Mobile Backhaul Solution Design Guide

Design Guide

Mobile Backhaul Solution Design Guide Key Design Considerations, Topologies and Configuration for Juniper Networks Mobile Backhaul Solution for 2G/3G and LTE Networks

Copyright © 2012, Juniper Networks, Inc.

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Design Guide - Juniper Mobile Backhaul Solution Design Guide

Table of Contents Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Solution-Type Design Guidance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Mobile Backhaul Solution with ACX Series Universal Access Routers for Multi-Generation Networks. . . . . . . . . . . . . . . . .3 Solution Description – Key Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Design Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Taking MPLS to the Access Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Architecture and Network Design Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Network Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Network and Service Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Solution Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Network Topology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 IGP Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 MPLS Label Transport Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 BGP Setup in the Aggregation and Edge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Service Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Layer 3 VPN Service Model for LTE Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Layer 2 VPN Pseudowire Service for 2G/3G/LTE Traffic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Appendixes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Introduction to Mobile Backhaul Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 BTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 BSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Mobile Core: PDSN/GGSN/SGSN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 What is a Mobile Backhaul. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 About Juniper Networks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

List of Figures Figure 1: Architectural Transformation in the Mobile Service Provider Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Figure 2: Juniper Mobile Backhaul Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Figure 3: Juniper mobile backhaul solution deployment example for 2G/3G/LTE services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Figure 4: RSVP tunnels with fast reroute in access and aggregation rings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Figure 5: Layer 3 VPN Service Model for LTE Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Figure 6: L2 VPN pseudowire service between CSR and PE router . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Figure 7: Overview of a generic mobile backhaul . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Figure 8: Subcomponents of mobile backhaul . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

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Copyright © 2012, Juniper Networks, Inc.

Design Guide - Juniper Mobile Backhaul Solution Design Guide

Introduction Convergence and network simplification on the network edge and core have been hallmark trends for service providers in recent years. Access networks could also benefit from consolidation, but this has remained a challenge due to the disparate technologies developed for mobile, residential, and business access. The varieties of network access have evolved over time, from circuits to packets, from time-division multiplexing (TDM) to IP/Ethernet, and from wireline to wireless. So it is only natural that there are multiple access networks for different applications with many touch points, and this reality leaves operators with an obvious management challenge. As the bandwidth demands from smartphones and other mobile devices has grown exponentially over the years, the first logical choice has been to focus on adding capacity in the form of point-to-point bandwidth from access to aggregation, with the only innovation being to replace TDM with Ethernet. Truck rolls are typically required for minor operational changes with this approach, and there is inconsistent quality in telephone calls (jitter, dropped calls) and Internet access connections. As more and more access connections require wireless support and with the proliferation of mobile-to-mobile and mobile-to-machine applications, the challenges facing mobile operators become of paramount concern. These challenges range from the rising tide of packet traffic, to the underlying transport technology, to management of the end-to-end network. Instead of relying on separate access devices to connect customers, it is desirable to have a converged access network to deliver both a more predictable experience to users and better economics for service providers and shareholders. Juniper’s Universal Access solution is based on the high-performance Juniper Networks® ACX Series Universal Access Routers, anchoring the first fully integrated, end-to-end network architecture that combines operational intelligence with capital cost savings. With Universal Access, operators can extend the edge network and its capabilities to the customer, whether that’s a cell tower, a multi-tenant unit, or a residential aggregation point. This creates a seamless network architecture that’s critical to delivering the benefits of fourth-generation (4G) radio and packet core evolution with minimal truck rolls, paving the way for new revenue, new business models, and a more flexible and efficient network.

Scope Addressing the challenges faced in the access network by mobile service providers (MSPs), this document describes Juniper’s mobile backhaul solution with ACX Series Universal Access Routers to specifically address the legacy and evolution needs of the mobile network. The solution describes design considerations and deployment choices across the multiple segments of the network, while providing implementation guidelines to support services that can accommodate today’s mobile network needs and support not only legacy services on 2G/3G networks, but also a migration path to Long Term Evolution (LTE)-based services.

Solution-Type Design Guidance Mobile Backhaul Solution with ACX Series Universal Access Routers for Multi-Generation Networks The move towards all-packet infrastructure has been a key objective for many service providers as they modernize their networks to handle perpetual data traffic growth and evolving subscriber behaviors. The adoption of 4G LTE will require large-scale capacity increases and drive the need for increased performance, scale, and network reliability. Inherent support for IP in LTE network architectures helps drive towards more efficient network design, but often there is also a preceding need to seamlessly migrate or expand successive generations of existing 2G and 3G deployments. While many radio vendors have incorporated IP capabilities into 3G radio base stations to optimize network efficiency and ease packet transition, support for transporting legacy TDM, or Asynchronous Transfer Mode (ATM) traffic across packet networks remains a requirement in multi-generation networks. Circuit emulation technologies such as SAToP or CESoPSN provide support for these technologies, but often call for additional consideration in the areas of resiliency, Operation, Administration, and Maintenance (OAM), quality of service (QoS), and synchronization. ACX Series Universal Access Routers support rich GbE and 10GbE capabilities for uplink, along with support for legacy interfaces and GbE interfaces for radio/NodeB connectivity in a compact form factor that is environmentally hardened and passively cooled. Seamless MPLS, a common multiservice technology, can be used end-to-end to address legacy as well as emerging requirements. This also provides the foundation for a converged network, utilizing the same mobile backhaul infrastructure to also carry business or residential services.

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Design Guide - Juniper Mobile Backhaul Solution Design Guide

Hosted Services

Internet

Internet Off-net Services

PSTN HLR HSS PCRF

IP

MSC/GW

GGSN IP

SGSN ATM/IP

On-net Services IP

HSS PCRF

Hierarchical to Flat; Hub-Spoke to Fully Meshed; TDM/ATM to All-IP

MME-Pool

SGW

Control Plane

PGW

User Plane 3GPP Evolved Packet System

RNC/BSC IP TDM/ATM

ULTRAN NodeB

NodeB

Enhanced NodeB

Figure 1: Architectural Transformation in the Mobile Service Provider Network

Solution Description – Key Components Juniper’s mobile backhaul solution is designed to address the challenges of today’s mobile network needs and support the future service needs of growing user and application demands. As the mobile network evolves from 2G/3G to 4G and LTE, Juniper’s solution is based on the vision of one converged access network, and has specifically been developed to realize the full range of benefits from this evolution. Key components of Juniper’s mobile backhaul solution include: • ACX Series Universal Access Routers at the cell site • Juniper Networks MX Series 3D Universal Edge Routers for the pre-aggregation and aggregation network • MX240, MX480, and MX960 3D Universal Edge Routers at the provider edge • Juniper Networks Junos® Space for unified network management Figure 2 illustrates the key solution components in a typical mobile network.

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Design Guide - Juniper Mobile Backhaul Solution Design Guide

Universal Edge

1588v2 Grand Master SyncE Master

ACX Series 2G GSM/ CDMA

1588v2 BC

Mobile Access (Eth/MPLS/MPLS-TP)

MX Series

GGSN SGSN

MX240

ACX Series 3G UMTS/CDMA 1x EV-DO

MX Series MX10/MX40/ MX80

Pre-Aggregation (Eth/MPLS/MPLS-TP)

RNC/BSC

Metro Aggregation (MPLS/MPLS-TP)

1588v2 Grand Master

SGW

MME

PGW MX Series

ACX Series

BRAS and BNG MX240

ACX Series

Converged Access (Eth/MPLS/MPLS-TP)

4G LTE and LTE-Advanced

AAA MX240

1588v2 Grand Master

ACX Series

Multimedia

Database Server

ACX Series Small Cells

Figure 2: Juniper Mobile Backhaul Solution

Design Considerations Taking MPLS to the Access Network Over the last few years, the industry has seen a growing investment in Ethernet as the transport infrastructure, and in MPLS as the packet-switching technology. Juniper’s advanced mobile backhaul solution with ACX Series routers is designed to help MSPs move to an all IP/MPLS packet network and address the growing services needs of increasing bandwidth and enhanced quality of experience (QoE). Further, recent studies indicate that use of MPLS in the access network results in better network economics over traditional Layer 2 Ethernet networks.1 Juniper provides an industryleading solution to deliver a services architecture that moves MPLS from core and aggregation into the access layer, providing the necessary functionality and performance needed to build highly resilient, large-scale, modern day networks. The key benefits of building an end-to-end MPLS network for wireless services include: • MPLS can support multiple types of transport infrastructure. It can efficiently carry both packet and non-packet application traffic over hybrid underlying infrastructure that includes TDM, ATM, and Ethernet. • Taking MPLS into the access network, and enabling MPLS end-to-end in a single domain with MPLS as the single packet transport mechanism, can allow services to be decoupled from the underlying infrastructure. Services can be initiated as MPLS pseudowire or MPLS Layer 3 VPN at the cell site, and can be flexibly mapped to MPLS services at the aggregation and edge nodes further upstream in the network. In contrast, traditional networks have relied on backhauling L2 technologies and carrying traffic over Ethernet VLANs, Frame Relay data-link connection identifier (DLCI) or ATM virtual circuits. This resulted in a tighter coupling of the service provisioning to the underlying topology and limited flexibility in operations having to deal with several technologies for any given service. • With a homogenous MPLS transport network-wide, operators can benefit from a simplified service provisioning model and minimize the number of provisioning touch points, resulting in faster deployment of services and simpler operations. • An all-MPLS network with MPLS services originating at the cell site router can significantly streamline operations. For example, when re-parenting of cell sites is needed, it is much easier and more cost-effective to move MPLS Layer 3 services than to reconfigure hard provisioned Frame Relay DLCI or ATM virtual circuits. • With the notion of end-to-end label-switched paths (LSPs), MPLS delivers strong and resilient traffic engineering capabilities to redirect traffic in the event of network node or link failures and also to maximize the use of network resources in stable conditions. Juniper’s MPLS portfolio supports a comprehensive OAM toolkit to facilitate speedy detection of failures, as well as the necessary service restoration features to ensure sub-second convergence to deliver carrier-class functionality. 1

See Pietro Belotti, Comparison of MPLS and Ethernet Networks at the Access-Aggregation Level (http://myweb.clemson.edu/~pbelott/papers/comparison-eth-mpls.pdf).

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Design Guide - Juniper Mobile Backhaul Solution Design Guide

• MPLS, when deployed systematically network-wide, can meet the scaling needs of the largest of modern day networks. Juniper’s solution with seamless MPLS is specifically designed to support large-scale networks of the order of 100,000 nodes. Key features such as BGP labeled unicast and LDP downstream on demand (DoD) can be utilized to enable and extend the right level of service and operational intelligence in the several layers of the network. • MPLS also tends to be an easier platform for deploying and integrating multi-market services. With the topological independence that MPLS creates at the service layer, services such as Wi-Fi offload, access point name (APN), or support for multiple MSPs on one cell site can easily be accommodated with the virtualization provided by MPLS L3 VPNs

Architecture and Network Design Components There are several factors to consider when designing an MSP packet network. Design considerations need to include choosing the right network elements for each layer in the network, determining the type of topology, as well as protocols for the control plane and the service plane. In the next few sections, we will describe the network elements that make up the several layers and their unique requirements, the choices in network topology, and the service architecture choices available with Juniper’s industry-leading mobile backhaul solution.

Network Elements Cell Site Router The cell site router is typically deployed at the cell site and connects the base station (BS) to the packet network. Several cell site routers can be connected in a ring or hub-and-spoke fashion to the upstream pre-aggregation/ aggregation routers. Key requirements of a cell site router include: • Support for TDM and Ethernet interfaces to meet multi-generation needs (2G/3G/4G/LTE) • Timing and synchronization support for voice and TDM traffic • Performance and bandwidth to meet growing service needs • Software features to deliver an enhanced Quality of Experience (QoE)—class of service, network resiliency, and OAM) Juniper Networks ACX Series Universal Access Routers meet and often exceed the key requirements for a cell site router. The ACX Series includes four fixed 1 U compact models (the ACX1000, ACX1100, ACX 2000, and ACX2100 Universal Access Routers) and a 2.5 U modular ACX4000 Universal Access Router model. ACX Series 1 U fixed models are European Telecommunication Standards Institute (ETSI) 300 compliant, as well as environmentally hardened and passively cooled for easy deployment where space and cooling are limited. The ACX Series supports multiple high precision timing options (SyncE , 1588v2, etc.) to deliver the highest QoE. Juniper’s mobile backhaul solution also provides comprehensive delay and jitter measurements with the unified Junos Space platform. Using the ACX Series as a cell site router, providers can eliminate the need for external appliances deployed specifically for timing and packet delay variation (PDV) measurements. The ACX Series routers support TDM (T1/E1) and Ethernet (10/100/1000 copper and GbE/10GbE fiber) interfaces to support both the legacy and evolution needs of the mobile network. Support for Power over Ethernet (PoE+) at 65 watts per port mitigates the need for additional electrical cabling for microwaves or other access interfaces. The ACX Series is powered by Juniper Networks Junos operating system, and it supports extensive L2 and L3 features, IP/MPLS with traffic engineering, rich network management, fault management, service monitoring and OAM capabilities, and an open software development kit (SDK) system that allows providers to customize and integrate operations with their own management systems. With industry-leading performance of up to 60 Gbps and support for 10GbE interfaces, the ACX Series is well positioned to address the growing bandwidth needs of service providers, with platforms that deliver the necessary scale and performance needed to support multi-generation services. Pre-Aggregation and Aggregation Router Multiple access networks typically connect to an upstream pre-aggregation and/or aggregation network in the metro areas before they can be handed off to regional points of presence (POPs). The key features needed at the preaggregation and aggregations segments of the network include: • High-density Ethernet • Support for versatile L2 and L3 carrier Ethernet/MPLS features • OAM and network resiliency features • Inline timing support for voice and TDM applications The MX Series mid-range routers are ideal for pre-aggregation and aggregation layers of the network with support for a unique pay-as-you-grow model that allows operators to scale their network resources with growing service demands in a nondisruptive fashion. The mid-range MX Series routers include the Juniper Networks MX5 and MX80 3D Universal Edge Routers—both in a compact 2 U form factor.

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Design Guide - Juniper Mobile Backhaul Solution Design Guide

Edge Router The edge router is typically the service or provider edge that separates the access and aggregation layers from the service provider core. This is typically the most complex segment in a provider network with the highest demand for control plane and service plane scalability. This is also typically the network segment where diverse access and aggregation networks converge. Key requirements include: • High-density Ethernet • SONET and TDM interfaces for legacy applications • Scale for control plane, service plane, and data plane • System redundancy and network resiliency features • Extensive L2 and L3 IP/MPLS features to support diverse applications • L2 and L3 virtualization support (pseudowire, virtual private LAN service, L3 VPN) • Ability to receive timing from grand master and transmit out to the slave routers in the aggregation and access networks The high-end MX Series 3D Universal Edge Routers (MX240, MX480, and MX960) have revolutionized the network edge deployments in service provider networks with Juniper’s industry-leading support for three-dimensional scale for bandwidth, subscribers, and services. These MX Series platforms support a versatile feature set for both L2 and L3 IP/ MPLS applications for both unicast and multicast traffic. With redundancy for all common system components and a comprehensive Ethernet/MPLS OAM toolkit, the MX Series has proven to be the cornerstone for large-scale carrierclass networks.

Network and Service Architecture As described earlier in this design guide, there are several segments in the MSP network—access, pre-aggregation, aggregation, edge, and core. The access, pre-aggregation, and aggregation segments can each be a combination of several physical topologies. Depending on the individual segment scale and resiliency needs, each segment can be built in a hub-and-spoke fashion, ring, partial mesh, or a combination of these topologies. Operators may also begin with a hub-and-spoke topology and convert to a ring network as the scale demands grow. Traditionally, services are typically tightly coupled with the underlying network topology. However with MPLS in the access and a seamless MPLS network, operators can now have added flexibility in service provisioning, and the services topology can be defined efficiently and inline with the evolutionary changes brought on by LTE, for example. The service itself may have multiple components through the several segments of the network. For example, the service may initiate as a point-to-point L2 pseudowire from the access network and then get mapped to a multipoint virtual private LAN service (VPLS) or multipoint L3 MPLS VPNs in the aggregation/edge layer. The key is to have a network architecture and network elements that can support multiple models to meet legacy and evolutionary needs. Juniper’s mobile backhaul solution with the ACX Series, MX Series, and Junos Space include the necessary hardware (interface density and types) and software features to support any of these network topologies for efficient and scalable service delivery. With the cell site and aggregation routers all powered by one Junos OS, and comprehensive end-to-end Ethernet/MPLS OAM features, operators can enjoy better network economics and cost optimize the total solution. With the unified Junos Space network management system, network provisioning and operations can be streamlined. Junos Space is a suite of comprehensive web-based tools for operational management and administration of Juniper Networks routers, including the ACX Series and MX Series platforms. Juniper has extended Junos Space with powerful new features designed to address the demanding requirements of mobile backhaul.

Solution Implementation Overview There is no one solution that can fit all needs. The choice of a solution depends on many factors such as physical access and geography, network segment ownership, network size, mobile service technology being used (2G/3G/4G/ LTE), and the types of traffic and extended services carried over the several segments of the network. Juniper’s mobile backhaul solution can support multiple network topologies and service types from the access to the aggregation and edge segments into the mobile packet core. For illustration purposes, we will consider one example in this guide. In the solution described here, the ACX Series is used in the access layer as cell site routers, and the MX Series is used for aggregation and edge routers. The sample deployment includes a L2 pseudowire solution for legacy 2G/3G/LTE services, and MPLS L3 VPNs for LTE services on an end-to-end seamless MPLS network.

Network Topology Figure 3 illustrates the overall network topology with IS-IS as the interior gateway protocol (IGP) in the aggregation and access rings, and hierarchical labeled BGP between the access and aggregation rings.

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Design Guide - Juniper Mobile Backhaul Solution Design Guide

1588v2 Grand Master 65.1.1.2

Lo0: 1.1.2.1

Lo0: 1.1.10.1 Lo0: 1.1.4.1

acx2-01 [CSR]

Lo0: 1.1.1.1

23.0.1.1 mx80-3 [AG2-1]

Lo0: 1.1.14.1 23.0.1.2

mx80-2 [AG1-1]

Access BGP AS 65001

1588v2 Slave Clock

65.1.1.1

Lo0: 1.1.9.1

mbh-acx2-02

TCA8000 Grand Master

Aggregation BGP AS 65001

Lo0: 1.1.5.1

23.0.2.1 [PE]

mx80-3 [AG1-2]

23.0.2.2 Universal Edge BGP AS 65002

AG2-2 mbh-mx80-1 Lo0: 1.1.7.1 Lo0: 1.1..12.1

LDP DoD for Label Distribution in Access Ring

I-BGP Labeled Unicast

RSVP Label Transport

RSVP Label Transport

ISIS level 1

ISIS level 2

E-BGP Labeled Unicast

eBGP

Figure 3: Juniper mobile backhaul solution deployment example for 2G/3G/LTE services

Configuration IGP Setup The access and aggregation rings are in a common BGP autonomous system (AS) (65001) and are segmented with IS-IS IGP, with IS-IS level 1 in the access ring and IS-IS level 2 links in the aggregation. The provider edge (PE) router is in a separate BGP AS that nicely separates the regional aggregation and access rings from the service provider core network. ACX2-01 (CSR) IS-IS Configuration

level 2 disable; interface ge-0/2/0.0; interface ge-0/2/1.0; interface lo0.0; MX80-2 (AG1-1) IS-IS Configuration

export export-isis; interface ge-1/2/2.1 level 2 disable; } interface ge-1/2/2.2 level 1 disable; } interface ge-1/3/3.0 level 2 disable; } interface ge-1/3/4.0 level 1 disable; } interface lo0.0;

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Design Guide - Juniper Mobile Backhaul Solution Design Guide

MX480 (AG2-1) IS-IS Configuration interface ge-0/0/0.0 { level 1 disable; } interface ge-5/0/1.0 { level 1 disable; } interface ge-5/0/2.1 { level 1 disable; } interface lo0.0; Provider Edge (PE) The PE is in a separate BGP AS and does not share IS-IS domain with the aggregation or access segments.

MPLS Label Transport Setup In this example, we use RSVP as the label transport within each network segment inline with the IGP separation (see Figure 4). RSVP tunnels are set up in each access ring up to the aggregation level 1 routers. RSVP tunnels are also set up in the aggregation ring up to the upstream AG2-1 and AG2-2 routers that then connect to the PE router. We configure two RSVP tunnels from Cell Switch Router (CSR) (acx2-01) to the aggregation routers AG1-1 and AG1-2. Each of these tunnels is configured with primary and secondary path, and fast reroute is enabled on each tunnel for protection against link and node failures in the ring. To ensure speedy detection of any failures on the tunnel path, we use multihop Bidirectional Forwarding Detection (BFD) on the RSVP tunnels with a 100 msec BFD timer. Primary 1 Primary 1

mbh-acx2-02 Lo0: 1.1.2.1 Lo0: 1.1.1.1 acx2-01 [CSR]

Primary 2

Lo0: 1.1.4.1 Lo0: 1.1.10.1 mx80-2 [AG1-1]

Secondary 2

Secondary 1

mx80-3 [AG2-1]

Primary 2

Secondary 2 mx80-3 [AG1-2]

[PE]

Lo0: 1.1.11.1 Secondary 1

Lo0: 1.1.5.1

Universal Edge BGP AS 65002

AG2-2

mbh-mx80-1 Lo0: 1.1.7.1 Access BGP AS 65001

ISIS level 1

Aggregation BGP AS 65001

ISIS level 2

eBGP

Figure 4: RSVP tunnels with fast reroute in access and aggregation rings

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ACX2-01 (CSR) RSVP Tunnels Configuration

egress@mbh-acx2-01# show protocols mpls label-switched-path acx2-01-to-mx80-2 { from 1.1.1.1; to 1.1.4.1; oam { bfd-liveness-detection { minimum-interval 100; } } fast-reroute; primary to_acx2-02; secondary to_mx80-1 { standby; } } label-switched-path acx2-01-to-mx80-3 { to 1.1.5.1; oam { bfd-liveness-detection { minimum-interval 100; } } fast-reroute; primary to_mx80-1; secondary to_acx2-02 { standby; } } path to_acx2-02 { 21.0.6.1 strict } path to_mx80-1 { 21.0.0.2 strict; } interface all; interface fxp0.0 { disable; r} BGP Setup in the Aggregation and Edge With BGP Labeled Unicast (BGP-LU) for label distribution, the network can be segmented into multiple hierarchical levels, thereby enabling the network to scale efficiently. The aggregation nodes are configured in a single BGP AS 65001. In this deployment, we use AG2-1 and AG2-2 as route reflectors in the aggregation ring for ease of operations and scalability.

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BGP Labeled Unicast Configuration for Aggregation Routers BGP configuration for AG1-1 is shown below with AG1-1 as a route reflector client to AG2-1 and AG2-2 routers: group ag2_rr { type internal; local-address 1.1.4.1; peer-as 65001; local-as 65001; multipath; neighbor 1.1.10.1 { family inet { labeled-unicast { rib-group inet3-to-inet0; rib { inet.3; } } } export get_pes; bfd-liveness-detection { minimum-interval 150; multiplier 3; session-mode multihop; } } neighbor 1.1.11.1 { family inet { labeled-unicast { rib-group inet3-to-inet0; rib { inet.3; } } } bfd-liveness-detection { minimum-interval 200; session-mode multihop; } } }

BGP-LU is used for label distribution in the aggregation ring. BGP configuration on route reflector node AG2-1 below includes AG1-1 as route reflector client and AG2-2 as iBGP peer. We also configure multihop BFD on the BGP sessions to enable speedy detection of BGP session failures and allow the clients to switch to the second route reflector to restore services quickly. In this example, we use BFD on RSVP tunnels and BGP sessions, and the BFD timers for each should be tuned based on the network size and convergence requirements.

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group ag1_rr { type internal; local-address 1.1.10.1; export nh-self; cluster 1.1.10.1; peer-as 65001; local-as 65001; neighbor 1.1.4.1 { family inet { labeled-unicast { rib { inet.3; } } } bfd-liveness-detection { minimum-interval 150; multiplier 3; session-mode multihop; } } group ag2_ibgp { type internal; local-address 1.1.10.1; peer-as 65001; local-as 65001; neighbor 1.1.11.1 { family inet { labeled-unicast { rib { inet.3; } } } bfd-liveness-detection { minimum-interval 150; } } } BGP Configuration on the PE Router The upstream PE router is configured in AS 65002 and has EBGP sessions with BGP–LU to the aggregation routers AG2-1 and AG2-2. Configuration snippet is shown below:

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regress@pe# show protocols bgp group ebgp_lu { type external; export send-pe; peer-as 65001; local-as 65002; neighbor 23.0.1.1 { local-address 23.0.1.2; family inet { labeled-unicast { rib-group inet3-to-inet0; rib { inet.3; } } } } neighbor 23.0.2.2 { local-address 23.0.2.1; family inet { labeled-unicast { rib-group inet3-to-inet0; rib { inet.3; } } } bfd-liveness-detection { minimum-interval 150; } }

}

LDP DoD in the Access Ring for Label Distribution For the access routes CSR, we enable LDP on the RSVP tunnels in the access by using “ldp-tunneling” knob as shown below:

label-switched-path acx2-01-to-mx80-2 { from 1.1.1.1; to 1.1.4.1; ldp-tunneling; oam { bfd-liveness-detection { minimum-interval 100; } } fast-reroute; primary to_acx2-02; secondary to_mx80-1 { standby; } } To keep the CSR simple and enable just the necessary prefix/label intelligence, we use LDP downstream on demand as illustrated here. We run LDP DoD sessions from the CSR to the two aggregation nodes AG1-1 and AG1-2.

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dod-request-policy get_dod_prefix; interface lo0.0; session 1.1.4.1 { downstream-on-demand; } session 1.1.5.1 { downstream-on-demand; } The policy “get_dod_prefix” determines the prefixes that the CSR needs labels for: egress@mbh-acx2-01# show policy-options policy-statement get_dod_prefix term 10 { from { prefix-list dod_prefix; } then accept; } [edit] regress@mbh-acx2-01# show policy-options prefix-list dod_prefix 1.1.10.1/32; 1.1.11.1/32; 1.1.14.1/32; This completes the base IGP, BGP, and label transport configuration for the access, aggregation, and edge network. The next step is to map services on top of this network architecture. Before we enable the services, we will look at the timing configuration on this network. Timing Configuration The timing grand master can be set up in the aggregation or at the edge network, depending on the services model in the MSP network. In our example, we have a grandmaster Juniper Networks TCA8000 Timing Server connected to the PE router, and we use 1588v2 timing. The PE router then transmits this timing to the downstream network nodes in the aggregation and access layers. Configuration the configuration of the 1588-2008 timing protocol also know as Precision timing protocol (PTP), the CSR is configured as a slave and is receiving timing on interface ge-0/2/0.0 from the master connected to AG2-1 (65.1.1.2).

regress@mbh-acx2-01# show protocols ptp clock-mode ordinary; unicast-negotiation; slave { interface ge-0/2/0.0 { unicast-mode { transport ipv4; clock-source 65.1.1.2 local-ip-address 21.0.6.2; } } }

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Service Configuration Layer 3 VPN Service Model for LTE Traffic In this deployment solution, we configure L3 VPN service at the CSR for LTE traffic (see Figure 5). L3 VPN service has several benefits for LTE application in the mobile backhaul. It is an Layer 3 multipoint service that relies on L3 routing and fast convergence for service restoration and eliminates the need for L2 loop prevention protocols. This deployment model also allows low latency X2 traffic communication between eNB nodes to be turned around at the first aggregation PE router. Configuration and addition of cell site routers is simple and does not cause any service reconfiguration on existing nodes. 1588v2 Grand Master 65.1.1.2

TCA8000 Grand Master

1588v2 Slave Clock

65.1.1.1 Lo0: 1.1.9.1

mbh-acx2-02 Lo0: 1.1.2.1

Lo0: 1.1.10.1 Lo0: 1.1.4.1

acx2-01 [CSR]

Lo0: 1.1.1.1

Lo0: 1.1.14.1 23.0.1.2

mx80-2 [AG1-1]

Access BGP AS 65001

23.0.1.1 mx80-3 [AG2-1] 23.0.2.1

Aggregation BGP AS 65001

Lo0: 1.1.5.1

PE

Lo0: 1.1.11.1 mx80-3 [AG1-2]

23.0.2.2 Universal Edge BGP AS 65002

AG2-2 mbh-mx80-1 Lo0: 1.1.7.1 Lo0: 1.1..12.1 MP-IGBP CSR to AG1-1 for L3VPN on CSR

MP-EBGP for L3VPN Service [Option C 2547 bis on AG1-1 and PE]

LDP DoD for Label Distribution in Access Ring

I-BGP Labeled Unicast

RSVP Label Transport

RSVP Label Transport

ISIS level 1

ISIS level 2

E-BGP Labeled Unicast

eBGP

Figure 5: Layer 3 VPN Service Model for LTE Traffic Setup MPLS VPNs at the CSR To set up MPLS VPNs on the CSR:

regress@mbh-acx2-01# show routing-instances csr_l3vpn { instance-type vrf; interface ge-0/1/7.0; interface lo0.1; route-distinguisher 200:200; vrf-target target:200:200; routing-options { static { route 1.1.0.100/32 next-hop 20.0.0.2; } router-id 1.1.1.100; autonomous-system 64901; } }

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We configuring Multiprotocal Border Gateway Protocol (MP-BGP) for VPN label exchange between CSR and AG1-1 and AG1-2 as shown below:

regress@mbh-acx2-01# show protocols bgp group mbh_csr_ibgp { type internal; multipath; neighbor 1.1.4.1 { local-address 1.1.1.1; family inet-vpn { unicast; } local-as 65001; bfd-liveness-detection { minimum-interval 150; } } neighbor 1.1.5.1 { local-address 1.1.1.1; family inet-vpn { unicast; } local-as 65001; bfd-liveness-detection { minimum-interval 150; } } } L3 VPN Configuration on Aggregation Router AG1-1 We set up 2547 option C L3 VPN at the aggregation router as described below:

regress@mbh-mx80-2# show routing-instances csr_vpn { instance-type vrf; interface lo0.1; route-distinguisher 200:200; vrf-target target:200:200; vrf-table-label; routing-options { router-id 1.1.4.100; } } regress@mbh-mx80-2# show protocols bgp group option_c type external; neighbor 1.1.14.1 { multihop { ttl 64; } local-address 1.1.4.1; family inet-vpn { unicast; } peer-as 65002; local-as 65001; }

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MP-BGP for L3 VPN Configuration on the PE Router On the PE router, BGP and VPN routing and forwarding table (VRF) configurations are as shown below:

group option_c { type external; neighbor 1.1.4.1 { multihop { ttl 64; } local-address 1.1.14.1; family inet-vpn { unicast; } peer-as 65001; local-as 65002; } neighbor 1.1.5.1 { multihop { ttl 64; } local-address 1.1.14.1; family inet-vpn { unicast; } peer-as 65001; local-as 65002; } }

MPLS L3 VPN Configuration on the PE Router To configure MPLS L3 VPN on the PE router:

regress@pe# show routing-instances csr_l3vpn { instance-type vrf; interface ge-3/0/2.0; interface lo0.1; route-distinguisher 200:200; vrf-target target:200:200; routing-options { static { route 1.1.15.100/32 { next-hop 24.0.0.2; resolve; } } router-id 1.1.14.100; autonomous-system 64990; } }

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Layer 2 VPN Pseudowire Service for 2G/3G/LTE Traffic This section demonstrates L2 pseudowire service configuration for 2G/3G traffic. In this example, we set up both VLAN and T1 Structure-Agnostic TDM over Packet (SATOP) pseudowires between the CSR and the PE router (see Figure 6 below). 1588v2 Grand Master TCA8000 Grand Master Lo0: 1.1.9.1

mbh-acx2-02 Lo0: 1.1.2.1

Lo0: 1.1.10.1 Lo0: 1.1.4.1

acx2-01 [CSR]

23.0.1.1 mx80-3 [AG2-1]

Lo0: 1.1.14.1 23.0.1.2

mx80-2 [AG1-1]

Access BGP AS 65001 Lo0: 1.1.1.1

1588v2 Slave Clock

23.0.2.1

Aggregation BGP AS 65001

Lo0: 1.1.5.1

PE

Lo0: 1.1.11.1 mx80-3 [AG1-2]

23.0.2.2 Universal Edge BGP AS 65002

AG2-2 mbh-mx80-1 Lo0: 1.1.7.1 Lo0: 1.1..12.1 Point-to-Point PW L2VPN Service LDP DoD for Label Distribution in Access Ring

I-BGP Labeled Unicast

RSVP Label Transport

RSVP Label Transport

ISIS level 1

ISIS level 2

E-BGP Labeled Unicast

eBGP

Figure 6: L2 VPN pseudowire service between CSR and PE router L2 Circuit Configuration at the CSR (acx2-01): To configure L2 VLAN and SAToP pseudowire between CSR and PE:

l2circuit { neighbor 1.1.14.1 { interface ge-0/1/7.1 { virtual-circuit-id 123; no-control-word; } } neighbor 1.1.14.1 { interface t1-0/0/0.0 { virtual-circuit-id 100; standby; } } } }

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L2 Pseudowire Configuration at the PE Router

l2circuit { neighbor 1.1.1.1 { interface ge-3/0/2.1 { virtual-circuit-id 123; no-control-word; } } } l2circuit { neighbor 1.1.1.1 { interface t1-4/0/0:1:1.0 { virtual-circuit-id 100; } } } CFM Configuration for the VLAN Pseudowire This section provides the configuration for enabling a connectivity fault management (CFM) continuity check and enables quick failure detection along the pseudowire path. The pseudowire at the CSR can also be configured with a remote backup to which traffic can be redirected in the event the primary path pseudowire fails.

protocols { oam { ethernet { connectivity-fault-management { maintenance-domain md6 { level 6; maintenance-association ma6 { continuity-check { interval 10s; } mep 2 { interface ge-0/1/7.0; direction up; auto-discovery; } } } maintenance-domain md0 { level 0; maintenance-association ma0 { continuity-check { interval 100ms; } mep 100 { interface ge-2/2/0.0; auto-discovery; }}}}}}}}

With this section, the basic configuration for Layer 3 and Layer 2 VPNs over a seamless MPLS network is complete. These services can be used alone or in combination to meet the service needs of the MSP across multi-generational networks (2G/3G/4G/LTE)

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Summary Over time, network access has evolved from circuits to packets, from TDM to IP/Ethernet, and from wireline to wireless. This has resulted in multiple access networks for different applications with many touch points, leaving operators with an obvious management challenge. As more and more access connections require wireless support, and with the proliferation of mobile-to-mobile and mobile-to-machine applications, the challenges facing mobile operators are ever on the rise. What is required is a network architecture and network elements that can support multiple models to meet both legacy and evolutionary needs. One of the main advantages of using IP-based networks is the ability to transport different traffic types over a common IP/MPLS-based infrastructure in addition to providing QoS guarantees and meeting security requirements. But as MSPs transition to an all IP/MPLS infrastructure, they will need to support both legacy and next-generation service needs. Juniper’s high-performance mobile backhaul solution—ACX Series Universal Access Routers, MX Series 3D Universal Edge Routers, and Junos Space unified network management system—is designed to meet the growing bandwidth and service needs for these multiple 2G/2.5G/3G/4G generations. With Juniper’s seamless MPLS solution powered by a single Junos OS and a comprehensive OAM toolkit across the various network elements, this solution enables operational efficiency for large-scale MSP networks today and into the future.

Appendixes Introduction to Mobile Backhaul Technologies Mobile technologies are classified into different generations (referred to as 2G/2.5G/3G/4G). Each generation of mobile technology provides users with enhanced services, higher speeds, and better network capacity. Different bodies and forums such as Third-Generation Partnership Project (3GPP/3GPP2), European Telecommunications Standardization Institute (ETSI), and International Telecommunication Union (ITU) recommend, approve standards, and advance the various technologies underlying each generation. The main components of a Radio Access Network (RAN) are described briefly in the following sections. The terminology used for these components differs based on the technology that is used. Table 1 lists the different naming conventions used in the case of each technology.

BTS A base transceiver station (BTS) is a device that can provide communication between mobile user equipment and a mobile network. The BTS communicates with mobile user device over the air interfaces. There can typically be as many as 50 BTS devices controlled by one base station controller (BSC). (This document uses the generic term BS or RAN BS to refer to a cell tower/BTS.)

BSC The main function of a BSC is to communicate and control multiple BTS devices over either the Abis or Iub interface. The BSC also controls hand-offs that occur as a result of mobile devices moving between cell sites, and it communicates with the mobile core (with the type of communication depending on the interface to core that in turn depends on the technology). A single 2G BSC can typically control as many as 50 BTS devices, while a 3G radio network controller (RNC) can control 200 NodeBs and up to 800 base stations per BSC/RNC in a 2.5G/3G network. (This document uses the generic term RNC or RAN NC to refer to a BSC.)

Mobile Core: PDSN/GGSN/SGSN The mobile core network can consist of a packet data serving node (PDSN) or gateway GSN/Serving GPRS Support Node (GGSN/SGSN) that acts as a gateway to the external packet data network.

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Table 1: RAN Components for Different Mobile Technologies Mobile Technology Generation

Type of Technology

RAN Components

Example of Role

2G

Global System for Mobile Communications (GSM)

BTS BSC MSC

• Communication between air interface and BSC • Controls multiple BS • Handles voice calls and short message service (SMS)

2.5G

General Packet Radio Service (GPRS)

BTS SGSN GGSN BSC + PCU

• Communication between air interface and BSC • Mobility management, data delivery to and from mobile user devices • Gateway to external data network • Controls multiple BS and processes data packets

3G

Evolution-Data Optimized (EVDO)

BTS RNC PDSN

• Communication between air interface and RNC • Call processing and hand-offs, communication with PDSN • Gateway to external network

Universal mobile telecommunications system (UMTS) Terrestrial Radio Access Network (UTRAN)

NodeB RNC MSC

• Performs functions similar to BTS • Performs functions similar to BSC • Handles voice calls and SMS

Long Term Evolution (LTE)

eNodeB SGW (Serving Gateway) MME (Mobility Management Entity) Public data network (PDN) Gateway

• Performs functions similar to BTS and radio resource management • Routing and forwarding of user data, mobility anchoring • Tracking idle user devices, hand-off management • Gateway to external data network

Worldwide Interoperability for Microwave Access (WiMAX)

BS Access service network gateway (ASN GW) Connectivity service network gateway (CSN GW)

• Dynamic Host Configuration Protocol (DHCP), QoS policy enforcement, traffic classification • Layer 2 traffic aggregation point ASN • Connectivity to the Internet, external public or private networks

Generation

4G

What is a Mobile Backhaul In a nutshell, the backhaul can be considered to be the portion of the network that connects the BS (and air interface) to the BSCs and mobile core network. The backhaul can consist of a group of cell sites that are aggregated at a series of hub sites. (A cell site or cell tower consists of antennas, transmitting and receiving equipment mounted on a tower.) Figure 1 gives a high-level representation of the mobile backhaul. The cell site may either consist of a single BS that is connected to the aggregation device or a collection of BSs that are aggregated.

Mobile Backhaul BS

BSC Figure 7: Overview of a generic mobile backhaul

The generic model for the newer backhaul networks consists of a cell, hub sites, or both connected to aggregation devices that in turn can either belong or be connected to a metro network. Figure 8 shows the different subcomponents of the mobile backhaul network. The most commonly proposed metro network for 3G/4G technologies is an Ethernetbased services network. This network should be capable of providing multi-access to different Layer 2 technologies such as Frame Relay/ATM/TDM, and IP.

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Another perspective of the mobile backhaul could lead to following classification of functionality:

Mobile Backhaul Cell Site Devices

Hub/Aggregation Site Devices

Metro Network

Figure 8: Subcomponents of mobile backhaul Another perspective of the mobile backhaul could lead to the following classification of functionality: • Multi-access gateway—Consisting of devices that can support TDM/ATM or Ethernet connectivity at the cell/hub sites • Transport—Data from the different cell sites carried over pseudowires that support circuit emulation • Timing synchronization—Clocking for the TDM data that needs to be synchronized across the network • Aggregation—An aggregation device performing aggregation of all incoming connections before they reach the mobile core The connectivity type offered by the backhaul network is influenced by the technology used in the RAN and factors such as geographical location of the cell site, bandwidth requirements, and local regulations. For instance, remote cell sites that cannot be connected via physical links use a microwave backhaul instead to connect to the BSC and mobile core network. The amount of available frequency spectrum and the spectral efficiency of the air interface influence the bandwidth requirements of a cell site. Hence, the backhaul network can consist of either one or a combination of different physical media and transport mechanisms. Selecting between the different available options depends upon the type of radio technology, applications that are expected to be used, and transport mechanism. A 2G/2.5G network typically has a BS that supports TDM transport, where a 3G BS may only support ATM, and a 3G/4G BS will support all Ethernet/IP interfaces. The move to using IP in the backhaul is driven by the requirements imposed by 3G/4G technologies. The term flat IP architecture can be applied to a network where all of the nodes can reach each other via IP connectivity. A flat IP architecture can be applied to a network where the radio and routing functionality is pushed to the edge of the network. The end-to-end connectivity is achieved through a packet-based core network. Technologies such as LTE are based on a flat IP architecture. One of the main advantages of using IP-based networks is the capability to transport different traffic types over a common IP/MPLS-based infrastructure in addition to providing QoS guarantees and meeting security requirements. For example, circuit-based voice, and 2G- or 3G-based voice and data can all be carried over a common IP/MPLS network. The main objectives driving the usage of IP-based architecture are the following: • Requirement for lower latency (serialization of data on a TDM network adds to latency delay) • Requirement for lower cost • Reducing the total volume of equipment that is used (an objective that can be achieved when equipment has the capability of BTS, RNC, mobile core, or all three.)

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About Juniper Networks Juniper Networks is in the business of network innovation. From devices to data centers, from consumers to cloud providers, Juniper Networks delivers the software, silicon and systems that transform the experience and economics of networking. The company serves customers and partners worldwide. Additional information can be found at www.juniper.net.

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