Internet Engineering Task Force Q. Fu, Ed.
Internet-Draft China Mobile
Intended status: Informational S. Gundavelli
Expires: January 2, 2016 Cisco
H. Deng
China Mobile
July 2015
Motivations, usecases and Models of VCPE
draft-fu-dmm-vcpe-models-00
Abstract
This document introduces the concept of Virtual Customer Premises
Equipment (VCPE). Such concept was first proposed in Broadband Forum
(BBF) as Network Enhanced Residential Gateway (NERG). The VCPE is
the Home Agent (HA) of the Mobile Nodes (MN) attached to the physical
CPE (pCPE). In this document, we explain the motivation and
advantages of VCPE. Three usecases of VCPE is further discussed in
the enterprise network, the residential network, and the Internet of
Things (IoT) Network. Two models of field deployment of VCPE are
discussed afterwards. The models of VCPE decompose the Control Plane
(CP) and the Data Plane (DP), which makes it easier for the
deployment of the distributed mobility model.
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Internet-Draft Motivations, usecases and Models of VCPE July 2015
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Motivation and Advantage of VCPE . . . . . . . . . . . . . . 3
4. Use case of VCPE . . . . . . . . . . . . . . . . . . . . . . 4
5. Models of VCPE Deployment . . . . . . . . . . . . . . . . . . 5
6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Informative References . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
This document introduces the concept of VCPE. The concept of VCPE is
to shift most of the networking and service functionalities from the
customer side to the network side. In this way, the customer side's
equipment, that is the pCPE (Physical Customer Premises Equiptment),
can be simplified. The VCPE refers to one or a set of equipments at
the network side to execute the networking and service
functionalities used to be executed at the CPE. In such
architecture, the CPE can be a simple L2 switch, which is only
responsible for forwarding packets to a certain next hop. The
concept of VCPE was first introduced in BBF as NERG (WT-317), which
mainly focuses on shifting some of the functionalities of a
residential gateway to the operator's network, for enabling network
based features. The aim is to facilitate the deployment, maintenance
and evolution of both existing and new capabilities without adding
complexity to the RG and/or the home network.
Figure 1 shows the architecture of the pCPE and the VCPE. In this
architecture, the VCPE is the HA for the mobile nodes adhear to the
pCPE at the network side.
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+---+ +-----+ +-----+
|MN1|====|pCPE1|================|VCPE1|
+---+ +-----+ +-----+
+-----+
|pCPE2|
+-----+
+---+ +-----+ +-----+
|MN2|====|pCPE3|================|vCPE2|
+---+ +-----+ +-----+
Figure 1: VCPE Architecture
In this document, we would like to further propose such concept in
the following aspects:
(1) Motivation and advantages of VCPE.
(2) Usecases of VCPE. We propose three usecases, including the
enterprise network, the residential network, and the IoT (Internet of
things) network.
(3) Models of VCPE deployment. We propose two models for the field
deployment of VCPE. Such models can be used for deployments in
multiple scenarios, including both residential network and enterprise
network.
2. Terminology
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 [RFC2119].
3. Motivation and Advantage of VCPE
The motivation and advantage of introduting VCPE can be concluded as
follows:
(1) It will reduce the cost of manufacturing and maintaining of the
pCPE. By shifting most of the complicated functions from the
customer's side to the operator's side, the cost of the pCPE can be
reduced significantly. Such redunction can be remarkable in the
enterprise network, since network functions, such as Firewall and
NAT(Network Address Translator) at the customer side can be
expensive. In the meantime, deployment of VCPE can also reducing the
OPEX of operators. Orders of on-site repair can be reduced because
of the simplicity of the customer equiptments.
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(2) It will avoid complicating the pCPE devices when providing value-
added L3-L7 services to the customers. Take the transport network as
example. Traditionally, pCPEs at the enterprise customer side are
simple L2 devices in the transport network. In order to meet the
requirements for value-added L3-L7 services from the customers, the
pCPEs should be redesigned to become L3 or even more complicated
devices. Such devices will not only result in an increase of
manufacture and maintenance cost, and will also request addtional
efforts for frequent update to meet the constantly increased
requirements of the customers. Nevertheless, by utilizing the VCPE
achitecture, pCPE can remain to be a simple L2 device, which is only
responsible for L2 forwarding. In this way, frequent update of these
pCPEs is not necessary, which will greatly decrease both CAPEX and
OPEX of the network operators.
(3) It will greatly speed up the service launching period. Since
most of the complicated functions are located at the VCPE in the
network side, operators have more power over services. Benefitting
from the recent NFV (Network Function Virtualization) and cloud
technologies, VCPE can be accomplished using SFC in the virtual
network, where different services can act as different VNFs (Virtual
Network Functions). Operators only need to add new VNFs on the VCPE
side to launch new services to the customers. In this way, Operators
can provide a variety of services through the network.
(4) It will provide user-define-network experience. By introducing
SFC concept into the VCPE, users can define his own service order and
sequence. Therefore, enterprise customers can enjoy the self-defined
services over the public network.
4. Use case of VCPE
The concept of VCPE can be used in multiple scenarios. In this
section, we will propose two use cases of VCPE, one in residential
network, and the other in the enterprise network.
(1) Use Case of VCPE in the Enterprise network.
Traditional enterprise network uses the tranport network access.
Multiple network functions, including Firewall (FW) and NAT, are
deployed at the enterprise customer's side. Such deployment not only
increases the cost of the equiptment at the customer side, but also
makes it difficult for both the enterprise customers and the service
providers operating and maintaining the functions.
By introducing VCPE into the transport network, functions such as FW
and NAT can be shifted to the aggregate network or core network,
acting as VCPE at the service provider's side. Moreover, value-added
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services can be provided. For example, by deploying a virtual Deep
Packet Inspection (vDPI), service providers can provide fine grained
data control to the enterprise customers.
(2) Use case of VCPE in the residential network.
In the residential network, traditionally, pCPE locates at the
customer premises terminates the home network and connect the LAN
devices to the Internet or to some service platforms through the
broadband access network. With the expansion of the broadband access
and the development of the OTT (Over The Top) industry, the quantity
and requirements of addtional functions of pCPE increases rapidly.
By shifting most of the complicated functions to VCPE, the cost of
the largely deployed CPE can be saved. In the meantime, deployment
of new features by service providers can be accelerated.
Taking PPPoE access as example. By shifting PPPoE client to VCPE,
pCPE can be a simple L2 device. In this case, VCPE takes the
responsibility to initiate PPPoE request to BRAS once receiving
traffic flow from the customers. When receiving the certification
from BRAS, VCPE will act as DHCP server by assigning IP address to
the traffic generating port. Such approach can also be used for IPv6
upgrade,in which case VCPE can act as IPv6 DHCP relay.
(3) Use case of VCPE in the IoT (Internet of Things) network.
VCPE can also be used in the IoT network. So far, multiple wireless
communication standards, including Wi-Fi, Zigbee, Blue Tooth, and
etc., exist for the connection of the IoT devices to the GW. The IoT
GW is responsible for decomposing the L2 packets from the devices,
composing them into L3 packets and transferring to the Internet
Server. Due to these various wireless communication standards,
multiple IoT GWs have to be deployed at users' home to support
different IoT devices. By shifting the packet transforming function
to VCPE, IoT GW can be a simple and unified L2 forwarding GW, while
VCPE will support different standard stacks and is responsible for
transforming packets following different communication standards to
IP packets.
5. Models of VCPE Deployment
There are multiple models when deploying VCPE in use cases as are
discussed in the previous section. In this document, we conclude the
deployment of VCPE into two models. In the first model, a logical
instance of VCPE is deployed in the cloud for each pCPE instance.
All traffic from pCPE goes through the vCPE. In the second model,
the VCPE is based on service chains attached to BNG. The classifier
on BNG puts the pCPE traffic through the correct set of service
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functions. Both of these two models can easily introduce CP/DP
decompositon at the VCPE side, and the DMM protocol can be used.
Figure 1 and Figure 2 show the two models of VCPE deployment. For
the first model, logical instance of VCPE is deployed. Such logical
instance can be a seperate instance deployed before or after the BNG,
as is shown in Figure 1(a) and Figure 1(b). It can also be deployed
by upgrading the traditional BNG to include the functions of VCPE, as
is shown in Figure 1(c).
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+------+
| pCPE +--------+
+------+ |
| +------+ ________
+------+ +--+---+ +-----+ |SFC in| / \
| pCPE +-----+ VCPE +---+ BNG +-----+WAN DC+---+ Internet |
+------+ +--+---+ +-----+ +------+ \________/
|
+------+ |
| pCPE +--------+
+------+
Figure 1(a) VCPE instance deployed before BNG
+------+
| pCPE +--------+
+------+ |
| +------+ ________
+------+ +--+---+ +-----+ |SFC in| / \
| pCPE +-----+ BNG +---+VCPE +-----+WAN DC+---+ Internet |
+------+ +--+---+ +-----+ +------+ \________/
|
+------+ |
| pCPE +--------+
+------+
Figure 1(b) VCPE instance deployed after BNG
+------+
| pCPE +--------+
+------+ |
+--+---------+ +------+ ________
+------+ |BNG +-----+ | |SFC in| / \
| pCPE +-----+ |VCPE | +---+WAN DC+---+ Internet |
+------+ + +-----+ | +------+ \________/
+--+---------+
+------+ |
| pCPE +--------+
+------+
Figure 1(c) VCPE instance deployed through upgrading BNG
Figure 2: VCPE deployment model NO.1: Logical Instance of VCPE
For the second models, no logical instance exists as VCPE. VCPE is
realized as a sequence of service function chaining (SFC) in the WAN
DC. In this model, BNG is acting as the classifier of SFC. Such
classfication should be based on user profile, in which case, users
can define his own VCPE service.
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SDN (Software Define Network) controllers can also be introduced in
the second model. In which case, all of the pCPEs and the BNG data
plane (BNG-dp) can be controlled by the SDN-controller (also acting
as the BNG control plane(BNG-cp)), as is shown in Figure 3. When the
customer selects a set of services, the SDN-controller will inform
the pCPE and the BNG-dp to direct the traffic flow to a certain SFC.
the Service Classification Function (SCF) is located in the BNG,
responsible for classifing traffic from different customer/network/
service. The SCF is controlled by the SDN-controller. When a packet
arrives, the SCF will ask the controller which Service Founction Path
(SFP) this flow should follow, and put corresponding SFC
encapsulation into the packet. The packet then goes into the service
founction region, and will be directed to different Service
Founctions (SF) based on the encapsulation.
+------+ ...............
| pCPE +--------+ : VCPE :
+------+ | : +----+ :
| : +--+sfp1+-----------+
+------+ +--+---+ : | +----+ : ___|____
| pCPE +-----+ BNG +----| +----+ : / \
+------+ +--+---+ : +--+sfp2+------+ Internet |
| : | +----+ : \________/
+------+ | : | +----+ : |
| pCPE +--------+ : +--+sfp3+-----------+
+------+ : +----+ :
:.............:
Figure 3: VCPE deployment model NO.2: SFC realization of VCPE
6. Conclusion
In this document, the concept of VCPE is illustrated in detail. The
basic concept of VCPE is to shift the complicated functions from the
pCPE at the customer side to the VCPE at the service provider side.
The motivation of such shifting can be concluded as reducing the
Capex and Opex of the pCPE, and providing quick launched customer
defined services in the meantime. Three use cases are proposed for
VCPE, including scenarios in the enterprise network, the residential
network and the IoT network. Two models are then discussed for the
field deployment of VCPE.
7. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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Authors' Addresses
Qiao Fu (editor)
China Mobile
Xuanwumenxi Ave. No.32
Beijing
China
Email: fuqiao1@outlook.com
Sri Gundavelli
Cisco
Email: sgundave@cisco.com
Hui Deng
China Mobile
Xuanwumenxi Ave. No.32
Beijing
China
Email: denghui@chinamobile.com
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