Internet DRAFT - draft-li-mpls-network-virtualization-framework
draft-li-mpls-network-virtualization-framework
Network Working Group Z. Li
Internet-Draft M. Li
Intended status: Informational Huawei Technologies
Expires: April 24, 2014 October 21, 2013
Framework of Network Virtualization Based on MPLS Global Label
draft-li-mpls-network-virtualization-framework-00
Abstract
As the virtual network operators develop, it is desirable to provide
better network virtualization solutions to facilitate the service
provision. In the past years, MPLS plays a key role in the process
of implementing network virtualization. This document introduces a
new framework to implement network virtualization based on MPLS
global label. It can provide the virtualized network topology, nodes
and links using MPLS global label which can make up the virtual
network.
Requirements 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].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
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."
This Internet-Draft will expire on April 24, 2014.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Framework . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. MPLS Virtualization of Network Topology . . . . . . . . . . . 6
5. MPLS Virtualization of Network Nodes . . . . . . . . . . . . 8
6. MPLS Virtualization of Network Links . . . . . . . . . . . . 9
7. Forwarding in Virtual Network . . . . . . . . . . . . . . . . 10
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
9. Security Considerations . . . . . . . . . . . . . . . . . . . 12
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
10.1. Normative References . . . . . . . . . . . . . . . . . . 12
10.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
The virtual network operators are in fast development. They can
deploy possible services based on the virtual network which is
provided by the underlying network. Owing to the technology
limitation, the virtual network operators face following challenges:
-- It is hard to get the traffic and data information of internal
nodes. So it is hard to develop value-added services.
-- Traditional VPN technology is just to provide a transparent pipe
for virtual network operators which cannot control and manage the
internal nodes.
-- Traditional technologies can not implement virtualization of
network nodes and links. It is hard to provide flexible virtual
networks.
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-- It is unable to implement central control, which is hard to
provide customized virtual networks based on policies and open APIs.
For the virtual network operators, in order to provide better
services it is necessary to get more control on the internal network
nodes. Traditional VPN solutions is just to provide virtual networks
on the network edge. This can not satisfy the new network
virtualization requirement. On the other hand, the underlying
network operators do not hope to expose much internal network details
to the virtual network operators. Furthermore, it also exerts much
burden on the virtual network operation and management if there is
much internal network details for the virtual network operators.
In order to solve the problems of existing solutions and satisfy new
virtual network requirements, it is desirable to provide a central
controlled network virtualization solution which can provide flexible
customized virtual networks easily. This document introduces a new
framework to implement network virtualization based on MPLS global
label. It can provide the virtualized network topology, nodes and
links using MPLS global label which can make up the virtual network
easily.
2. Terminology
Underlying Network: It is the network which the virtual network is
built based on. The underlying network can be the physical network
or the virtual network.
MPLS Virtual Network: The virtual network is built based on the
underlying network. It is composed by virtual nodes and virtual
links which are identified by MPLS global label. In this document,
the concept of virtual network is the same as that of MPLS virtual
network.
MPLS Virtual Network Topology: It is the topology of the MPLS virtual
network. It can be identified by multi-topology ID of corresponding
virtual network. MPLS global label is allocated to represent the
virtual network topology.
Underlying Link: It is the link in the underlying network which the
virtual link is built based on. The underlying link can be physical
link or the virtual link.
MPLS Virtual Link: The virtual link is built based on the underlying
link with specific attribute requirement. It can be identified by
MPLS global label. In this document, the concept of virtual link is
the same as that of MPLS virtual link.
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Underlying Node: It is the node in the underlying network which the
virtual node is built based on. The underlying node can be physical
node or the virtual node.
MPLS Virtual Node: The virtual node is built based on the underlying
node with specific attribute requirement. It can be identified by
MPLS global label. In this document, the concept of virtual node is
the same as that of MPLS virtual node.
3. Framework
MPLS is always a basic technology to implement network
virtualization. L3VPN and VPLS are typical network virtualization
solutions based on MPLS technologies. VPN technologies provides
virtual network at the network edge based on BGP or T-LDP. In order
to provide better virtual network services the internal network
should be virtualized to be provided to the virtual network
operators. Then IGP is a better choice to combine with MPLS
technologies to provide these virtual networks.
In the MPLS virtual network, virtual nodes and virtual links are
basic components. They can be represented by unique MPLS global
label values. In addition, in order to differentiate virtual
networks, the virtual network topology can be identified by multi-
topology ID and the unique MPLS global label value can also be
allocated to represent the virtual network topology. Thus the
network topology, the node and the link can be virtualized by MPLS.
They can hide the details of the underlying network.
The architecture to construct virtual network is shown in the
following figure. There is a central controller to control network
nodes. The controller can construct different virtual networks
according to the requirements proposed by the virtual network
operators. IGP runs among the controller and the network nodes.
MPLS global labels can be allocated by the IGP controller for the
virtual network topologies, the virtual nodes and the virtual links.
The label binding between the MPLS global label and the virtual
network topology/node/link are flooded among the controller and the
network nodes. When the network nodes receive the label mapping
messages, they will install corresponding MPLS forwarding entries
accordingly.
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+---------------------------------------------------------+
| Virtual Network Operators |
| |
| ________ /\ \ VN n / |
| / / / \ \ / |
| / VN 1 / /VN 2\ ...... ---- |
| /_______/ /______\ / \ |
| |
+---------------------------------------------------------+
|
|
+---------------------------------------------------------+
| |
| IGP Controller |
| (Underlying Network) |
| |
+---------------------------------------------------------+
| | |
| | |
+-----|---------------------------|-------------------------|------+
| | | | |
| | +---------+ | |
| | | NODE 1 | | |
| | | | | |
| | /| IGP |\ | |
| | / | CLIENT | \ | |
| | / +---------+ \ | |
| | / \ | |
| +--------+ / \ +--------+ |
| | NODE 2 | / \ | NODE n | |
| | |__________/ \_________| | |
| | IGP | ...... | IGP | |
| | CLIENT | | CLIENT | |
| +--------+ +--------+ |
| |
+------------------------------------------------------------------+
Figure 1 Architecture of MPLS Virtual Network
Figure 2 shows an example of the virtual network built based on the
underlying network. The virtual network topology is represented by
the Virtual Topology Global Label (VT-GL). The virtual node is
represented by the Node Global Label (N-GL). The virtual link is
represented by the Link Global Label (L-GL). In the virtual network
shown in the figure 2, there are three virtual links identified by
L-GL 1, L-GL 2 and L-GL 3 and there are three virtual nodes
identified by N-GL 1, N-GL 2 and N-GL 3. All virtual nodes and links
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constructs a triangle virtual topology identified by VT-GL 1. The
virtual network operators can provision their own service based on
the virtual network. Especially, for the virtual link, it can have
common attributes such as bandwidth, MTU, etc. like the physical
link. The virtual network operators need not care about the physical
details of links of the virtual network. For example, the bandwidth
for the virtual link is 10G. It may be an independent physical
interface, or a virtual link allocating 10G bandwidth from a physical
interface, or a virtual interface constructed by compositing several
physical interfaces. All the details of the underlying network are
hidden from the virtual network operators. This can simplify the
network operation and management for the virtual network operators
which can focus more on their own service provision. On the other
hand, the hidden details can improve security of the underlying
network to some extent.
Virtual Network 1: VT-GL 1
+--------+
| NODE 1 |
| |
/| N-GL 1 |\
#1 / | | \ #2
L-GL 1 / +--------+ \ L-GL 2
/ \
/ \
/ \
+--------+ / \ +--------+
| NODE 2 |/ #3 \| NODE 3 |
| | L-GL 3 | |
| N-GL 2 |--------------------------| N-GL 3 |
| | | |
+--------+ +--------+
Figure 2 An Example of MPLS Virtual Network
4. MPLS Virtualization of Network Topology
In essence, constructing virtual networks is to construct different
virtual network topologies based on the underlying network. The
virtual network topology can be identified by the Multi-Topology ID.
The global label for the virtual network topology is allocated by the
IGP controller. The label binding between the Multi-Topology ID and
the Global Label are flooded from the IGP controller to the network
nodes.
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The network nodes should support the multi-topology. It can install
FIBs for multi-topologies. That is, there are multiple forwarding
instances in one network node. Each forwarding instance is
corresponding to a virtual network topology.
When network nodes receive the label binding between the Multi-
Topology ID and the Global Label, it will install one MPLS forwarding
entry: The incoming label is the Global Label. It will be mapped to
the forwarding instance corresponding to the Multi-Topology.
When packets of different virtual networks are forwarded in the
network nodes, they must encapsulate the global label binded with the
Multi-Topology, Thus the network node receiving the packet will get
the label from the MPLS encapsulation and find the corresponding MPLS
forwarding entry. Then the packet will be mapped to the
corresponding forwarding instance to determine how to forward in the
corresponding virtual network. If the packet is to be forwarded to
the next hop in the virtual network, when it leaves the network node,
the global label must be encapsulated again.
Step 1:
Incoming Packet
+--------+-----------+
| VT-GL | PAYLOAD | ----|
+--------+-----------+ |
|
|
Forwarding Entry |
+---------------------------------------------+
| +----------------------+ |
| +--------+ | Multi-Topology | |
| | VT-GL |--->| Forwarding Instance | |
| +--------+ | | |
| +----------------------+ |
+---------------------------------------------+
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Step 2:
Transiting Packet
+-----------+
| PAYLOAD |-------------------------|
+-----------+ |
|
|
Forwarding Entry |
+----------------------------------------------------------+
| Multi-Topology FIB |
| |
| +-----------+-------------+ +-------------+--------+ |
| | FWD INFO | OUTGOING ID |---->| OUTGOING ID | VT-GL | |
| +-----------+-------------+ +-------------+--------+ |
+----------------------------------------------------------+
Step 3:
Outgoing Packet
+--------+-----------+
| VT-GL | PAYLOAD |
+--------+-----------+
Figure 3 Forwarding Process for MPLS Virtual Topology
5. MPLS Virtualization of Network Nodes
MPLS Virtual nodes can be built based on the underlying node in a
specific underlying network. They can be identified by unique MPLS
global label allocated for the tuple { Multi-Topology ID, Underlying
Node Identification, Attributes of the Virtualized Node }. Multi-
topology ID is the identification of the corresponding multi-topology
of the underlying network. The underlying node can be identified by
the node's address (typically the loopback address) if the underlying
node is the physical network node or it can be identified by another
global label corresponding to the underlying virtual node. When
implement virtual nodes, IGP controller will allocate the global
label for the tuple { Multi-Topology ID, Underlying Node
Identification, Attributes of the Virtualized Node }. Then the label
binding between the tuple and the Global Label are flooded from the
IGP controller to the network nodes.
When network nodes receive the label binding between the tuple and
the Global Label, it will install one MPLS forwarding entry in the
forwarding instance corresponding to the Multi-Topology ID: The
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incoming label is the Global Label. It will be mapped to the
forwarding information related with the virtualized nodes. The
forwarding information is derived according to the specific
application requirement. For example, in Segment Routing, the
forwarding information can be the shortest path to the underlying
node. In addition, the forwarding identification for the specified
attributes to the virtual node can also be provided in the forwarding
information.
+---------------------------------------------+
| Multi-Topology FIB |
| +----------------------+ |
| +--------+ | Forwarding Info | |
| | N-GL |--->| binding with | |
| +--------+ | Virtualized Node | |
| +----------------------+ |
+---------------------------------------------+
6. MPLS Virtualization of Network Links
MPLS Virtual links can be built based on the underlying link in a
specific underlying network. They can be identified by unique MPLS
global label allocated for the tuple { Multi-Topology ID, Underlying
Link Identification, Attributes of the Virtualized Link }. Multi-
topology ID is the identification of the corresponding multi-topology
of the underlying network. The underlying link can be identified by
the link ID or the link's address (typically the pair of the
addresses of two end-points of the link) if the underlying link is
the physical network link or it can be identified by another global
label corresponding to the underlying virtual link. When implement
virtual links, IGP controller will allocate the global label for the
tuple { Multi-Topology ID, Underlying Link Identification, Attributes
of the Virtualized Link }. Then the label binding between the tuple
and the Global Label are flooded from the IGP controller to the
network nodes.
When network nodes receive the label binding between the tuple and
the Global Label, it will install one MPLS forwarding entry in the
forwarding instance corresponding to the Multi-Topology ID: The
incoming label is the Global Label. It will be mapped to the
forwarding information related with the virtualized links. The
forwarding information is derived according to the specific
application requirement.
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+---------------------------------------------+
| Multi-Topology FIB |
| +----------------------+ |
| +--------+ | Forwarding Info | |
| | L-GL |--->| binding with | |
| +--------+ | Virtualized Link | |
| +----------------------+ |
+---------------------------------------------+
The typical attribute for the virtualized link is the bandwidth.
When the virtual network need a virtual link with specific bandwidth
requirement, IGP controller will create the virtual link by
allocating the global label for the tuple {Multi-Topology ID,
Underlying Link Identification, Bandwidth} and flood the label
binding to the network nodes. When network nodes receive the label
binding, it will reserve the bandwidth firstly based on the
underlying link to provide QoS service of bandwidth guarantee. Then
it will create the MPLS forwarding entry shown in the following
figure:
+---------------------------------------------------------------+
| Multi-Topology FIB |
| +--------------+ |
| +--------+ +---------------------+ | QOS Process | |
| | L-GL |--->| Underlying Link |QID|--->| based on | |
| +--------+ +---------------------+ | Bandwidth | |
| +--------------+ |
+---------------------------------------------------------------+
7. Forwarding in Virtual Network
If the packet is forwarded in a specific virtual network, the global
label binding with the virtual network topology should be
encapsulated in the packet. Thus the network node receiving the
packet will get the VT-GL to map to the corresponding forwarding
instance to determine how to forward the packet in the virtual
network.
There are two ways to use the virtualized nodes and links for
forwarding.
1. Traditional SPF or CSPF Path Calculation
The virtualized nodes and links can be added to the LSDB or be added
to the TEDB after applying specific MPLS TE attributes. Then these
nodes and links can be involved in the path calculation based on SPF
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or CSPF. Then the IP forwarding entry or MPLS TE forwarding entry
may be created which can use the virtual link as the outgoing link.
A typical IP Routing forwarding entry is shown in the following
figure:
+----------------------------------------------------------------------------+
| Multi-Topology FIB |
| +--------------+ |
| +------------------+------+ +-----------------------+ | QOS Process | |
| | D-IP | D-IP Mask | L-GL |-->| Underlying Link | QID |-->| based on | |
| +------------------+------+ +-----------------------+ | Bandwidth | |
| +--------------+ |
+----------------------------------------------------------------------------+
In this case, the forwarding entry related with L-GL is not an
independent entry. It is combined with other information
(Destination IP address and destination IP mask in the example) to
compose the forwarding entry. For packets which may use the
forwarding entry, they need not encapsulate the L-GL. The L-GL is
just like an internal index to link different parts of the forwarding
information.
2. Segment Routing
The MPLS virtual nodes and links can also be used for Segment
Routing. The MPLS forwarding entry for the virtualized nodes and
links can be created for the Segment Routing. The MPLS virtual node
is just like the Node Segment in the Segment Routing. The MPLS
virtual link is just like the Adjacency Segment in the Segment
Routing. The difference is that MPLS global label is used for the
Adjacency instead of the local label since in the virtual network the
unique identification based on the MPLS global label can simplify the
network operation and management. In addition, there are specific
attributes for the virtual link and virtual node, there should be
fowarding process identification of the corresponding attribute in
the forwarding entry. The typical Segment Routing forwarding entry
is shown in the following figure:
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+---------------------------------------------------------------+
| Multi-Topology FIB |
| +-----------+ |
| +--------+ +--------------------------+ | Attribute | |
| | N-GL |--->|Outgoing Link|Nexthop| ID |-->| | |
| +--------+ +--------------------------+ | Process | |
| +-----------+ |
| +--------------+ |
| +-------+ +-----------------------+ | QOS Process | |
| | L-GL |--->| Underlying Link | QID |--->| based on | |
| +-------+ +-----------------------+ | Bandwidth | |
| +--------------+ |
+---------------------------------------------------------------+
In this case, the forwarding entry related with N-GL or L-GL is the
independent MPLS forwarding entry. For packets which may use the
forwarding entry, they must encapsulate the N-GL or the L-GL.
8. IANA Considerations
This document makes no request of IANA.
9. Security Considerations
TBD.
10. References
10.1. Normative References
[I-D.li-rtgwg-cc-igp-arch]
Li, Z., Chen, H., and G. Yan, "An Architecture of Central
Controlled Interior Gateway Protocol (IGP)", draft-li-
rtgwg-cc-igp-arch-00 (work in progress), October 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
10.2. Informative References
[I-D.filsfils-rtgwg-segment-routing]
Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,
Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe,
"Segment Routing Architecture", draft-filsfils-rtgwg-
segment-routing-00 (work in progress), June 2013.
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[I-D.li-mpls-global-label-framework]
Li, Z., Zhao, Q., and T. Yang, "A Framework of MPLS Global
Label", draft-li-mpls-global-label-framework-00 (work in
progress), July 2013.
Authors' Addresses
Zhenbin Li
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: lizhenbin@huawei.com
Ming Li
Huawei Technologies
2330 Central Expressway
Santa Clara, CA 95050
USA
Email: mli@huawei.com
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