Internet DRAFT - draft-renwei-l3vpn-big-label
draft-renwei-l3vpn-big-label
L3VPN Working Group R. Li
Internet-Draft K. Zhao
Intended status: Standards Track W. Wu
Expires: January 01, 2014 Huawei Technologies
June 30, 2013
The Use of Big Labels for BGP/MPLS IP VPN
draft-renwei-l3vpn-big-label-00.txt
Abstract
This document describes big labels in L3VPN.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirement Language . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Use Cases and Scenarios . . . . . . . . . . . . . . . . . . . 3
2.1. VXLAN . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. NVGRE . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3. NVO3 . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. Big Labels . . . . . . . . . . . . . . . . . . . . . . . . . 8
4. VRFs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5. VPN Route Distribution . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Network virtualization and server virtualization are being designed
and deployed in data center networks, and new data encapsulation
methods and protocols are being defined and specified, for example,
VXLAN, NVGRE and NVO3. The general idea is to add a new virtual
network header so that a physical network can be used to support
millions (16M) of virtualized overlaid networks. Network overlay
virtualization have placed a new requirement on the access method to
such virtualized overlaid networks.
BGP/MPLS IP VPNs, as specified in RFC 2547 and RFC 4364, provide a
market-proven technology and solution for end-to-end IP VPNs. In BGP
/MPLS IP VPNs, all the customer sites are connected to the service
provider networks through PE-CE link. It is desirable to extend the
BGP/MPLS scheme so that customers can access their virtualized
networks hosted in a data center by using BGP/MPLS IP VPNs.
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In the data plane of BGP/MPLS IP VPNs, the customer VPN/VRF instances
are represented by an MPLS label (VPN label) locally assgined by the
PE connecting to CE. Since MPLS labels are 20 bits long, a PE can
maximally support 1 million VPNs/VRFs, which are not sufficient to
support 16 millions of virtual networks that are being standardized
in VXLAN, NVGRE and NVO3. When BGP/MPLS IP VPNs are extended to
access virtualized networks in data centers, we will have to provide
a solution on how to associate a customer to a virtual network. This
document will describe some use cases and specify a solution to this
problem.
1.1. Requirement Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
1.2. Terminology
The following terms are used in this document:
VXLAN - Virtual eXtensible Local Area Network
NVGRE - Network Virtualization using Generic Routing Encapsulation
NVO3 - Network Virtualization Over layer 3
BGP - Border Gateway Protocol
MPLS - Multiprotocol Label Switching
VPN - Virtual private network
PE - Provider Edge
CE - Customer Edge
VRF - Virtual Routing and Forwarding
NVE - Network Virtualization Edge
VTEP - VXLAN Tunnel End Point
VNI - VXLAN Network Identifier (VXLAN)
VSID -Virtual Subnet ID (NVGRE)
VNID - Virtual Network ID (NVO3)
VM - Virtual Machine
TS - Tenant System
VLAN - Virtual Local Area Network
2. Use Cases and Scenarios
In BGP/MPLS IP VPN reference models, at each site there are one or
more Customer Edge (CE) devices, each of which is attached to one or
more Provider Edge (PE) routers via some sort of attachment circuit
such as PPP, Ethernet/VLAN, etc.
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When the BGP/MPLS IP VPNs reference model is extended to connect to a
virtual network, the Customer Edge (CE) devices and Provider Edge
(PE) devices on the data center site can be physically the same
device: it will be both the PE device with respect to the VPN model
and the NVE device with respect to the network virtualization, as
illustrated in the following diagram
-----------+ +----------------+ +----------------
| | | |
+---+--+ +------+ +-------+--+
| CE |----| PE | MPLS | PE-NVE | Data center
Site 1 |device| |device| network | device | virtualized
+---+--+ +------+ +-------+--+ network
| | | |
-----------+ +----------------+ +----------------
In addition to the VPN PE functionalities of RFC 4364, PE-NVE will
also perform the functionalities of network overlay virtualization.
In what follows we describe three use cases for VXLAN, NVGRE, and
NVO3, respectively.
2.1. VXLAN
In this use case, the VXLAN protocol of [I-D.mahalingam-dutt-dcops-
vxlan] is used for network overlay virtualiztion.
..................................
. .
. +------------+ .
. |+----+ +---+| .
. || | |VM || .
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. /+| | +---+| .
. / ||VTEP| +---+| .
-----+ +----------------+ . +------------+ || | |VM || .
| | | . | | |+----+ +---+| .
+---+--+ +------+ +---+---+--+ VXLAN | | Server | .
| CE |---| PE | MPLS | PE-VTEP | network | +------------+ .
|device| |device| network | device | over L3 | .
+---+--+ +------+ +---+---+--+ network | +------------+ .
| / | | . | | |+----+ +---+| .
-----+ / +----------------+ . +------------+ || | |VM || .
/ . \ || | +---+| .
-----+ / . \+|VTEP| +---+| .
| / . || | |VM || .
+---+--+ . |+----+ +---+| .
| CE | . | Server | .
|device| . Data Center +------------+ .
+---+--+ ..................................
|
-----+
+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+
|LSP label| | Outer Header |
+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+
|VPN label| | VXLAN Header |
+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+
| VM IP | | Inner Header |
+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+
Packet format Packet format
out of PE device out of PE-VTEP device
to MPLS network to VXLAN network
When one PC in a CE site wants to send a packet to one VM in the data
center, the outgoing packet headers of PE device and PE-VTEP device
are described as above. VPN label is mapped to VNI in VXLAN Header.
The Provider Edge device connecting to the virtual networks will
perform the following functionalities:
VPN PE functions: (1) It uses BGP to distribute VPN routes; (2) It
maintains VRFs; (3) It uses MPLS to receive and forward packets
from and to the MPLS network.
VXLAN VTEP functions: (1) It originates and terminates VXLAN
tunnels; (2) It runs all the necessary protocols to build and tear
down the VXLAN tunnels; (3) It maintains the VXLAN tunnel
forwarding states including the MAC table;
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L3VPN-VXLAN Interworking Functions: It maintains the mapping
information between L3VPN label and VXLAN Network Identifier
(VNI). This mapping information is used to receive packets from
the MPLS network and forward them to the VXLAN network, and
receive packets from the VXLAN network and forward them to the
MPLS network
In order to correctly provide one-one mapping between VPN labels and
VNI, we need to extend the MPLS label space to have at least 16
million labels.
2.2. NVGRE
In this use case, the NVGRE protocol of [I-D.sridharan-
virtualization-nvgre] is used for network overlay virtualiztion.
..................................
. .
. +------------+ .
. |+----+ +---+| .
. || | |VM || .
. /+| | +---+| .
. / ||NVE | +---+| .
-----+ +----------------+ . +------------+ || | |VM || .
| | | . | | |+----+ +---+| .
+---+--+ +------+ +---+---+--+ NVGRE | | Server | .
| CE |---| PE | MPLS | PE-NVE | network | +------------+ .
|device| |device| network | device | over L3 | .
+---+--+ +------+ +---+---+--+ network | +------------+ .
| / | | . | | |+----+ +---+| .
-----+ / +----------------+ . +------------+ || | |VM || .
/ . \ || | +---+| .
-----+ / . \+|NVE | +---+| .
| / . || | |VM || .
+---+--+ . |+----+ +---+| .
| CE | . | Server | .
|device| . Data Center +------------+ .
+---+--+ ..................................
|
-----+
+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+
|LSP label| | Outer Header |
+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+
|VPN label| | NVGRE Header |
+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+
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| VM IP | | Inner Header |
+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+
Packet format Packet format
out of PE device out of PE-NVE device
to MPLS network to NVGRE network
When one PC in a CE site wants to send a packet to one VM in the data
center, the outgoing packet headers of PE device and PE-NVE device
are described as above. VPN label is mapped to VSID in NVGRE Header.
The Provider Edge device connecting to the virtual networks will
perform the following functionalities:
VPN PE functions: (1) It uses BGP to distribute VPN routes; (2) It
maintains VRFs; (3) It uses MPLS to receive and forward packets
from and to the MPLS network.
NVGRE Endpoint functions: It originates and terminates NVGRE
packets; (2) It maintains the NVGRE Virtual Subnet Identifier
(VSID) for NVGRE
L3VPN-NVGRE Interworking Functions: It maintains the mapping
information between L3VPN label and NVGRE Virtual Subnet
Identifier (VSID). This mapping information is used to receive
packets from the MPLS network and forward them to the NVGRE
virtual network, and receive packets from the NVGRE virtual
network and forward them to the MPLS network
In order to correctly provide one-one mapping between VPN labels and
VSID, we need to extend the MPLS label space to have at least 16
million labels.
2.3. NVO3
NVO3 is an on-going effort to standardize solutions to data center
virtualizaiton with the goal of providing viable data encapsulation
and protocols across a scaling range of a few thousand VMs to several
million VMs running on greater than one hundred thousand physical
servers. NVO3 considers approaches to multi-tenancy that reside at
the network layer rather than using traditional isolation mechanisms
that rely on the underlying layer 2 technology (e.g. VLANs).
Based on NVO3 framework and problem statement, NVO3 will deliver 16
million virtual networks in a physical data center. If L3VPN is used
to access the virtual networks inside the data center, we need to
solve the problem of associating MPLS labels to NVO3 VNIDs.
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..................................
. .
. +------------+ .
. |+----+ +---+| .
. || | |VM || .
. /+|NVE | +---+| .
. / || | +---+| .
-----+ +----------------+ . +------------+ || | |VM || .
| | | . | | |+----+ +---+| .
+---+--+ +------+ +---+---+--+ NVO3 | | Server | .
| CE |---| PE | MPLS | PE-NVE | network | +------------+ .
|device| |device| network | device | over L3 | .
+---+--+ +------+ +---+---+--+ network | +------------+ .
| / | | . | | |+----+ +---+| .
-----+ / +----------------+ . +------------+ || | |VM || .
/ . \ ||NVE | +---+| .
-----+ / . \+| | +---+| .
| / . || | |VM || .
+---+--+ . |+----+ +---+| .
| CE | . | Server | .
|device| . Data Center +------------+ .
+---+--+ ..................................
|
-----+
3. Big Labels
A PE device uses VPN labels to find the associated VRFs for VPN
packet forwarding. Since there are potentially 16 millions of
virtual networks, 20 bits label are not sufficient; we need to
specify a new type of labels: big labels. A big label is an
extension to the MPLS label format of RFC 3032 so that the label
space is bigger than the 20-bit space with the minimum of 16 millions
of labels.
The exact big label format is described in [I-D.draft-renwei-mpls-
big-label]. One option of the big label format is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Big Label Indicator | Exp |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Big Label Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Exp: Experimental Use, 3 bits
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S: Bottom of Stack, 1 bit
TTL: Time to Live, 8 bits
The Big Label Indicator is a reserved MPLS label. The currently
unassigned reserved label range is 4-6 and 8-12. We will temporarily
use label 8 for big label indicator, but the final value will be
assigned by IANA. The Big Label Value is a 32-bit value.
When an MPLS LSR receivs an MPLS packet, it reads out the MPLS label.
If the MPLS label is a Big Label Indicator, it will use the
subsequent 32-bit value as the MPLS label for the forwarding purpose.
4. VRFs
In BGP/MPLS L3VPN models, A VRF on each PE is associated to a local
attachment circuit connected to a customer site and routing targets
connected to remote sites. When BGP/MPLS L3VPN model is extended to
connect a virtulized network, A VRF on each PE-NVE device is
associated to a virtual network instance which is significant locally
to the virtualized networks in the data center.
Except for big labels being used, there are no changes to VRFs. In
particular, the operational procedure is the same as common label-
based VRFs.
5. VPN Route Distribution
VPN route distribution is performed by BGP in the same way as in RFC
2547 except that the labels associated to VRFs are "big labels". The
detailed changes to BGP protocols are described in [I-D.draft-renwei-
mpls-bgp-big-label].
6. IANA Considerations
The requirements on IANA are specified in other related documents
[I-D.draft-renwei-mpls-big-label] and [I-D.draft-renwei-mpls-bgp-big-
label], which request a reserved label to represent Big Label
Indicator and BGP capabilities for big labels.
7. Security Considerations
This draft does not add any additional security implications to the
BGP/MPLS IP VPNs. All existing authentication and security
mechanisms for BGP and MPLS still apply.
8. References
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8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2547] Rosen, E. and Y. Rekhter, "BGP/MPLS VPNs", RFC 2547, March
1999.
[RFC3107] Rekhter, Y. and E. Rosen, "Carrying Label Information in
BGP-4", RFC 3107, May 2001.
8.2. Informative References
[I-D.mahalingam-dutt-dcops-vxlan]
Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
L., Sridhar, T., Bursell, M., and C. Wright, "VXLAN: A
Framework for Overlaying Virtualized Layer 2 Networks over
Layer 3 Networks", draft-mahalingam-dutt-dcops-vxlan-03
(work in progress), February 2013.
[I-D.sridharan-virtualization-nvgre]
Sridharan, M., Greenberg, A., Venkataramaiah, N., Wang,
Y., Duda, K., Ganga, I., Lin, G., Pearson, M., Thaler, P.,
and C. Tumuluri, "NVGRE: Network Virtualization using
Generic Routing Encapsulation", draft-sridharan-
virtualization-nvgre-02 (work in progress), February 2013.
Authors' Addresses
Renwei Li
Huawei Technologies
2330 Central Expressway
Santa Clara, CA 95050
USA
Email: renwei.li@huawei.com
Katherine Zhao
Huawei Technologies
2330 Central Expressway
Santa Clara, CA 95050
USA
Email: katherine.zhao@huawei.com
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Walter Wu
Huawei Technologies
2330 Central Expressway
Santa Clara, CA 95050
USA
Email: walter.wu@huawei.com
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