunnel TLV is advertised along with
EVPN IMET route.
If a SA is required between a pair of tenant's devices represented by
a pair of IP addresses, then IPsec tunnel TLV is advertised along
with EVPN IP Prefix Advertisement Route or EVPN MAC/IP Advertisement
route.
If a SA is required between a pair of tenant's devices represented by
a pair of MAC addresses, then IPsec tunnel TLV is advertised along
with EVPN MAC/IP Advertisement route.
If a SA is required between a pair of tenant's devices represented by
a VLAN or a port, then IPsec tunnel TLV is advertised along with EVPN
Ethernet AD route.
3.1 Distribution of Public Keys and Policies
One of the requirements for this solution is to support a single DH
group and a single policy for all SAs as well as to support multiple
DH groups and policies among the SAs. The following subsections
describe what pieces of information (what Sub-TLVs) are needed to be
exchanged to support a single DH group and a single policy versus
multiple DH groups and multiple policies.
3.1.1 Minimum Set
For SA establishment, at the minimum, a PE needs to advertise to
other PEs, its ID, a notification to indicate if this is its initial
contact, key exchange including DH public number and DH group, and
Nonce. When a single policy is used among all SAs, it is assumed that
this single policy is configured by the management system in all the
PE devices and thus there is no need to signal it. The information
that need to be signaled (using RFC7296 notations) are:
ID, [N(INITIAL_CONTACT),] KE, Ni; where
ID payload is defined in section 3.5 of [RFC7296]
N (Notify) Payload in section 3.10 of [RFC7296]
KE (Key Exchange) payload in section 3.4 of [RFC7296]
Ni (Nonce) payload in section 3.9 of [RFC7296]
KE payload contains the DH public number and also identifies which DH
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group to use. ID sub-TLV would not be needed in BGP because tunnel
attribute already carries originator ID. Section 5 details these sub-
TLVs as part of IPsec tunnel TLV in BGP Tunnel Encapsulation
Attribute.
3.1.2 Single Policy
If a single policy needs to be signaled among per tenant or per
subnet among a set of PEs, then in addition to the information
described in section 3.1.1, Security Association sub-TLV needs to be
signaled as well. The payload for this sub-TLV is defined in section
3.3 of [RFC7296] and detailed in section 5.3.
ID, [N(INITIAL_CONTACT),SA, KE, Ni
SA (Security Association) payload in section 3.3 of [RFC7296]
A single SA payload identifies a single IPsec policy. One important
restriction on the SA Payload is that an standard IKE SA payload can
contain multiple transform; however, [CONTROLLER-IKE] restricts the
SA payload to only a single transform for each transform type as
described in section A.3.1 of [CONTROLLER-IKE].
3.1.3 Policy-list & DH-group-list
There can be scenarios for which there is a need to have multiple
policy options. This can happen when there is a need for policy
change and smooth migration among all PE devices to the new policy is
required. It can also happen if different PE devices have different
capabilities within the network. In these scenairos, PE devices need
to be able to choose the correct policy to use for each other. This
multi-policy scheme is described in section 6 of [CONTROLLER-IKE]. In
order to support this multi-policy feature, a PE device MUST
distribute a policy list. This list consists of multiple distinct
policies in order of preference, where the first policy is the most
preferred one. The receiving PE selects the policy by taking the
received list (starting with the first policy) and comparing that
against its own list and choosing the first one found in common. If
there is no match, this indicates a configuration error and the PEs
MUST NOT establish new SAs until a message is received that does
produce a match.
Furthermore, when a device supports more than one DH group, then a
unique DH public number MUST be specified for each in order of
preference. The selection of which DH group to use follows the same
logic as Policy selection, using the receiver's list order until a
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match is found in the initiator's list.
In order to support multi-policy a policy list is signaled in
addition to the information described in section 3.1.1. Furthermore,
in order to support multi-DH-groups, a DH group list along with its
nonce list are signaled instead of a single DH group and a single
nonce as described in section 3.1.1.
ID, [N(INITIAL_CONTACT), [SA], [KE], [Ni]
[SA] list of IPsec policies (i.e., list of SA payloads)
[KE] list of KE payloads
3.2 Initial IPsec SAs Generation
The procedure for generation of initial IPsec SAs is described in
section 3 of [CONTROLLER-IKE]. This section gives a summary of it in
context of BGP signaling. When a PE device first comes up and wants
to setup an IPsec SA between itself and each of the interested remote
PEs, it generates a DH pair along for each of its intended IPsec SA
using an algorithm defined in the IKEv2 Diffie-Hellman Group
Transform IDs [IKEv2-IANA]. The originating PE distributes DH public
value along with a nonce (using IPsec Tunnel TLV in Tunnel
Encapsulation Attribute) to other remote PEs via the RR. Each
receiving PE uses this DH public number and the corresponding nonce
in creation of IPsec SA pair to the originating PE - i.e., an
outbound SA and an inbound SA. The detail procedures are described in
section 5.2 of [CONTROLLER-IKE].
3.3 Re-Keying
A PE can initiate re-keying at any time due to local time or volume
based policy or due to the result of cipher counter nearing its final
value. The rekey process is performed individually for each remote
PE. If rekeying is performed with multiple PEs simultaneously, then
the decision process and rules described in this rekey are performed
independently for each PE. Section 4 of [CONTROLLER-IKE] describes
this rekeying process in details and gives examples for a single
IPsec device (e.g., a single PE) rekey versus multiple PE devices
rekey simultaneously.
3.4 IPsec Databases
The Peer Authorization Database (PAD), the Security Policy Database
(SPD), and the Security Association Database (SAD) all need to be
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setup as defined in the IPsec Security Architecture [RFC4301].
Section 5 of [CONTROLLER-IKE] gives a summary description of how
these databases are setup for the controller-based model where key is
exchanged via P2MP signaling via the controller (e.g., the RR) and
the policy can be either signaled via the RR (in case of multiple
policies) or configured by the management station (in case of single
policy).
4 Encapsulation
Vast majority of Encapsulation for Network Virtualization Overlay
(NVO) networks in deployment are based on UDP/IP with UDP destination
port ID indicating the type of NVO encapsulation (e.g., VxLAN, GPE,
GENEVE, GUE) and UDP source port ID representing flow entropy for
load-balancing of the traffic within the fabric based on n-tuple that
includes UDP header. When encrypting NVO encapsulated packets using
IP Encapsulating Security Payload (ESP), the following two options
can be used: a) adding a UDP header before ESP header (e.g., UDP
header in clear) and b) no UDP header before ESP header (e.g.,
standard ESP encapsulation). The following subsection describe these
encapsulation in further details.
4.1 Standard ESP Encapsulation
When standard IP Encapsulating Security Payload (ESP) is used
(without outer UDP header) for encryption of NVO packets, it is used
in transport mode as depicted below. When such encapsulation is used,
the Tunnel Type of Tunnel Encapsulation TLV is set to ESP-Transport
and the Tunnel Type of Encapsulation Extended Community is set to NVO
encapsulation type (e.g., VxLAN, GENEVE, GPE, etc.). This implies
that the customer packets are first encapsulated using NVO
encapsulation type and then it is further encapsulated & encrypted
using ESP-Transport mode.
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+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Header | | MAC Header |
+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+
| Eth Type = IPv4/IPv6 | | Eth Type = IPv4/IPv6 |
+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+
| IP Header | | IP Header |
| Protocol = UDP | | Protocol = ESP |
+-----------------------+ +-----------------------+
| UDP Header | | ESP Header |
| Dest Port = VxLAN | +-----------------------+
+-----------------------+ | UDP Header |
| VxLAN Header | | Dest Port = VxLAN |
+-----------------------+ +-----------------------+
| Inner MAC Header | | VxLAN Header |
+-----------------------+ +-----------------------+
| Inner Eth Payload | | Inner MAC Header |
+-----------------------+ +-----------------------+
| CRC | | Inner Eth Payload |
+-----------------------+ +-----------------------+
| ESP Trailer (NP=UDP) |
+-----------------------+
| CRC |
+-----------------------+
Figure 3: VxLAN Encapsulation within ESP
4.2 ESP Encapsulation within UDP packet
In scenarios where NAT traversal is required ([RFC3948]) or where
load balancing using UDP header is required, then ESP encapsulation
within UDP packet as depicted in the following figure is used. The
ESP for NVO applications is in transport mode. The outer UDP header
(before the ESP header) has its source port set to flow entropy and
its destination port set to 4500 (indicating ESP header follows). A
non-zero SPI value in ESP header implies that this is a data packet
(i.e., it is not an IKE packet). The Next Protocol field in the ESP
trailer indicates what follows the ESP header, is a UDP header. This
inner UDP header has a destination port ID that identifies NVO
encapsulation type (e.g., VxLAN). Optimization of this packet format
where only a single UDP header is used (only the outer UDP header) is
for future study.
When such encapsulation is used, the Tunnel Type of Tunnel
Encapsulation TLV is set to ESP-in-UDP-Transport and the Tunnel Type
of Encapsulation Extended Community is set to NVO encapsulation type
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(e.g., VxLAN, GENEVE, GPE, etc.). This implies that the customer
packets are first encapsulated using NVO encapsulation type and then
it is further encapsulated & encrypted using ESP-in-UDP with
Transport mode.
[RFC3948]
+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Header | | MAC Header |
+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+
| Eth Type = IPv4/IPv6 | | Eth Type = IPv4/IPv6 |
+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+
| IP Header | | IP Header |
| Protocol = UDP | | Protocol = UDP |
+-----------------------+ +-----------------------+
| UDP Header | | UDP Header |
| Dest Port = VxLAN | | Dest Port = 4500(ESP) |
+-----------------------+ +-----------------------+
| VxLAN Header | | ESP Header |
+-----------------------+ +-----------------------+
| Inner MAC Header | | UDP Header |
+-----------------------+ | Dest Port = VxLAN |
| Inner Eth Payload | +-----------------------+
+-----------------------+ | VxLAN Header |
| CRC | +-----------------------+
+-----------------------+ | Inner MAC Header |
+-----------------------+
| Inner Eth Payload |
+-----------------------+
| ESP Trailer (NP=UDP) |
+-----------------------+
| CRC |
+-----------------------+
Figure 4: VxLAN Encapsulation within ESP Within UDP
5 BGP Encoding
This document defines two new Tunnel Types along with its associated
sub-TLVs for The Tunnel Encapsulation Attribute [TUNNEL-ENCAP]. These
tunnel types correspond to ESP-Transport and ESP-in-UDP-Transport as
described in section 4. The following sub-TLVs apply to both tunnel
types unless stated otherwise.
5.1 ESP Notify Sub-TLV
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This sub-TLV corresponds to Notify payload of IPsec Encapsulation
Security Payload protocol as defined in IKEv2 [RFC7296]. This payload
is defined and described in section 3.10 of [RFC7296].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Payload |C| Reserved | Payload Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol ID | SPI Size | Notify Message Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Security Parameter Index (SPI) ~
| |
+---------------------------------------------------------------+
| |
~ Notification Data ~
| |
+---------------------------------------------------------------+
Figure 5: Notify Payload Format
5.2 ESP Key Exchange Sub-TLV
This sub-TLV corresponds to Key Exchange payload of IPsec
Encapsulation Security Payload protocol as defined in IKEv2
[RFC7296]. This payload is defined and described in section 3.4 of
[RFC7296].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Payload |C| Reserved | Payload Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Diffie-Hellman Group Number | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Key Exchange Data ~
| |
+---------------------------------------------------------------+
Figure 6: Key Exchange Payload Format
5.3 ESP Nonce Sub-TLV
This sub-TLV corresponds to Nonce payload of IPsec Encapsulation
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Security Payload protocol as defined in IKEv2 [RFC7296]. This payload
is defined and described in section 3.9 of [RFC7296].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Payload |C| Reserved | Payload Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Nonce Data ~
| |
+---------------------------------------------------------------+
Figure 7: Nonce Payload Format
5.3 ESP Proposals Sub-TLV
This sub-TLV corresponds to Proposal payload of IPsec Encapsulation
Security Payload protocol as defined in IKEv2 [RFC7296]. This payload
is defined and described in section 3.3 of [RFC7296].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Payload |C| Reserved | Payload Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ <Proposals> ~
| |
+---------------------------------------------------------------+
Figure 8: Security Association Payload
Proposals (Variable) - one or more proposal substructures
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Last Substruc | Reserved | Proposal Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Proposal Num | Protocol ID | SPI Size | Num Transforms|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ SPI (Variable) ~
| |
+---------------------------------------------------------------+
| |
~ <Transforms> ~
| |
+---------------------------------------------------------------+
Figure 9: Proposal Substructure
6 Applicability to other VPN types
Although P2MP BGP signaling for establishment and maintenance of SAs
among PE devices is described in this document in context of EVPN,
there is no reason why it cannot be extended to other VPN
technologies such as IP-VPN [RFC4364], VPLS [RFC4761] & [RFC4762],
and MVPN [RFC6513] & [RFC6514] with ingress replication. The reason
EVPN has been chosen is because of its pervasiveness in DC, SP, and
Enterprise applications and because of its ability to support SA
establishment at different granularity levels such as: per PE, Per
tenant, per subnet, per Ethernet Segment, per IP address, and per
MAC. For other VPN technology types, a much smaller granularity
levels can be supported. For example for VPLS, only the granularity
of per PE and per subnet can be supported. For per-PE granularity
level, the mechanism is the same among all the VPN technologies as
IPsec tunnel type (and its associated TLV and sub-TLVs) are sent
along with the PE's loopback IPv4 (or IPv6) address. For VPLS, if
per-subnet (per bridge domain) granularity level needs to be
supported, then the IPsec tunnel type and TLV are sent along with
VPLS AD route.
The following table lists what level of granularity can be supported
by a given VPN technology and with what BGP route.
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Functionality | EVPN | IP-VPN | MVPN | VPLS |
+---------------+-------------+-------------+-----------+---------+
| per PE |IPv4/v6 route|IPv4/v6 route|IPv4/v6 rte|IPv4/v6 |
+---------------+-------------+-------------+-----------+---------+
| per tenant |IMET (or new)|lpbk (or new)| I-PMSI | N/A |
+---------------+-------------+-------------+-----------+---------+
| per subnet | IMET | N/A | N/A | VPLS AD |
+---------------+-------------+-------------+-----------+---------+
| per IP |EVPN RT2/RT5 | VPN IP rt | *,G or S,G| N/A |
+---------------+-------------+-------------+-----------+---------+
| per MAC | EVPN RT2 | N/A | N/A | N/A |
+---------------+-------------+-------------+-----------+---------+
7 Acknowledgements
8 Security Considerations
9 IANA Considerations
A new transitive extended community Type of 0x06 and Sub-Type of TBD
for EVPN Attachment Circuit Extended Community needs to be allocated
by IANA.
10 References
10.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC2119
Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May
2017.
[RFC7432] Sajassi et al., "BGP MPLS Based Ethernet VPN", RFC 7432,
February, 2015.
[RFC8365] Sajassi et al., "A Network Virtualization Overlay Solution
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INTERNET DRAFT Secure EVPN October 20, 2018
Using Ethernet VPN (EVPN)", RFC 8365, March, 2018.
[TUNNEL-ENCAP] Rosen et al., "The BGP Tunnel Encapsulation
Attribute", draft-ietf-idr-tunnel-encaps-03, November
2016.
[CONTROLLER-IKE] Carrel et al., "IPsec Key Exchange using a
Controller", draft-carrel-ipsecme-controller-ike-00, July,
2018.
[RFC3948] Huttunen et al., "UDP Encapsulation of IPsec ESP Packets",
RFC 3948, January 2005.
[IKEV2-IANA] IANA, "Internet Key Exchange Version 2 (IKEv2)
Parameters", February 2016,
www.iana.org/assignments/ikev2-parameters/ikev2-
parameters.xhtml.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
December 2005.
10.2 Informative References
[RFC4364] Rosen, E., et. al., "BGP/MPLS IP Virtual Private Networks
(VPNs)", RFC 4364, February 2006.
[RFC4761] Kompella, K., et. al., "Virtual Private LAN Service (VPLS)
Using BGP for Auto-Discovery and Signaling", RFC 4761, January 2007.
[RFC4762] Kompella, K., et. al., "Virtual Private LAN Service (VPLS)
Using Label Distribution Protocol (LDP) Signaling", RFC 4762, January
2007.
[RFC6513] Rosen, E., et. al., "Multicast in MPLS/BGP IP VPNs", RFC
6513, February 2012.
[RFC6514] Rosen, E., et. al., "BGP Encodings and Procedures for
Multicast in MPLS/BGP IP VPNs", RFC 6514, February 2012.
[RFC7606] Chen, E., Scudder, J., Mohapatra, P., and K. Patel,
"Revised Error Handling for BGP UPDATE Messages", RFC 7606, August
2015, <http://www.rfc-editor.org/info/rfc7606>.
[802.1Q] "IEEE Standard for Local and metropolitan area networks -
Media Access Control (MAC) Bridges and Virtual Bridged Local Area
Networks", IEEE Std 802.1Q(tm), 2014 Edition, November 2014.
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[RFC7348] Mahalingam, M., et al., "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.
[GENEVE] Gross, J., et al., "Geneve: Generic Network Virtualization
Encapsulation", Work in Progress, draft-ietf-nvo3-geneve-06, March
2018.
Authors' Addresses
Ali Sajassi
Cisco
Email: sajassi@cisco.com
Ayan Banerjee
Cisco
Email: ayabaner@cisco.com
Samir Thoria
Cisco
Email: sthoria@cisco.com
David Carrel
Cisco
Email: carrel@cisco.com
Brian Weis
Cisco
Email: bew@cisco.com
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