Internet DRAFT - draft-gu-nfvrg-cloud-bng-architecture
draft-gu-nfvrg-cloud-bng-architecture
NFVRG R. Gu
Internet-Draft S. Hu
Intended status: Informational China Mobile
Expires: January 3, 2018 July 2, 2017
Control and User Plane Separation Architecture of BNG
draft-gu-nfvrg-cloud-bng-architecture-01
Abstract
This document defines the new architecture of BNG devices with
control plane (CP) and user plane (UP) separation. BNG-CP is a user
control management component while BNG-UP takes responsibility as the
network edge and user policy implementation componenet. Both BNG-CP
and BNG-UP are core components for fixed broadband services and
deployed separately at different network layer in actual network.
Status of This Memo
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This Internet-Draft will expire on January 3, 2018.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Definition of terms . . . . . . . . . . . . . . . . . . . . . 2
4. C/U separated BNG architecture . . . . . . . . . . . . . . . 3
5. C/U separated BNG use case . . . . . . . . . . . . . . . . . 4
6. Advantages of C/U seperated BNG . . . . . . . . . . . . . . . 8
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
9. Normative References . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
BNG device is defined as an Ethernet-centric IP edge router, and the
aggregation point for the user traffic. It performs Ethernet
aggregation and packets forwarding via IP/MPLS, and supports user
management, access protocols termination, QoS and policy management,
etc.
The basic idea of control plane and user plane separation is to
extract and centralize the user management function of multiple BNG
devices forming a separate and concentrated CP, while UP takes
function as traditional router's control plane and BNG forwarding
plane. Thus a BNG is constructed of CP and UP which is benefit in
cloud-based BNG with the advantages of resource utilization
improvement, resource control centralization, new service rapid
provision and so on.
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. Definition of terms
AAA:Authentication Authorization Accounting
BNG:Broadband Network Gateway
CP:Control Plane
DHCP:Dynamic Host Configuration Protocol
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MANO:Management and Orchestration
NFV:Network Function Virtualization
PPPoE:Point to Point Protocol over Ethernet
UP: User Plane
4. C/U separated BNG architecture
There are two parts of functions in traditional BNG: one is user
access management function, the other is router function. While in
cloud-based BNG, we find out that tearing these two functions apart
can make a difference. Actually the user management function can be
centralized deployed as a concentrated module or device which can be
called BNG-CP (Control Plane). The reserved functions such as router
function and forwarding engine can be deployed in the form of BNG
User Plane. Thus the Cloud-based BNG architecture is made up of
control plane and user plane.
+--------------------------------------------------------------+
|+----------+ +---+ +----------+ +------++------++-----------+ |
|| Address | |AAA| |Subscriber| |Radius||PPPoE/|| UP | |
||management| | | |management| | ||IPoE ||management | |
|+----------+ +---+ +----------+ +------++------++-----------+ |
| CP |
+-----------+++---------------------------------+++------------+
||| |||
||| |||
||| |||
+-----------+++-------------+ +------------+++-----------+
| +------------------+ | | +------------------+ |
| | Routing control | | | | Routing control | |
| +------------------+ | ... | +------------------+ |
| +------------------+ | | +------------------+ |
| |Forwarding engine | | | |Forwarding engine | |
| +------------------+ UP | | +------------------+ UP|
+---------------------------+ +--------------------------+
Figure 1: Architecture of C/U Seperation BNG
The CP is a user control management component that supports
(1)Address management:unified address pool management
(2)AAA and RADIUS:cooperation with the RADIUS server and others to
implement AAA for access users
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(3)Subscriber management:user entry management and forwarding policy
management
(4)PPPoE/IPoE:process user dialup packets of PPPoE/IPoE
(5)UP management:management of UP interface status, and the setup,
deletion, maintenance of channels between CP and UP
The UP is a network edge and user policy implementation component,
including
(1)Control plane functions including routing, multicast and MPLS
(2)Forwarding plane functions including traffic forwarding, QoS and
traffic statistics collection
5. C/U separated BNG use case
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+------------------------------------------------------------------+
| Neighboring policy and resource management systems |
| |
| +-------------+ +-----------+ +---------+ +----------+ |
| |Radius Server| |DHCP Server| | EMS | | MANO | |
| +-------------+ +-----------+ +---------+ +----------+ |
+--------------------------------+---------------------------------+
|
|
|
+-----------------+-----------------+
| |
| BNG-CP |
| |
+---------------+------------+------+
Service| Control| Management| |||
Interface| Interface| Interface| |||
(VXLAN-GPE)| (OF,etc.)| (Netconf)| |||
| | | |||
+--------------+------------+ +---------------------------+
| | | |
| BNG-UP | | BNG-UP |
| | | |
+-------------+-------------+ +--------------+------------+
| |
| |
+-------------+-------------+ +--------------+------------+
| | | |
| Access Network | | Access Network |
| | | |
+-+-----------+-----------+-+ +-+--------+-----------+----+
| | | | | |
| | | | | |
| | | | | |
+-----++ +----+-+ +---+--+ +----+-+ +----+-+ +--+---+
|User11| |User12| ... |User1N| |User21| |User22| ... |User2N|
+------+ +------+ +------+ +------+ +------+ +------+
Figure 2: Cloud BNG use case
In the actual deployment, a C/U separated BNG device is composed of
CP and UPs. CP is centralized deployed which takes responsiblity of
a user control management component managing UP's resources such as
the user entry and forwarding policy. And UP is distributed in the
bottom acting as a network edge and user policy implementation
component.
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In order to fulfill a service, Neighboring policy and resource
management systems is deployed outside. In the neighboring system,
different service systems such as RADIUS server,DHCP server and EMS
are included. Besides if BNG-CP is virtualized as a NFV. The NFV
infrastructure management system MANO is also included here. BNG-CP
has connections with the outside neighboring systems to transmit
management traffic.
There are three kinds of interfaces between BNG-CP and BNG-UP
according to its traffic catergories: Service Interface, Control
Interface, and Management Interface. Service Interface is used to
transmit PPPoE/IPoE packets for the authentication. Control
Interface is used for setting forwarding entries on UP. Some choose
OpenFlow as the protocol. Management Interface is used to carry out
basic configurations through NETCONF.
Besides, now we have three related drafts which describes these
interfaces in detail. One is VXLAN-GPE extention draft for C/U
separated BNG related with Servie Interface in [draft-huang-nov3-
vxlan-gpe-extension-for-vbng-00]. One is YANG data model for
Management Interface in [draft-hu-opsawg-cu-separation-yang-model-
00]. The other is the information model covering Control Interface
and Management Interface which makes the abstraction of information
in modeling in [draft-wcg-i2rs-cu-separation-info-model-01].
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+-------------------+
| |
| Internet |
| |
+---------^---------+
|
+---+---+
| | +------------------------+
| CR | | |
| | | +--------+ |
+---^---+ | +------+ Radius | |
| | | +--------+ |
| | +--+---+ |
+---+---+ | | | +--------+ |
| +--------------+ | +--+ DHCP | |
| BNG-UP+--------------+ | BNG | +--------+ |
| +--------------+ | -cp | |
+---^---+ | | | +--------+ |
| | | +--+ EMS | |
| | | | +--------+ |
+---+---+ | +--+---+ |
| | | | +--------+ |
| OLT | | +------+ MANO | |
| | | +--------+ |
+---^---+ | Management|Network |
| +------------------------+
+---+---+
| USER |
+-------+
Figure 3: User Dialup process
In the C/U seprated BNG architecture, there are several processes
when a home user accesses the Internet.
(1)User dialup packets of PPPoE or IPoE from BNG-UP which will send
to BNG-CP from BNG-UP's Service Interface.
(2)BNG-CP processes the dialup packet. Confirming with the outside
neighboring systems in the management network, BNG-CP makes the
decision to permit or deny of the dial through certification.
(3)After that, BNG-CP tells UP to do the responding forwarding
actions with related policies.
(4)If the user is certificated and permitted, the UP forwards the
traffic into the Internet with related policies such as limited
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bandwidth, etc. Otherwise, the user is denied to access the
Internet.
6. Advantages of C/U seperated BNG
Due to the bandnew C/U separated BNG architecture, there are a lot of
brilliant advantages.
(1)Resources can be central controlled and balanced
Centralized control plane takes the responsibility of control and
management. Thus it has the overall view of resources and can
distribute the resources as required.
(2)Device can be more efficient in extension
Control plane and user plane can be extended separately according to
different situations such as the session overload and extremely high
throughput.
(3)Management can be much easier as the BNG-CP is the only one facing
to the outside system such as EMS, DHCP server, Radius and so on.
(4)BNG-CP can be virtualized as a VNF with its management of MANO.
(5)BNG-UP can be a virtual machine or physical device as demand.
7. Security Considerations
None.
8. IANA Considerations
None.
9. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, DOI 10.17487/RFC2234,
November 1997, <http://www.rfc-editor.org/info/rfc2234>.
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Authors' Addresses
Rong Gu
China Mobile
32 Xuanwumen West Ave, Xicheng District
Beijing, Beijing 100053
China
Email: gurong_cmcc@outlook.com
Shujun Hu
China Mobile
32 Xuanwumen West Ave, Xicheng District
Beijing, Beijing 100053
China
Email: hushujun@chinamobile.com.com
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