Internet DRAFT - draft-hares-use-case-vn-vc
draft-hares-use-case-vn-vc
Routing Area Working Group S. Hares
Internet-Draft Huawei Technologies (USA)
Intended status: Informational M. Chen
Expires: April 18, 2013 Huawei
October 15, 2012
Use Cases for Virtual Connections on Demand (VCoD) and Virtual Network
on Demand using Interface to Routing System
draft-hares-use-case-vn-vc-00
Abstract
Software Defined Networks (SDN) provide a way to virtualize and
abstract the network and present the virtual or abstract resources to
the third-party applications running in software. The application
can utilize a programmable interface to receiving these virtual or
abstract resources in a form that allows monitoring or manipulation
of resources. Various programmatic interfaces have been proposed to
interface directly to the forwarding plane (OpenFlow, ForCES), or do
device configuration (NETCONF). ALTO has proposed a informational
interface to the application. Only the progammatic Interface to the
Routing System (IRS) provides an interface directly to the routing
system to utilize all aspects of the routing system as a system.
The IRS system interacts with the control plane processes to monitor
best paths to any destination and to change the routing information
base (RIB) or MPLS label information Base (LIB) which feeds the
forwarding tables the information needed to actually switch traffic
at a local level.
This document outlines how SDN networks can use the IRS interface to
implement an automated set of network services for Virtual Connection
on Demand (VCoD) and Virtual Network on Demand (VNoD)
Status of this Memo
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 18, 2013.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Virtual Circuit on Demand . . . . . . . . . . . . . . . . . . 6
4. Virtual Network on Demand (VNoD) . . . . . . . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. Normative References . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
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1. Introduction
The Interface to the Routing System Framework [IRS] desribes a
mechanism where the distributed control plane can be augmented by an
outside control plane through an open, accessible interface,
including the Routing Information Base (RIB) and the label interface
(LIB) individual devices. IRS provides a "halfway point" between
completely replacing the traditional distributed control planes and
directly configure devices via off-board processes.
This draft proposes a set of use cases to use IRS mechanisms to
implement a Software Defined Network (SDN) with virtual connections
and virtual networks as automated services. This document focuses on
how IRS would support two automated network services: Virtual
Connection on Demand (VCoD) and Virtual Network on Demand (VNoD).
The SDN service provides the basic connection and a guidance ("self-
help") functionality.
This paper contains a background section, a use case for IRS in VCoD,
and a use case for IRS in VNoD.
SDN is a new adventure for the Internet space. Each new adventure in
the Internet space requires lots of use cases so that the IETF may
determine the critical protocols.
2. Background
Applications and network layer flows have run independently since the
Internet started in the late 1980s. Provisioning of network
servivces and big flows has been done by service providers statically
or with proprietary. Recently, new server and host technologies have
increase application data traffic flows across the network. With the
advent of data center providers and cloud services, applications life
cycles have shortened to weeks rather than years. The need for fast
automated provisioning of virtual network connections or quick
provisioning of virtual private networks has increased.
Software Defined Neworks have have three areas of challenge to
provide such quick network services: a) how to control the network
flows, b) interfaces to networks, and c) how do calculate where these
network flows go.
Network flows can be controlled at the forwarding device level or the
network control plane level. Various progammable interfaces have
been proposed to provide control over individual forwarding devices.
OpenFlow, for instance, provides a mechanism to replace the dynamic
control plane processes on individual forwarding devices throughout a
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network with off box processes that interact with the forwarding
tables on each device. Another example is NETCONF, which provides a
fast and flexible mechanism to interact with device configuration and
policy.
The tradeoff with the device level approach to control flows has to
do with benefits and challenges of having control systems off-board.
The benefit of off-board control systems is that the calculation unit
can be centralized. The challenge of the off-board control system
has a technical challenge and a deployment challenge. The technical
challenge is that off-board control systems may encounter time-delays
and communication failure. The deployment issues concerns utilizing
new protocols for this communication which may also have issues in
deployment. The promised benefits of off-board devices are reduction
in operational costs, improving scaling, control, and visiblity.
OpenFlow, for instance, provides a mechanism to replace the dynamic
control plane processes on individual forwarding devices throughout a
network with off box processes that interact with the forwarding
tables on each device. Another example is NETCONF, which provides a
fast and flexible mechanism to interact with device configuration and
policy.
The Interface to Routing System (IRS) interface provides an interface
to all aspects of the routing system as a system. This interface
allows the SDN approach to utilize the existing control plane
software without changing it. The IRS system interacts with the
control plane processes to monitor best paths to any destination and
to interact with the routing information base (RIB) or MPLS label
information base (LIB) which feeds the forwarding tables the
information needed to actually switch traffic at a local level.
Let us turn to the next challenge, the interface to the applciations.
Many academic efforts (e.g. Internet) have examined the benefits in
allowing applications to obtain more network information when making
decisions on how connect webs of interfaces. Recently, the IETF ALTO
protocol has been charted to provide resource information for peer-
to-peer applications. Expansions to ALTO's application interface
have been proposed to pass information regarding bandwidth and
network topologies. This ALTO work may apply to some large flow
Virtual Connections or Virtual Private networks need. However, these
ALTO use cases do not necessarily consider the on-demand issues or
IRS. This document presents these use cases.
This document describes a set of use cases which describe how
automated creation of Virtual Connection on Demand (VCoD) and Virtual
Networks On Demand (VNoD) based in SDN logic can be accomplished by
using an interface to the routing system (IRS).
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There are several types of network services that can be considered as
network services over which virtual connections or virtual networks
can be created. These network services include: optical, Ethernet
(VLAN and SPB), Internet Protocol (IP), Multiprotocol Label Switching
(MPLS). Each of these networks can provide traffic engineered paths,
olicy control (e.g. Access control Lists (ACLs)), security services,
or some form of virtual LAN services (VLAN, VxAN, L2/L3 VPN). The
examples in this document focus on the transport and VPN related
services that can be abstracted into Virtual Connection (VC) and
Virtual Network (VN).
These abstract services (VC or VN) are logical services that can be
mapped to specific services. For example, a flow can be mapped to a
flow such as OpenFlow might provision through a set of networks. Or
a Flow might be mapped to a TE-LSP. These logical services provide a
uniform abstract service model that allows applications to configure
VC or VN services independent of the actual network technology
implementing it.
The use cases below leverage the SDN architecture and model and the
IRS Frmewaork to implement Virtual Circuit on Demand (VCoD) and
Virtual Network on Demand (VNoD).
Please note that this draft builds on the premise that SDN solutions
can augment rather than replace traditional distributed control
planes. Each use case is presented in its own section.
3. Virtual Circuit on Demand
The Virtual circuit on demand (VCoD) first needs to discover where
the IRS commissioners acting as controllers are. After selecting the
IRS commissioner which will control the VCoD circuit, the application
sends a requests to create, delete, modify or query circuits. At
this point, the IRS Controller takes these requests and performs the
appropriate operations. The discovery protocol and these
communications are outside the IRS protocol and framework. The
protocol could be ALTO that informs application which IRS
commissioner can support VCoD service.
Once the IRS Commissioner is chartered with the task of setting up
virtual circuits, the IRS Commission will communicate with the IRS
Agents in the nodes (routing/switching/optial) to set-up these
virtual circuits. In the example topoology below, IRS Commissioner 1
has received a request to set up a Virtual circuit from edge 1 to
edge 2. The IRS commmissioner works with the IRS Agent1 on node 1,
the IRS Agent 2 on node 2, the IRS Agent 3 on node 3, and the IRS
Agent 4 on node 4 to set up the virtual circuit. IRS Commissioner 1
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is a VCoD capable IRS commissioner with logic to aid set-up,
monitoring, changing, and decommissioning of this circuit. IRS
Agents 1-4 contain the necessary logic to translate the IRS
Commissioner's commands to create the virtual circuit's link on their
interface.
The IRS framework defines the portion of this system that goes from
the VCoD-capable IRS commissioner to/from the VCoD-capable IRS
Agents. The IRS Commissioner can request information from the IRS
Agent such as topology or interface statics or available circuits,
and influence how the IRS Agents create the circuits. The topology
information passed between the IRS commission and Agent would include
for this application possible virtual connections to a destination
and the available bandwidth on that circuit. The interface
statistics exchanged could involve historical or instant statistics
on exit point performance, jitter, delay. The available of circuits
could involve any time-based availabilty for on-demand future usage.
Past solutions in this area have included uses of device
configuration across multiple nodes (SNMP or NETCONF based) with
proprietary services combined with topology queries. The lack of a
coordinated responses to routing topology queries has created
problems in quickly obtaining and configuring changes for Virtual
Circuits. New algorithms services in routing/switch such as Fast-
Reroute of RSVP or IGPs have aided the automatic re-establishment of
some circuits, but the complexity of some of these algorithms
increases cost within the network elements. It's often difficult to
justify the added complexity in the database and algorithms of
routing protools to solve what is considered a point case.
The following things need to be supported for this application:
o IRS Agents should provide the ability to read the virtual
connection topology database for the technology supported. For
optical, these are the optical connections and what node they
connect to. For MPLS, this is virtual circuit available, and what
nodes they connect to. For IP technologies, this could include
the GRE tunnels and what interface it connects to. For Ethernet
circuits this should involve circuit type (e.g, point-to-point
(p2p) or point-to-multipoint (p2mp)) and what nodes it can reach.
o IRS Agent should provide the ability to influence the
configuration of a virtual circuit in a node.
o IRS Agent should provide monitor and provide statistics on the
virtual connection to the IRS Commissioner. The IRS commissioner
can then determine if the connection falls below a quality level
the application has requested. If the IRS Commissioner does
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determine the circuit is below the required quality, it could
create another circuit. The IRS Commission may choose to create
the second virtual circuit, transfer flows, and then break the
first circuit.
Example Topology for Virtual Circuit on Demand (VCoD).
-------------------------
| Application |
---------------------------
| |
| |
+------------------+< Policy +-------------------+< Policy
|IRS Commissioner-1|< PCE info |IRS Commissioner-2 |< PCEP
|VC controller | | VN controller |
+------------------+ +-------------------+
| | |-----------+ | |
| | | | |
+--------+ +--------+ +---------+ +----------+
| IRS | | IRS | | IRS | | IRS |
| Agent-1| |Agent-2 | | Agent-3 | | Agent-4 |
|--------| |--------+ +---------+ +----------+
| node 1 | | node 2 | | node 3 | | node 4 |
+--------+ +--------+ +---------+ +----------+
| | | | | |
edge1 |--------| |------------| |
|----edge2
While the set-up of these virtual circuits is possible with current
technoloyg, the lack of the IRS-like framework makes VCoD network
complex. With this support, VCoD may be able to reduce complexity on
the individual nodes.
4. Virtual Network on Demand (VNoD)
Virtual Networks on Demand (VNoD) are simply extensions to the
Virtual Connections on Demand concept. The IRS Commissioner is
tasked to create a Virtual network instead of a single connection.
The example sequence would be that the application discovers IRS
Commission-2 who is a VNoD via a protocol outside the IRS framework
(e.g. ALTO). The IRS Commissioner-2 works with the IRS AGents 1-4
to set-up a virtual network. This involves the following:
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o gathering potential topology information (in order to create the
network,
o set-up the virtual network (via influencing configurations on
node),
o monitoring changes in topology (in order to potential failovers,
o influencing changes to virtual network via configurations, and
o removing the virtual network after the demand has epxired.
--------------------------
| Application |
---------------------------
| |
| |
+------------------+< Policy +-------------------+< Policy
|IRS Commissioner-1|< PCE info |IRS Commissioner-2 |< PCEP
|VC controller | | VN controller |
+------------------+ +-------------------+
| | | |
|----------------------------+ | | |
| +------------------ | |
| | | |
+--------+ +--------+ +---------+ +----------+
| IRS | | IRS | | IRS | | IRS |
| Agent-1| |Agent-2 | | Agent-3 | | Agent-4 |
|--------| |--------+ +---------+ +----------+
| node 1 | | node 2 | | node 3 | | node 4 |
+--------+ +--------+ +---------+ +----------+
| | | | | | | | |
| |--------| |------------| | +------+ |-end-point-3
| | |
end-point-1 |
|----end-point2
This topology shares some configuration needs with the central
membership computation for MPLS VPNs from (draft-white-irs-use-cases)
but the mechanisms are not specific to MPlS VPNS.
5. IANA Considerations
This document includes no request to IANA.
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6. Security Considerations
This document has no security issues as just contains use cases.
7. Normative References
[I-D.amante-irs-topology-use-cases]
Amante, S., Medved, J., and T. Nadeau, "Topology API Use
Cases", draft-amante-irs-topology-use-cases-00 (work in
progress), October 2012.
[I-D.atlas-irs-policy-framework]
Atlas, A., Hares, S., and J. Halpern, "A Policy Framework
for the Interface to the Routing System",
draft-atlas-irs-policy-framework-00 (work in progress),
September 2012.
[I-D.atlas-irs-problem-statement]
Atlas, A., Nadeau, T., and D. Ward, "Interface to the
Routing System Problem Statement",
draft-atlas-irs-problem-statement-00 (work in progress),
July 2012.
[I-D.bernstein-alto-large-bandwidth-cases]
Bernstein, G. and Y. Lee, "Use Cases for High Bandwidth
Query and Control of Core Networks",
draft-bernstein-alto-large-bandwidth-cases-02 (work in
progress), July 2012.
[I-D.medved-irs-topology-requirements]
Medved, J., Gredler, H., Previdi, S., and S. Amante,
"Topology API Requirements",
draft-medved-irs-topology-requirements-00 (work in
progress), October 2012.
[I-D.rfernando-irs-framework-requirement]
Fernando, R., Medved, J., Ward, D., Atlas, A., and B.
Rijsman, "IRS Framework Requirements",
draft-rfernando-irs-framework-requirement-00 (work in
progress), October 2012.
[I-D.ward-irs-framework]
Atlas, A., Nadeau, T., and D. Ward, "Interface to the
Routing System Framework", draft-ward-irs-framework-00
(work in progress), July 2012.
[I-D.white-irs-use-case]
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White, R., Hares, S., and R. Fernando, "Use Cases for an
Interface to the Routing System",
draft-white-irs-use-case-00 (work in progress),
September 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
Authors' Addresses
Susan Hares
Huawei Technologies (USA)
2330 Central Expressway
Santa Clara, CA 95050
USA
Email: Susan.Hares@huawei.com
Mach Chen
Huawei
No. 3 Xinxi Road, Shangdo-di
Hai-Dan District, Beijing 100085
USA
Email: mach@huawei.com
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