Hybrid Access Network Architecture
draft-lhwxz-hybrid-access-network-architecture-00

Abstract

In practice, people have realized that it may be difficult to update or rebuild existing copper networks when they are deployed in certain areas. At the same time, the requirements of customers on bandwidth are continually increased. This document tries to discuss the general network architectures which could be used to address this problem by bundling multiple hybrid access networks together according to the certain management policies.

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 working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.

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This Internet-Draft will expire on December 27, 2014.

Copyright Notice

Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

• 1. Introduction
• 2. Terminology
• 3. Motivation Scenario
• 4. Flow-Based Forwarding versus Packet-Based Forwarding
• 5. An Architecture for Packet-Based HYA
• 6. Existing Technologies and Gap Analysis
• 7. Security Considerations
• 8. Acknowledgements
• 9. Normative References
• Authors' Addresses

1. Introduction

It could be difficult for operators to upgrade or rebuild their copper access networks deployed in certain places (e.g., the old downtown areas). However, at the same time, the requirements of customers on broader bandwidth become stronger. To address this problem, the possibility of combining different or hybrid access networks (e.g., LTE and DSL) for a higher bandwidth is being discussed.

To achieve this functionality, the mechanism for binding multiple hybrid access networks need to be designed, which is called as HYbrid access (HYA) mechanism in this document. A HYA mechanism may need to have the capability in flexibly deciding the paths to forward data traffics. This document attempts identify the potential issues and requirements related with the HYA mechanisms and proposes general architectural design suggestions.

The remainder of this document is organized as follows. Section 2 lists the key terms used in this document. Section 3 introduces a motivation scenario and requirements in combining hybrid access networks. Section 4 discusses the criteria of identifying the packet forwarding paths between the combined hybrid access networks. In section 5, a general HYA architecture is proposed for constructing the packet-based forwarding solutions. Section 6 discusses the possibility of using existing multi-path technologies in addressing the HYA issues and tries to identify the gaps.

2. Terminology

Customer Premise Equipment (CPE):

A device that connects multiple hosts to provide connectivity to the service providers network.

HYbrid Access (HYA):

HYbrid Access (HYA) is the bundling of two or more access lines over different technologies (e.g. DSL and LTE) to one Internet connection for end customers.

Hybrid Access Aggregation Point (HAAP):

The HAAP which acts as a service termination and a service creation implements bonding mechanism and sets up a high speed Internet dual stack IP connection with CPE on top of two or more hybrid access technologies. The packet reorder, reassemble functions in packet-based solutions should be supported on HAAP.

Path:

A sequence of links between the CPE and HAAP, typically DSL path and LTE path are defined in this document.

3. Motivation Scenario

The figureFigure 1 illustrates a motivation scenario, in which a customer accesses the Internet through a DSL access Network. The requirements of the customer on broader bandwidth for better service experience become stronger. However, the bandwidth of the DSL access network has been fully occupied (i.e., the traffics on the copper line has reached to a pre-specified threshold) and cannot satisfy any further bandwidth requirements from the customer. In addition, because the customer is located in an old downtown street, it may take a long time or be extremely difficult for the operator to get the official construction permit to update the DSL access network or deploy a new one in that area. Whereas, at the same time, the operator has already deployed a LTE backhaul network in the downtown area which is still not used to its fullest. If the operator is able to take advantage of the bandwidth resources of the LTE and DSL network to transfer the traffics of the customer concurrently, it is possible to provide a higher bandwidth to the customer and guarantee good customer experiences.

                          ------
                       /          \
               %======+            +===+
                      |    LTE     |    \   *****
                       \          /       **     **
                          ------         *         *
            +-----+                     *  Internet *
 +----+     |     |       ------         *         *
 |    |     |     |    /          \       **     **
 |HOST+-----+ CPE +---+            |    /   *****
 |    |     |     |   |    DSL     +---/
 +----+     |     |    \          /
            +-----+       ------

                           ------
                        /          \
             +-----+   |            +---\
             |     | +-+    LTE     |    \   *****
  +----+     |    E+-+  \          /       **     **
  |    |     |     |       ------         *         *
  |HOST+-----+ CPE |                     *  Internet *
  |    |     |     |       ------         *         *
  +----+     |    D+-+  /          \       **     **
             |     | +-+            |    /   *****
             +-----+   |    DSL     +---/
                        \          /
                           ------

                          ------
                       /          \
            +-----+   |            +---\
            |     +---+    LTE     |    \   *****
 +----<=======A===========================>**     **
 |          |     |    \  ------  /      *         *
 |HOST+-----+ CPE |                     *  Internet *
 |    |     |     |    /  ------ \       *         *
 +----<.......B...........................>**     **
            |     +---+            |    /   *****
            +-----+   |    DSL     +---/
                       \          /
                          ------

                          ------
                       /          \
            +-----+   |            +---\+----+
            | CPE +---+    LTE     |    |Agg.|      *****
 +----+     |     .........................  |    **     **
 |    |     |     .    \  ------  /     | .  |   *         *
 |HOST+-----+     .                     | .  +--*  Internet *
 |    <...........*    /  ------ \      | *.....>*         *
 +----+     |     .........................  |    **     **
            |     +---+            |    |    |      *****
            +-----+   |    DSL     +---/+----+
                       \          /
                          ------

         |==============================================|
         | <............ LTE path   ..................> |
    <--->| <............ DSL path   ..................> |<--->
         |==============================================|           -----
      +--+---+       Internet Connection           +----+----+    /       \
      |      |                                     |         |   | Internet|
      | CPE  |                                     |  HAAP   +---+         |
      +-+--+-+                                     +----+----+    \       /
        |  |              LTE Network                   |           -----
        |  |      *......................... *          |
        |  |      < +------+       +------+  >          |
        |  +--------+      +-------+      +-------------+ 
        |         < |eNodeB|       | EPC  |  >          |
        |         < +------+       +------+  >          |
        |         *..........................*          |
        |         *......................... *          |
        |         ( +------+       +------+  )          |
        +-----------+      +-------+      +-------------+
                  ( |  AN  |       | SN   |  )
                  ( +------+       +------+  )
                  *..........................*
                          DSL Network
   Legend:
   AN      Access Node
   SN      Service Node
   EPC     Evolved Packet Core