Internet DRAFT - draft-giust-dmm-cpdp-deployment
draft-giust-dmm-cpdp-deployment
DMM Working Group F. Giust
Internet-Draft M. Liebsch
Intended status: Informational NEC
Expires: January 7, 2016 July 6, 2015
Deployment of Control-/Data-Plane separation in DMM
draft-giust-dmm-cpdp-deployment-00
Abstract
The DMM working group is currently looking at solutions for mobility
management based on control and data plane separation. In this
context, the network entities in charge for the mobility control
function are separated from the data plane nodes, responsible mainly
for, but not limited to, data packet forwarding. This vision allows
for the design of different interaction methods between the mobility
control function and the data plane nodes. One of such mechanisms
being currently discussed devises an SDN-based abstraction layer
between control and data planes, embodied by an SDN Network
Controller. This latter interfaces to the mobility control function
through a north-bound interface (NBI), and programs the underneath
infrastructure through a south-bound interface (SBI), e.g., OpenFlow.
This draft describes multiple deployment scenarios for NBI and SBI
interworking, given that multiple network controllers could be
deployed in order to meet performance requirements e.g., related to
latency.
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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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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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 January 7, 2016.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Control plane and data plane separation: deployment scenarios 6
3.1. Scenario 1 . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Scenario 2 . . . . . . . . . . . . . . . . . . . . . . . 7
3.3. Scenario 3 . . . . . . . . . . . . . . . . . . . . . . . 7
4. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Normative References . . . . . . . . . . . . . . . . . . 8
4.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
The Distributed Mobility Management (DMM) working group is currently
investigating solutions, which are based on the separation of
mobility management functions' Control- and Data-Plane. The network
functions in charge of the mobility control are separated from the
data plane nodes, responsible mainly for, but not limited to, data
packet forwarding. In this scenario, it is possible to design
different mechanisms for the interaction between the mobility control
function and the data plane nodes.
One of these mechanisms devises a Software Defined Networking (SDN)
abstraction layer between control and data planes, embodied by an SDN
Network Controller (NC). The NC enforces instructions from different
mobility control functions, which operate on top of a Network
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Controller and hold the mobility states, to Data-Plane nodes (DPNs),
such as switches or routers, within a defined network scope. DPNs in
different networks may be controlled by physically separated NCs.
The NC configures Data-Plane nodes with forwarding and policy
enforcement related rules, either with the accuracy of a single data
flow or as aggregated rule, such as for an IP address prefix.
An example of a Control-Plane function is the Control-Plane of a
Local Mobility Anchor (LMA-C) as per the Proxy Mobile IPv6 (PMIPv6)
architecture [RFC5213] or a Packet Data Network (PDN) Gateway's
Control-Plane functions as per the 3rd Generation Partnership
Project's architecture for cellular mobile communications. These
functions perform protocol operation with remote Control-Plane
functions for mobility management, e.g. the Control-Plane of a Mobile
Access Gateway (MAG) as per the PMIPv6 protocol.
Control-Plane functions associated with mobility management need to
interact with the NC to enforce forwarding and policy rules in the
Data-Plane. By taking again the PMIPv6 architecture as an example,
the Data-Plane nodes have the role of the Data-Plane functions within
an LMA or MAG.
This document discusses various deployment options for mobility
management in a Control-/Data-Plane separated setup utilizing SDN and
how results of the chartered work about Forwarding Policy Control
(FPC) [I-D.ietf-dmm-fpc-cpdp] can be used in such setup.
The diagrams and descriptions as per this document are meant for
discussion and consideration in the DMM working group's chartered
item about DMM deployment options.
The WG document [I-D.ietf-dmm-fpc-cpdp] specifies an abstraction and
information model for DMM control and data plane separation. The
specified functional architecture comprises a Client function, which
is associated with the mobility management Control-Plane, and an
Agent function, which is associated with Data-Plane configuration.
Client and Agent interact with each other as per the specification in
[I-D.ietf-dmm-fpc-cpdp] to enforce forwarding and policy rules from
the mobility management Control-Plane in the Data-Plane. Such rules
comprise, for example, forwarding of defined traffic through a GRE
tunnel to a remote Data-Plane node while the traffic should
experience prioritization as per a defined Quality-of-Service class.
Such interaction is illustrated in Figure 1
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+-------------------------+
| Mobility Control-Plane |
| |
|+--------[API]----------+|
|| FPC Client Function ||
|+----------^------------+|
+-----------|-------------+
|
| DMM FPC protocol
|
+-----------|-------------+
|+----------v------------+|
|| FPC Agent Function ||
|+-----------------------+|
| |
| DPN Configuration API |
+-------------------------+
Figure 1: Illustration of the functional reference architecture for
DMM Forwarding Policy Configuration (FPC)
In the present document we describe a base reference model from
[I-D.ietf-dmm-fpc-cpdp], to then propose some sub-scenarios of
interest for practical deployment. In the base reference model, as
depicted in Figure 2, the Control-/Data-Plane interaction is
performed through an NC that exhibits a southbound interface (SBI),
e.g. the OpenFlow protocol, to configure DPNs, and exposes a
northbound interface (NBI) towards mobility management Control-Plane
functions utilizing the Client and Agent functions as well as the
abstraction and configuration model as per [I-D.ietf-dmm-fpc-cpdp].
This enables the mobility management Control-Plane using the NC's NBI
to enforce rules and policies in the Data-Plane, which are relevant
for the Control-Plane's operation, without the need to be aware of a
Data-Plane node's configuration details and whether the Data-Plane
node is a switch or a router.
An SDN-based Control- and Data-plane separation for DMM has been
proposed also in [I-D.yang-dmm-sdn-dmm]. In such draft the mobility
function is co-located with the SDN Network Controller. By doing so,
the mobility protocol is highly coupled with the NC and the SBI
interface. The present draft extends [I-D.yang-dmm-sdn-dmm] by
introducing the use of an NBI as an additional abstraction layer. In
this way the architecture gains in flexibility as the mobility
function is independent from the specific SBI and NC used. The NBI
hides Data-Plane configuration details from Control-Plane functions
and is represented by a protocol implementation as per
[I-D.ietf-dmm-fpc-cpdp].
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___.......___
,-' mobility `-.
| control |
`._ function _,
`--[Client]---'
|
|
| NBI
+--[Agent]---+
| network |
| controller |
`,----+---+--'
____/ | \ SBI
| | | \____
+----+ | | | data
+----+ +----+ plane
| | nodes
+----+
Figure 2: Reference communication model
The flexibility introduced by splitting the Control-/Data-Plane
reference point into two different interfaces, namely the NBI and the
SBI, may lead to practical limitations for a single network
controller to handle the whole set of data plane nodes. As a
consequence, when multiple NCs are to be deployed, different
scenarios arise with different characteristics. This documents
explores three possible deployment scenarios.
2. Terminology
The following terms are defined and used in this document:
FPCP (Forwarding Policy Configuration Protocol)
MCF (Mobility Control Function)
NC (Network Controller)
NBI (North-bound Interface)
SBI (South-bound Interface)
DPN (Data Plane Node)
MN (Mobile Node)
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3. Control plane and data plane separation: deployment scenarios
A single network controller may lead to practical limitations when it
comes to handle the operations in large network, like scalability
issues and protocol promptness.
The mobility management protocol should execute quickly in order to
guarantee optimal service to users. For this reason the network
controller should not be too distant from the DPNs. Therefore, a
network administrator might deploy multiple NCs, each responsible for
a network sub-domain or site.
By deploying multiple NCs, the Control-/Data-Plane reference model as
depicted in Figure 2 suffers some variations as described in the
following subsections.
3.1. Scenario 1
In this scenario the NCs from different sites are directly
interacting with the mobility control function by means of the NBI
interface. The mobility control function possesses a holistic view
of the network domain and propagates the instruction to the NCs
accordingly. The mobility control function, which is associated with
the Client function as per [I-D.ietf-dmm-fpc-cpdp], connects to two
Agent functions, each associated with one NC. This scenario is
illustrated in Figure 3.
_______________________________
,-' mobility `-.
| control function |
`. _____________________ _,
`------[______ Client _______]---'
| |
| NBI |
+----[Agent]-+ +-[Agent]----+
| NC | | NC |
| site 1 | | site 2 |
`,----+---+--' `,----+---+--'
____/ | \ ____/ | \
|DPN | | SBI \____ |DPN | | SBI \____
+----+ | | | +----+ | | |
+----+ +----+ +----+ +----+
| | | |
+----+ +----+
Figure 3: Scenario 1
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3.2. Scenario 2
In this scenario, the mobility control Client function interacts with
a single Agent co-located with one NC, which in turns propagates the
configuration through an east-west interface (EWI) to other NCs.
This scenario is illustrated in Figure 4.
__________
,-' mobility `-.
| control |
`._ function _,
`-[Client]--'
|
| NBI
+---[Agent]--+ +-----+------+
| NC |_____________| NC |
| site 1 | EWI | site 2 |
`,----+---+--' `,----+---+--'
____/ | \ ____/ | \
|DPN | | SBI \____ |DPN | | SBI \____
+----+ | | | +----+ | | |
+----+ +----+ +----+ +----+
| | | |
+----+ +----+
Figure 4: Scenario 2
3.3. Scenario 3
In this scenario, each NC interacts through an Agent with a dedicated
instance of the mobility function Client. It is then up to the
different mobility control entities to coordinate the operations
among different sites. This scenario is illustrated in Figure 5.
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_________ _________
,-' mobility`-. / mobility \
| support |___________| control |
`._ entity _, \_ entity /
`-[Client]-' `[Client]'
| |
| NBI NBI |
+---[Agent]--+ +---[Agent]--+
| NC | | NC |
| site 1 | | site 2 |
`,----+---+--' `,----+---+--'
____/ | \ ____/ | \
|DPN | | SBI \____ |DPN | | SBI \____
+----+ | | | +----+ | | |
+----+ +----+ +----+ +----+
| | | |
+----+ +----+
Figure 5: Scenario 3
4. References
4.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
4.2. Informative References
[I-D.ietf-dmm-fpc-cpdp]
Liebsch, M., Matsushima, S., Gundavelli, S., and D. Moses,
"Protocol for Forwarding Policy Configuration (FPC) in
DMM", draft-ietf-dmm-fpc-cpdp-00 (work in progress), May
2015.
[I-D.yang-dmm-sdn-dmm]
yangun@dcn.ssu.ac.kr, y. and Y. Kim, "Routing Optimization
with SDN", draft-yang-dmm-sdn-dmm-03 (work in progress),
March 2015.
Authors' Addresses
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Fabio Giust
NEC Laboratories Europe
NEC Europe Ltd.
Kurfuersten-Anlage 36
Heidelberg D-69115
Germany
Phone: +49 6221 4342216
Email: fabio.giust@neclab.eu
Marco Liebsch
NEC Laboratories Europe
NEC Europe Ltd.
Kurfuersten-Anlage 36
Heidelberg D-69115
Germany
Phone: +49 6221 4342146
Email: liebsch@neclab.eu
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