Deployment Model of Control Plane and User Plane Separation BNG
draft-cuspdt-rtgwg-cu-separation-bng-deployment-00
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| Authors | Rong Gu , Sujun Hu , Zitao Wang | ||
| Last updated | 2017-10-28 | ||
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draft-cuspdt-rtgwg-cu-separation-bng-deployment-00
rtgwg R. Gu
Internet-Draft S. Hu
Intended status: Informational China Mobile
Expires: May 1, 2018 Michael. Wang
Huawei
October 28, 2017
Deployment Model of Control Plane and User Plane Separation BNG
draft-cuspdt-rtgwg-cu-separation-bng-deployment-00
Abstract
This document introduces deployment model of BNG device with Control
Plane and User Plane separation in order to give guidance of the
deployment of CP and UP separation BNG devices in operators' network.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on May 1, 2018.
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Table of Contents
1. Introduction and Overview . . . . . . . . . . . . . . . . . . 2
2. Concept and Terminology . . . . . . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
3. Deployment Model of BNG with CP and UP Separation . . . . . . 4
3.1. CP and UP of BNG deployment within only one district . . 4
3.2. CP and UP of BNG deployment within different districts . 5
4. The Process of BNG with CP and UP in Home Broadband Service . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction and Overview
BNG is an Ethernet-centric IP edge router and acts as the aggregation
point for the user traffic with some additional functions such as
address management, AAA and Radius cooperating with AAA and Radius
systems and subscriber management. According to the rapid
development of new services, such as 4K, IoT, etc. and the increasing
numbers of distributed home broadband service users, high resource
utilization, management of high-efficiency, and fast service
provision are required. Thus a new architecture of BNG with CP and
UP separation which is also called Cloud BNG is proposed in [BBF-
CloudCO] and [I-D.draft-gu-nfvrg-cloud-bng-architecture].
The bandnew CP and UP separation architecture of BNG is constructed
by Control Plane and Uer Plane, with concentrated CP responsible for
control and management of UP's resrouces and subscribers' informaiton
while distributed UP taking charge of policy implementation and
traffic forwarding. The obvious advantages of this new architecture
can be listed as belows.
Resource Utilization Improvement: Centralized Control Plane provides
the capability of unitfied management of network resources and users
information. CP has an overview of all the resources and can
distribute resources as specific user required, thus resources can be
totally controlled and balances.
Management with High Effiency: Centralized CP provides unified
management interface to the outside systems such as EMS, DHCP Server,
Radius Server and etc. In this situation, management can be much
easier for centralized CP is the only device facing to the outside
systems.
Dynamic and Flexibility: CP can be virtualized as a VNF with MANO
management in NFV, while UP can be a virtual machine or physical
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device as demand. Software-oriented CP can be designed with
flexibility. CP can handle all the situations dynamically such as
few users accessing and large numbers of users access.
Fast TTM: CP and UP can be deployed separately with CP deployed
centrally and UP deployed in distribution closing to users. Thus
according to different situations such as session overload or
extremely high throughput, CP and UP can be extended separately as
well. It can help shorten the time to marketing.
As noted that the new architecture of BNG consists with CP and UP
separation, CP and UP are deployed due to practical requiement. This
document gives out CU separation BNG deployment model according to
the actual deployment.
2. Concept and 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].
2.1. Terminology
BNG: Broadband Network Gateway. A broadband remote access server
(BRAS, B-RAS or BBRAS) routes traffic to and from broadband remote
access devices such as digital subscriber line access multiplexers
(DSLAM) on an Internet service provider's (ISP) network. BRAS can
also be referred to as a Broadband Network Gateway (BNG).
CP: Control Plane. The CP is a user control management component
which support to manage UP's resources such as the user entry and
user's QoS policy
UP: User Plane. UP is a network edge and user policy implementation
component. The traditional router's Control Plane and forwarding
plane are both preserved on BNG devices in the form of a user plane.
TTM: Time to Market. It is the length of time it takes from a
product or a service being conceived until its being available for
sale.
MANO: Management and Orchestration. Functions are collectively
provided by NFVO, VNFM and VIM.
VNF: Virtual Network Function. Implementation of a Network Function
that can be deployed on a Network Function Virtualization
Infrastructure (NFVI).
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PNF: Physical Network Function
AAA: Authentication Authorization Accounting
DHCP: Dynamic Host Configuration Protocol
PPPoE: Point to Point Protocol over Ethernet
IPoE: Internet Protocol over Ethernet
3. Deployment Model of BNG with CP and UP Separation
3.1. CP and UP of BNG deployment within only one district
+-------------------+
| |
| Internet |
| |
+---------^---------+
|
+---+---+
| | +------------------------+
| CR | | |
| | | +--------+ |
+---^---+ | +------+ Radius | |
| | | +--------+ |
| | +--+---+ |
+---+---+ | | | +--------+ |
| +---SERVICE----+ | +--+ DHCP | |
| BNG-UP+---CONTROL----+ | BNG | +--------+ |
|VNF/PNF+----MGNT------+ | -CP | |
+---^---+ | | VNF | +--------+ |
| | | +--+ EMS | |
| | | | +--------+ |
+---+---+ | +--+---+ |
| | | | +--------+ |
| OLT | | +------+ MANO | |
| | | +--------+ |
+---^---+ | Management Network |
| +------------------------+
+---+---+
| USER |
+-------+
Figure 1: Cloud BNG Deployed in One Disctict
Take one district as an example, here BNG-CP and BNG-UP are separated
deployed. As CP is computational intensive, virtualized CP acting as
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a VNF can meet the requirement of flexibility and fast calculation.
UP is traffic intensive, which can be virtualized or stay physical
depending on traffic. The virtualized UP with low expcense and high
flexibility can be suitable in light traffic. In hugh traffic,
special hardware is needed with high traffic forwarding performance.
In order to fulfill the function of BNG, BNG-CP needs to communicate
with outside systems such as Radius and many others in the management
network. In addition, BNG-CP has different interfaces with BNG-UP
including service interface, control interface and management
interface, seeing in [I-D.draft-gu-nfvrg-cloud-bng-architecture]and
[I-D.draft-wcg-i2rs-cu-separation-infor-model-01].
3.2. CP and UP of BNG deployment within different districts
+-------------------+
| |
| Internet |
| |
+---------^---------+
| +------+ +----+ +---+ +----+
+---+---+ |Radius| |DHCP| |EMS| |MANO|
| | +---+--+ +--+-+ +-+-+ +-+--+
| | | | | |
+---+ CR +-----+ +---+-------+-----+-----+--+
| | | | | BNG-CP |
| | | | +---.--.------------.------+
| +---^---+ +---------.--.--+ .
| ....|.................... . | .
| . | ............ | .
| . +-------+ . | .........
+-+---.-+ +-+---.-+ +---+-.-+
| | | | | |
| BNG-UP| | BNG-UP| | BNG-UP|
|VNF/PNF| |VNF/PNF| |VNF/PNF|
+---^---+ +---^---+ +---^---+
| | |
| | |
+---+---+ +---+---+ +---+---+
| OLT | | OLT | | OLT |
+---+---+ +---+---+ +---+---+
+-----|-----+ | +-----|-----+
+---+---+ +---+---+ +---+---+ +---+---+ +---+---+
|USER A1| |USER A2| |USER B1| |USER C1| |USER C2|
+-------+ +-------+ +-------+ +-------+ +-------+
Figure 2: Cloud BNG Deployed in Several Discticts
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If scubscribers are distributed in serveral districts, CP is deployed
centrally with UP deployed in different districts closing to
subscribers. Take three districts A B C for example. Here three UPs
are placed which share one CP. CP is usually deployed in Core Date
Center with UP in edge Date Centers. In the Data Centers design, we
have core data centers and edge data centers according to their
location and responsibility. Core datacenters are often planned in
province for the control and management , while edge datacenters in
cities or towns for easy service access.
In this scenario, centralized CP faces to the subsystems outside and
communicate with all these UPs for the control and management.
Under the CP's control, the corresponding traffic is forwarded by UP
to the Internet.
4. The Process of BNG with CP and UP in Home Broadband Service
Take a user Bob accessing to the Internet by Home Broadband Service
as an example. The process includs the service traffic from user to
the internet and signaling traffic between BNG-UP and BNG-CP. Below
is the whole process.
(1)User Bob dialups with packets of PPPoE or IPoE from BNG-UP which
will send to BNG-CP with its information. This belongs to signaling
traffic.
(2)BNG-CP processes the dialup packets. Confirming with the outside
neighboring systems in the management network, BNG-CP makes the
decision to permit or deny of the dial through certification. In
this step, BNG-CP manages resources and generates tables with
information such as User Infor, IP Infor, QoS Info and etc. This
belongs to signaling traffic.
(3)BNG-CP sends tables to the corresponding UP or choose one UP in
corresponding UPs. This belongs to signaling traffic.
(4)BNG-UP receives the tables, matches rules and performs
corresponding actions.
(5)If Bob is certificated and permitted, the UP forwards the traffic
into the Internet with related policies such as limited bandwidth,
etc. Otherwise, Bob is denied to access the Internet. This belongs
to service traffic.
From Step 2 to Step 4, the information model defined in [I-D.draft-
wcg-i2rs-cu-separation-infor-model-01] can be used.
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5. Security Considerations
None.
6. IANA Considerations
None.
7. 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,
<https://www.rfc-editor.org/info/rfc2119>.
Authors' Addresses
Rong Gu
China Mobile
32 Xuanwumen West Ave, Xicheng District
Beijing, Beijing 100053
China
Email: gurong_cmcc@outlook.com
Sujun Hu
China Mobile
32 Xuanwumen West Ave, Xicheng District
Beijing, Beijing 100053
China
Email: shujun_hu@outlook.com
Michael Wang
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: wangzitao@huawei.com
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