Internet DRAFT - draft-fang-l3vpn-virtual-pe
draft-fang-l3vpn-virtual-pe
INTERNET-DRAFT Luyuan Fang, Ed.
Intended Status: Standards track Microsoft
Expires: January 4, 2015 David Ward
Rex Fernando
Ning So Cisco
Vinci Systems Maria Napierala
Jim Guichard AT&T
Cisco Nabil Bitar
Wen Wang Verizon
CenturyLink Dhananjaya Rao
Manuel Paul Cisco
Deutsche Telekom Bruno Rijsman
Wim Henderichx Juniper
Alcatel-Lucent
July 4, 2014
BGP/MPLS VPN Virtual PE
draft-fang-l3vpn-virtual-pe-05
Abstract
This document describes the architecture solutions for BGP/MPLS L3
and L2 Virtual Private Networks (VPNs) with virtual Provider Edge
(vPE) routers. It provides a functional description of the vPE
control, forwarding, and management. The proposed vPE solutions
support both the Software Defined Networks (SDN) approach which
allows physical decoupling of the control and the forwarding, and the
traditional distributed routing approach. A vPE can reside in any
network or compute devices, such as a server as co-resident with the
application virtual machines (VMs), or a Top-of-Rack (ToR) switch in
a Data Center (DC) network.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Virtual PE Architecture . . . . . . . . . . . . . . . . . . . . 6
2.1 Virtual PE definitions . . . . . . . . . . . . . . . . . . . 6
2.2 vPE Architecture and Design options . . . . . . . . . . . . 8
2.2.1 vPE-F host location . . . . . . . . . . . . . . . . . . 8
2.2.2 vPE control plane topology . . . . . . . . . . . . . . . 8
2.2.3 Data Center orchestration models . . . . . . . . . . . . 8
2.3 vPE Architecture reference models . . . . . . . . . . . . . 8
2.3.1 vPE-F in an end-device and vPE-C in the controller . . . 8
2.3.2 vPE-F and vPE-C on the same end-device . . . . . . . . . 10
2.3.3 vPE-F and vPE-C are on the ToR . . . . . . . . . . . . . 11
2.3.4 vPE-F on the ToR and vPE-C on the controller . . . . . . 12
2.3.5 The server view of a vPE . . . . . . . . . . . . . . . . 12
3. Control Plane . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 vPE Control Plane (vPE-C) . . . . . . . . . . . . . . . . . 13
3.1.1 The SDN approach . . . . . . . . . . . . . . . . . . . . 13
3.1.2 Distributed control plane . . . . . . . . . . . . . . . 14
3.3 Use of router reflector . . . . . . . . . . . . . . . . . . 14
3.4 Use of Constrained Route Distribution [RFC4684] . . . . . . 14
4. Forwarding Plane . . . . . . . . . . . . . . . . . . . . . . . 14
4.1 Virtual Interface . . . . . . . . . . . . . . . . . . . . . 14
4.2 Virtual Provider Edge Forwarder (vPE-F) . . . . . . . . . . 15
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4.3 Encapsulation . . . . . . . . . . . . . . . . . . . . . . . 15
4.4 Optimal forwarding . . . . . . . . . . . . . . . . . . . . . 15
4.5 Routing and Bridging Services . . . . . . . . . . . . . . . 16
5. Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.1 IPv4 and IPv6 support . . . . . . . . . . . . . . . . . . . 17
5.2 Address space separation . . . . . . . . . . . . . . . . . . 17
6.0 Inter-connection considerations . . . . . . . . . . . . . . 17
7. Management, Control, and Orchestration . . . . . . . . . . . . 18
7.1 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . 18
7.2 Management/Orchestration system interfaces . . . . . . . . . 19
7.3 Service VM Management . . . . . . . . . . . . . . . . . . . 19
7.4 Orchestration and MPLS VPN inter-provisioning . . . . . . . 19
7.4.1 vPE Push model . . . . . . . . . . . . . . . . . . . . . 20
7.4.2 vPE Pull model . . . . . . . . . . . . . . . . . . . . . 21
8. Security Considerations . . . . . . . . . . . . . . . . . . . 21
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
11.1 Normative References . . . . . . . . . . . . . . . . . . . 22
11.2 Informative References . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24
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1 Introduction
Network virtualization enables multiple isolated individual networks
over a shared common network infrastructure. BGP/MPLS IP Virtual
Private Networks (IP VPNs) [RFC4364] have been widely deployed to
provide network based Layer 3 VPNs solutions. [RFC4364] provides
routing isolation among different customer VPNs and allow address
overlap among these VPNs through the implementation of per VPN
Virtual Routing and Forwarding instances (VRFs) at a Service Provider
Edge (PE) routers, while forwarding customer traffic over a common
IP/MPLS network. For L2 VPN, a similar technology is being defined in
[I-D.ietf-l2vpn-evpn] on the basis of BGP/MPLS, to provide switching
isolation and allow MAC address overlap.
With the advent of compute capabilities and the proliferation of
virtualization in Data Center servers, multi-tenant Data Centers are
becoming the norm. As applications and appliances are increasingly
being virtualized, support for virtual edge devices, such as virtual
L3/L2 VPN PE routers, becomes feasible and desirable for Service
Providers who want to extend their existing MPLS VPN deployments into
Data Centers to provide end-to-end Virtual Private Cloud (VPC)
services. Virtual PE work is also one of early effort for Network
Functions Virtualization (NFV). In general, scalability, agility, and
cost efficiency are primary motivations for vPE solutions.
The virtual Provider Edge (vPE) solution described in this document
allows for the extension of the PE functionality of L3/L2 VPN to an
end device, such as a server where the applications reside, or to a
first hop routing/switching device, such as a Top of the Rack (ToR)
switch in a DC.
The vPE solutions support both the Software Defined Networks (SDN)
approach, which allows physical decoupling of the control and the
forwarding, and the traditional distributed routing approach.
1.1 Terminology
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 [RFC2119].
Term Definition
----------- --------------------------------------------------
ASBR Autonomous System Border Router
BGP Border Gateway Protocol
CE Customer Edge
Forwarder IP VPN forwarding function
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GRE Generic Routing Encapsulation
Hypervisor Virtual Machine Manager
I2RS Interface to Routing Systems
LDP Label Distribution Protocol
MP-BGP Multi-Protocol Border Gateway Protocol
MPLS Multi-Protocol Label Switching
PCEF Policy Charging and Enforcement Function
QoS Quality of Service
RR Route Reflector
RT Route Target
RTC RT Constraint
SDN Software Defined Networks
ToR Top-of-Rack switch
VI Virtual Interface
vCE virtual Customer Edge Router
VM Virtual Machine
vPC virtual Private Cloud
vPE virtual Provider Edge Router
vPE-C virtual Provider Edge Control plane
vPE-F virtual Provider Edge Forwarder
VPN Virtual Private Network
vRR virtual Route Reflector
WAN Wide Area Network
End device: where Guest OS, Host OS/Hypervisor, applications, VMs,
and virtual router may reside.
1.2 Requirements
The following are key requirements for vPE solutions.
1) MUST support end device multi-tenancy, per tenant routing
isolation and traffic separation.
2) MUST support large scale MPLS VPNs in the Data Center, upto tens
of thousands of end devices and millions of VMs in the single Data
Center.
3) MUST support end-to-end MPLS VPN connectivity, e.g. MPLS VPN can
start from a DC end device, connect to a corresponding MPLS VPN in
the WAN, and terminate in another Data Center end device.
4) MUST allow physical decoupling of MPLS VPN PE control and
forwarding for network virtualization and abstraction.
5) MUST support the control plane with both SDN controller approach,
and the traditional distributed control plane approach with MP-BGP
protocol.
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6) MUST support VM mobility.
7) MUST support orchestration/auto-provisioning deployment model.
8) SHOULD be capable to support service chaining as part of the
solution [I-D.rfernando-l3vpn-service-chaining],
[I-D.bitar-i2rs-service-chaining].
The architecture and protocols defined in BGP/MPLS IP VPN [RFC4364]
and BGP/MPLS EVPN [I-D.ietf-l2vpn-evpn] provide the foundation for
vPE extension. Certain protocol extensions may be needed to support
the virtual PE solutions.
2. Virtual PE Architecture
2.1 Virtual PE definitions
As defined in [RFC4364] and [I-D.ietf-l2vpn-evpn], an MPLS VPN is
created by applying policies to form a subset of sites among all
sites connected to the backbone networks. It is a collection of
"sites". A site can be considered as a set of IP/ETH systems
maintaining IP/ETH inter-connectivity without direct connecting
through the backbone. The typical use of L3/L2 VPN has been to
inter-connect different sites of an Enterprise networks through a
Service Provider's BGP MPLS VPNs in the WAN.
A virtual PE (vPE) is a BGP/MPLS L3/L2 VPN PE software instance which
may reside in any network or computing devices. The control and
forwarding components of the vPE can be decoupled, they may reside in
the same physical device, or in different physical devices.
A virtualized Provider Edge Forwarder (vPE-F) is the forwarding
element of a vPE. vPE-F can reside in an end device, such as a server
in a Data Center where multiple application Virtual Machines (VMs)
are supported, or a Top-of-Rack switch (ToR) which is the first hop
switch from the Data Center edge. When a vPE-F is residing in a
server, its connection to a co-resident VM can be viewed as similar
to the PE- CE relationship in the regular BGP L3/L2 VPNs, but without
routing protocols or static routing between the virtual PE and end-
host because the connection is internal to the device.
The vPE Control plane (vPE-C) is the control element of a vPE. When
using the approach where control plane is decoupled from the physical
topology, the vPE-F may be in a server and co-resident with
application VMs, while one vPE-C can be in a separate device, such as
an SDN Controller where control plane elements and orchestration
functions are located. Alternatively, the vPE-C can reside in the
same physical device as the vPE-F. In this case, it is similar to the
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traditional implementation of VPN PEs where, distributed MP-BGP is
used for L3/L2 VPN information exchange, though the vPE is not a
dedicated physical entity as it is in a physical PE implementation.
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2.2 vPE Architecture and Design options
2.2.1 vPE-F host location
Option 1a. vPE-F is on an end device as co-resident with application
VMs. For example, the vPE-F is on a server in a Data Center.
Option 1b. vPE-F forwarder is on a ToR or other first hop devices in
a DC, not as co-resident with the application VMs.
Option 1c. vPE-F is on any network or compute devices in any types of
networks.
2.2.2 vPE control plane topology
Option 2a. vPE control plane is physically decoupled from the vPE-F.
The control plane may be located in a controller in a separate device
(a stand alone device or can be in the gateway as well) from the vPE
forwarding plane.
Option 2b. vPE control plane is supported through dynamic routing
protocols and located in the same physical device as the vPE-F.
2.2.3 Data Center orchestration models
Option 3a. Push model: It is a top down approach, push IP VPN
provisioning state from a network management system or other
centrally controlled provisioning system to the IP VPN network
elements.
Option 3b. Pull model: It is a bottom-up approach, pull state
information from network elements to network management/AAA based
upon data plane or control plane activity.
2.3 vPE Architecture reference models
2.3.1 vPE-F in an end-device and vPE-C in the controller
Figure 1 illustrates the reference model for a vPE solution with the
vPE-F in the end device co-resident with applications VMs, while the
vPE-C is physically decoupled and residing on a controller.
The Data Center is connected to the IP/MPLS core via the
Gatways/ASBRs. The MPLS VPN , e.g. VPN RED, has a single termination
point within the DC at one of the VPE-F, and is inter-connected in
the WAN to other member sites which belong to the same client, and
the remote ends of VPN RED can be a PE which has VPN RED attached to
it, or another vPE in a different Data Center.
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Note that the DC fabrics/intermediate underlay devices in the DC do
not participate IP VPNs, their function is the same as provider
backbone routers in the IP/MPLS back bone and they do not maintain
the VPN states, nor they are VPN aware.
,-----.
( ')
.--(. '.---.
( ' ' )
( IP/MPLS WAN )
(. .)
( ( .)
WAN ''--' '-''---'
----------------|----------|------------------------
Service/DC | |
Network +-------+ +-------+
|Gateway|---|Gateway| *
| /ASBR | | /ASBR | *
+-------+ +-------+ *
| | +-------------+
| ,---. | |Controller |
.---. ( '.---. |(vPE-C and |
( ' ' ') |orchestrator)|
( Data Center ) +-------------+
(. Fabric ) *
( ( ).--' *
/ ''--' '-''--' \ *
/ / \ \ *
+-------+ +-------+ +-------+ +-------+
| vPE-F | | vPE-F | | vPE-F | | vPE-F |
+---+---+ +---+---+ +---+---+ +---+---+
|VM |VM | |VM |VM | |VM |VM | |VM |VM |
+---+---+ +---+---+ +---+---+ +---+---+
|VM |VM | |VM |VM | |VM |VM | |VM |VM |
+---+---+ +---+---+ +---+---+ +---+---+
End Device End Device End Device End Device
Figure 1. Virtualized Data Center with vPE at
the end device and vPE-C and vPE-F physically decoupled
Note:
a) *** represents Controller logical connections to the all
Gateway/ASBRs and to all vPE-F.
b) ToR is assumed included in the Data Center cloud.
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2.3.2 vPE-F and vPE-C on the same end-device
In this option, vPE-F and vPE-C functionality are both resident in
the end-device. The vPE functions the same as it is in a physical PE.
MP-BGP is used for the VPN control plane. Virtual or physical Route
Reflectors (RR) (not shown in the diagram) can be used to assist
scaling.
,-----.
( ')
.--(. '.---.
( ' ' )
( IP/MPLS WAN )
(. .)
( ( .)
WAN ''--' '-''---'
----------------|----------|----------------------
Service/DC | |
Network +-------+ +-------+
|Gateway|---|Gateway|
| /ASBR | | /ASBR | *
+-------+ +-------+ *
| | * MP-BGP
| ,---. | *
.---. ( '.---. *
( ' ' ') *
( Data Center ) *
(. Fabric ) *
( ( ).--' *
/ ''--' '-''--' \ *
/ / \ \ *
+-------+ +-------+ +-------+ +-------+
| vPE | | vPE | | vPE | | vPE |
+---+---+ +---+---+ +---+---+ +---+---+
|VM |VM | |VM |VM | |VM |VM | |VM |VM |
+---+---+ +---+---+ +---+---+ +---+---+
|VM |VM | |VM |VM | |VM |VM | |VM |VM |
+---+---+ +---+---+ +---+---+ +---+---+
End Device End Device End Device End Device
Figure 2. Virtualized Data Center with vPE at
the end device, VPN control signal uses MP-BGP
Note:
a) *** represents the logical connections using MP-BGP among the
Gateway/ASBRs and to the vPEs on the end devices.
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b) ToR is assumed included in the Data Center cloud.
2.3.3 vPE-F and vPE-C are on the ToR
In this option, vPE functionality is the same as a physical PE. MP-
BGP is used for the VPN control plane. Virtual or physical Route
Reflector (RR) (not shown in the diagram) can be used to assist
scaling.
,-----.
( ')
.--(. '.---.
( ' ' )
( IP/MPLS WAN )
(. .)
( ( .)
WAN ''--' '-''---'
----------------|----------|----------------------
Service/DC | |
Network +-------+ +-------+
|Gateway|---|Gateway|
| /ASBR | | /ASBR | *
+-------+ +-------+ *
| | * MP-BGP
| ,---. | *
.---. ( '.---. *
( ' ' ') *
( Data Center ) *
(. Fabric ) *
( ( ).--' *
/''--' '-/'--' \ *
+---+---+ +---+---+ +---+---+
|vPE| | |vPE| | |vPE| |
+---+ | +---+ | +---+ |
| ToR | | ToR | | ToR |
+-------+ +-------+ +-------+
/ \ / \ / \
+-------+ +-------+ +-------+ +-------+
| vPE | | vPE | | vPE | | vPE |
+---+---+ +---+---+ +---+---+ +---+---+
|VM |VM | |VM |VM | |VM |VM | |VM |VM |
+---+---+ +---+---+ +---+---+ +---+---+
|VM |VM | |VM |VM | |VM |VM | |VM |VM |
+---+---+ +---+---+ +---+---+ +---+---+
End Device End Device End Device End Device
Figure 3. Virtualized Data Center with vPE at
the ToP, VPN control signal uses MP-BGP
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Note: *** represents the logical connections using MP-BGP among the
Gateway/ASBRs and to the vPEs on the ToRs.
2.3.4 vPE-F on the ToR and vPE-C on the controller
In this option, the L3/L2 VPN termination is at the ToR, but the
control plane decoupled from the data plane and resided in a
controller, which can be on a stand alone device, or can be placed at
the Gateway/ASBR.
2.3.5 The server view of a vPE
An end device shown in Figure 4 is a virtualized server that hosts
multiple VMs. The virtual PE is co-resident in the server with
application VMs. The vPE supports multiple VRFs, VRF Red, VRF Grn,
VRF Yel, VRF Blu, etc. Each application VM is associated to a
particular VRF as a member of the particular VPN. For example, VM1 is
associated to VRF Red, VM2 and VM47 are associated to VRF Grn, etc.
Routing/switching isolation applies between VPNs for multi-tenancy
support. For example, VM1 and VM2 cannot communicate directly in a
simple intranet VPN topology as shown in the configuration.
The vPE connectivity relationship between vPE and the application VM
is similar to the PE-to-CE relationship in regular BGP VPNs. However,
as the vPE and end-host functions are co-resident in the same server,
the connection between them is an internal implementation of the
server.
+----------------------------------------------------+
| +---------+ +---------+ +---------+ +---------+ |
| | VM1 | | VM2 | | VM47 | | VM48 | |
| |(VPN Red)| |(VPN Grn)|... |(VPN Grn)| |(VPN Blu)| |
| +----+----+ +---+-----+ +----+----+ +----+----+ |
| | | | | |
| +---+ | +-------------+ +---+ |
| | | | | |
to | +---+------+-+---------------------+---+ |
Gateway| | | | | | | |
PE | | +-+-+ ++-++ +---+ +-+-+ | |
| | |VRF| |VRF| ....... |VRF| |VRF| | |
<------+------+ |Red| |Grn| |Yel| |Blu| | |
| | +---+ +---+ +---+ +---+ | |
| | L3 VPN virtual PE | |
| +--------------------------------------+ |
| |
| End Device |
+----------------------------------------------------+
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Figure 4. Server View of vPE to VM relationship
An application VM may send packets to a vPE forwarder that need to be
bridged, either locally to another VM, or to a remote destination. In
this case, the vPE contains a virtual bridge instance to which the
application VMs (CEs) are attached.
+----------------------------------------------------+
| +---------+ +---------+ +---------+ |
| | VM1 | | VM2 | | VM47 | |
| |(VPN Red)| |(VPN Grn)|...|(VPN Grn)| |
| +----+----+ +----+----+ +----+----+ |
| | | | |
| +---+ +----+ +----+ |
| | | | |
to | +---+------------+---+-----------------+ |
Gateway| | | | | | |
PE | | +-+--+--+ +-+---+-+ | |
| | |VBridge| |VBridge| ....... | |
<------+------+ |Red | |Grn | | |
| | +-------+ +-------+ | |
| | vPE | |
| +--------------------------------------+ |
| |
| End Device |
+----------------------------------------------------+
Figure 4. Bridging Service at vPE
3. Control Plane
3.1 vPE Control Plane (vPE-C)
3.1.1 The SDN approach
This approach is appropriate when the vPE control and data planes are
physically decoupled. The control plane directing the data flow may
reside elsewhere, e.g. in a SDN controller. This approach requires a
standard interface to the routing system. The Interface to Routing
System (I2RS) is work in progress in IETF as described in
[I-D.ietf-i2rs-architecture], [I-D.ietf-i2rs-problem-statement].
Although MP-BGP is often the de facto preferred choice between vPE
and gateway-PE/ASBR, the use of extensible signaling messaging
protocols MAY often be more practical in a Data Center environment.
One such proposal that uses this approach is detailed in
[I-D.ietf-l3vpn-end-system].
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3.1.2 Distributed control plane
In the distributed control plane approach, the vPE participates in
the overlay L3/L2 VPN control protocol: MP-BGP [RFC4364].
When the vPE function is on a ToR, it participates the underlay
routing through IGP protocols (ISIS or OSPF) or BGP.
When the vPE function is on a server, it functions as a host attached
to a server.
3.3 Use of router reflector
Modern Data Centers can be very large in scale. For example, the
number of VPNs routes in a very large DC can surpass the scale of
those in a Service Provider backbone VPN networks. There may be tens
of thousands of end devices in a single DC.
Use of Router Reflector (RR) is necessary in large-scale IP VPN
networks to avoid a full iBGP mesh among all vPEs and PEs. The VPN
routes can be partitioned to a set of RRs, the partitioning
techniques are detailed in [RFC4364] and [I-D.ietf-l2vpn-evpn].
When a RR software instance is residing in a physical device, e.g., a
server, which is partitioned to support multi-functions and
application VMs, the RR becomes a virtualized RR (vRR). Since RR
performs control functions only, a dedicated or virtualized server
with large scale of computing power and memory can be a good
candidate as host of vRRs. The vRR can also reside in a Gateway
PE/ASBR, or in an end device.
3.4 Use of Constrained Route Distribution [RFC4684]
The Constrained Route Distribution [RFC4684] is a powerful tool for
selective VPN route distribution. With RTC, only the BGP receivers
(e.g, PE/vPE/RR/vRR/ASBRs, etc.) with the particular IP VPNs attached
will receive the route update for the corresponding VPNs. It is
critical to use constrained route distribution to support large-scale
IP VPN developments.
4. Forwarding Plane
4.1 Virtual Interface
A Virtual Interface (VI) is an interface within an end device that is
used for connection of the vPE to the application VMs in the same end
device. Such application VMs are treated as CEs in the regular VPN's
view.
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4.2 Virtual Provider Edge Forwarder (vPE-F)
The Virtual Provider Edge Forwarder (vPE-F) is the forwarding
component of a vPE where the tenant identifiers (for example, MPLS
VPN labels) are pushed/popped.
The vPE-F location options include:
1) Within the end device where the virtual interface and application
VMs are located.
2) In an external device such as a Top of the Rack switch (ToR) in a
DC into which the end device connects.
Multiple factors should be considered for the location of the vPE-F,
including device capabilities, overall solution economics,
QoS/firewall/NAT placement, optimal forwarding, latency and
performance, operational impact, etc. There are design tradeoffs, it
is worth the effort to study the traffic pattern and forwarding
looking trend in your own unique Data Center as part of the exercise.
4.3 Encapsulation
BGP/MPLS VPNs can be tunneled through the network as overlays using
MPLS-based or IP-based encapsulation.
In the case of MPLS-based encapsulation, most existing core
deployments use distributed protocols such as Label Distribution
Protocol (LDP), [RFC3032][RFC5036], or RSVP-TE [RFC3209].
Due to its maturity, scalability, and header efficiency, MPLS Label
Stacking is gaining traction by service providers, and large-scale
cloud providers in particular, as the unified forwarding mechanism of
choice.
With the emergence of the SDN paradigm, label distribution may be
achieved through SDN controllers, or via a combination of centralized
control and distributed protocols.
In the case of IP-based encapsulation, MPLS VPN packets are
encapsulated in IP or Generic Routing Encapsulation (GRE), [RFC4023],
[RFC4797]. IP-based encapsulation has not been extensively deployed
for BGP/MPLS VPN in the core; however it is considered as one of the
tunneling options for carrying MPLS VPN overlays in the data center.
Note that when IP encapsulation is used, the associated security
properties must be analyzed carefully.
4.4 Optimal forwarding
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Many large cloud service providers have reported the DC traffic is
now dominated by East-West across subnet traffic (between the end
device hosting different applications in different subnets) rather
than North-South traffic (going in/out of the Data Center and to/from
the WAN) or switched traffic within subnets. This is the primary
reason that newer DC design has moved away from traditional Layer-2
design to Layer-3, especially for the overlay networks.
When forwarding the traffic within the same VPN, the vPE SHOULD be
capable to provide direct communication among the VMs/application
senders/receivers without the need of going through Gateway devices.
If the senders and the receivers are on the same end device, the
traffic SHOULD NOT need to leave the device. If they are on different
end devices, optimal routing SHOULD be applied.
Extranet MPLS VPN techniques can be used for multiple VPNs access
without the need of Gateway facilitation. This is done through the
use of VPN policy control mechanisms.
In addition, ECMP is a built in IP mechanism for load sharing.
Optimal use of available bandwidth can be achieved by virtue of using
ECMP in the underlay, as long as the encapsulation includes certain
entropy in the header, VXLAN is such an example.
4.5 Routing and Bridging Services
A VPN forwarder (vPE-F) may support both IP forwarding as well as
Layer 2 bridging for traffic from attached end hosts. This traffic
may be between end hosts attached to the same VPN forwarder or to
different VPN forwarders.
In both cases, forwarding at a VPN forwarder takes place based on the
IP or MAC entries provisioned by the vPE controller.
When the vPE is providing Layer 3 service to the attached CEs, the
VPN forwarder has a VPN VRF instance with IP routes installed for
both locally attached end-hosts and ones reachable via other VPN
forwarders. The vPE may perform IP routing for all IP packets in this
mode.
When the vPE provides Layer 2 service to the attached end-hosts, the
VPN forwarder has an E-VPN instance with appropriate MAC entries.
The vPE may support an Integrated Routing and Bridging service, in
which case the relevant VPN forwarders will have both MAC and IP
table entries installed, and will appropriately route or switch
incoming packets.
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The vPE controller performs the necessary provisioning functions to
support various services, as defined by an user.
5. Addressing
5.1 IPv4 and IPv6 support
IPv4 and IPv6 MUST be supported in the vPE solution.
This may present a challenge for older devices, but this normally is
not an issue for the newer generation of forwarding devices and
servers. Note that a server is replaced much more frequently than a
network router/switch, and newer equipment SHOULD be capable of IPv6
support.
5.2 Address space separation
The addresses used for the IP VPN overlay in a DC, SHOULD be taken
from separate address blocks outside the ones used for the underlay
infrastructure of the DC. This practice is to protect the DC
infrastructure from being attacked if the attacker gains access to
the tenant VPNs.
Similarity, the addresses used for the DC SHOULD be separated from
the WAN backbone addresses space.
6.0 Inter-connection considerations
The inter-connection considerations in this section are focused on
intra-DC inter-connections.
There are deployment scenarios where BGP/MPLS IP VPN may not be
supported in every segment of the networks to provide end-to-end IP
VPN connectivity. A vPE may be reachable only via an intermediate
inter-connecting network; interconnection may be needed in these
cases.
When multiple technologies are employed in the solution, a clear
demarcation should be preserved at the inter-connecting points. The
problems encountered in one domain SHOULD NOT impact other domains.
From an IP VPN point of view: An IP VPN vPE that implements [RFC4364]
is a component of the IP VPN network only. An IP VPN VRF on a
physical PE or vPE contains IP routes only, including routes learnt
over the locally attached network.
The IP VPN vPE should ideally be located as close to the "customer"
edge devices as possible. When this is not possible, simple existing
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"IP VPN CE connectivity" mechanisms should be used, such as static,
or direct VM attachments such as described in the vCE
[I-D.fang-l3vpn-virtual-ce] option below.
Consider the following scenarios when BGP MPLS VPN technology is
considered as whole or partial deployment:
Scenario 1: All VPN sites (CEs/VMs) support IP connectivity. The most
suited BGP solution is to use IP VPNs [RFC4364] for all sites with PE
and/or vPE solutions.
Scenario 2: Legacy Layer 2 connectivity must be supported in certain
sites/CEs/VMs, and the rest of the sites/CEs/VMs need only Layer 3
connectivity.
One can consider using a combined vPE and vCE
[I-D.fang-l3vpn-virtual-ce] solution to solve the problem. Use IP VPN
for all sites with IP connectivity, and a physical or virtual CE
(vCE, may reside on the end device) to aggregate the Layer 2 sites
which for example, are in a single container in a Data Center. The
CE/vCE can be considered as inter-connecting points, where the Layer
2 network is terminated and the corresponding routes for connectivity
of the L2 network are inserted into IP VPN VRFs. The Layer 2 aspect
is transparent to the L3VPN in this case.
Reducing operation complicity and maintaining the robustness of the
solution are the primary reasons for the recommendations.
The interconnection of MPLS VPN in the data center and the MPLS core
through ASBR using existing inter-AS options is discussed in detail
in [I-D.fang-l3vpn-data-center-interconnect].
7. Management, Control, and Orchestration
7.1 Assumptions
The discussion in this section is based on the following set of
assumptions:
- The WAN and the inter-connecting Data Center, MAY be under control
of separate administrative domains
- WAN Gateways/ASBRs/PEs are provisioned by existing WAN provisioning
systems
- If a single Gateway/ASBR/PE connecting to the WAN on one side, and
connecting to the Data Center network on the other side, then this
Gateway/ASBR/PE is the demarcation point between the two networks.
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- vPEs and VMs are provisioned by Data Center Orchestration systems.
- Managing IP VPNs in the WAN is not within the scope of this
document except the inter-connection points.
7.2 Management/Orchestration system interfaces
The Management/Orchestration system CAN be used to communicate with
both the DC Gateway/ASBR, and the end devices.
The Management/Orchestration system MUST support standard,
programmatic interface for full-duplex, streaming state transfer in
and out of the routing system at the Gateway.
The programmatic interface is currently under definition in IETF
Interface to Routing Systems (I2RS)) initiative.
[I-D.ietf-i2rs-architecture], and [I-D.ietf-i2rs-problem-statement].
Standard data modeling languages will be defined/identified in I2RS.
YANG - A Data Modeling Language for the Network Configuration
Protocol (NETCONF) [RFC6020] is a promising candidate currently under
investigation.
To support remote access between applications running on an end
device (e.g., a server) and routers in the network (e.g. the DC
Gateway), a standard mechanism is expected to be identified and
defined in I2RS to provide the transfer syntax, as defined by a
protocol, for communication between the application and the
network/routing systems. The protocol(s) SHOULD be lightweight and
familiar by the computing communities. Candidate examples include
ReSTful web services, JSON [RFC7159], NETCONF [RFC6241], XMPP
[RFC6120], and XML. [I-D.ietf-i2rs-architecture].
7.3 Service VM Management
Service VM Management SHOULD be hypervisor agnostic, e.g. On demand
service VMs turning-up SHOULD be supported.
7.4 Orchestration and MPLS VPN inter-provisioning
The orchestration system
1) MUST support MPLS VPN service activation in virtualized DC.
2) MUST support automated cross-provisioning accounting correlation
between the WAN MPLS VPN and Data Center for the same tenant.
3) MUST support automated cross provisioning state correlation
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between WAN MPLS VPN and Data Center for the same tenant
There are two primary approaches for IP VPN provisioning - push and
pull, both CAN be used for provisioning/orchestration.
7.4.1 vPE Push model
Push model: push IP VPN provisioning from management/orchestration
systems to the IP VPN network elements.
This approach supports service activation and it is commonly used in
existing MPLS VPN Enterprise deployments. When extending existing WAN
IP VPN solutions into the a Data Center, it MUST support off-line
accounting correlation between the WAN MPLS VPN and the cloud/DC MPLS
VPN for the tenant. The systems SHOULD be able to bind interface
accounting to particular tenant. It MAY requires offline state
correlation as well, for example, binding of interface state to
tenant.
Provisioning the vPE solution:
1) Provisioning process
a. The WAN provisioning system periodically provides to the DC
orchestration system the VPN tenant and RT context.
b. DC orchestration system configures vPE on a per request basis
2) Auto state correlation
3) Inter-connection options:
Inter-AS options defined in [RFC4364] may or may not be sufficient
for a given inter-connection scenario. BGP IP VPN inter-connection
with the Data Center is discussed in
[I-D.fang-l3vpn-data-center-interconnect].
This model requires offline accounting correlation
1) Cloud/DC orchestration configures vPE
2) Orchestration initiates WAN IP VPN provisioning; passes
connection IDs (e.g., of VLAN/VXLAN) and tenant context to WAN IP
VPN provisioning systems.
3) WAN MPLS VPN provisioning system provisions PE VRF and policies
as in typical Enterprise IP VPN provisioning processes.
4) Cloud/DC Orchestration system or WAN IP VPN provisioning system
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MUST have the knowledge of the connection topology between the DC
and WAN, including the particular interfaces on core router and
connecting interfaces on the DC PE and/or vPE.
In short, this approach requires off-line accounting correlation
and state correlation, and requires per WAN Service Provider
integration.
Dynamic BGP sessions between PE/vPE and vCE MAY be used to
automate the PE provisioning in the PE-vCE model, that will remove
the needs for PE configuration. Caution: This is only under the
assumption that the DC provisioning system is trusted and can
support dynamic establishment of PE-vCE BGP neighbor
relationships, for example, the WAN network and the cloud/DC
belong to the same Service Provider.
7.4.2 vPE Pull model
Pull model: pull from network elements to network management/AAA
based upon data plane or control plane activity. It supports
service activation. This approach is often used in broadband
deployments. Dynamic accounting correlation and dynamic state
correlation are supported. For example, session based accounting
is implicitly includes tenant context state correlation, as well
as session-based state that implicitly includes tenant context.
Note that the pull model is less common for vPE deployment
solutions.
Provisioning process:
1) Cloud/DC orchestration configures vPE
2) Orchestration primes WAN MPLS VPN provisioning/AAA for new
service, passes connection IDs (e.g., VLAN/VXLAN) and tenant
context.
3) Cloud/DC ASBR detects new VLAN and sends Radius Access-Request
(or Diameter Base Protocol request message [RFC6733]).
4) Radius Access-Accept (or Diameter Answer) with VRF and other
policies
Auto accounting correlation and auto state correlation is
supported.
8. Security Considerations
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As vPE is an extended BGP/MPLS VPN solution, security threats and
defense techniques described in RFC 4111 [RFC4111] generally
apply.
When the SDN approach is used, the protocols between the vPE agent
and the vPE-C in the controller MUST be mutually authenticated.
Given the potentially very large scale and the dynamic nature in
the cloud/DC environment, the choice of key management mechanisms
need to be further studied.
VMs in the servers can belong to different tenants with different
characteristics depending on the application. Classification of
the VMs must be done through the orchestration system and
appropriate security policies must be applied based on such
classification before turning on the services.
9. IANA Considerations
None.
10. Acknowledgments
The authors would like to thank Daniel Voyer for his review and
comments.
11. References
11.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, January 2001.
[RFC3209] Awduche, D., et al., "RSVP-TE: Extension to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC4023] Worster, T., Rekhter, Y., and E. Rosen, Ed.,
"Encapsulating MPLS in IP or Generic Routing Encapsulation
(GRE)", RFC 4023, March 2005.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, February 2006.
[RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk,
R., Patel, K., and J. Guichard, "Constrained Route
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Distribution for Border Gateway Protocol/MultiProtocol
Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual
Private Networks (VPNs)", RFC 4684, November 2006.
[RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,
"LDP Specification", RFC 5036, October 2007.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
October 2010.
[RFC6120] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Core", RFC 6120, March 2011.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, June 2011.
[RFC6733] Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn,
Ed., "Diameter Base Protocol", RFC 6733, October 2012.
11.2 Informative References
[RFC4111] Fang, L., Ed., "Security Framework for Provider-
Provisioned Virtual Private Networks (PPVPNs)", RFC 4111,
July 2005.
[RFC7159] Bray, T., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, March 2014.
[RFC4797] Rekhter, Y., Bonica, R., and E. Rosen, "Use of Provider
Edge to Provider Edge (PE-PE) Generic Routing
Encapsulation (GRE) or IP in BGP/MPLS IP Virtual Private
Networks", RFC 4797, January 2007.
[I-D.ietf-l3vpn-end-system] Marques, P., Fang, L., Pan, P., Shukla,
A., Napierala, M., Bitar, N., "BGP-signaled end-system
IP/VPNs", draft-ietf-l3vpn-end-system, work in progress.
[I-D.rfernando-l3vpn-service-chaining] Fernando, R., Rao, D., Fang,
L., Napierala, M., So, N., draft-rfernando-l3vpn-service-
chaining, work in progress.
[I-D.fang-l3vpn-virtual-ce] Fang, L., Evans, J., Ward, D., Fernando,
R., Mullooly, J., So, N., Bitar., N., Napierala, M., "BGP
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IP VPN Virtual PE", draft-fang-l3vpn-virtual-ce, work in
progress.
[I-D.ietf-i2rs-architecture] Atlas, A., Halpern, J., Hares, S., Ward,
D., and Nadeau, T., "An Architecture for the Interface to
the Routing System", draft-ietf-i2rs-architecture, work in
progress.
[I-D.ietf-i2rs-problem-statement] Atlas, A., Nadeau, T., and Ward,
D., "Interface to the Routing System Problem Statement",
draft-ietf-i2rs-problem-statement, work in progress.
[I-D.bitar-i2rs-service-chaining] Bitar, N., Geron, G., Fang, L.,
Krishnan, R., Leymann, N., Shah, H., Chakrabarti, S.,
Haddad, W., draft-bitar-i2rs-service-chaining, work in
progress.
[I-D.fang-l3vpn-data-center-interconnect] Fang, L., Fernando, R.,
Rao, D., Boutros, S., "BGP IP VPN Data Center
Interconnect", draft-fang-l3vpn-data-center-interconnect,
work in progress.
[I-D.ietf-l2vpn-evpn] Sajassi, A., et al., "BGP MPLS Based Ethernet
VPN", draft-ietf-l2vpn-evpn, work in progress.
Authors' Addresses
Luyuan Fang
Microsoft
5600 148th Ave NE
Redmond, WA 98052
Email: lufang@microsoft.com
David Ward
Cisco
170 W Tasman Dr
San Jose, CA 95134
Email: wardd@cisco.com
Rex Fernando
Cisco
170 W Tasman Dr
San Jose, CA
Email: rex@cisco.com
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Maria Napierala
AT&T
200 Laurel Avenue
Middletown, NJ 07748
Email: mnapierala@att.com
Nabil Bitar
Verizon
40 Sylvan Road
Waltham, MA 02145
Email: nabil.bitar@verizon.com
Dhananjaya Rao
Cisco
170 W Tasman Dr
San Jose, CA
Email: dhrao@cisco.com
Bruno Rijsman
Juniper Networks
10 Technology Park Drive
Westford, MA 01886
Email: brijsman@juniper.net
Ning So
Vinci Systems
Plano, TX 75082, USA
Email: ning.so@vinci-systems.com
Jim Guichard
Cisco
Boxborough, MA 01719
Email: jguichar@cisco.com
Wen Wang
CenturyLink
2355 Dulles Corner Blvd.
Herndon, VA 20171
Email:Wen.Wang@CenturyLink.com
Manuel Paul
Deutsche Telekom
Winterfeldtstr. 21-27
10781 Berlin, Germany
Email: manuel.paul@telekom.de
Wim Henderichx
Alcatel-Lucent
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Email: wim.henderichx@alcatel-lucent.com
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