Internet DRAFT - draft-renwei-mpls-big-label
draft-renwei-mpls-big-label
MPLS Working Group R. Li
Internet-Draft M. Li
Intended status: Standards Track Huawei Technologies
Expires: January 01, 2014 June 30, 2013
Encoding of Big Labels in MPLS Label Stacks
draft-renwei-mpls-big-label-00.txt
Abstract
This document specifies encoding and encapsulation methods for MPLS
big labels. Big labels are required for accessing virtual networks
in data centers by using, for example, BGP/MPLS IP VPNs. Data center
virtualization encapsulation methods and protocols such as VXLAN,
NVGRE and NVO3 are being standardized to support a few millions of
virtual networks, but the currently label format can support up to
one million of labels. When the BGP/MPLS IP VPN method, for example,
is used by an enterprise/customer to access its corresponding virtual
networks, more than one million of labels are required to map VPN
labels and Virtual Network Identifiers.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirement Language . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Motivations . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Review of MPLS Label Stack . . . . . . . . . . . . . . . . . 4
4. Big Labels . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
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 has placed a new requirement on the access method to
such huge number of virtulized 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
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BGP/MPLS scheme so that customers can access their virtualized
networks hosted in a data center by using BGP/MPLS IP VPNs.
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, but the PE is required 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, [I-D.draft-renwei-l3vpn-
big-label] specifies use cases and solutions to use big labels to
represent the VPN and maps them to virtual network instances.
This document specifies the label format and encoding methods of big
labels in the MPLS label stack of [RFC 3032].
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 GRE
NVO3
Network Virtualization Overlay over Layer 3
PE
Provider Edge, the provider edge router connected to CE.
CE
Customer Edge, the customer edge router connected to PE
2. Motivations
In [I-D.draft-renwei-l3vpn-big-label], several use cases are
described so that an enterprise/customer can use provider-provided
BGP/MPLS IP VPN to access its corresponding virtual network hosted in
a data center.
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The virtual network may be provided by VXLAN, NVGRE or NVO3. In all
such network virtualization frameworks, 16 millions of virtual
networks may be supported. This implies that up to 16 millions of
enterprises/customers can have their own data centers hosted by data
center service providers. On the other hand, BGP/MPLS IP VPNs have
been used widely by the service providers. This imposes a new
requirement of using BGP/MPLS IP VPN protocols and solutions to
access the virtual networks in data centers. One problem and
obstacle of using BGP/MPLS IP VPN to access virtual networks is that
there are not enough labels to do one-one mapping between VPN label
space and virtual network identification space.
3. Review of MPLS Label Stack
The label stack is represented as a sequence of "label stack
entries". Each label stack entry is represented by 4 octets 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Label
| Label | Exp |S| TTL | Stack
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Entry
Label: Label Value, 20 bits
Exp: Experimental Use or for QoS, 3 bits.
S: Bottom of Stack, 1 bit
TTL: Time to Live, 8 bits
For BGP/MPLS IP VPN, the VPN labels share the same format as all
other common MPLS labels as defined as in the above figure.
4. 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 minimal space being 16
millions of labels.
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There are several options to define big labels. One option is to
totally re-define the label format; A second option is to extend the
length of label entry; A third option is, for the sake of backward
compatibility, to add a new field to the common label entry specified
in RFC 3032.
The exact format of the third option is defined 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 or for QoS, 3 bits
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.
All the EXP, S and TTL are also applicable to the Big Label Value as
follows:
EXP: Experimental Use or for QoS, 3 bits
S: Bottom of Stack, 1 bit
TTL: Time to Live, 8 bits
5. IANA Considerations
This draft will request IANA to assign a reserved label for Big Label
Indicator.
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6. 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.
7. References
7.1. 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.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, January 2001.
7.2. 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
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Ming Li
Huawei Technologies
2330 Central Expressway
Santa Clara, CA 95050
USA
Email: mli@huawei.com
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