One document matched: draft-hares-i2rs-use-case-vn-vc-02.txt
Differences from draft-hares-i2rs-use-case-vn-vc-01.txt
Routing Area Working Group S. Hares
Internet-Draft Hickory Hill Consulting
Intended status: Informational M. Chen
Expires: August 18, 2014 Huawei Technologies
February 14, 2014
Use Cases for Virtual Connections on Demand (VCoD) and Virtual Network
on Demand (VNoD) using Interface to Routing System
draft-hares-i2rs-use-case-vn-vc-02
Abstract
Software Defined Networks (SDN) provides a way to virtualize and
abstract the network and present the virtual or abstract resources to
third-party applications running in software. Applications can
utilize a programmable interface to receive these virtual or abstract
resources descriptions in a form that allows monitoring or
manipulation of resources within the network. The Interface to the
Routing System (I2RS) provides an interface directly to the routing
System to monitor best paths to any destination or change routes in
the routing information base (RIB) or MPLS Label Information Base
(LIB). The I2RS interfaces may be combined with other interfaces to
the forwarding plane (ForCES (RFC3746)), device configuration
(NETCONF), or mid-level/peer-to-peer (ALTO, draft-ietf-alto-protocol)
system to create these virtual pathways.
This document outlines how SDN networks can use the I2RS interface to
implement an automated set of network services for the Virtual
Connection on Demand (VCoD) and Virtual Network on Demand (VNoD).
These systems provide service routing a better way to create paths
within a hub and spoke environment, and provide service routing the
ability to create pathways based on service.
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
working documents as Internet-Drafts. The list of current Internet-
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."
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This Internet-Draft will expire on August 18, 2014.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Background . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Virtual Circuit on Demand . . . . . . . . . . . . . . . . . . 5
4. Virtual Network on Demand (VNoD) . . . . . . . . . . . . . . 8
5. Automated On Demand Networks . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
8.1. Normative References . . . . . . . . . . . . . . . . . . 11
8.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
The Interface to the Routing System (I2RS) architecture
([I-D.ietf-i2rs-architecture]) describes a mechanism where the
distributed control plane can be augmented by an outside control
plane through an open accessible programmatic interface. I2RS
provides a "halfway point" between completely replacing the
traditional distributed control planes and directly configuring
devices via off-board processes.
This draft proposes a set of use cases using I2RS mechanisms to
implement a Software Defined Network (SDN) to enact virtual
connections and virtual networks as automated services. This
document focuses on how I2RS would support two automated network
services: Virtual Connection on Demand (VCoD) and Virtual Network on
Demand (VNoD). The Virtual Connections on Demand (VCoD) and Virtual
Network on Demand (VNoD) may be used within hub-spoke networks and
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improved service routing. In the future, an application enabled SDN
services may provides the Virtual Circuits (VCoD) and Virtual
Networks on Demand (VNoD) for any type of network service.
This document contains a background section, a VCoD use case, a VNoD
use case, and notes on future on-demand network services (connections
and network). Those familiar with I2RS problem statement
([I-D.ietf-i2rs-problem-statement]), I2RS architecture
([I-D.ietf-i2rs-architecture]), and the concepts of Virtual
Connections (VCs) or Virtual Networks (VNs) may wish to skip directly
to the use cases.
SDN is a new to the Internet space. Each new adventure in Internet
network services requires lots of use cases so that the IETF may
determine the critical protocols to be developed.
2. Background
Applications and network layer flows have run independently since the
Internet started in the late 1980s. Provisioning of network services
and big flows has been done by service providers statically or with
proprietary processes. 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 Networks 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 programmatic interfaces have
been proposed to provide control over individual forwarding devices.
ForCES ([RFC3746]) provides mechanisms 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 trade-off 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 both technical challenges and deployment challenges. The
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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, improved scaling,
control, and visibility. 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 (I2RS) 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 I2RS agent 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), and forward the information to the I2RS
client. Applications associated with the I2RS client can compute
where network flows should go, and then instruct I2RS agents in the
appropriate nodes to change RIB or LIB routes to enact the changes to
traffic flows.
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 (I2RS). This document first
examines the current use case for I2RS of improved hub-spoke routing
and better service routing using VCoD (section 2), and VNoD (section
3). Secondly, this document examines the future I2RS use case of
VCoD and VNoD for any network enabled by application or SDN
processing.
A bit of context on abstract services may be useful as a background.
These abstract services (VC or VN) are logical services that can be
mapped to specific services. For example, a virtual circuit may 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.
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), Multi-protocol Label
Switching (MPLS). Each of these networks can provide traffic
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engineered paths, policy control (e.g. Access control Lists (ACLs)),
security services, or some form of virtual LAN services (VLAN, VxLAN,
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).
The use cases below leverage the SDN architecture and model and the
I2RS Framework 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) applications associates to I2RS
client (or clients) which can communicate with the I2RS agent (or
agents) which control the VCoD circuit's creation, deletion,
modification, query for information or status changes. This
information needs to include for this application network topology,
interface statistics, available circuits per node, available
bandwidth on circuits. Interface statistics might be required on a
historical and instantaneous time basis. The circuit statistics
might also need jitter, delay, and exit-point performance.
The virtual circuits may be obtained via RIB Informational Model (RIB
IM) ([I-D.ietf-i2rs-rib-info-model]) from the interface list, or from
the nexthop lists. Write access to set-up new interfaces is not
clearly spelled out in the current version of the RIB IM, nor are the
statistics (historical or time). This use case points out additional
Information Models (IMs) that need to be added to the I2RS
information models.
In the example topology below, the VCoD application's I2RS client
communicates with I2RS agents to set-up virtual circuits from Edge 1
to Edge 2. The I2RS client communicates with I2RS Agent-1 on node 1,
I2RS Agent-2 on node 2, I2RS Agent-3 on node 3, and I2RS Agent 4 on
node 4 for to set-up the virtual circuit. The VCoD application
contains the necessary logic to determine the pathway from Edge 1 to
Edge 2.
A second option VCoD is to have an application communicate with two
I2RS clients who cooperate to set-up the virtual connections between
Edge 1 and Edge 2. Information passed between the two clients can be
done via other IETF protocols (E.g. stateful PCE or ALTO).
Why I2RS enabled solutions are necessary
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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
coordinated responses to routing topology queries has created
problems in quickly obtaining and configuring changes for Virtual
Circuits. New algorithms can create better services in routing and
switching. These algorithms include Fast-Reroute of RSVP or IGPs
which aid 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 protocols to
solve what is considered a point case.
While the set-up of these virtual circuits is possible with current
technology, the lack of the I2RS-like framework makes VCoD network
complex. With this support, VCoD may be able to reduce complexity on
the individual nodes.
What's not in scope for I2RS
The means by which the VCoD application determines which I2RS client
to associate with is outside the I2RS protocol and architecture. A
list of virtual circuits per node may be queried from the RIB
Informational Model's (RIB IM) ([I-D.ietf-i2rs-rib-info-model])
interface and nexthop lists. However, other means may be used to
determine the possible interfaces on a node. For example, ALTO could
inform the application which nodes have an I2RS Agent supporting the
VCoD service, and SNMP/NETCONF could be used to determine which
interfaces were configured.
Example Topology for Virtual Circuit on Demand (VCoD).
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+----------------------------+
| Application (VCoD) |
+---*------------------------+
| |
| |
+-------*------------+< NETCONF >+-------------------+< NETCONF
|I2RS client 1 |< PCE info> |I2RS Commissioner-2 |< PCEP
|VC controller | | VN controller |
+--*----------*--*-*-+ +-------------------+
| | | | | |
| | | |--------------------------+ |
| | |-----------+ | | |
| | | | | |
+--------+ +--------+ +---------+ +----------+
| I2RS | | I2RS | | I2RS | | I2RS |
| Agent-1| |Agent-2 | | Agent-3 | | Agent-4 |
|--------| |--------+ +---------+ +----------+
| node 1 | | node 2 | | node 3 | | node 4 |
+--------+ +--------+ +---------+ +----------+
| | | | | |
edge1 |--------| |------------| |
|----edge2
The following things need to be supported for this application:
o I2RS 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 I2RS Agent should provide the ability to influence the
configuration of a virtual circuit in a node.
o I2RS Agent should provide monitor and provide statistics on the
virtual connection to the I2RS client. The I2RS client can then
determine if the connection falls below a quality level the
application has requested. If the I2RS client does determine the
circuit is below the required quality, it could create another
circuit. The I2RS may choose to create the second virtual
circuit, transfer flows, and then break the first circuit.
What is needed in the RIB IM Model
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The RIB IM model ([I-D.ietf-i2rs-rib-info-model] provides with each
route an associated nexthop-list 0-N members. Each nexthop list is
flagged with a protection preference (1 or 2), and a Load balance
weight (1 to 99). If the host routes for all nodes in the topology
exist within the RIB IM model's instantiation, then the nexthop
provides the following information:
o identifier for interface
o egress interface (logical, virtual, or physical)
o address of physical interface (IP address or MAC) plus RIB
o tunnel encapsulation for interface (IP GRE, MPLS tunnel),
o logical tunnel identifier
o RIB name (for resolved look-ups)
o flags for specialized look-ups (Discard packets, discard with
error notification, receive)
The RIB IM model's primitives need to be expanded to include circuit
type (p2p, mp2mp), optical connection information, and additional
statistics per virtual circuit. The RIB IM model's instantiation
within the protocol must provide an easy way to specify queries for
this information.
4. Virtual Network on Demand (VNoD)
Virtual Networks on Demand (VNoD) are simply extensions to the
Virtual Connections on Demand concept. The I2RS client 2 is tasked
to create a Virtual network instead of a single connection.
The example sequence would be that the application discovers the
appropriate I2RS clients (I2RS VNoD client 1 and I2RS VNoD Client 2)
which support VNoD via a protocol outside the I2RS framework (e.g.
ALTO). The I2RS Client-2 works with the I2RS Agents 1-4 to set-up a
virtual network. This involves the following:
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,
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o influencing changes to virtual network via configurations, and
o removing the virtual network after the demand has expired.
+-------------------------+
| Application |
+-------------------------+
| |
| |
+------------------+< Policy +-------------------+< Policy
|I2RS VNoD client 1|< PCE info |I2RS client 2 |< PCEP
| | | |
+------------------+ +-------------------+
| | | |
|----------------------------+ | | |
| +------------------ | |
| | | |
+--------+ +--------+ +---------+ +----------+
| I2RS | | I2RS | | I2RS | | I2RS |
| 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-i2rs-use-
cases) but the mechanisms are not specific to MPLS VPNS.
5. Automated On Demand Networks
Automated On-Demand networks becomes a reasonable technology within a
network by utilizing the I2RS architecture. While automated on-
demand circuit provisioning and de-provisioning is possible now, the
effort to configure and reconfigure nodes to provide the Automatic
On-Demand circuits can be difficult. With I2RS, the I2RS client can
instruct the I2RS Agents within a network to create On-Demand
circuits and then remove the circuits returning the network to its
configured state. With I2RS enhanced monitoring capability, the
monitoring needed for these state changes is incorporated within the
I2RS framework.
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The current scope for these Automated On-Demand Circuits in the
IETF's I2RS working group's charter is limited to hub-spoke networks
and service routing. This section discusses the progress on the I2RS
against the use cases, and proposes additional additional Automated
On-Demand Circuits.
Current Status of the Automated On-Demand Functionality
Both the hub-spoke network and service network may include a
centralized control network element such as
[I-D.ji-i2rs-usecases-ccne-service]. These centralized control
network elements may use I2RS access to individual node's RIB
information via the I2RS RIB Information Model (IM)
([I-D.ietf-i2rs-rib-info-model]), or obtain full network topology
information from other protocols (BGP Route Reflector, PCE
([RFC4655]), or ALTO [I-D.bernstein-alto-topo]). With the recent
inclusion of ISIS link-state information into BGP TLVs via
[I-D.ietf-idr-ls-distribution], all of these sources can provide
centralized service can provide topology maps at the AS and IGP
level.
I2RS Information Models (IM) are being proposed which can store:
o Network Topologies (IM) [I.D-medved-i2rs-topology-im], and
o Service Topologies IM) [I-D.wu-i2rs-IM-service-topo].
Needed Future On-Demand Networks
Large Carrier networks utilize MPLS in a variety of forms (LDP,
static MPLS TE, or dynamic TE LSPS created by RSVP-TE or CR-LDP).
These MPLS technologies can be used to create Hub-spoke topology and
service routing in networks in Carriers, Enterprise, and Data
Centers. The RIB IM supports logical tunnels of type MPLS as well as
IP, GRE, VxLAN and GRE.
Carriers using these MPLS technologies also use these MPLS and IP
networks to support networks for Mobile BackHaul, on-demand MPLS
overlays, and on-demand video conferencing networkings.
6. IANA Considerations
This document includes no request to IANA.
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7. Security Considerations
This document has no security issues as it just contains use cases.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
8.2. Informative References
[I-D.bernstein-alto-topo]
Bernstein, G., Yang, Y., and Y. Lee, "ALTO Topology
Service: Uses Cases, Requirements, and Framework", draft-
bernstein-alto-topo-00 (work in progress), October 2013.
[I-D.ietf-alto-protocol]
Alimi, R., Penno, R., and Y. Yang, "ALTO Protocol", draft-
ietf-alto-protocol-25 (work in progress), January 2014.
[I-D.ietf-i2rs-architecture]
Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
Nadeau, "An Architecture for the Interface to the Routing
System", draft-ietf-i2rs-architecture-01 (work in
progress), February 2014.
[I-D.ietf-i2rs-problem-statement]
Atlas, A., Nadeau, T., and D. Ward, "Interface to the
Routing System Problem Statement", draft-ietf-i2rs-
problem-statement-00 (work in progress), August 2013.
[I-D.ietf-i2rs-rib-info-model]
Bahadur, N., Folkes, R., Kini, S., and J. Medved, "Routing
Information Base Info Model", draft-ietf-i2rs-rib-info-
model-01 (work in progress), October 2013.
[I-D.ietf-idr-ls-distribution]
Gredler, H., Medved, J., Previdi, S., Farrel, A., and S.
Ray, "North-Bound Distribution of Link-State and TE
Information using BGP", draft-ietf-idr-ls-distribution-04
(work in progress), November 2013.
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[I-D.ji-i2rs-usecases-ccne-service]
Ji, X., Zhuang, S., and T. Huang, "I2RS Use Cases for
Control of Forwarding Path by Central Control Network
Element (CCNE)", draft-ji-i2rs-usecases-ccne-service-00
(work in progress), October 2013.
[I-D.keyupate-i2rs-bgp-usecases]
Patel, K., Fernando, R., Gredler, H., and S. Amante, "Use
Cases for an Interface to BGP Protocol", draft-keyupate-
i2rs-bgp-usecases-00 (work in progress), March 2013.
[I-D.white-i2rs-use-case]
White, R., Hares, S., and A. Retana, "Protocol Independent
Use Cases for an Interface to the Routing System", draft-
white-i2rs-use-case-01 (work in progress), August 2013.
[I-D.wu-i2rs-IM-service-topo]
Wu, Q., Hares, S., and X. Guan, "An Information Model for
Network Topologies", ID draft-medved-i2rs-topology-im-01,
October 2003.
[I.D-medved-i2rs-topology-im]
Medved, J., Bahadur, N., Clemm, A., and H.
Ananthakrishnan, "An Information Model for Network
Topologies", ID draft-medved-i2rs-topology-im-01, October
2003.
[RFC3746] Yang, L., Dantu, R., Anderson, T., and R. Gopal,
"Forwarding and Control Element Separation (ForCES)
Framework", RFC 3746, April 2004.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
Authors' Addresses
Susan Hares
Hickory Hill Consulting
7453 Hickory Hill
Saline, MI 48176
USA
Email: shares@ndzh.com
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Mach Chen
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: mach.chen@huawei.com
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